Andre Uzan

Effects of 4-(3-indolyl-alkyl)piperidine derivatives on uptake and release of noradrenaline, dopamine and 5-hydroxytryptamine in rat brain synaptosomes, rat heart and human blood platelets

Abstract 4-(3-Indolyl-alkyl)piperidine derivatives (LM 5005, LM 5008, LM 5015) strongly inhibited 5-HT accumulation into rat brain synaptosomes and human blood platelets in vitro but were weaker inhibitors of NA and DA uptake. These new compounds inhibited, like clomipramine, the neuronal membrane active transport whereas reserpine blocked the synaptic vesicle storage process of biogenic amines. They had no effect on 5-HT release from human blood platelets. The duration of 5-HT uptake inhibition in vivo by LM 5015 was equal to that observed with clomipramine (about 3 hr) and longer for LM 5008 and LM 5005. The piperidine derivatives did not inhibit 5-HT uptake into synaptosomes from specific regions of rat brain in the same manner. Unlike the trieyclic antidepressants, LM 5005 and LM 5008 did not block the in vivo uptake of NA into rat heart and LM 5015 was a weak inhibitor. These results suggest that 4-(3-indolyl-alkyl)piperidine derivatives represent a new class of potent and selective inhibitors of 5-HT uptake into rat brain synaptosomes and human blood platelets.

Are antihistamines sedative via a blockade of brain H1 receptors

Most antihistamines are known to induce sedative side but the mechanism remains unclear (Pollard et a1 1973). Such an impairment of central nervous function possibly be attributed to a blockade of the brain’s H~ receptors, recently shown biochemically (Chang et a1 1978; Hill et al1978; Tran et all978). Even if the role of histamine as putative neurotransmitter (Schwartz 1975 ; Schwartz et a1 1976) appears somewhat difficult to evaluate, both the presence of histaminergic fibres innerving the telencephalon via the lateral hypothalamic area (Dropp 1972) and the fact that brain histamine concentration or histamine turnover exhibited cirw d i a n variations (Orr & Quay 1975; Friedman & Walker 1968), might suggest a role of histamine on wakefulness and sleep (Verdiere et a1 1977). Recently, a new phenothiazine derivative, mequitazine or (10-[3-quinuclidinylmethyl]-phenothiazine) has * Correspondence.

Characterization of peripheral type benzodiazepine binding sites in human and rat platelets by using [3H]PK 11195. Studies in hypertensive patients

Peripheral type benzodiazepine binding sites have been studied in human and rat platelets and platelet membranes by using PK 11195 (1-(2-chlorophenyl)-N-methyl-N-(1-methyl propyl)-3-isoquinolinecarboxamide) as a ligand. [3H]PK 11195 binding to the intact cells and membranes is saturable, with a high affinity and presents the pharmacological specificity corresponding to the peripheral binding sites (PK 11195 greater than RO5-4864 greater than diazepam greater than clonazepam). [3H]PK 11195 affinity is not affected by cell lysis, but there is a loss of binding capacity, contrarily to RO5-4864 whose affinity is greatly diminished. For this reason [3H]RO5-4864 binding can only be demonstrated in intact cells. Furthermore opposite to RO5-4864, PK 11195 affinity is not decreased by increasing temperatures. No difference was found between binding parameters (KD and Bmax) for [3H]PK 11195 between normotensive and hypertensive subjects. The very high binding capacity of human and rat platelets (Bmax greater than pmole/10(8) cells) makes them a good biological model for studying the physiological significance of peripheral type benzodiazepine binding sites.

In vivo labelling in several rat tissues of peripheral type benzodiazepine binding sites

Peripheral type benzodiazepine binding sites in several rat tissues were labelled by intravenous injection of [3H]PK 11195 and [3H] RO5 -4864. Binding was saturable in all tissues studied and regional distribution paralleled the in vitro binding. A similar potency order of displacing compounds was found in vivo and in vitro PK 11195 greater than PK 11211 greater than RO5 -4864 greater than diazepam greater than dipyridamole greater than clonazepam. These results demonstrate the feasibility of using this technique to examine the effects of pharmacological manipulation on the binding sites in their native state. However some properties (broader maximum during time course, higher percentage of particulate binding in the brain and independence of temperature) make [3H]PK 11195 the most suitable ligand for this kind of studies.

Central dopaminergic neurons during development of genetic and doca-salt hypertension in the rat

The in vivo binding of [3H]spiroperidol was measured in discrete areas of the brain in 7-, 9- and 16-week-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) controls. An increase in the [3H]spiroperidol binding in the striatum, tuberculum olfactorium and frontal cortex but not in the cerebellum was detected at all ages in SHR. The increase was more pronounced in 7- than in 9- or 16-week-old SHR. In vitro data indicated an increase in Bmax but no variation in Kd in the striatum of 7-week-old SHR. Moreover no difference was detectable in the dopaminergic cell bodies (A9, A10). This increase was specific to [3H]spiroperidol binding sites since no difference was observed in the in vivo binding of [3H]QNB and [3H]LSD in the same brain regions. No variation in dopamine level or dopamine utilization, as estimated by measuring the disappearance of the amine induced by alpha-methyl-p-tyrosine, was observed. The DOPA accumulation after injection of the DOPA decarboxylase inhibitor NSD 1015 was greater in the tuberculum olfactorium from 7-week-old SHR. An increase in [3H]spiroperidol binding sites was also observed in the striatum and tuberculum olfactorium after 7 weeks of DOCA-salt treatment. These results suggest that dopaminergic neurons might be implicated in the onset of hypertension in the rat.

In vivo blockade of dopaminergic receptors from different rat brain regions by classical and atypical neuroleptics

Abstract The effect of haloperidol, chlorpromazine, clozapine, benzamides (sulpiride and isosulpride), 6-chloropyrimidines (mezilamine, UK 177) on the in vivo binding of [ 3 H]spiroperidol to striatum, tuberculum olfactorium, frontal cortex and cerebellum in the rat brain was investigated. Since these neuroleptics of various chemical classes were able to prevent the selective retention of [ 3 H]spiroperidol in the striatum and tuberculum olfactorium without modifying the level in the cerebellum, it has been assumed that [ 3 H]spiroperidol is a suitable ligand to label dopaminergic receptors in the living animal. All the neuroleptics (except the benzamides) were able to displace [ 3 H]spiroperidol from its receptors in the frontal cortex, suggesting a serotoninergic component in neuroleptic binding sites. Classical neuroleptics (haloperidol, chlorpromazine, UK 177) or atypical neuroleptics (clozapine, sulpiride, isosulpride, mezilamine) did not induce a selective blockade of dopaminergic receptors in the striatum or in the limbic system, respectively. These results indicate that there is no correlation between the selective regional stimulation of dopamine turnover after neuroleptics and the in vivo blockade of postsynpatic dopaminergic receptors.

Selective labelling of murine B lymphocytes by [3H]spiroperidol.

Recently we have located [3H]spiroperidol binding sites in a mixture of blood mononuclear leucocytes separated by Ficoll-Paque gradient centrifugation (Le Fur et al 1980) but the presence of T and B lymphocytes as well as monocytes (Zucker Franklin 1974) in this preparation raises the question of what kind of mononuclear leucocytes are really concerned with these binding sites. Such a study might be a valid preliminary approach to the understanding of the possible role of dopaminergic receptors in the cellularmediated immune response. We now report on more purified cell preparations isolated from blood, spleen, thymus o r peritoneal exudates. Female CD1 (from Charles River) Balb/C and Nu/Nu mice (20 12 g) (from Ifa-Credo) were used. Lymphocytes were isolated from fresh heparinized blood of spleen using a Ficoll-Paque gradient and hypotonic lysis of erythrocytes (Boyum 1967; Fotino et a1 1971). T lymphocytes were obtained after a passage of the cells over columns of glass wool (Pattengale et a1 1974). A monocyte-enriched population was obtained by passage over Sephadex G-I0 columns then mechanical agitation (Ly & Mishell 1974). Polymorphonuclear leucocytes were prepared by using a sedimentation in a high molecular height dextran (Galant et al 1978). Macrophages were obtained from peritoneal exudates (Fray et a1 1979). red blood cells after a passage over a cellulose column (Beutler et al 1976). platelet suspension according t o the method of Vargaftig et a1 (1976) and thyn~ocy tes according to Ford & Hunt (1973). Viability of the cells was determined by exclusion of trypan blue dye and was always greater than 9596. The cells were resuspended in Hanks balanced salt solution. Specific binding was determined as previously described (Le Fur et a1 1980) by incubating in triplicate 108 cells at 37 C in 1 ml of Hanks salt solution with 5 nM of [3Hlspiroperidoi (25.1 Ci mmol-I NEN) in the presence (non-specific binding) o r absence (total binding) of 10 p~ haloperidol. Cells were filtered after 60min using Whatman GF/B filters which were then rinsed 3 times with 4 ml of Hanks solution, dried and the radioactivity measured by liquid scintillation

On the regional and specific serotonin uptake inhibition by LM 5008.

Abstract LM 5008 is 6 to 7 times more effective than clomipramine and fluoxetine in inhibiting 5-HT uptake and always less active on the other neurotransmitters uptakes. LM 5008 does not affect muscarinic receptors. The weak in vivo 5-HT uptake inhibition into hypothalamus and striatum may be attributable to a reversible binding of LM 5008 to the hypothalamus presynaptic membranes and to a really slight effect in the striatum.

Effects on striatal and mesolimbic dopamine systems of a new potential antipsychotic drug -mezilamine- with weak cataleptogenic properties

Abstract Mezilamine (2-methylamino-4-N-methylpiperazino-5-methylthio-6-chloropyrimidine) inhibits dopamine-sensitive adenylate cyclase in rat nucleus accumbens and striatum both in vitro and in vivo. After parenteral administration, mezilamine produces a dose dependent increase in homovanillic acid in rat and rabbit brain. As with clozapine, this increase is more marked in the limbic system than in the striatum of rabbit brain whereas the reverse holds true in the rat. However, in rats pretreated with probenecid, mezilamine and clozapine produce a greater activity in the limbic system while that of chlorpromazine is more pronounced in the striatum. In both regions mezilamine is more active than chlorpromazine. After chronic treatment (15 days), the activity of mezilamine decreases in the striatum but not in the limbic system. The low cataleptogenic activity of mezilamine cannot be explained by anticholinergic properties, neither can it be related to GABA-mimetic properties. Among the hypotheses discussed that attributing α-adrenergic properties to mezilamine is supported by the catalepsy-inducing effect observed in the rat when associating mezilamine and phenoxybenzamine.

Effects of 4-(3-indolyl-alkyl) piperidine derivatives on brain 5-hydroxytryptamine turnover and on cardiac and brain noradrenaline or 5-hydroxytryptamine depletion induced by 6-hydroxydopamine, H 7512 and 4-chloroamphetamine

Abstract 4-(3-Indolyl-alkyl)piperidine derivatives (LM 5005, LM 5008 and LM 5015), like clomipramine, had no or little effects on brain 5-HT but reduced brain 5-HIAA levels and 5-HT turnover, after single or chronic treatment. Brain tryptophan levels remained unaffected by clomipramine, were slightly decreased by LM 5008 and increased by LM 5005 and LM 5015. The piperidine derivatives counteracted brain 5-HT depletion induced by H 75 12 and 4-chloroamphetamine more effectively than clomipramine, after i.p. or p.o. administration. On the contrary clomipramine was more effective in inhibiting cardiac NA depletion induced by 6-OH-dopamine than LM 5015; LM 5008 and LM 5005 were ineffective. The potential therapeutic effects of such compounds in mental diseases are discussed.