Effects of anesthetics and septal lesions and stimulation on 3H-acetylcholine formation in rat hippocampus

The rate of 3H-acetylcholine (ACh) formation from i.v. injected 3H-choline was studied in the rat hippocampus after various treatments which alter the activity of cholinergic septal hippocampal neurons. Administration of pentobarbital and placement of acute septal lesion reduced the formation of 3H-ACh but did not change 3H-choline content. Chloral hydrate administration reduced the formation of 3H-ACh and also increased 3H-choline content. The chloral hydrate induced increase in 3H-choline occurred also in animals with chronic septal lesions. Electrical stimulation of the septum caused an increase in both 3H-ACh and 3/-choline. Chronic septal lesion caused a reduction in both radioactive and endogenous ACh, but did not affect radioactive or endogenous choline. These findings suggest that there are multiple pools of choline in the brain and that the precursor pool for ACh synthesis is difficult to measure. Overall, the parameter that best correlated with cholinergic activity was the level of 3H-ACh. Possible mechanisms, for this finding are discussed.     

Molecular approaches to the diagnosis of male infertility

We investigated the effects of aging and/or swimming training on the antioxidant enzyme system in diaphragm of mice. Young (2 months old) and old (26 months old) male mice were swimming-trained for 6 weeks (1 h/day, 5 days/week). Cu,Zn-Superoxide dismutase (Cu,Zn-SOD) activity was significantly upregulated with aging, and swimming training definitely enhanced the activity only in young mice. Neither aging nor swimming training had overt effect on Mn-SOD activity. Glutathione peroxidase activity in young mice was significantly increased after training, but not in old mice. Both of immunoreactive Cu,Zn-SOD and Mn-SOD were significantly increased with aging but were unaffected by swimming training. Consequently, physical training significantly enhanced the specific activity of Cu,Zn-SOD in young mice, but not in old mice. Meanwhile, swimming training significantly increased xanthine oxidase activity in both age groups, the extent of the increase being greater in old mice than in young mice. We concluded that the antioxidant enzyme system in mouse diaphragm trends to be upregulated with aging, but that swimming training improved the system only in young mouse diaphragm.     

The influence of prostaglandin F-2alpha on pregnenolone metabolism by the autotransplanted ovary of the ewe

Eight ewes each with an autotransplanted ovary received infusions of tritium-labelled pregnenolone (41 muCi/hr) for 8 hr into the artery supplying the ovary, together with prostaglandin (PG) F-2alpha (30 mug/hr) for 3 hr beginning 2 hr after the start of the pregnenolone infusion. All animals exhibited oestrus 2-3 days after the start of the experiment. During the PGF-2alpha infusion blood flow through the ovaries was increased by 13%, but subsequently returned to pre-infusion levels. Secretion rates of endogenous progesterone and 20alpha-hydroxypregn-4-en-3-one dropped rapidly 5 hr after the PGF-2alpha infusion had started from values of 250 mug/hr and 25 mug/hr to values below 60 mug/hr and 8 mug/hr, respectively. At this time the conversion of radioactive pregnenolone to progesterone was reduced by 50% of its initial value, but the secretion of endogenous pregnenolone and the formation of radioactive metabolites other than progesterone were not diminished. In 4 control animals, which received pregnenolone only, no changes in ovarian blood flow, steroid secretion rates, or in the conversion of labelled pregnenolone were observed. These results suggest a possible involvement of PGF-2alpha in the regulation of progesterone biosynthesis by an action on the 3beta-hydroxysteroid oxidoreductase-delta5(-4) isomerase enzyme system.     

Local cerebral glucose utilization in the AS/AGU rat: a mutant with movement disorders

In order to examine the relative impairment of the diaphragm and other skeletal muscles in systolic ventricular dysfunction (VD), their structure and function were compared between rats with VD induced by left coronary artery ligation (n = 17) and sham-operated rats (Co, n = 10). In addition, in an attempt to unravel the mechanism of the observed impairment, we examined alterations in insulin-like growth factor-I (IGF-I) serum levels and IGF-I expression in the liver, diaphragm, and gastrocnemius. In a second series of rats (VD, n = 5 and Co, n = 5) hemodynamic measurements were performed. All measurements were performed 3 mo after the operation. Infarct size averaged 32 +/- 10 and 44 +/- 20% in the two series, respectively (NS). Hemodynamic measurements revealed a decrease in left ventricular peak systolic pressure of 19% (p < 0. 05). Significant diaphragm atrophy (weight: 622 +/- 52 mg in VD versus 750 +/- 54 mg in Co, p < 0.0005), without alterations in diaphragm contractile properties was present in VD animals. For all animals combined, the reduction in diaphragm weight was related to infarct size (r = -0.74, p < 0.001). No alterations were observed in the other inspiratory and peripheral muscles. ATPase staining of the diaphragm showed atrophy of type I and type IIx/b fibers, their cross-sectional area (CSA) being reduced by 13 and 16%, respectively (p < 0.05). There were no signs of myopathic alterations. IGF-I expression was increased by 55% in the diaphragm of rats with VD (p < 0.05). IGF-I expression in the liver and gastrocnemius and serum IGF-I levels were unaltered. These data suggest the presence of compensatory mechanisms aimed at minimizing diaphragmatic fiber atrophy. We conclude that systolic VD caused: (1) selective diaphragm atrophy, which was related to infarct size; (2) a decrease in diaphragm type I and IIx/b CSA not associated with myopathic changes; (3) an increase in the IGF-I mRNA content of the diaphragm. The selective diaphragm involvement in the present study may be related to the moderate degree of ventricular dysfunction induced.     

Metabolism of serotonin to N-acetylserotonin, melatonin, and 5-methoxytryptamine in hamster skin culture

Biotransformation of [3H]serotonin by cultured hamster skin to 3H-metabolites corresponding to N-acetylserotonin (NAS), melatonin, and 5-methoxytryptamine (5-MT) was demonstrated. This process was time-dependent, with the highest production of radioactive NAS and melatonin metabolites after 3 and 5 h of incubation followed by a decrease in the rate of metabolite release into the media. Conversely, the formation of radioactive metabolite corresponding to 5-MT increased gradually during skin culture, reaching the highest level after 24 h of incubation. The production of 3H-metabolites, corresponding to NAS, melatonin, and 5-MT, was stimulated by forskolin with a maximum effect of forskolin at 10 microM concentration. The gas chromatographic/mass spectroscopy analysis of the fraction eluting at the retention time of NAS standard material showed that it contained NAS, further confirming production and release of NAS into the media by hamster skin. Therefore, we conclude that mammalian skin can acetylate serotonin to NAS and postulate that the NAS is further metabolized by the skin to form melatonin which is subsequently transformed to 5-MT.     

Pathways linking L-phenylalanine and 2-phenylethylamine with p-tyramine in rabbit brain

Concentrations of labeled p-tyramine and 2-phenylethylamine were measured in rabbit brain 10 min after the intraventricular administration of either radioactive amine. In both cases the recoveries of the newly synthesized amine and of the unchanged precursor were significantly increased in animals pretreated with the monoamine oxidase inhibitor pargyline. Significant amounts of both amines were present in rabbit brain 10 min after the intraventricular injection of labeled L-phenylalanine. Pretreatment with pargyline increased their recoveries, whereas alpha-methyldopa (an L-aromatic amino acid decarboxylase enzyme inhibitor, L-AAADI) decreased them considerably, and no significant alteration was found in L-alpha-methyldopa hydrazine (a peripheral L-AAADI) pretreated animals. These results provide evidence for a new biochemical pathway in brain for p-tyramine biosynthesis, with L-phenylalanine (bypassing the formation of L-tyrosine) or 2-phenylethylamine as precursors. The significance and implications of these metabolic routes are discussed, especially considering that p-tyramine itself can be converted to catecholamines.     

Evidence for nickel in the soluble hydrogenase from the unicellular green alga Scenedesmus obliquus

Cultures of the green alga Scenedesmus obliquus were grown in the presence of either the chelating reagent EDTA or NiCl2 in various concentrations and assayed for hydrogenase catalyzed photohydrogen evolution after an anaerobic dark adaptation period. Cultivation of algae in the presence of 100 microM EDTA inhibited the formation of hydrogenase activity by 37%. After a cultivation of the cells in the presence of 5-20 microM NiCl2 photohydrogen evolution was increased by 20-40%. Addition of EDTA up to a final concentration of 1.5 mM had no effect on the activity of hydrogenase in cell-free hydrogenase preparations. Cultures grown in the presence of radioactive 63NiCl2 incorporated 63Ni in a parallel fashion to the cell growth. In radioactive labeled hydrogenase preparations a co-elution of radioactivity and hydrogenase activity could be observed using gel filtration chromatography.     

Ovarian steroid modulation of neurokinin contents in hypothalamus, pituitary, trigeminal nucleus, and cervical spinal cord of the ovariectomized female rat

Ovariectomized rats were treated with estradiol benzoate (EB) and progesterone in conditions known to negatively and positively regulate gonadotropin secretion. Injection with EB decreased the plasma concentration of substance P at the time of the positive feed-back exerted by EB on gonadotropin secretion, while having no effect on the plasma concentration of neurokinin A. In the hypothalamus, EB injection enhanced the substance P and neurokinin A content, while progesterone reduced the substance P content. In the anterior pituitary, the substance P content was increased after progesterone, and this increase was blocked by EB. Conversely, in the posterior pituitary, the substance P content was reduced after progesterone, and this effect was enhanced by EB. In the trigeminal nucleus, the substance P content was increased after progesterone and EB, while only progesterone affected neurokinin A content. Finally, in the cervical spinal cord, the substance P and neurokinin A contents were reduced after EB. We conclude that neurokinin contents are controlled by ovarian steroids not only in the hypothalamo-pituitary complex but also in the trigeminal nucleus and the cervical spinal cord.     

Influence of chloride and sodium pump activity on carbachol- and acetylaholine-induced depolarizations in denervated rat diphragm

The effect was measured of low chloride medium and ouabain on carbachol- and acetylcholine-induced depolarizations in denervated rat diaphragm. Membrane potentials were measured in rat diaphragm muscle fibers 10-14 days after denervation. Depolarizations induced by carbachol and acetycholine were increased when the extracellular chloride concentration was diminished from 110 to 40 or 10 mM. Sodium pump inhibition by ouabain (10(-4) M) dramatically enhanced the carbachol depolarizations. In 40 mM Cl- solutions, dose-response relations were determineed with ACh in the absence of presence of dTc. For ACh a pD2 value of 5.2 was found; the pA2 value for dTC appeared to be about 6.4. Therefore, the binding properties of the post-denervational receptors do not appear to be influenced by the chloride gradient. It was concluded that drug-induced depolarizations of the denervated rat diaphragm are short-circuited by chloride ions and counteracted by sodium pumping.     

Voluntary activation of the human diaphragm in health and disease

Intersubject comparison of the crural diaphragm electromyogram, as measured by an esophageal electrode, requires a reliable means for normalizing the signal. The present study set out 1) to evaluate which voluntary respiratory maneuvers provide high and reproducible diaphragm electromyogram root-mean-square (RMS) values and 2) to determine the relative diaphragm activation and mechanical and ventilatory outputs during breathing at rest in healthy subjects (n = 5), in patients with severe chronic obstructive pulmonary disease (COPD, n = 5), and in restrictive patients with prior polio infection (PPI, n = 6). In all groups, mean voluntary maximal RMS values were higher during inspiration to total lung capacity than during sniff inhalation through the nose (P = 0.035, ANOVA). The RMS (percentage of voluntary maximal RMS) during quiet breathing was 8% in healthy subjects, 43% in COPD patients, and 45% in PPI patients. Despite the large difference in relative RMS (P = 0.012), there were no differences in mean transdiaphragmatic pressure (P = 0.977) and tidal volumes (P = 0.426). We conclude that voluntary maximal RMS is reliably obtained during an inspiration to total lung capacity but a sniff inhalation could be a useful complementary maneuver. Severe COPD and PPI patients breathing at rest are characterized by increased diaphragm activation with no change in diaphragm pressure generation.     

Synthesis of glycoproteins in the Golgi complex of the mouse gallbladder epithelium during fasting, refeeding, and gallstone formation. A light microscopic autoradiographic and quantitative electron microscopic study

The mouse gallbladder epithelium was studied with light microscopic autoradiography and quantitative electron microscopy during fasting, refeeding and experimental gallstone formation. To determine the intracellular pathway of glycoproteins, H3-galactose was injected at different time intervals into the mice. At 10, 25 and 40 min after an intraperitoneal injection the gallbladders were fixed and prepared for light microscopy. As early as 10 min after injection, label was observed in supranuclear cytoplasmic regions and at 25 min, an increased radioactivity was present throughout the apical cytoplasm. At 40 min, silver grains were mainly present at the cell surface. Autoradiographs processed 25 min after an intraperitoneal H3-galactose injection after fasting for 48 h showed decreased supranuclear and apical radioactivity. After refeeding (12 h) there was an enhanced activity in both these regions. Animals fed a lithogenic diet for one month showed a marked increase of radioactive label mainly in cells of crypts and invaginations of the mouse gallbaldder mucosa. Morphometric measurements of the Golgi apparatus revealed that deprivation of food significantly dimished the volume density of the Golgi apparatus. Refeeding the amimals restored the volume density values to normal levels, In the course of gallstone formation there was a further significant increase in the volume density of the Golgi complexes as compared to controls.     

Course and dynamics of immunologic iridocyclitis in the rabbit

1 The catabolism of injected 14 C-putrescine was studied in mice treated with nandrolone phenpropionate, an anabolic steroid. 2 The putrescine was rapidly metabolized; almost 50% of the injected radioactivity was recovered within 2 h as 14 CO2 in the expired air. 3 Considerable amounts of radioactive gamma-aminobutyric acid (GABA) and an unidentified compound were found in the kidney and in the urine in addition to radioactive putrescine, spermidine and spermine both in controls and nandrolone-treated mice. 4 Nandrolone elevated the concentration of endogenous putrescine in the kidney and urine, eightfold and twentyfold, respectively, and the concentrations of spermidine and spermine were also increased 5 after the injection of 14C-putrescine the incorporation of 14C into spermidine was significantly increased in the kidney of mice receiving nandrolone.     

Differential regulation of substance P by all members of the nerve growth factor family of neurotrophins in avian dorsal root ganglia throughout development

This study examined the effects of nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4/5 on substance P levels in dorsal root ganglia of the quail shortly after ganglia formation (stage 26, embryonic day 4.5), during the middle of development (stage 33, embryonic day 7.5) and during late development (stage 44, embryonic day 14). It has already been shown that nerve growth factor increases levels of substance P during the middle and late stages of development, and that messenger RNA for the neurotrophin receptors, trkA, trkB and trkC is present at all of these stages. Dorsal root ganglia were isolated, rinsed with defined medium to dilute endogenous neurotrophins and exposed to one of the neurotrophins for either 4 or 20 h. Substance P levels were quantitated using enzyme immunoassay. None of the neurotrophins had any effect on substance P levels in dorsal root ganglia obtained at stage 26 after either a 4 or 20 h exposure time. Nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4/5 all significantly increased levels of substance P after either a 4 h or 20 h incubation in ganglia obtained at stages 33 and 44. The effects of nerve growth factor and neurotrophin-3 were specific: increases in substance P were completely blocked by simultaneous exposure to antibodies against either nerve growth factor or neurotrophin-3. The absence of any effect of neurotrophins on substance P expression during early development was unexpected, since dorsal root ganglia exhibit substantial levels of substance P and receptors for the neurotrophins are present and are apparently functional. It was also surprising that brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4/5 induced increases in substance P levels during the middle and late stages of development, since substance P was thought to be exclusively localized to small TrkA neurons in dorsal root ganglia. However, immunocytochemical examination of dorsal root ganglia at stages 33 and 44 revealed substance P-like immunoreactivity in larger neurons as well as in small neurons. The results of this study have shown that different cellular responses to neurotrophins, such as effects on survival and/or peptide expression, may be acquired with differing temporal patterns not strictly related to expression of their receptors. Further, the regulation of neuropeptide synthesis in dorsal root ganglia is not due to any one neurotrophic factor. and the factors that regulate expression during early development are still unknown.     

Lithium effects on magnesium, calcium, and phosphate metabolism in rats

Rats were treated with lithium chloride for 8 weeks. At the last day of lithium administration, the animals were given radioactive calcium, magnesium, and phosphate. Electrolyte content and radioactivity were determined in serum, bone, muscle, liver and brain. Lithium led to an increase of inorganic phosphate in muscle and a decrease in serum. Uptake of radioactive phosphate was increased in muscle and liver but reduced in bone. The amount of magnesium in muscle and serum was increased in the lithium-treated rats, whereas the uptake of radioactive magnesium into bone was decreased. Uptake of radioactive calcium into bone was reduced, and radioactive calcium in serum was increased after lithium.     

Effect of N-acetylcysteine on human diaphragm strength and fatigability

Free radical injury is believed to be important in diaphragm dysfunction. N-Acetylcysteine (NAC) is a potent free radical scavenger shown in animal models to attenuate diaphragm fatigue; however, its effects on human diaphragm function are unknown. We assessed diaphragm function by electrophrenic twitch stimulation (PdiT) and twitch occlusion (to yield Pdimax) in four healthy subjects 35 +/- 3 yr of age (mean +/- SD). We intravenously administered NAC (150 mg/kg in 250 ml D5W) or placebo (CON) (250 ml D5W) in a randomized manner after subjects were premedicated with antihistamines. There were no significant side effects with the infusion. After infusion, we measured baseline Pdimax and PdiT at FRC. Diaphragm fatigue was then induced by subjects breathing through an inspiratory resistive load. Pdimax and PdiT were then measured at 15 to 30 min and 1, 2, 3, 4, and 20-25 h after fatigue. Times to fatigue were 13 +/- 4 min (CON) and 21 +/- 6 min (NAC) (p = 0.04). At 15 min after fatigue, PdiT was reduced to 40% (CON) compared with 30% (NAC) initial PdiT value (p = 0.05). Other twitch characteristics (maximal rate of relaxation and maximal contraction rate) were reduced to a greater degree after placebo compared with NAC. There were no significant differences in the rate of recovery between CON and NAC. Pdimax at 30 min after fatigue was significantly greater with NAC; however, at 1 h after fatigue, Pdimax for CON and NAC were not different, suggesting similar rates of recovery in high-frequency fatigue. These data suggest that NAC may attenuate low-frequency human diaphragm fatigue.     

Diaphragm performance during maximal voluntary ventilation in chronic obstructive pulmonary disease

In normal subjects 2 min of maximal voluntary hyperventilation results in failure of tension generation and low-frequency fatigue of the diaphragm. Patients with severe chronic obstructive pulmonary disease (COPD) do not develop diaphragm fatigue during exhaustive treadmill exercise despite excessive inspiratory muscle loading and we hypothesized that they might be relatively resistant to the development of diaphragm fatigue during maximal ventilation. In six patients with severe COPD (mean FEV1 0.671) we therefore loaded the diaphragm using 2 min of maximal isocapnic ventilation (MIV). Initial mean ventilation was 28.6 L/min and diaphragm pressure-time product (PTPdi) 602 cm H2O x s/min; these values were sustained throughout MIV without significant decline. Mean twitch transdiaphragmatic pressure (Tw Pdi) was 19.7 cm H2O 25 min after a control run and 20.5 cm H2O at the same time after MIV [corrected]. Compared with normal subjects previously studied in our laboratory (Hamnegard, C.-H., et al. Eur. Respir. J. 1996;9:241-247) the reduction in PTPdi was disproportionately greater than the reduction in Tw Pdi. We conclude that, unlike normal subjects, 2 min of MIV causes neither failure of diaphragm performance nor low-frequency diaphragm fatigue in patients with severe COPD. It is likely that the diaphragm makes a relatively limited contribution to the generation of maximal levels of ventilation in severe COPD.     

Increased immune activation precedes the inflection point of CD4 T cells and the increased serum virus load in human immunodeficiency virus infection

In sickness-conditioned learning, animals become ill after sampling a new substance and develop an aversion that is expressed as avoidance of that substance in subsequent presentations. We examined the parameters of a one-trial, nongustatory, sickness-conditioned learning task in day-old chicks. Chicks pecked a bead and were made ill by i.p. injection of lithium chloride (LiCl). Both 0.5 and 1.0 M LiCl (0.1 ml) produced reliable avoidance at test. Chicks injected with LiCl between 15 and 45 min after training avoided the bead at test, whereas those injected within 5 or 10 min or more than 45 min after training did not. Avoidance was present until 24 h posttraining and absent after 48 h. Therefore, robust learning of the sickness-conditioned learning task occurs in one trial without the need for gustatory cues, and memory for the task lasts at least 24 h. Uses of this task to study memory formation in the day-old chick are discussed.     

Does the presence of xylitol in a sorbitol-containing chewing gum affect the adaptation to sorbitol by dental plaque?

It is known that xylitol inhibits sorbitol metabolism in some bacteria in vitro. The effect of xylitol/sorbitol-containing chewing gum on sorbitol adaptation of dental plaque was therefore examined. Ten subjects used this chewing gum for 12 wk, and plaque was collected before (control plaque) and after (test plaque) the exposure to sorbitol/xylitol. The metabolism of sorbitol by the plaque was examined with 14C-labeled sorbitol, and the radioactive metabolites were detected by high-performance liquid chromatography (HPLC). A considerable individual variation in acid formation was found. The mean values of total acids in the test plaque increased, as compared with the control plaque. An adaptation of dental plaque to sorbitol thus occurred in spite of the presence of xylitol in the chewing gum. The concentration of acetic acid predominated over other acids in both the control and test plaques. The proportions of acids expressed in percentage of total acids differed only slightly. Thus, long-term use of xylitol/sorbitol-containing chewing gum did not eliminate the adaptation of dental plaque to sorbitol.     

A 2-year longitudinal analysis of the relationships between violent assault and substance use in women.

Women experience alarming levels of physical and sexual assault, which may lead to escalation of substance use. Reciprocally, evidence from cross-sectional studies indicates that substance use may increase risk of assault. To date, directionality of this relationship remains unclear. This issue is addressed by the present 3-wave longitudinal study in which a national probability sample of 3,006 women were followed for 2 years. Dependent measures were obtained at each wave of the study and included questions about lifetime and new assault status, alcohol abuse, and drug use. Wave 1 use of drugs, but not abuse of alcohol, increased odds of new assault in the subsequent 2 years. Reciprocally, after a new assault, odds of both alcohol abuse and drug use were significantly increased, even among women with no previous use or assault history. For illicit drug use, findings support a vicious cycle relationship in which substance use increases risk of future assault and assault increases risk of subsequent substance use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Endogenous substance P inhibits the expression of corticotropin-releasing hormone during a chronic inflammatory stress

We have investigated the effects of a chronic inflammatory stress on substance P (SP) levels in the hypothalami of rats given adjuvant-induced arthritis (AA). Fourteen days after injection of Mycobacterium butyricum, substance P concentrations in the paraventricular nucleus (PVN) and median eminence/arcuate nucleus were significantly increased. In AA rats injected intraperitoneally with the specific neurokinin-1 receptor antagonist RP67580, plasma ACTH and corticosterone concentrations were significantly elevated, and corticotropin-releasing hormone (CRH) mRNA in the PVN was increased compared to the AA group which received saline alone. The increases in hypothalamic SP in AA, together with the data demonstrating that HPA axis activity is enhanced in AA following injection of a SP antagonist, are consistent with the hypothesis that SP is acting as an inhibitor of CRH expression in this model of chronic inflammatory stress.