High-affinity [3H]imipramine binding in rat hypothalamus: association with uptake of serotonin but not of norepinephrine.

Inhibition of the binding of [3H]imipramine and inhibition of the uptake of [3H]serotonin and [3H]norepinephrine by a series of antidepressants and other drugs were studied in the rat hypothalamus. No correlation was found between the potencies of these drugs for the inhibition of [3H]imipramine binding and the inhibition of [3H]norepinephrine uptake. There was, however, a highly significant correlation between the potencies of these drugs for the inhibition of [3H]serotonin uptake. These results suggest that high-affinity [3H]imipramine binding might be associated with the mechanism of serotonin uptake in the brain.

Tritiated imipramine binding sites are decreased in platelets of untreated depressed patients.

The high-affinity binding of triatiated imipramine to platelet membranes was compared in samples from 16 untreated depressed women and 21 age-matched controls of the same sex. The maximal binding in the depressed group was significantly lower than that of the controls, although the affinity constants were similar. These results suggest that binding of tritiated imipramine in human platelets may represent a biochemical index of depression, possibly reflecting similar changes in the brain.

Neuropharmacology of 5-hydroxytryptamine1B/D receptor ligands.

In spite of a lack of compounds acting selectively at the 5-hydroxytryptamine (5-HT)1B and 5-HT1D receptor subtypes, by cross-relating the available data, this review attempts to tentatively assign behavioural and other in vivo correlates of these receptor subtypes. In addition, a summary of data from microdialysis studies is included to develop an integrated view. Finally, a suggestion is made as to the possible pathophysiological consequences of 5-HT1D receptor dysfunction in man.

How local and state regulations affect the child care food environment: A qualitative study of child care center directors' perspectives.

Almost one-third of preschoolers spend regular time in child care centers where they can consume the majority of their daily dietary intake. The child care setting influences children's dietary intake. Thus, it is important to examine factors, such as local and state regulations, that influence the food environment at the center. This qualitative study explored directors' perceptions of how regulations influence the foods available at child care centers. Ten directors of centers in Travis County, Texas completed semi-structured interviews. Directors reported that changes in local health department regulations (e.g., kitchen specifications) result in less-healthful foods being served (e.g., more prepackaged foods). Directors of centers that do not participate in the federal Child and Adult Care Food Program (CACFP) said the state licensing regulations clarify the portion size and nutritional requirements for preschoolers thereby improving the nutritional quality of the food served. Directors of centers participating in CACFP said they are not affected by state mandates, because the CACFP regulations are more stringent. These findings suggest that state regulations that specify and quantify nutritional standards may beneficially impact preschoolers' diets. However, local health department regulations enacted to improve food safety may negatively influence the nutritional value of food served in centers.

Carnitine acetyltransferase activity is not changed with age in rat brain and human platelets.

Carnitine acetyltransferase activity was studied in different brain regions of the rat and in human platelets. The values of Km for carnitine and for acetyl-CoenzymeA (acetyl-CoA) were similar in cortex, hippocampus and striatum of the rat and in human platelets, suggesting that carnitine acetyltransferase might be a useful peripheral marker of its central activity. The activity of this enzyme was similar in the cortex and hippocampus of young and old rats. Furthermore, the determination of carnitine acetyltransferase activity in platelets from healthy volunteers showed no significant difference with age.

Sensitivity of the response of 5-HT autoreceptors to drugs modifying synaptic availability of 5-HT.

The effect of midalcipran, an equipotent inhibitor of the uptake of 5-hydroxytryptamine (5-HT) and noradrenaline (NA), on the inhibition of release of 5-HT induced by lysergic acid diethylamide (LSD), was investigated by studying the overflow of transmitter from slices of hypothalamus from the rat prelabelled with [3H]5-HT. The (Z)-enantiomer of midalcipran, at 0.1 microM, displaced to the right the concentration-effect curve of inhibition of release of [3H]5-HT elicited by electrical stimulation induced by LSD. In contrast, the (E)-enantiomer, which does not inhibit the uptake of monoamines, was devoid of any antagonizing effect. The inhibitory effect of 0.1 microM LSD was not modified in the presence of maprotiline, bupropion or mianserin at 1 microM. The results of this study show that the interaction between the 5-HT autoreceptor and the inhibitors of the uptake of 5-HT is related exclusively to their potency at inhibiting the uptake of 5-HT. The effect of the monoamine oxidase inhibitor, pargyline (1-10 microM), was also studied on the field-stimulated release of [3H]5-HT. The inhibitory effect of this drug was antagonized by methiothepin at 0.1 and 1 microM, by phentolamine 1 microM and 10 microM and by the inhibitor of the uptake of 5-HT, citalopram at 0.1 and 1 microM. The action of pargyline appeared to be mediated through the activation of the serotonergic autoreceptor and of the presynaptic alpha-adrenoceptor located on serotonergic nerve terminals. The results obtained with pargyline are consistent with the hypothesis of an interaction between the 5-HT autoreceptor and the uptake site for 5-HT.(ABSTRACT TRUNCATED AT 250 WORDS)

5-HT autoreceptors in the regulation of 5-HT release from guinea pig raphe nucleus and hypothalamus.

5-HT autoreceptors involved in the regulation of 5-HT release in the guinea pig dorsal raphe nucleus have been studied in comparison with those in the hypothalamus. In vitro release was measured in slices of raphe and hypothalamus prelabelled with [3H]5-HT, superfused with Krebs solution and depolarized electrically. The non-selective 5-HT receptor agonist, 5-carboxamidotryptamine (5-CT) (0.1-10 nM for raphe: 1-100 nM for hypothalamus) and antagonist, methiothepin (10-1000nM), decreased and increased, respectively, the release of [3H]5-HT evoked by electrical stimulation in either of these regions when given alone. The selective 5-HT1B/D receptor antagonist, GR127935 (100-1000 nM), and the 5-HT1D receptor antagonist, ketanserin (300-1000 nM), had no significant effect on this release in either of these regions. Methiothepin and GR127935 (100-1000 nM) shifted to the right the concentration-effect curve of 5-CT in both the raphe and the hypothalamus. At 300 nM, ketanserin shifted to the right the concentration-effect curve of 5-CT in the raphe but did not modify the 5-CT curve in the hypothalamus. In microdialysis experiments ketanserin, applied locally at 10 microM, increased the extracellular levels of 5-HT in the dorsal raphe nucleus of the freely moving guinea pig, whereas 5-HT levels were unchanged in the hypothalamus. Ketanserin at 1 microM did not affect the decrease in 5-HT output induced by the selective 5-HT1B/D receptor agonist, naratriptan (used at 10 microM in raphe and 0.1 microM in hypothalamus), in the raphe or the hypothalamus. In the raphe, WAY100635, a 5-HT1A receptor antagonist, at 1 microM, did not prevent naratriptan (10 microM) from reducing the extracellular levels of 5-HT. These results suggest that, in the conditions used in this study, the release of 5-HT in the dorsal raphe nucleus is possibly modulated in part by 5-HT1B receptors but essentially the control is through 5-HT receptors whose subtype is still to be determined. In the hypothalamus, however, it is clear that only 5-HT1B receptors are involved in the modulation of 5-HT neurotransmission.

Dihydroergocristine-induced stimulation of the 5-HT autoreceptor in the hypothalamus of the rat.

In slices of the hypothalamus of the rat, prelabelled with [3H]5-hydroxytryptamine ([3H]5-HT), dihydroergocristine (DHEC) decreased in a concentration-dependent manner (0.01-1 microM) the release of [3H]transmitter elicited by stimulation. In the presence of phentolamine (1 microM), sulpiride (1 microM), atropine (1 microM) or methiothepin (0.1 microM), the effect of DHEC remained unchanged. However, methiothepin at 1 microM and citalopram at 1 microM antagonized the inhibition induced by DHEC. Methiothepin at 0.1 microM has been shown to be sufficient to shift to the right the concentration-effect curve of D-lysergic acid diethylamide (LSD) on the stimulation-evoked release of [3H]5-HT by a factor of 10. However, in the present experiments, 1 microM methiothepin was required to antagonize the effect of DHEC. Thus, the alpha adrenergic, dopaminergic and cholinergic activities of DHEC do not seem to be responsible for its effect on the release of 5-HT. The lower potency of methiothepin suggests, however, that stimulation of the 5-HT autoreceptor by DHEC may not fully explain the results.

Muscarinic receptor plasticity in rats lesioned in the nucleus basalis of Meynert.

The present study investigated the effects of chronic treatment with scopolamine (10 mg/kg i.p. for 21 days) on the muscarinic acetylcholine receptors in the frontoparietal cortex of rats, lesioned at the level of the nucleus basalis of Meynert. Ibotenic acid (25 nmol in 0.5 microliters) was injected bilaterally or unilaterally into the area of this nucleus and produced a major impairment of the cortical cholinergic system. These lesions depleted specifically frontoparietal cortical choline acetyltransferase activity. Sham-operated rats were similarly operated but no neurotoxin was injected. The chronic treatment with scopolamine caused a significant increase in the binding of [3H](-)quinuclidinylbenzilate to muscarinic receptors in the frontoparietal cortex of control and sham-operated rats but not in lesioned animals. This increase was due to an up-regulation in the number of muscarinic acetylcholine receptors, without significant change in their affinity. These results suggest that a functional presynaptic cholinergic terminal is necessary for the plasticity of muscarinic receptors in the central nervous system.

Effect of antidepressant drugs on monoamine synthesis in brain in vivo.

The activity of tryptophan and tyrosine hydroxylase were estimated in vivo by measuring the accumulation during 30 min of 5-hydroxytryptophan (5-HTP) and 3,4-dihydroxyphenylalanine (DOPA), respectively, after inhibition of aromatic amino acid decarboxylase by administration of m-hydroxybenzylhydrazine (NSD 1015) (100 mg/kg, i.p.). Whereas the activity of tyrosine hydroxylase in the dopamine-rich striatum was sensitive to haloperidol, which caused a significant increase in accumulation of DOPA, there was no effect of haloperidol in the predominantly noradrenergic frontoparietal cortex, confirming that the activity of tyrosine hydroxylase, measured in the frontoparietal cortex, is essentially localized in noradrenergic neurones. In the frontoparietal cortex of the rat the in vivo activity of tryptophan and tyrosine hydroxylase were equipotently attenuated by imipramine, while the selective blocker of the uptake of noradrenaline, desipramine and the selective blocker of the uptake of serotonin, citalopram, reduced only tyrosine or tyrosine hydroxylase respectively. Milnacipran, an antidepressant which inhibits the uptake of both monoamines to a similar extent, decreased the synthesis of both monoamines equipotently. The monoamine oxidase inhibitor, clorgyline, also reduced the synthesis of both monoamines. Thus, the in vivo inhibition of the synthesis of monoamines would appear to be mediated by an increase in synaptic concentration of monoamines, resulting from the inhibition of the uptake or catabolism of monoamines. Chronic administration of citalopram led to a significant increase of the basal synthesis of 5-hydroxytryptamine (5-HT). Milnacipran, given chronically, significantly enhanced the basal synthesis of both 5-HT and noradrenaline (NA).(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of effect of repeated administration of milnacipran, a double noradrenaline and serotonin reuptake inhibitor, on the beta-adrenoceptor-linked adenylate cyclase system in the rat cerebral cortex.

The effects of subacute administration of the double noradrenaline and serotonin uptake inhibitor antidepressant, milnacipran, and the tricyclic antidepressant, imipramine, on radioligand binding to beta-adrenergic receptors and on beta-adrenergic agonist-stimulated adenylate cyclase activity, in the rat cerebral cortex, have been determined. Rats were injected intraperitoneally for 21 days with milnacipran (3, 10 or 30 mg/kg/day) or imipramine (10 mg/kg/day). The treatment with milnacipran up to 30 mg/kg/day did not modify either the maximum number of [3H]CGP-12177 binding sites (Bmax) or the equilibrium dissociation constant (Kd). On the other hand, treatment of the rats with 10 mg/kg/day imipramine induced a decrease (27%) in Bmax [3H]CGP-12177 binding sites without affecting the Kd value. Furthermore, milnacipran did not affect the stimulation of cAMP production induced by either 30 microM isoprenaline, 10 microM GTP gamma S or 10 microM forskolin. Under similar conditions, treatment with imipramine reduced by 70% the isoprenaline-induced stimulation of cAMP production without affecting that induced by either GTP gamma S or forskolin. These results demonstrate that, unlike imipramine, subacute administration of milnacipran does not produce any change in beta-adrenoceptor sensitivity in the rat brain cortex.

Biochemical profile of midalcipran (F 2207), 1-phenyl-1-diethyl-aminocarbonyl-2-aminomethyl-cyclopropane (Z) hydrochloride, a potential fourth generation antidepressant drug.

The present study of midalcipran (F 2207), 1-phenyl-1-diethyl-aminocarbonyl-2-aminomethyl-cyclopropane(Z) hydrochloride, was undertaken to determine its biochemical profile. The properties of midalcipran, in inhibiting the uptake of monoamines were tested and compared with that of imipramine. In vitro, midalcipran was found to inhibit the uptake of radiolabelled serotonin and noradrenaline (IC50 = 203 and 100 nM, respectively), but not that of dopamine, into brain slices. Hyperthermia induced by the centrally-acting displacers of monoamines, H77/77 and H75/12, were almost equipotently antagonized by midalcipran, confirming the inhibition of the uptake of serotonin and noradrenaline by midalcipran in vivo (ID50 = 11 and 4.8 mg/kg, respectively). Midalcipran showed no inhibition of the activity of monoamine oxidase in vitro or in vivo. The interaction between midalcipran and neurotransmitter receptors and binding sites in the CNS was studied in the rat in comparison with imipramine and desipramine. In contrast to these two antidepressant drugs, midalcipran showed no affinity for alpha- or beta-adrenoceptors, muscarinic, histaminergic H1, dopaminergic D2 or serotonergic 5-HT2 receptors, suggesting a general absence of anticholinergic, sedative and other side-effects. Midalcipran was equipotent with imipramine at inhibiting the binding of [3H]imipramine. Chronic administration of midalcipran to rats did not alter the number of beta-adrenergic receptors in the cortex, in contrast to imipramine and desipramine which decreased the binding of beta-adrenoceptors. Thus midalcipran appears to act exclusively presynaptically, inhibiting the uptake of serotonin and noradrenaline. This activity, coupled to the total absence of interaction at postsynaptic sites, suggests that midalcipran may be a useful and novel antidepressant drug.

Effects of prolonged administration of milnacipran, a new antidepressant, on receptors and monoamine uptake in the brain of the rat.

Most antidepressants produce changes in monoamine receptors in brain after chronic administration in animals. The most commonly described alterations are a decreased density and function of beta-adrenergic receptors and have been postulated to be the mechanisms by which antidepressants exert their therapeutic effect. Milnacipran (previous name midalcipran) is a new, clinically-effective antidepressant, which inhibits the uptake of both serotonin and noradrenaline but has no affinity for any pre- or postsynaptic receptor studied. When given either orally at 7.5 mg/kg twice daily for 3 days, at 30 mg/kg once daily for 3 weeks, by osmotic mini-pump at 30 mg/kg/day for 27 days, or in drinking water at approximately 15 mg/kg/day for 6 weeks and after a washout period of 24 hr, milnacipran produced no down-regulation of beta-adrenoceptors. In addition, there were no alterations of alpha 1- or alpha 2-adrenoceptors, 5-HT1, 5-HT2 receptors or benzodiazepine binding sites. Moreover, uptake and accumulation of serotonin and noradrenaline were unmodified. In addition, the potency for milnacipran to inhibit monoamine uptake in vitro in the cortex was not altered in treated rats, compared to control animals. Thus, in spite of its action on both the uptake of serotonin and noradrenaline, milnacipran appears to be without long-term action on beta-adrenoceptors or the other receptors studied, suggesting that, at least for this antidepressant, these modifications are not essential for clinical activity.

1-Aryl-2-(aminomethyl)cyclopropanecarboxylic acid derivatives. A new series of potential antidepressants.

A series of 1-aryl-2-(aminomethyl)cyclopropanecarboxylic acid derivatives were synthesized and evaluated as potential antidepressants. Compounds with the Z configuration were synthesized from 1-aryl-2-oxo-3-oxabicyclo[3.1.0]hexane and those with the E configuration from (E)-1-phenyl-2-(hydroxymethyl)cyclopropanecarboxylic acid. The compounds were evaluated in animal tests designed to reveal potential antidepressant activity and the existence of undesirable side effects. Several derivatives were more active than imipramine and desipramine. On the basis of its activity in pharmacological animal tests of antidepressant activity and its potential lack of side effects, 1-phenyl-1-[(diethylamino)carbonyl]-2- (aminomethyl)cyclopropane hydrochloride, midalcipran (INN), was selected for further development. This compound is currently in phase III clinical evaluation.

Novel [2-(4-piperidinyl)ethyl](thio)ureas: synthesis and antiacetylcholinesterase activity.

A series of 1-ar(o)yl-3-[2-(1-benzyl-4-piperidinyl)ethyl](thio)urea derivatives was synthesized and evaluated for antiacetylcholinesterase activity. Most aroyl(thio)urea derivatives showed potent inhibitory activity in the sub-micromolar range. A comparable potency was obtained with the aryl(thio)urea analogues by replacing the phenyl with a 2-pyridyl group. The substituted guanidine variations proved to be almost inactive whereas the nitroethylene analogues appeared to be quite efficient. These results were interpreted in terms of the preferential cis-trans conformation of the aroyl(thio)urea and 2-pyridyl(thio)urea moieties involving the existence of hydrogen bonding. In vivo experiments showed that compound 7m had maximal antiamnestic activity at 0.03 mg/kg with a therapeutic ratio greater than 1000, while cholinergic side effects were only seen at doses 100-fold the maximally effective antiamnestic dose. Compound 7m represents a potentially interesting antidementia agent.

Flexible 1-[(2-aminoethoxy)alkyl]-3-ar(o)yl(thio)ureas as novel acetylcholinesterase inhibitors. Synthesis and biochemical evaluation.

A series of flexible 1-(2-aminoethoxy)-3-ar(o)yl(thio)ureas was synthesized and assessed for antiacetylcholinesterase activity. This series was designed in order to optimize the spacer length linking the two pharmacophoric moieties, i.e., the basic nitrogen and the ar(o)yl(thio)-urea unit, and to test compounds with greater conformational flexibility. Thus, the replacement of the previously described spacer, 4-piperidinylethyl, by a linear ethoxyethyl chain gave compounds of slightly comparable potency, providing that they were correctly substituted. The results show that this new flexible spacer is compatible with high inhibitory activities. The optimal chain length corresponds to five methylene groups, allowing an efficient interaction between the two pharmacophoric units and the two reported hypothetical enzyme hydrophobic binding sites. Moreover, the initially optimized benzyl group, attached to the basic nitrogen, was found to be advantageously replaced by a cyclohexyl group, showing that an aromatic residue does not represent a prerequisite for activity.

Evidence against beta-adrenoceptor blocking activity of diltiazem, a drug with calcium antagonist properties.

1 The isolated spontaneously beating atria of the rat, diltiazem (0.01 to 0.1 microM) shifted the atrial rate concentration-response curves to isoprenaline to the right in a non-parallel manner and depressed their maxima. Under the same experimental conditions, (+/-)-propranolol (0.03 to 0.1 microM) behaved as a competitive beta-adrenoceptor antagonist. 2 Whereas (+/-)-propranolol (IC50 = 12 nM) and isoprenaline (IC50 = 0.9 microM) inhibited (-)-[3H]-dihydroalprenolol binding to rat brain membrane preparations, diltiazem failed to do so in concentrations up to 10 microM. 3 Diltiazem but not (+/-)-propranolol, antagonized the positive chronotropic responses to calcium in spontaneously beating rat atria. 4 It is proposed that diltiazem inhibited the tachycardia induced by isoprenaline through an effect on calcium which may be an essential modulator of the sequence of events linking the beta-adrenoceptor activation and heart rate response.

Identification of 5-hydroxytryptamine1D binding sites in sheep caudate nucleus membranes.

Radioligand binding measurements were performed in membranes of sheep caudate nucleus using [3H]5-hydroxytryptamine (5-HT). [3H]5-HT labeled a population of high affinity binding sites with a Kd of 1.9 +/- 0.1 nM and a Bmax of 19.8 +/- 2.2 fmol/mg tissue. Combined 5-HTID/E binding sites were the predominant 5-HT1 subtype, accounting for 78% of the total population of 5-HT1 binding sites. 5-Carboxamidotryptamine (5-CT) and sumatriptan yielded inhibition curves which best fitted a two-site model with high affinity values of 0.8 and 10.1 nM, and 1000 and 206 nM for their low affinity components. The proportion of the high affinity 5-CT and sumatriptan binding sites was 79 and 72%. The binding affinity profile of 5-HT1D binding sites [5-CT > 5-HT > d-LSD > 5-MeOT > sumatriptan > RU 24,969 > metergoline > tryptamine = rauwolscine = methylsergide > yohimbine = methiothepin > TFMPP = 8-OH-DPAT > 2-methyl-5-HT > mCPP = quipazine = CP 93,129 > ketanserin > (-)-propranolol = haloperidol = ipsapirone] compares well to that reported for 5-HT1D receptor sites in human caudate and cortex (correlation coefficient: 0.99 and 0.98). The present results indicate that sheep caudate nucleus is a valid tissue for studying interaction of compounds with 5-HT1D binding sites in the relative absence of 5-HT1E binding sites.

Effects of four non-cholinergic cognitive enhancers in comparison with tacrine and galanthamine on scopolamine-induced amnesia in rats.

Amnesia can be induced in rats in the passive avoidance paradigm by administration of scopolamine, a central muscarinic receptor antagonist. Tacrine or galanthamine, inhibitors of acetylcholinesterase, given in conjunction with scopolamine partially reversed the scopolamine-induced deficit in passive avoidance performance. Four so-called cognitive enhancers, all widely used for the treatment of the symptoms associated with mental aging, cerebral insufficiency and senile memory disorder, were investigated in this paradigm. Piracetam, an extract of Ginkgo biloba, dihydroergocristine and a combination of raubasine with dihydroergocristine, all attenuated the amnesia induced by scopolamine. In contrast, nicergoline had no significant effect. Raubasine alone also failed to significantly attenuate scopolamine-induced amnesia, although some doses of raubasine had a non-significant tendency (P less than 0.10) to reduce the amnesia.

The benzodiazepine antagonist flumazenil blocks the effects of CCK receptor agonists and antagonists in the elevated plus-maze.

Peripheral administration of the unsulphated cholecystokinin octapeptide (CCK-8us) led to an anxiogenic-like action in the elevated plus-maze model of anxiety in rats. Devazepide and L-365,260 showed potent anxiolytic-like effects at similar doses. The fact that devazepide is 1000 times more potent as a CCK-A receptor antagonist than L-365,260, whereas the two compounds are nearly equipotent at the CCK-B receptor subtype, suggests that CCK-B rather than CCK-A receptors are involved in these effects. Similar results were obtained in mice using the two-compartment test. In the elevated plus-maze, the benzodiazepine antagonist, flumazenil, which was inactive when given alone, significantly antagonized the anxiogenic-like activity of CCK-8us and the anxiolytic-like effects of devazepide and L-365,260. These results suggest a complex interaction between benzodiazepine and CCK receptor mechanisms in the regulation of anxiety states.