Nutritionally small-for-dates rats: their subsequent growth, regional brain 5-hydroxytryptamine turnover, and behavior

Rats were subjected to nutritional growth retardation either from conception to 5 postnatal days of age (fetal and neonatal restriction (FNR) group), or from 5 to 25 postnatal days of age (infantile restriction (IR) group). The FNR group may serve as a model for the human small-for-dates baby. At 20 weeks of age cerebellum, midbrain, and cerebrum were significantly reduced in weight by 4%, 5%, and 4%, respectively, in FNR animals when compared with controls. Only cerebellum and midbrain were affected in IR rats of the same age, but in both regions the percentage deficits (8% and 9%, respectively) were greater than in FNR animals. Both cerebellum and midbrain weighed significantly less in IR than in FNR rats. The timing of nutritional growth retardation appeared to be of little consequence to the regional brain turnover of 5-hydroxytryptamine in adulthood. The rate of synthesis in the hippocampus of both FNR and IR animals was significantly faster (67% and 75% respectively) than in controls. The increased turnover could perhaps represent "overactivity" of those 5-hydroxytryptaminergic neurons terminating in the hippocampus. Some differences in the behavior of the previously undernourished adult animals were also evident. On the fifth day of testing, control rats were most venturesome in the open field. Eighteen control rats left the edge zone within 2 min, whereas only 8 FNR and 11 IR rats did so. Most animals froze immediately after a 7-sex exposure to a loud electric bell. The delay before moving about again differentiated the three groups. FNR rats took longest to move out of the area in which they froze.     

Localization of 5-hydroxytryptamine1A and 5-hydroxytryptamine7 receptors in rabbit ocular and brain tissues

Serotonin is thought to play a physiological role in various tissues of the rabbit eye, yet little is known about the relative distribution of the different serotonin receptors. Demonstration of the receptor subtypes present in the various ocular tissues is essential in order to understand the function of serotonin in the eye. Using a combination of in situ hybridization histochemistry, in vitro receptor autoradiography and polymerase chain reaction studies, we have explored the distribution of the 5-hydroxytryptamine1A and 5-hydroxytryptamine7 receptors in the rabbit eye. As these receptors have not been sequenced in the rabbit, we initially established the suitability of the oligonucleotide probes by analysis of brain tissue. The distributions of 5-hydroxytryptamine1A and 5-hydroxytryptamine7 receptor messenger RNAs in rabbit brain correlated well with those in other species, confirming the specificity of the probes for detection of the messenger RNAs in rabbit tissues. In the eye, the expression of 5-hydroxytryptamine1A receptors appears to be restricted to the epithelial cell layer of the ciliary processes, although very low levels may appear in the retina. In contrast, the expression of 5-hydroxytryptamine7 receptor messenger RNA is more widespread with positive signals evident in the ciliary processes, retina and iris. The results confirm the existence of 5-hydroxytryptamine1A receptors in the ciliary body and their localization in the ciliary epithelium supports the hypothesis that they are involved in the secretion of aqueous humour. Unexpectedly, there was little evidence to support the idea that 5-hydroxytryptamine1A receptors are present in the retina and iris sphincter. However, the subsequent finding of 5-hydroxytryptamine7 receptor messenger RNA in the retina and iris may explain the apparent absence of 5-hydroxytryptamine1A receptors in these tissues. The presence of both 5-hydroxytryptamine1A and 5-hydroxytryptamine7 receptors in the ciliary processes may account for the complex intraocular pressure response of the rabbit to serotonin.     

Sphincter of Oddi dysfunction is associated with chronic pancreatitis

To clarify whether the content of glutathione (GSH) in the brain can be estimated by the uptake of 99mTc-meso-HMPAO, we conducted the following in vivo and in vitro experiments. METHODS: We investigated the effect of diethyl maleate (DEM) and buthionine sulfoximine (BSO) administration on the brain uptake of 99mTc-meso-HMPAO in the mouse, rat and rabbit, and the chemical specificity of in vitro interaction of 99mTc-HMPAO to GSH using measurements of octanol-extractable radioactivity as an index of remaining intact tracer. RESULTS: The uptake of 99mTc-meso-HMPAO in the mouse and rat brain were reduced together with decreased content of GSH by preloading of DEM, a GSH depletor that acts through glutathione S-transferase. Neither 99mTc-meso-HMPAO uptake nor GSH content was affected in the rabbit brain. Similarly, the uptake of 99mTc-meso-HMPAO and GSH content in the mouse brain was reduced by preinjection of BSO, a GSH depletor that acts through gamma-glutamylcysteine synthetase. In an in vitro study, 99mTc-HMPAO showed reactivity to the molecules possessing a -SH group, but were not specific to GSH. The order of 99mTc-meso-HMPAO reactivity to the mouse brain homogenate agreed with the order of GSH concentration: normal > BSO > DEM. GSH was a major contributor to the conversion reaction of 99mTc-meso-HMPAO to hydrophilic complex in mouse brain homogenate. CONCLUSION: GSH may have a major responsibility for trapping 99mTc-HMPAO in the brain, suggesting the possibility of in vivo measurement of brain GSH with 99mTc-meso-HMPAO.     

Alniditan, a new 5-hydroxytryptamine1D agonist and migraine-abortive agent: ligand-binding properties of human 5-hydroxytryptamine1D alpha, human 5-hydroxytryptamine1D beta, and calf 5-hydroxytryptamine1D receptors investigated with [3H]5-hydroxytryptamine and [3H]alniditan

Alniditan is a new migraine-abortive agent. It is a benzopyran derivative and therefore structurally unrelated to sumatriptan and other indole-derivatives and to ergoline derivatives. The action of sumatriptan is thought to be mediated by 5-hydroxytryptamine (5-HT)1D-type receptors. We investigated the receptor-binding profile in vitro of alniditan compared with sumatriptan and dihydroergotamine for 28 neurotransmitter receptor subtypes, several receptors for peptides and lipid-derived factors, ion channel-binding sites, and monoamine transporters. Alniditan revealed nanomolar affinity for calf substantia nigra 5-HT1D and for cloned h5-HT1D alpha, h5-HT1D beta and h5-HT1A receptors (Ki = 0.8, 0.4, 1.1, and 3.8 nM, respectively). Alniditan was more potent than sumatriptan at 5-HT1D-type and 5-HT1A receptors. Alniditan showed moderate-to-low or no affinity for other investigated receptors; sumatriptan showed additional binding to 5-HT1F receptors. Dihydroergotamine had a much broader profile with high affinity for several 5-HT, adrenergic and dopaminergic receptors. In signal transduction assays using cells expressing recombinant h5-HT1D alpha, h5-HT1D beta, or h5-HT1A receptors, alniditan (like 5-HT) was a full agonist for inhibition of stimulated adenylyl cyclase (IC50 = 1.1, 1.3, and 74 nM, respectively, for alniditan). Therefore, in functional assays, the potency of alniditan was much higher at 5-HT1D receptors than at 5-HT1A receptors. We further compared the properties of [3H]alniditan, as a new radioligand for 5-HT1D-type receptors, with those of [3H]5-HT in membrane preparations of calf substantia nigra, C6 glioma cells expressing h5-HT1D alpha, and L929 cells expressing h5-HT1D beta receptors. [3H]Alniditan revealed very rapid association and dissociation binding kinetics and showed slightly higher affinity (Kd = 1-2 nM) than [3H]5-HT. We investigated 25 compounds for inhibition of [3H]alniditan and [3H]5-HT binding in the three membrane preparations; Ki values of the radioligands were largely similar, although some subtle differences appeared. Most compounds did not differentiate between 5-HT1D alpha and 5-HT1D beta receptors, except methysergide, ritanserin, ocaperidone, risperidone, and ketanserin, which showed 10-60-fold higher affinity for the 5-HT1D alpha receptor. The Ki values of the compounds obtained with 5-HT1D receptors in calf substantia nigra indicated that these receptors are of the 5-HT1D beta-type. We demonstrated that alniditan is a potent agonist at h5-HT1D alpha and h5-HT1D beta receptors; its properties probably underlie its cranial vasoconstrictive and antimigraine properties.     

On the relationship of 5-hydroxytryptamine neurons to 5-hydroxytryptamine 2A receptor-immunoreactive neuronal processes in the brain stem of rats. A double immunolabelling analysis

The distribution of 5-HT2A receptor immunoreactivity in the brain stem was studied by means of a commercial 5-HT2A mouse monoclonal antibody against the N-terminal portion of the receptor (amino acids 1-72). The 5-HT2A immunoreactivity demonstrated in the nerve terminal or dendritic-like structures of regions of the nucleus raphe pallidus, nucleus interfascicularis, motor nucleus of the trigeminal nerve, the ventral and dorsal tegmental nuclei and the median eminence by means of double immunofluorescence procedures were shown to be associated with 5-HT immunoreactive cell body-dendritic and/or nerve terminal structures. Besides synaptic transmission the relationships are compatible with the existence of short distance volume transmission (in the microm range) in 5-HT2A mediated 5-HT communication through terminal (5-HT)-terminal (5-HT2A) or soma/dendro (5-HT)-terminal (5-HT2A) and terminal (5-HT)-dendritic (5-HT2A) interactions in discrete brain stem nuclei.     

Rat brain neurotransmitter turnover rates altered during withdrawal from chronic cocaine administration

This experiment utilized neurotransmitter turnover rates to assess the effects of withdrawal from chronic cocaine on the brain. A triad-littermate design was used to evaluate the importance of response dependency on the effects of withdrawal from chronic cocaine administration upon brain biogenic monoamine and amino acid putative neurotransmitter turnover rates. Each member of a triad was exposed to one of three conditions. Cocaine infusions (0.33 mg/inf) were used to engender and maintain lever pressing by one rat under an FR 2 schedule, while the second and third rats received simultaneous infusions of either cocaine or saline, respectively. After a minimum of 15 days exposure to the three treatment conditions and 24 h after the start of the last drug session, the triads were pulse labeled with [14C]glucose, [3H]tyrosine and [3H]tryptophan and killed 60 or 90 min later by total immersion in liquid nitrogen, The frozen brains were removed and dissected at -20 degrees C into 22 areas. The content and specific radioactivities for dopamine (DA), noradrenaline (NA), serotonin (5-HT), aspartate (Asp), glutamate (Glu), glycine (Gly) and gamma-aminobutyric acid (GABA) were determined in each brain region using high pressure liquid chromatography with electrochemical (biogenic monoamines) or fluorescence (amino acids) detection followed by liquid scintillation spectrometry. Turnover rates (TOR) were calculated and compared across treatment conditions. The significant decreases in TOR resulting from chronic cocaine exposure included 5-HT in the frontal cortex, DA in the cingulate cortex, entorhinal-subicular and motor-somatosensory cortices and NA in the inferior colliculus. Significant increases in TOR were also observed which included 5-HT in the preoptic-diagonal band region, DA in the hippocampus and NA in the pyriform and temporal-auditory cortices, the dentate gyrus and brainstem. GABA TOR was also increased in the preoptic-diagonal band region, dentate gyrus and brainstem of both groups receiving cocaine as was Glu TOR in the pyriform cortex and cerebellum. In addition, changes were seen in the rats under the ratio schedule of cocaine self-administration that were not seen in rats receiving yoked-cocaine infusions that included increased TOR of 5-HT in the pyriform cortex, NA in the caudate-putamen and GABA in the pyriform and motor-somatosensory cortices. Decreased 5-HT TO was seen in the motor-somatosensory cortex and dentate gyrus in the rats that had self-administered cocaine compared to the yoked-cocaine infused group. Perhaps the most interesting changes were those seen in the yoked-cocaine group that were reversed in the rats whose responding was maintained by cocaine.(ABSTRACT TRUNCATED AT 400 WORDS)     

Hypertension mediated by the activation of the rat brain 5-hydroxytryptamine receptor sites

5-Hydroxytryptamine (5-HT) administered intraventricularly (i.vent.) in rats produced hypertension without considerable changes in heart rate. After transsection of the spinal cord or i.vent. administration of methysergide, 5-HT failed to produce the pressor effect. Thus, the hypertension results from the activation of 5-HT receptor sites of the rat brain.     

Big BU/CY is associated with a favorable long-term outcome in patients allotransplanted for chronic myelogenous leukemia in chronic phase

Twenty-six adult patients, median age 36 years (range 21-53) with chronic myeloid leukemia in first chronic phase were allotransplanted between October 1989 and May 1995. The preparative regimen consisted of busulphan 16 mg/kg and cyclophosphamide 200 mg/kg (big BU/CY). Cyclosporin A and methotrexate were used for GVHD prophylaxis. Twenty-two donors were HLA-identical siblings and four donors were mismatched for one antigen of class I. The global incidence of acute GVHD was 50%, that of severe aGVHD (grades 3-4) was 11%; the global incidence of chronic GVHD was 30%. No patients developed veno-occlusive disease of the liver or interstitial pneumonia. Five patients died, one of relapse, four of transplant-related causes, mostly related to aGVHD; thus, the transplant-related mortality was 16%. Twenty-one patients are alive, in remission, with a median follow-up of 55 months (range 24-90); actuarial probability of survival is 78% (CI 64-96). Our study shows that this conditioning regimen is relatively easy to administer and seems to be as effective as, if not superior to, regimens containing TBI, in patients with chronic myeloid leukemia in chronic phase and the transplant-related mortality is not excessive even in older patients.     

Human chagasic disease is not associated with an antiheart humoral response

An inflammatory cardiomyopathy occurs in humans with chronic Trypanosoma cruzi infection (Chagas' disease). This study finds that T. cruzi infection is not associated with the production of cardiac-specific autoantibodies in humans with cardiac manifestations.     

Integrative visuomotor behavior is associated with interregionally coherent oscillations in the human brain

Coherent electrical brain activity has been demonstrated to be associated with perceptual events in mammals. It is unclear whether or not it is also a mechanism instrumental in the performance of sensorimotor tasks requiring the continuous processing of information between primarily executive and receptive brain areas. In particular it is unknown whether or not interregional coherent activity detectable in electroencephalographic (EEG) recordings on the scalp reflects interareal functional cooperativity in humans. We studied patterns of changes in EEG-coherence associated with a visuomotor force-tracking task in seven subjects. Interregional coherence of EEG signals recorded from scalp regions overlying the visual and the motor cortex increased in comparison to a resting condition when subjects tracked a visual target by producing an isometric force with their right index finger. Coherence between visual and motor cortex decreased when the subjects produced a similar motor output in the presence of a visual distractor and was unchanged in a purely visual and purely motor task. Increases and decreases of coherence were best differentiated in the low beta frequency range (13-21 Hz). This observation suggests a special functional significance of low frequency oscillations in information processing in large-scale networks. These findings substantiate the view that coherent brain activity underlies integrative sensorimotor behavior.     

Plasma oestrogens in a pregnancy associated with chronic haemodialysis

Pregnancy in a patient undergoing regular haemodialysis at home is described. The pregnancy was complicated by antepartum haemorrhage due to a Type I placenta praevia, and premature labour occurred at 32 weeks, resulting in spontaneous vaginal delivery of a live infant which survived. Plasma progesterone oestrone, unconjugated oestradiol and oestriol levels were normal during the last two weeks of pregnancy, but failed to show a characteristic fall in the puerperium. The conjugated oestriol fraction was 20 to 30 times the normal mean level and did not fall after delivery. These findings are discussed.     

Endothelial expression of the 5-hydroxytryptamine1B antimigraine drug receptor in rat and human brain microvessels

In addition to triggering vasoconstriction of peripheral blood vessels, which led to its discovery as a circulating neurohormone 50 years ago, serotonin (5-hydroxytryptamine) acts as a neurotransmitter/ modulator in the central nervous system and regulates local cerebral blood flow and vascular permeability through direct and indirect effects on intraparenchymal microvessels. Among the various 5-hydroxytryptamine receptors which mediate these effects, particular attention has been paid to the 5-hydroxytryptamine1B and 5-hydroxytryptamine1D subtypes, as the preferred targets of modern antimigraine agents. Immunoelectron microscopic labeling of the 5-hydroxytryptamine1B receptor in rat brain parenchyma has revealed a distinct localization to the endothelium of microvessels, which was predominantly cytoplasmic as opposed to membrane-bound, contrary to that on preterminal unmyelinated axons [Riad et al. (1997) Soc. Neurosci. Abstr. 23, 1214]. Similar observations have now been made in human cortical tissue, in which the expected localization of the vascular 5-hydroxytryptamine1B receptor to periarteriolar myocytes was also confirmed. Such a dual localization in human brain microvessels suggests that the 5-hydroxytryptamine1B receptor might mediate opposite effects, vasodilatory and contractile, depending upon its activation by circulating or centrally released 5-hydroxytryptamine. It raises new possibilities as regards 5-hydroxytryptamine effects on human brain microvessels in health and disease, and notably the triggering of migraine headache.     

Elevated environmental temperatures can induce hyperthermia during d-fenfluramine exposure and enhance 5-hydroxytryptamine (5-HT) depletion in the brain

d-Fenfluramine (d-Fen) has been demonstrated to alter body temperature (BT), decrease 5-hydroxytryptamine (5-HT) and decrease 5-HT plasma membrane transporters (PMT) in rats. Therefore, experiments were designed to test whether a correlation existed between elevated BT and brain 5-HT depletions. It was hypothesized that d-Fen would induce hyperthermia if the environmental temperature was elevated. Experiments were conducted to determine 1) the dose-response of d-Fen on BT in a 28 degrees C environment, 2) the acute effect of d-Fen on long-term depletion of 5-HT and 5-HT PMT in a 4 degrees C, 22 degrees C or 28 degrees C environment and 3) the effect of a 22 degrees C environment vs. a 28 degrees C environment on the plasma levels of d-Fen and d-norfenfluramine. d-Fen produced a dose-dependent elevation of BT in the 28 degrees C environment, decreased BT in the 4 degrees C environment and had no effect on BT in the 22 degrees C environment. Exposure to d-Fen in the 4 degrees C or 22 degrees C environment reduced 5-HT and 5-HT PMT concentrations compared with control. However, greater reductions of 5-HT and 5-HT PMT concentrations occurred in the 28 degrees C environment. Conversely, the plasma levels of d-Fen and d-norfenfluramine were not altered. Thus these experiments demonstrate that increased BT during d-Fen exposure occurs at elevated environmental temperatures without altering the plasma concentrations of the drug and results in an enhanced long-term depletion of brain 5-HT and 5-HT PMT.     

Treatment of pruritus in chronic liver disease with the 5-hydroxytryptamine receptor type 3 antagonist ondansetron: a randomized, placebo-controlled, double-blind cross-over trial

BACKGROUND: Recently, the serotonin antagonist ondansetron has been reported to have a positive effect on cholestasis-associated pruritus. OBJECTIVES: To study the effect of orally administered ondansetron on pruritus in chronic liver disease in a randomized, placebo-controlled, double-blind, cross-over study. METHODS: Subjective severity of pruritus was assessed using a visual analogue scale (VAS) recorded four times daily by the patients. After a one week pretreatment baseline period the patients were randomized to receive ondansetron tablets 8 mg tds or placebo tablets tds for one week. Following a one week wash-out period patients were switched to the other treatment for one week. The study was ended by an additional follow-up week without medication. For each day peak VAS values were determined and the mean value of the last five days of each week was calculated and referred to as the composite peak VAS score. RESULTS: We observed a significant but moderate reduction of the composite peak VAS score of 1.34 points (CI(95%): 0.12-2.56; P=0.033) during treatment with ondansetron as compared to placebo (treatment effect). In addition, a period effect was observed: a reduction of composite peak VAS score by 1.26 points (C1(95%): 0.04-2.48; P=0.044) was seen in the second treatment period as compared to the first period, irrespective of the kind of treatment. Although under treatment with ondansetron a significant improvement of itching as assessed by the VAS score was demonstrated, this treatment was not preferred over placebo by the patients. CONCLUSIONS: The 5-hydroxytryptamine receptor type 3 antagonist ondansetron has a small, but significant positive effect on pruritus in chronic liver disease as compared to placebo.     

Hyperhomocysteinemia is associated with atherosclerotic occlusive arterial accidents in predialysis chronic renal failure patients

Hyperhomocysteinemia has been shown to constitute an independent risk factor for premature occlusive arterial disease. Moderate hyperhomocysteinemia is present in chronic uremic patients, who often develop premature atherosclerosis, but no direct evidence of an association between the occurrence of atherosclerotic cardiovascular accidents (CVAs) and hyperhomocysteinemia has yet been reported in such patients. We serially determined total plasma homocysteine (Hcy) levels in a cohort of 93 consecutive chronic renal failure, undialyzed patients (57 males, 36 females) with creatinine clearance (Ccr) < 50 ml/min.1.73 m2 and age > or = 50 years at start of follow-up, together with serial assessment of Ccr and blood lipid parameters. From January 1989 to December 1995, 24 patients (group 1) experienced myocardial infarction (18 cases, 13 males) or cerebral infarction (6 cases, 3 males) while the remaining 69 (group 2) remained free of CVAs. Patients in groups 1 and 2 did not differ with respect to age (66 +/- 1.8 vs. 65 +/- 1.1 years, mean +/- Se) or serum creatinine (227 +/- 24 vs. 251 +/- 36 mumol/l) at onset of a CVA (group 1) or at the end of follow-up (group 2). The mean Hcy level was significantly higher in group 1 (20.7 +/- 1.6 vs. 12.8 +/- 0.5 mumol/l, p < 0.0001), as was the proportion of patients with Hcy in excess of 14 mumol/l, the upper limit in healthy controls (83 vs. 30%, p < 0.0001). Logistic regression analysis identified Hcy as an independent risk factor for CVA, with an odds ratio of 11.4 (95% confidence interval 3.5-37.7), which remained significant after adjustment on other variables. We conclude that an elevated Hcy level is associated with a risk of occlusive arterial accidents in patients with chronic renal failure and that hyperhomocysteinemia contributes to the accelerated atherosclerosis complicating chronic uremia.