Nutritional parameters modify muricidal behavior of male Wistar rats: preventive effects of amino acids and 4' Cl diazepam

In male Wistar rats fed a diet enriched in polyunsaturated fatty acids and starch (PUFA+S), the percentage of muricidal (Mu) rats increased to 82% within 60 days. Mu rats had higher serum triglyceride levels and lower cholesterol levels than non-Mu rats. Water intake decreased in all rats on the PUFA+S diet concurrently with the increase in the proportion of Mu rats; protracted water restriction in rats fed standard diet also increased the percentage of Mu rats. In the offspring of two Wistar females fed the PUFA+S diet, the proportion of young Mu rats was 67%. When the PUFA+S diet was replaced with standard diet, the induced Mu behavior was not reversed. PK11195 (6 mg/kg i.p.), clonazepam (0.2 mg/kg i.p.), and flumazenil (15 mg/kg i.p.) were ineffective in reversing the induced Mu behavior, whereas 4'-chlorodiazepam (5 mg/kg i.p.) or muscimol (0.5 mg/kg i.p.) caused reversals of 63% or 50%, respectively. A 5-hydroxytryptophan overload (60 mg/kg i.p.) also reversed Mu behavior by 71%. All reversal effects were temporary. Pretreatment with yeast for 7 days before the PUFA+S diet was given prevented induction for more than 90 days on the PUFA+S diet, while similar pretreatment 4'Cl-diazepam resulted in 71% prevention of induction. The results are analyzed in terms of the involvement of endozepin, vasopressin, and serotonin receptors, and of possible genetic parameters.

Regional distribution of benzodiazepine binding sites in the human newborn and infant hypothalamus. A quantitative autoradiographic study

Using in vitro quantitative autoradiography and [3H]flunitrazepam we examined the rostrocaudal distribution of benzodiazepine binding sites in the human neonate/infant hypothalamus. The autoradiographic analysis shows the presence of a heterogeneous distribution throughout the rostrocaudal extent of this brain structure. High [3H]flunitrazepam binding corresponds primarily to the diagonal band of Broca and the preoptic region. The labelling in the preoptic region showed a rostrocaudal increase, contrasting in that with the other hypothalamic structures. Intermediate densities were present in the septohypothalamic, suprachiasmatic, periventricular and paraventricular nuclei as well as in the mammillary complex. Low binding was observed in the other hypothalamic structures. The benzodiazepine binding sites analyzed belong mostly to type II receptors. In an attempt to unravel possible differences related to age, we compared the autoradiographic distribution in three postnatal age ranges. The topographical distribution of these binding sites was almost identical in each period analyzed. We found, however, that benzodiazepine binding is generally low in the neonatal period and a tendency in increasing densities is observed during development. Taken together, these results provide evidence for a large distribution of benzodiazepine binding sites in neonate/infant hypothalamus, suggesting their implication in the development of this brain structure and the maintenance of its various functions.

Benzodiazepine binding sites in the human hypothalamus. Autoradiographic study

Using in vitro labelling and autoradiographic techniques, we have analyzed the fine and the detailed distribution of benzodiazepine binding sites in the post-mortem human hypothalamus. Binding sites were labelled in mounted tissue sections from adult brains, using the selective high affinity ligand [3H]-Flunitrazepam. A heterogeneous distribution of benzodiazepine binding sites was found throughout the rostrocaudal extent of human hypothalamus. The autoradiographic labelling was shown in the three hypothalamic parts, i.e., anterior, mediobasal and posterior levels. At the anterior level, the highest densities were present in the diagonal band of Broca, the preoptic area (medial and lateral parts) and the septohypothalamic nucleus. At the mediobasal hypothalamic level, the highest densities were mainly localized in the ventromedial nucleus, whereas the other structures were moderately labelled with [3H]-Flunitrazepam. The mammillary complex as well as the posterior hypothalamic area represented the most heavily labelled structures in the posterior hypothalamus. The results obtained in this study, indicate the presence of a large and heterogeneous distribution of benzodiazepine binding sites in human adult hypothalamus. This could support their implication in the control of distinct neural functions (like neuroendocrine role).

Cholesterol and triglyceride levels in the serum of muricidal male Wistar rats: indices of mitochondrial benzodiazepine receptors?

Cholesterol and triglyceride levels were studied in the serum of aggressive muricidal and non-muricidal male Wistar rats. The muricidal behavior was either spontaneous or induced by a long-term isolation or by adrenalectomy. Cholesterol levels were slightly higher in the whole population of muricidal rats; this was mainly observed in spontaneously and in adrenalectomized muricidal rats, as compared to non-muricidal rats of the same series. As regards triglyceride levels, they were significantly higher in the whole population of muricidal rats, mainly in isolation- and adrenalectomy-induced muricidal rats; the ratio of triglycerides to body weight was higher in the serum of muricidal rats of all series. The possible significance of these results is discussed in light of the data of the literature and related to the functional role of either mitochondrial benzodiazepine receptors or serotonin.

Evaluation of endozepine-like immunoreactivity in the frontal cortex of suicide victims

Diazepam-binding inhibitor (DBI) and its processing products, including the octadecaneuropeptide (ODN), are polypeptides called endozepines which have multiple biological effects, including regulation of mitochondrial steroidogenesis and modulation of GABA-gated chloride channels. Concentrations of ODN-like immunoreactivity (ODN-Li) were measured by radioimmunoassay in the frontal cortex of nine drug-free suicides and nine drug-free sudden-death victims. The level of ODN-Li was higher in the right than in the left frontal cortex, in both suicide (p < 0.05) and control (p < 0.02) subjects. No significant differences were found between suicides and controls either in the right and left cortex, or when considering the gender and the post-mortem diagnosis of depression.

Prevention of ACTH- and adrenalectomy-induced muricidal behavior: by benzodiazepinic ligands

We investigated the effect of treatment with central (neuronal and glial) benzodiazepine binding site-active molecules on ACTH- or adrenalectomy (ADX)-induced muricidal behavior in male Wistar rats. Pretreatment (IP) with either flumazenil or clonazepam prevented the subsequent induction of ADX-induced behavior, but only flumazenil protected against ACTH-induced behavior; posttreatment in both cases induced no significant modifications. Using 4'-chloro-diazepam or PK 11195, both pre- and posttreatment afforded protection, the effect lasting longer (> 1 week) than that induced by flumazenil or clonazepam (2 days). Pretreatment with the GABAA agonist, muscimol, also resulted in complete protection, whereas posttreatment had only a slight effect.

Induction of muricidal behavior by ACTH or adrenalectomy in young male Wistar rats

ACTH administered IP induces a muricidal behavior in 52% of male Wistar rats that do not express it before; such behavior is also observed spontaneously in 68% of adrenalectomized animals. This change in behavior is characterized by an exceptionally long duration (several months in some animals), and by its prevention by previous or substitutive treatments with dexamethasone. Data obtained using hypophysectomized or adrenalectomized animals with or without ACTH treatments suggest that the muricidal-inducing effect of ACTH might have, at least partially, a central origin.

Long-term isolation of Wistar rats alters brain monoamine turnover, blood corticosterone, and ACTH

In this work, we investigated neurochemical parameters in the brain of male Wistar rats after isolation times (13 weeks) longer than those previously reported with this strain: a large majority of animals became muricidal under these conditions. Changes in monoamines turnover in hippocampus, cortex, and cerebellum and, in the blood, ACTH, and corticosterone were investigated. Monoamine turnover was analysed using two different approaches: first, by measuring neurotransmitter and metabolite levels and second, by measuring rate of accumulation of the precursor after decarboxylase. Both methods revealed a significant increase in catecholamine turnover in the three regions studied after the 13-week isolation; in contrast, only a modest elevation of 5-hydroxytryptophan accumulation was obtained in cortex and cerebellum of isolated rats. We also observed a decrease in corticosterone levels in blood concomitant with an increase of ACTH.

Benzodiazepine binding sites and their modulators in hippocampus of violent suicide victims

Benzodiazepine binding sites were studied by autoradiography in several hippocampic layers in brains of drug-free violent suicide victims (hanging) and matched controls. Kd was increased in suicides, and when brain sections from control subjects were incubated in the bath fluid that had previously served to incubate sections from suicides, Kd was increased in the same way. Results are discussed in terms of possible modulators of benzodiazepine binding sites, mainly tissue GABA and amino acid concentrations.

Quantitation by gas chromatography with selected-ion monitoring mass spectrometry of "natural" diazepam, N-desmethyldiazepam and oxazepam in normal human serum

During the past five years, the literature has tended to prove the occurrence of "natural benzodiazepines" in tissues and biological fluids of non-medicated humans. Several have been identified but very few papers deal with their quantitation in biological material. We present here a method for the specific and sensitive measurement of serum levels of diazepam, N-desmethyldiazepam and oxazepam by gas chromatography with selected-ion monitoring mass spectrometry in twenty human volunteers without medication. Diazepam was found over the whole population, in the range 7.3-32.0 pg/ml, identical in males and females. The other two were present in only some individuals (1.0-7.6 pg/ml for N-desmethyldiazepam and 2.0-13.0 pg/ml for oxazepam). The origin (endogenous, dietary or microbial) of these substances is still to be elucidated.

Quantitative evaluation of octadecaneuropeptide-like immunoreactivity in hippocampus, cortex and cerebellum of long-term isolated male Wistar rats

Quantitative evaluation of octadecaneuropeptide-like immunoreactivity (ODN-Li) was carried out in hippocampus, cortex and cerebellum of group-reared or three month isolated male Wistar rats, whether muricidal or not. ODN-Li was lower in cortex and cerebellum of isolated animals, (mainly in muricidal) than of group-reared ones. A similar trend was apparent in the hippocampus. No significant differences were observed between muricidal and non-muricidal animals. The results are discussed in terms of the involvement of the endogenous ligands of the GABA-benzodiazepine receptor complex in the integrations related to mood and behaviour.

Isolation-induced changes in radioligand binding to benzodiazepine binding sites

Binding of [3H]flunitrazepam was studied in brain tissues of isolated Wistar rats and compared to group-reared animals. Modifications were observed in hippocampus and cortex (Kd increased) and in cerebellum (Bmax decreased) and when brain sections of control rats were incubated in the bath fluid that had served to incubate sections from isolated rats, a flattening of the saturation curve was observed. Results are discussed in terms of possible modulators of benzodiazepine binding sites, mainly tissue GABA concentrations.

Benzodiazepine receptor and neurotransmitter studies in the brain of suicides

The characteristics of benzodiazepine binding sites (affinity, number heterogeneity) were studied on frozen sections of hippocampus of 7 suicides and 5 controls subjects, using biochemical and autoradiographic techniques. 3H flunitrazepam was used as ligand, clonazepam and CL 218,872 as displacing agents. Some neurotransmitters or their derivatives (GABA, catecholamines, hydroxy-indols) were evaluated quantitatively in parallel in the hippocampal tissue by liquid chromatography. We observed mainly an increase in the Ki of CL 218,872 subtype I binding sites in suicides, (7.48 +/- 1.7 to 17.24 +/- 1.7 nM, P less than 0.01), (m +/- SEM) and an increase in % of type I binding sites (30 +/- 4.2 to 42 +/- 2.5, P = 0.01). Among neurotransmitters, only norepinephrine differed significantly between controls and suicides (11.34 +/- 1.9 to 24.34 ng/g tissue, P = 0.02).

Autoradiographic and quantitative study of benzodiazepine-binding sites in human hippocampus

Benzodiazepine-binding sites were studied on frozen sections of 5 human hippocampi, using autoradiographic and biochemical techniques. The affinity, density, distribution and heterogeneity (two types) of sites were investigated using [3H]flunitrazepam as a ligand, clonazepam or C1 218872 as displacing agents. The autoradiographic images evidence a differential distribution of the binding sites in the histologic layers of the hippocampus. Subtypes I and II coexist in the same proportion in the three layers exhibiting the highest densities of binding sites (stratum granulosum and pyramidale, deep layer of stratum radiatum). The Kd, Bmax and Ki values found here are analogous to those described in animal studies, but the anatomical distribution of the sites in human hippocampus seems to differ slightly from that previously described in that of the rat.

Identification of catecholamine cell bodies in the pons and pons-mesencephalon junction of the cat brain, using tyrosine hydroxylase and dopamine-beta-hydroxylase immunohistochemistry

Using a double labeling immunohistochemical method with antibodies to tyrosine hydroxylase and dopamine-beta-hydroxylase, we reexamined the topographical distribution of dopaminergic (DA) and noradrenergic (NA) cells in the pons-mesencephalon junction of the cat. Besides DA cells of SN and its extensions, DA cells were also observed more caudally in nucleus raphe linearis intermedius and dorsalis, decussation of brachium conjunctivum, fasciculus longitudinalis medialis and periaqueductal gray. In nucleus locus coeruleus, cells exhibited variable levels of DBH, but dopaminergic cells were not evidenced in this structure.

[Relation between dopamine and serotonin motor effects on isolated rat duodenum. Possible participation of an excitatory dopaminergic receptor]

The experimental facts presented here allow us to establish a relationship between DA motor effects on isolated rat duodenum, studied in a previous work, (excito-motor between 10(-9) M and 10(-5) M and inhibitor beyond 10(-5) M) and the functional aptitude of this duodenum to answer to 5-HT : 5-HT excito-motor effects are amplified by DA at concentrations less than or equal to 2.6 X 10(-6) M and on the contrary antagonized by DA at concentrations above 5 X 10(-6) M. On the other hand, DA excito-motor effects do not appear on 5-HT-desensitized duodenums. The study of 5-HT dose-response curves in the presence of different concentrations of DA suggests that the amplification of serotonergic effects observed with small DA concentrations can be possibly related to the additional effects of 5-HT on its own receptors and of DA on another receptor. The receptor involved in DA excito-motor action seems to be closely related to the 5-HT receptor since its effects are blocked by the same molecules (methylsergide, cyproheptadine) and since DA excito-motor action is no more evident on 5-HT-desensitized duodenums, but several arguments support the specificity of this receptor for DA (though it is not blocked by haloperidol). Some of its effects are in line with those of DA receptors made conspicuous in other territories and not blocked by haloperidol : central and human colon receptors. On the contrary, DA used at high concentrations (greater than or equal to 5 X 10(-6) M) seems to be able to occupy serotonergic sites, preventing 5-HT access to its receptors until its concentration is high enough to displace DA. From a functional point of view, this antagonistic effect of DA at high concentrations against 5-HT excito-motor effects could facilitate alpha- and beta-mediated inhibitory effects.

[Effects of precursors and metabolites of catecholamines on motricity of isolated rat duodenum. Particular reference to dopamine]

Studying the effects, on the isolated rat duodenum motricity, of ten compounds precursors or metabolites of catecholamines, the following results were obtained: The direct metabolites of epinephrine and norepinephrine (metanephrine, normetanephrine), are either ineffective at concentrations below 5 X 10(-6) M, or weakly inhibitory at higher concentrations. Such inhibitory effects are prevented by alpha- and beta-blockers. 3-methoxy, 4-hydroxyphenylglycol and vanylmandelic acid have no significant effect. The catecholamine precursor, dopamine, the related compounds DOPA, 3 methoxytyramine, and to a lesser extent, 3-O methyl DOPA and homovanillic acid, have excito-motor effects at concentrations ranging mainly from 10(-7) M to 10(-5) M. At higher concentrations, the same compounds frequently exhibit inhibitory effects. The excito-motor effects might be due to a serotoninergic mechanism, since they are suppressed by the serotoninergic blocking agents methysergide and cyproheptadine. Furthermore, in the case of DOPA, we were able to establish a relationship between the excito-motor effects and duodenal serotonin stores. As for the inhibitory effects, they may be prevented by using alpha and beta blocking agents. Dihydroxyphenylacetic acid has no effect on the isolated rat duodenum motricity. The fact that dopamine and related compounds may have excitomotor effects at some concentrations, correlated with some physiopathological observations in man and animal allows some considerations about the eventual role of dopamine on intestinal motricity.

[Role of duodenal serotonin in the pharmacological effects of DOPA and dopamine in the isolated rat duodenum]

We have studied the responsibility of tissue serotonin reserves in the excito-motor effects induced by DOPA and dopamine on the isolated rat duodenum in vitro in certain experimental conditions. Two groups of experiments have been performed: first the determination of serotonin endogenous stores after administration of repeated high doses of DOPA and dopamine in the organ bath, secondly the evaluation of motor effects of DOPA and dopamine on rat duodenums experimentally depleted of their endogenous serotonin stores. Serotonin levels were lowered after DOPA and the excito-motor effect of this compound was suppressed in serotonin-depleted duodenums. After dopamine, serotonin tissue levels were not significantly lowered, and the excito-motor effect was observed whatever the serotonin stores may be, depleted or not. Our results are consistent with a relationship between the excito-motor effects of DOPA and serotonin release from endogenous stores; but, concerning dopamine, experimental proofs supporting this hypothesis have not been obtained.