The behavioral syndrome induced by adreno corticotropic hormone in rats is prevented by Ca++ channel blockade

Cellular levels of O6-methylguanine-DNA methyltransferase (MGMT) correlate strongly with cellular resistance to carcinogenic and chemotherapeutic agents that produce adducts at the O6-position of guanine in DNA. Although biochemical and molecular assays can indicate the average MGMT content of tissues or tumors, they cannot distinguish mixed populations of cells, such as those that exist in tumor biopsy samples. We have determined MGMT at the cellular level in a panel of pediatric rhabdomyosarcoma xenografts by in situ immunostaining with a human MGMT-specific antibody employing a very sensitive procedure that involves biotin-avidin coupled horseradish peroxidase with silver-enhanced diaminobenzidine-nickel staining. Two xenograft tumor lines known to be MGMT-deficient were not stained, whereas the nuclei in three MGMT-expressing lines were clearly stained. This is the first demonstration of an in situ procedure that discriminates drug-sensitive MGMT-deficient tumors from drug-resistant MGMT expressing tumors. This procedure should prove useful, therefore, for predicting the susceptibility of tissues and tumors to O6-guanine alkylating agents.     

Feeding induced by pharmacological blockade of fatty acid metabolism is selectively attenuated by hindbrain injections of the galanin receptor antagonist, M40

Distal transcutaneous oxygen pressure measurement (TcPo2) is a noninvasive method of evaluating tissular hypoxemia in peripheral arterial disease. The poststress area of hypoxemia is a usefull technique for globally quantifying different parameters represented by TcPo2 curves during exercise. Although its use is increasingly widespread, the reproducibility of this method is poorly documented. TcPo2 was monitored three times at twenty-four hour intervals in 5 patients with stage II obliterative arterial disease during a treadmill walking test. In order to get uniform measurement conditions, each patient remained lying and then stood until TcPo2 became stable. The stress duration was calculated so that the pain step could not be reached. TcPo2 curves were digitized and a specific image analyzer was used to make replicate measurements. The area under the curve was computed, the horizontal axis determining the mean TcPo2 value at rest, the vertical axis representing the end of the exercise period. The corresponding areas under the curves ranged from 34 to 2212 mm2 (573.60; SD 826). Significant correlation coefficients were obtained among replicate measurements (first-second day, first-third day). However, owing to the wide range of area values, the authors decided to compute and use the coefficient of variation (STD/mean), since it was more representative of reproducibility. The mean of its value for 5 patients was 21%. Observation of the examination conditions resulted in several findings, especially the ability of certain patients to adapt their efforts to the exercise. These results indicate that TcPo2 poststress area measurements are reproducible, but the conditions of the exercise have to be rigorously defined and may still be improved.     

Potentiation of isolation-induced vocalization by brief exposure of rat pups to maternal cues

Since their discovery in 1956, the highest rates of ultrasonic vocalization (USV) have been recorded from infant rats when first isolated in an unfamiliar place. We now report that peak USV rates can be doubled by allowing test pups a brief initial period of contact with their anesthetized dam (1-10 min) in the test chamber before isolating the pup by her removal. Potentiation of the isolation response was specific to the dam, for it failed to occur following initial contact with a group of 4 warm, anesthetized littermates. Control experiments showed that potentiation could not be attributed to thermal contrast, experimenter handling, general behavioral activation, novelty of maternal cues, or nursing deprivation. Furthermore, it did not occur when pups were taken for isolation testing directly from prolonged contact with their anesthetized dam in the home cage. Potentiation may be understood in terms of the communicative role of the pups' call and/or prior learning contingencies within the mother-infant interaction.     

Short exposure to endotoxin increases the constriction induced by angiotensin II in rat aorta

The contraction elicited by angiotensin II (ANG II) was studied by using standard isometric tension techniques in aortic rings exposed for 1 h to 1 or 10 micrograms/ml Escherichia coli lipopolysaccharide endotoxin (LPS). This contraction was 18 and 71% greater for the two doses of LPS, respectively, than in unexposed control rings. In endothelium-denuded rings, the LPS-induced increase in contraction in response to ANG II was completely abolished. Because the contraction induced by ANG II is modulated by the simultaneous release of prostaglandins, we tested the hypothesis that LPS interferes with this modulation. We found that the LPS-induced increase in contraction to ANG II was inhibited in the presence of the cyclooxygenase inhibitor indomethacin (10(-5) M) or the prostaglandin H2/thromboxane A2-receptor antagonist SQ-29548 (2 x 10(-7) M). Conversely, the LPS-induced increase in contraction in response to ANG II was not inhibited by the presence of dexamethasone (10(-6) M), which inhibits new protein synthesis. In addition, there was no loss of vasodilator response to the endothelium-dependent receptor agonist acetylcholine (10(-8)-10(-4) M) or in the constrictor responses to norepinephrine (10(-9)-10(-5) M) and KCl (20-100 mM). We conclude that short exposure to LPS produces a specific increase in the constrictor response to ANG II via mechanisms mediated by prostaglandin H2/thromboxane A2. This effect could be a LPS-induced shift in favor of constrictor prostanoids in the balance of dilator/constrictor prostanoids, the release of which is associated with stimulation by ANG II.     

Strychnine-dependent allodynia in the urethane-anesthetized rat is segmentally distributed and prevented by intrathecal glycine and betaine

The blockade of spinal glycine receptors with intrathecal strychnine produces a reversible allodynia-like state in the rat. Thus, hair deflection, in the presence of intrathecal strychnine, induces cardiovascular and motor withdrawal responses comparable with those evoked by noxious thermal, mechanical, or chemical stimulation in the absence of strychnine. In the present study, we mapped the cutaneous sites of abnormal sensitivity to hair deflection throughout the strychnine time course to investigate the segmental distribution of strychnine-induced allodynia. The ability of intrathecal glycine and the glycine derivative betaine to reverse strychnine-induced allodynia was also determined using dose-response analysis. Following intrathecal strychnine (40 micrograms), stroking the legs, flanks, lower back, and tail with a cotton-tipped applicator evoked a pronounced increase in mean arterial pressure, tachycardia, and an abrupt motor withdrawal response in urethane-anesthetized rats. These abnormal responses were only evoked by hair deflection at discrete sites, corresponding to the cutaneous dermatomes innervated by spinal segments near the site of strychnine injection. In rats with intrathecal catheters lying laterally in the subarachnoid space, allodynic sites were observed unilaterally on the ipsilateral side of intrathecal strychnine injection. Recovery from strychnine was complete by 30 min in all affected dermatomes. The cardiovascular and motor withdrawal responses to hair deflection were dose dependently inhibited by intrathecal glycine and intrathecal betaine. The ED50 (95% confidence interval) for intrathecal glycine was 609 (429-865) micrograms for the heart rate response, 694 (548-878) micrograms for the pressor response, and 549 (458-658) micrograms for the motor withdrawal response. The corresponding values for intrathecal betaine were 981 (509-1889), 1045 (740-1476), and 1083 (843-1391) micrograms, respectively. There was no difference in the effect of betaine on sensory-evoked cardiovascular and motor responses. Cortical electroencephalographic activity was not affected by intrathecal glycine or betaine, consistent with a spinal locus of action in reversing strychnine-induced allodynia. These results support the hypothesis that removal of spinal glycinergic modulation from low threshold afferent input with intrathecal strychnine results in segmentally localized, tactile-evoked allodynia.     

The fatty acid composition of maternal diet affects the response to excitotoxic neural injury in neonatal rat pups

OBJECTIVE: To determine if perineural invasion (PNI) of small nerves affects the outcome of patients with squamous cell carcinoma (SCC) of the upper aerodigestive tract. DESIGN: Retrospective clinicopathological study of patients with at least 2 years of follow-up and with negative margins and no prior, synchronous, or metachronous SCC. SETTING: Academic otolaryngology department. PATIENTS: One hundred forty-two patients who had SCC of the oral cavity, oropharynx and hypopharynx, or larynx resected between 1981 and 1991. INTERVENTION: Surgery with or without adjuvant therapy. MAIN OUTCOME MEASURES: Local recurrence was examined with respect to PNI, nerve diameter, and microvascular or microlymphatic invasion. Perineural invasion was correlated with lymph node metastasis, extracapsular spread, and survival. RESULTS: Perineural invasion of nerves less than 1 mm in diameter was present in 74 patients, lymphatic invasion in 53, and vascular invasion in 9. Perineural invasion was significantly associated with local recurrence (23% for PNI vs 9% for no PNI; P=. 02), and disease-specific mortality (54% mortality for PNI vs 25% for no PNI; P<.001). With extralaryngeal tumors, PNI was associated with nodal metastasis (73% vs 46%; P=.03). Perineural invasion was not associated with extracapsular spread (P=.47). Microvascular invasion, lymphatic invasion, and nerve diameter were not significantly related to local recurrence. CONCLUSIONS: Perineural invasion of small nerves is associated with an increased risk of local recurrence and cervical metastasis and is, independent of extracapsular spread, a predictor of survival for patients with SCC of the upper aerodigestive tract.     

Responses of laying hens to a low-protein diet supplemented with essential amino acids, L-glutamic acid and/or intact protein

1. Three sequential experiments, each lasting 8 weeks, were carried out on 576 singly-caged light hybrids. 2. In experiment 1 egg production was 84% using a conventional control diet, 61% with a basal low-protein diet, and 79% with the basal diet supplemented with 10 essential amino acids+L-glutamic acid (GA). 3. In experiment 2 supplementation with lysine and methionine (L+M) alone increased egg production significantly from 54 to 72%, compared with 83% with the conventional diet. 4. In experiment 3 egg production was 55% with the basal diet, 71% with the basal diet+L+M, 75% with a diet containing 141 g protein/kg+L+M, and 73% with the conventional diet. 5. In all three experiments supplementation with GA alone either gave no significant response or a depression in production. 6. Daily intakes of 1-24 g nitrogen as non-essential amino acids and 13 to 14 g total crude protein per bird resulted in good egg production. Supplementation of the basal diet with L+M resulted in a daily intake of 413 mg methionine/bird day which was considered adequate, and a daily intake of 710 mg lysine which was considered slightly inadequate.     

Defects in embryonic hindbrain development and fetal resorption resulting from vitamin A deficiency in the rat are prevented by feeding pharmacological levels of all-trans-retinoic acid

Vitamin A is required for reproduction and normal embryonic development. We have determined that all-trans-retinoic acid (atRA) can support development of the mammalian embryo to parturition in vitamin A-deficient (VAD) rats. At embryonic day (E) 0.5, VAD dams were fed purified diets containing either 12 micrograms of atRA per g of diet (230 micrograms per rat per day) or 250 micrograms of atRA per g of diet (4.5 mg per rat per day) or were fed the purified diet supplemented with a source of retinol (100 units of retinyl palmitate per day). An additional group was fed both 250 micrograms of atRA per g of diet in combination with retinyl palmitate. Embryonic survival to E12.5 was similar for all groups. However, embryonic development in the group fed 12 micrograms of atRA per g of diet was grossly abnormal. The most notable defects were in the region of the hindbrain, which included a loss of posterior cranial nerves (IX, X, XI, and XII) and postotic pharyngeal arches as well as the presence of ectopic otic vesicles and a swollen anterior cardinal vein. All embryonic abnormalities at E12.5 were prevented by feeding pharmacological amounts of atRA (250 micrograms/g diet) or by supplementation with retinyl palmitate. Embryos from VAD dams receiving 12 micrograms of atRA per g of diet were resorbed by E18.5, whereas those in the group fed 250 micrograms of atRA per g of diet survived to parturition but died shortly thereafter. Equivalent results were obtained by using commercial grade atRA or atRA that had been purified to eliminate any potential contamination by neutral retinoids, such as retinol. Thus, 250 micrograms of atRA per g of diet fed to VAD dams (approximately 4.5 mg per rat per day) can prevent the death of embryos at midgestation and prevents the early embryonic abnormalities that arise when VAD dams are fed insufficient amounts of atRA.     

Amphetamine reinstates polydipsia induced by chronic exposure to quinpirole, a dopaminergic D2 agonist, in rats

The hypothesis that the combined activation of D1 and D2 dopaminergic receptors is instrumental in inducing amphetamine (AMPH)-mediated hyperdipsia was tested in rats. The D1 agonist SKF-38393 (SKF) and the D2 agonist quinpirole (QNP) were i.p. injected, alone or in combination, to male rats for 10 days. After 2 days of wash-out, a single dose of AMPH (3 mg/kg) was administered. Intake of water and food and diuresis were daily measured at 2, 5 and 24 h. In two further experiments the higher dose of QNP (0.56 mg/kg) was given with two different doses of the D1 antagonist SCH-23390 (SCH), or, respectively, of the peripheral D2 antagonist domperidone (DMP). In a fourth experiment, the possibility that QNP, given alone or in combination with SKF, produces an AMPH-like internal state was evaluated by using a drug-discrimination paradigm. Results show that chronic administration of QNP produced a significant increase of 24 h water intake that was reinstated by AMPH. This QNP effect was only partially prevented by DMP, suggesting a main central mechanism of action. By itself D1 receptor manipulation did not affect water intake, but influenced QNP polydipsia that, accordingly, was enhanced by the lower dose of SKF (0.3 mg/kg) and inhibited by the lower dose of SCH (0.01 mg/kg). In rats trained to discriminate AMPH from solvent, QNP partially generalized for the AMPH stimulus, an effect that was potentiated by SKF. In conclusion, a D1-modulated sensitization of D2 dopaminergic mechanisms is probably involved in AMPH-induced hyperdipsia.     

Increase in skeletal muscle protein content by the beta-2 selective adrenergic agonist clenbuterol exacerbates hypoalbuminemia in rats fed a low-protein diet

Between 1990 and 1995, 214 implants were placed in 29 maxillae and mandibles of 22 patients following extraction of all residual teeth as a consequence of severe periodontal disease. All patients were discharged wearing immediate dentures. The implants were analyzed with regard to the number per arch, location, length, and diameter. The 5-year cumulative survival rate was 98.5%. The mean number of implants per arch was 7.5 for the maxilla and 7.2 for the mandible. The preferred implant locations were canines, central incisors, lateral incisors, and second premolars in the maxilla; and lateral incisors, first molars, and canines in the mandible. The mean implant length was 14.7 mm in the mandible and 14.5 mm in the maxilla. The mean implant diameter was 3.8 mm in the maxilla and 3.8 mm in the mandible. The results of the present study indicate that immediate implantation for fixed full-arch reconstruction can be considered a viable treatment alternative in patients with severe periodontal disease.     

Experimental diabetes is associated with functional activation of protein kinase C epsilon and phosphorylation of troponin I in the heart, which are prevented by angiotensin II receptor blockade

We investigated the effects of epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha on migration, invasion and matrix metalloproteinase (MMP) expression of uterine cervical-carcinoma SKG-IIIb cells, and whether these growth factors affect pyrimidine-nucleoside-phosphorylase (PyNPase) activity and 5'-deoxy-5-fluorouridine (5'-dFUrd) sensitivity of tumor cells. Tumor-cell migration along a gradient of substratum-bound fibronectin and invasion into reconstituted basement membrane were stimulated by 0.1 to 100 ng/ml of EGF and TGF-alpha in a concentration-dependent manner. The zymography of tumor-conditioned medium showed that the treatment of tumor cells with EGF and TGF-alpha resulted in an increase of the 92-kDa type-IV collagenase (MMP-9), which was confirmed by immunoblot analysis. These growth factors also up-regulated the expression of PyNPase activity of tumor cells and consequently enhanced the anti-proliferative action of 5'-dFUrd, a cytostatic that is biotransformed to 5-fluorouracil (5-FUra) by PyNPase. However, EGF and TGF-alpha did not have significant effects on the 5-FUra sensitivity of tumor cells. These results suggest that EGF and TGF-alpha, tumor environmental factors, simultaneously up-regulate the potential of uterine cervical-carcinoma cells to invade extracellular matrices and their PyNPase activity, which are subsequently associated with the specific action of 5'-dFUrd selectively killing tumor cells of gynecological origin with high invasive and metastatic potential.     

Effects of alpha- and beta-adrenoceptor blockade on purine secretion induced by sympathetic nerve stimulation in the rat kidney

To characterize the effects of renal sympathetic nerve activation (RSNA) on renal purine secretion, 13 perfused rat kidneys were stimulated with periarterial electrodes at 7 Hz for 3 min, and purine secretion was determined by measuring with high-performance liquid chromatography purines in the renal venous perfusate 1 min before and during the last minute of RSNA. RSNA significantly increased renal perfusion pressure and significantly increased the secretion of adenosine and adenosine metabolites (inosine, hypoxanthine, and xanthine) by 2- to 5-fold. To investigate the participation of alpha- and beta-adrenoceptors in this response, four groups of perfused kidneys (n = 5/group) were pretreated with either vehicle, prazosin (alpha1-adrenoceptor antagonist; 0.03 microM), phentolamine (alpha1/2-adrenoceptor antagonist; 3 microM), or propranolol (beta1/2-adrenoceptor antagonist; 0.1 microM), and purine secretion was measured before and during RSNA at 1, 3, 5, 7, and 9 Hz. Prazosin, phentolamine, and propranolol abolished the RSNA-induced increase in the secretion of adenosine, inosine, hypoxanthine, and xanthine. In contrast, prazosin and phentolamine nearly abolished, whereas propranolol only slightly reduced, renal vascular responses to RSNA. Our results indicate that RSNA increases renal purine secretion via a mechanism that requires both alpha- and beta-adrenoceptors. It is well known that in the kidney adenosine activates renal afferent nerves, enhances renovascular responses to norepinephrine and angiotensin II, and increases sodium reabsorption; therefore, RSNA-induced adenosine production may contribute to the hypertensive effects of RSNA. Moreover, the antihypertensive effects of beta-adrenoceptor antagonists may in part be due to inhibition of RSNA-induced renal adenosine production.     

Anandamide synthesis is induced by arachidonate mobilizing agonists in cells of the immune system

The hypothesis that the capability of agents to mobilize arachidonic acid (AA) could predict increased anandamide (ANA) synthesis in a macrophage cell line has been examined. Lipopolysaccharide (LPS), platelet-activating factor (PAF) and cannabinoids such as Delta9-tetrahydrocannabinol (THC) and anandamide were all found to be agonists for the release of AA and led to increased ANA synthesis in RAW264.7 mouse macrophage cells. Nitric oxide, in contrast, stimulated AA release without raising ANA levels. ANA stimulation of its own synthesis indicates the existence of a positive feedback mechanism. The possible involvement of the CB2 receptor in THC-mediated AA release and ANA synthesis is addressed using the antagonist SR144528. ANA synthesis is also increased by the combination of calcium ionophore and indomethacin, suggesting that ANA is metabolized by a cyclooxygenase in this system. The data imply that ANA could play a role in the response of the immune system to cannabinoids and bacterial endotoxins and that AA mobilization is a predictor for increased ANA synthesis.     

Hydrogen peroxide induced impairment of post-ischemic ventricular function is prevented by the sodium-hydrogen exchange inhibitor HOE 642 (cariporide)

Using highly degenerate, serine-protease-specific PCR primers on a midgut-specific cDNA library it was estimated that a minimum of 24 independent serine proteases were expressed in the midgut of Stomoxys calcitrans. The relative abundance of these 24 independent serine proteases has been estimated by restriction analysis of PCR products, showing that 69% fall into six almost equally abundant groups. Two highly abundant serine protease cDNAs (Ssp1 and Ssp2) were isolated and sequenced. They encode preproenzymes of 272 amino acids (Mr 28521) and 255 amino acids (Mr 27097) with putative signal peptides of 17 amino acids and 16 amino acids, putative activation peptides of 15 amino acids and 10 amino acids and mature enzymes of 239 amino acids (Mr 25322; pI 4.89) and 228 amino acids (Mr 24182; pI 7.59), respectively. Both deduced amino acid sequences contain the Asp/His/Ser catalytic triad and the highly conserved sequences surrounding it. Ssp2 also has the aspartate and two glycine residues in the specificity pocket, marking this as a typical trypsin. The positioning of the residues in the specificity pocket of Sspl is unusual; aspartate and glycine residues are present, which is typical of trypsin, but both are separated from surrounding conserved residues by additional amino acids; the second glycine found in the specificity pocket of trypsin is replaced by a serine, which is typical of chymotrypsin. Although a serine protease, the precise substrate specificity of Sspl remains to be determined. Northern analysis shows that both serine proteases are expressed constitutively with only a 20% change in the levels of expression of Ssp1 and Ssp2 through the digestive cycle, and that expression occurs predominantly in the opaque region of the midgut, the region responsible for secretion of digestive enzymes.     

Maintenance of maternal diet-induced hypertension in the rat is dependent on glucocorticoids

Recent epidemiological evidence suggests that adult cardiovascular risk is determined by birth weight and factors that influence birth weight, such as maternal nutrition. Data from animal models suggest that an interaction between nutrition and glucocorticoid hormones "programs" increased risk of adult hypertension. Increased fetal exposure to maternal glucocorticoids that is proposed to occur from a reduction in the placental barrier to maternal glucocorticoid, 11beta-hydroxysteroid dehydrogenase, is suggested to program hypertension in the resultant offspring from both glucocorticoid-treated and maternally protein-restricted rats. The extent to which postnatal glucocorticoid stimulation may influence the progression of hypertension in the offspring from protein-restricted rat dams was assessed in 6-week-old male Wistar rats, prenatally exposed to either an 18% casein (control) or 9% casein (low protein) diet. Rats from each dietary group were sham operated, adrenalectomized or adrenalectomized, and treated with 20 mg corticosterone/kg body weight per day. Before surgery, systolic blood pressure was significantly higher in the low protein-exposed rats compared with controls (165+/-3.8 versus 142+/-3.3 mm Hg, P<.0001). Adrenalectomy of the low protein-exposed animals significantly reduced the blood pressure to control levels, while corticosterone replacement restored the hypertensive state. No effect of adrenalectomy on blood pressure was observed in 18% casein controls. In both dietary groups adrenalectomy decreased brain, but not hepatic, glucocorticoid-sensitive enzyme activities and corticosterone treatment elevated activities of all enzymes. The data suggest that maternal diet-induced hypertension is dependent on an intact adrenal gland postnatally and that glucocorticoids are key trophic agents in maintaining the high blood pressure.     

Motor effects induced by a blockade of adenosine A2A receptors in the caudate-putamen

Motor effects mediated through adenosine A2A receptors within the caudate-putamen were investigated in rats using bilateral microinfusions of MSX-3 (9 microg in 1 microl per side), a water-soluble phosphate prodrug of the selective A2A receptor antagonist MSX-2. Blockade of striatal A2A receptors produced a significant motor stimulation measured by an enhanced sniffing activity. Furthermore, catalepsy induced by systemic dopamine D1 (0.75 mg/kg SCH23390, i.p.) or dopamine D2 receptor blockade (1.5 mg/kg raclopride, i.p.) was potently reversed. These findings suggest that A2A receptors within the caudate-putamen are tonically activated by endogenous adenosine and that a striatal A2A receptor blockade produces motor stimulant effects, in particular in animals with dopamine hypofunction. The present results support the view that A2A receptor antagonists may be potentially useful therapeutics for the treatment of Parkinson's disease.     

Modifying the n-3 fatty acid content of the maternal diet to determine the requirements of the fetal and suckling rat

During perinatal development, docosahexaenoic acid (22:6n-3) accumulates extensively in membrane phospholipids of the nervous system. To evaluate the n-3 fatty acid requirements of fetal and suckling rats, we investigated the accumulation of 22:6n-3 in the brain and liver of pup rats from birth to day 14 postpartum when their dams received increasing amounts of dietary 18:3n-3 (from 5 to 800 mg/100 g diet) during the pregnancy-lactation period. The fatty acid composition of brain and liver phospholipids of pups, as well as that of dam's milk, was determined. At birth, 22:6n-3 increased regularly to reach the highest level when the maternal diet contained 800 mg 18:3n-3/100 g. On days 7 and 14 postpartum, brain 22:6n-3 plateaued at a maternal dietary supply of 200 mg/100 g. Docosapentaenoic acid (22:5n-6) had the opposite temporal pattern. The unusually high concentration of eicosapentaenoic acid (20:5n-3) in liver and dam's milk observed at the highest 18:3n-3 intake suggests an excessive dietary supply of this fatty acid. All these data suggest that the n-3 fatty acid requirements of the pregnant rat are around 400 mg 18:3n-3 and those of the lactating rat at 200 mg (i.e., 0.9 and 0.45% of dietary energy, respectively). The values of 18:3n-3 and 22:6n-3 milk content which allowed brain 22:6n-3 to reach a plateau value in suckling pups were 1% of total fatty acids and 0.9% (colostrum) to 0.2% (mature milk), respectively. These levels are similar to those recommended for infant formulas.     

Interactive effects of prenatal cocaine and nicotine exposure on maternal toxicity, postnatal development and behavior in the rat

Two experiments were performed to investigate the interactive effects of prenatal coadministration of cocaine hydrochloride (C) and nicotine tartrate (N). Experiment I was designed to determine doses of C and N that could be coadministered without altering maternal gestational parameters and/or fetal viability. Exposure of Sprague-Dawley rats to combined high-dose C (20 mg/kg) and high-dose N (5.0 mg/kg) on gestation days 8-21 was not more toxic to dam or fetus that that of exposure to C alone. Experiment II investigated pregnancy outcome, postnatal development, and behavior of the offspring following drug exposure to either high-dose cocaine (20 mg/kg: CS), high-dose nicotine (5.0 mg/kg: NS), or both (NC) on gestation days 8-21. N was administered by osmotic minipump and C by sc injection. Saline-injected dams, fitted with saline-fitted pumps (SS), and untreated dams, pair-fed (PF) to NC females, served as controls. Alterations in maternal variables were limited to a 10-15% decrease in food consumption in NC and CS groups. Pregnancy outcome and birth statistics were unaffected by prenatal treatment, as was offspring body weight during the first four postnatal weeks. However, the development of surface righting was delayed inC CS pups, and only CS offspring were underresponsive to the stimulatory effects of dopamine agonists on activity and stereotypy. Behavioral responses to N challenge were similar in all groups. In addition, only CS offspring showed altered behavioral responses in a spontaneous alternation task. Treatment effects on dopamine D1 and D2 binding in the caudate nucleus were not observed. The combination of N and C did not exacerbate any of the behavioral changes seen in CS offspring. These results support the hypothesis that C is a behavioral teratogen in rodents, and suggest that in the present model, nicotine can mitigate some of the consequences of in utero exposure to cocaine.     

Epithelial cell hyperproliferation induced in the exocrine pancreas of mice by a western-style diet

BACKGROUND: Pancreatic cancer is a common cause of mortality in the United States, with an estimated 27,800 people dying of the disease in this country in 1996. Epidemiologic studies have suggested that Western diets containing high fat, high protein, and low calcium contents are associated with increased incidence of pancreatic cancer. PURPOSE: We investigated whether a Western-style diet containing increased fat content and decreased calcium and vitamin D contents would induce epithelial cell hyperproliferation (excess cell duplication) or hyperplasia (excess cell accumulation) in the pancreas, as was previously demonstrated in the colon and mammary gland. METHODS: C57BL/6J mice at 4 weeks of age were randomly assigned to one of two groups of 14 mice each. One group received the control diet ad libitum, and the other group was given the Western-style diet ad libitum. After 6, 9, and 15 weeks on the diet, four or five mice per group were infused with 5-bromo-2'-deoxyuridine (BrdU) for 72 hours by use of subcutaneously implanted Alzet osmotic pumps. The mice were then killed, and the pancreas of each mouse was removed. In the exocrine pancreas with ductal secretion, the duct system (including interlobular and intralobular ducts and centroacinar [i.e., centroductular] cells) and acini were measured both histopathologically and immunohistochemically (BrdU) and were analyzed without knowledge of the source of the specimens. Two-way analysis of variance was carried out. All P values were generated from two-sided tests for statistical significance. RESULTS: The number of pancreatic ducts (interlobular, intralobular, and centro-acinar-cancer-prone regions in certain rodent models and in humans) and acini per mouse in the Western-style diet group was similar to that in the control diet group during the entire feeding period (P = .76, .32, .93, and .42, respectively). Statistically significant higher BrdU-labeling indices of the ductal interlobular and intralobular epithelial cells were seen in mice fed the Western-style diet than in mice fed the control diet during the entire observation period (P = .014 and .016, respectively). There was no statistically significant difference (P = .098) between both diet groups in the BrdU-labeling indices of the centroacinar epithelial cells. CONCLUSIONS: A Western-style diet induced pancreatic epithelial cell hyperproliferation in mice, further suggesting that increased fat content and decreased calcium and vitamin D contribute to the development of pancreatic neoplasms.