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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Drug discrimination is a technique for investigating the stimulus properties of centrally active drugs. Although many studies have employed animals to investigate the stimulus properties of substances used clinically for the treatment of anxiety and depression, it would be a mistake to consider the internal discriminative stimuli as being related specifically to the anxiolytic or antidepressant properties of these drugs. Rather drug cues are better considered as relating to the pharmacological action of classes of compounds. Thus, benzodiazepine cues generalize to other compounds acting at benzodiazepine receptors, but not to substances (anxiolytic or otherwise) acting at 5-HT1A receptors. Similarly, antidepressants with different pharmacological properties, for example the tricyclic imipramine, or the phenylaminoketone buproprion produce distinct, unrelated discriminative stimuli. For this reason, the limits of drug discrimination techniques for investigating novel anxiolytic or antidepressant drugs should be clearly recognized. Attempts to identify an anxiogenic discriminative stimulus using pentylenetetrazole have also been misguided. In this technique it has proven difficult to separate unequivocally the pharmacological proconvulsant effects of the drug from the psychological construct anxiety. Nevertheless, drug discrimination remains a valuable technique for investigating pharmacological interactions in animals and man.
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PMID:Drug discrimination models in anxiety and depression. 197 45

The response of guinea pig trachea to 5-hydroxytryptamine (serotonin; 5-HT) was investigated by studying tracheal strips suspended in organ chambers for isometric tension measurements. Serotonin concentrations of 0.1 to 10 microM produced concentration-dependent contractions, whereas at higher concentrations (10-300 microM) the agonist caused concentration-dependent relaxations. The 5-HT2 antagonist ketanserin shifted the bimodal 5-HT response-curve to the right (pA2 for ketanserin was 8.98). The 5-HT1A agonist, (+)-8-hydroxy-2-(di-N-propylamino)tetralin hydrobromide and 5-HT3 antagonist, ICS 205930 (3-tropanyl-indole-3-carboxylate) had no effect on the 5-HT-response curve. Incubation with atropine resulted in a depression of the maximal contractility and an increase in the EC50 without changing the bimodal nature of the concentration-response curve. Hexamethonium was able to block the atropine effect without significantly affecting the 5-HT concentration-response curve. Neither the constriction nor the relaxation was altered by propranolol, chlorpheniramine or capsaicin pretreatment. Histamine and carbachol preconstricted airways were also relaxed by 5-HT in a concentration-dependent fashion and this relaxation was antagonized by ketanserin (pKb for ketanserin in histamine preconstricted airways was 9.4). Epithelial denudation did not inhibit the 5-HT-induced relaxation. 5-HT stimulated inositol-monophosphate production which also exhibited a bimodal response and correlated well with the functional response. The above findings suggest that 5-HT causes both constriction and relaxation of the guinea pig airway, and that both responses are antagonized by a 5-HT2 receptor blocker. In addition, part of the constrictor response of 5-HT is mediated through a cholinergic preganglionic pathway. Finally, inositol-monophosphate production induced by 5-HT correlates with the functional response.
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PMID:Serotonin induces constriction and relaxation of the guinea pig airway. 197 97

The selective 5-HT1A receptor ligand ipsapirone (IPS) induces corticotropin (ACTH) and cortisol secretion in humans. To explore 5-HT1A receptor-mediated hypothalamic-pituitary-adrenal (HPA) system activation in depression, 24 subjects (12 patients with unipolar depression and 12 individually matched controls) were given 0.3 mg/kg IPS or placebo in random order. Compared with controls, the depressed patients exhibited significantly decreased ACTH and cortisol responses to IPS in association with increased basal cortisol secretion. The impaired HPA response following 5-HT1A receptor challenge in unipolar depression could have resulted from glucocorticoid-dependent subsensitivity of the (post-synaptic) 5-HT1A receptor itself and/or from a defective postreceptor signaling pathway [inhibitory guanine nucleotide-binding protein (Gi)-adenylate cyclase complex function], thus supporting the hypothesis that a disintegrated 5-HT and HPA system interaction may be present in depression. Future studies of the HPA response to direct-acting 5-HT1A ligands, such as IPS, should facilitate the assessment of 5-HT/HPA system integrity in various affective disorders and its involvement in psychotropic drug effects.
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PMID:5-HT1A receptor responsivity in unipolar depression. Evaluation of ipsapirone-induced ACTH and cortisol secretion in patients and controls. 197 79

Twenty-four patients with major depression were treated in a single-blind design with 25 mg to 75 mg gepirone, a pyrimidinyl piperidinedione analog of buspirone with serotonin1A (5-HT1A) receptor affinity properties. Twenty-four-Item Hamilton Rating Scale for Depression-(HAM-D) scores decreased by 36 percent when mean baseline scores were compared with an endpoint analysis of 6 weeks' gepirone treatment. Several subjects demonstrated marked improvements over baseline. The data are discussed within the context of 5-HT1A receptor desensitization as a potential component of antidepressant treatment.
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PMID:Gepirone as a 5-HT1A agonist in the treatment of major depression. 197 70

5-HT1 and 5-HT1A binding sites were measured in brain tissue obtained at postmortem from 19 suicides, with definite evidence of depression, and 19 sex and age-matched controls. Thirteen of the depressed suicides had not been prescribed psychoactive drugs recently (drug-free suicides); six had been receiving antidepressant drugs, alone or in combination with other drugs (antidepressant-treated suicides). No significant differences were found in the number or affinity of 5-HT1 and 5-HT1A binding sites in frontal or temporal cortex between drug-free suicides and controls. The number of 5-HT1 sites was significantly lower (by 20%), affinity unaltered, in hippocampus and the affinity significantly lower (by 33%), number unaltered, in amygdala of drug-free suicides than controls. The number of 5-HT1 binding sites tended to be higher and the affinity lower in the antidepressant-treated compared to drug-free suicides, and significantly so in hippocampus. The present results, together with our previous studies, provide no evidence of altered cortical 5-HT markers in depressed suicides, but further emphasise abnormalities in the hippocampus.
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PMID:Brain 5-HT1 binding sites in depressed suicides. 209 12

Cocaine potently inhibits the spontaneous activity of dorsal raphe serotonin (5-hydroxytryptamine [5-HT] neurons which possess impulse-modulating receptors of the 5-HT1A subtype. In an investigation of the neuropharmacologic mechanisms underlying this electrophysiologic effect, we have compared cocaine with structurally and functionally similar compounds, attempted to reverse cocaine-induced suppression of 5-HT dorsal raphe nucleus (DRN) neuronal activity, and assessed the effects of 5-HT depletion on the response to cocaine. Extracellular recordings in chloral hydrate-anesthetized rats were obtained using single-unit recording techniques; drugs were infused intravenously IV) in a cumulative dose manner. The active isomer (-)-cocaine (ID50 = 0.5 +/- 0.15 mg/kg) and the phenyltropane analogue WIN 35428 (ID50 = 0.17 +/- 0.03 mg/kg) that share the ability of cocaine to block monoamine uptake also inhibit impulse activity in 5-HT neurons. In contrast, the inactive isomers (+)-cocaine, (+)-pseudococaine and the metabolite benzoylecgonine do not exhibit the same range of potency (maximal 20% to 30% inhibition at a cumulative dose of 8 to 16 mg/kg). A selective inhibitor of uptake for 5-HT (fluoxetine; ID50 = 1.8 +/- 0.5 mg/kg), but not norepinephrine (desipramine) or dopamine (GBR 12909), mimicked cocaine, as did the monoamine releaser amphetamine (ID50 = 2.86 +/- 0.46 mg/kg). The putative 5-HT1A autoreceptor antagonist spiperone reversed the cocaine-induced depression of firing rate in 64% of 5-HT neurons tested whereas receptor antagonists for dopamine D2 (haloperidol), 5-HT2 (ketanserin), gamma-aminobutyric acid (picrotoxin) and 5-HT1/beta-adrenergic (propranolol) were ineffective. Following treatment with the 5-HT synthesis inhibitor p-chlorophenylalanine (100 mg/kg/day of the base for 3 days), impulse depression induced by cocaine was significantly attenuated as compared to control, which suggests that the effects of cocaine may be dependent on endogenous 5-HT stores. In summary, these findings support the hypothesis that the inhibitory effects of cocaine on 5-HT DRN neurons are mediated by increased 5-HT available for interaction with 5-HT1A impulse-regulating autoreceptors in the DRN, as a consequence of cocaine-induced blockade of 5-HT reuptake processes. Further studies are required to clarify the relative contribution of cocaine-5-HT interactions to the behavioral and physiologic effects of this psychostimulant.
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PMID:The interaction of cocaine with serotonin dorsal raphe neurons. Single-unit extracellular recording studies. 213 98

In animal models of depression, the 5-HT1A agonists, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), buspirone, gepirone and ipsapirone administered i.p. have been shown to mimic the behavioural effects of antidepressants. For instance, in the present study, using the learned helplessness paradigm, 8-OH-DPAT dose-dependently reversed helpless behaviour. To assess the possible role of pre- or postsynaptic 5-HT1A receptors in this effect, the ability of 8-OH-DPAT to reduce helpless behaviour was investigated following (1) i.p. administration (0.125 or 0.25 mg/kg/day) in rats whose ascending 5-HT neurons were partially destroyed by previous 5,7-dihydroxytryptamine (5,7-DHT) injection (5 micrograms free base in 0.6 microliter) into the raphe nuclei or (2) after local microinjection (0.1 or 1.0 microgram in 0.5 microliter) into the raphe nuclei or into the septum. The reversal of helpless behaviour by 8-OH-DPAT (i.p.) was still observed in 5,7-DHT-treated rats with telencephalic 5-HT uptake reduced by 50-75% depending on the region. 8-OH-DPAT microinjected into the raphe nuclei did not reverse helpless behaviour; in contrast, 8-OH-DPAT microinjected into the septum reversed helpless behaviour. These results suggest that the ability of 8-OH-DPAT to reverse helpless behaviour probably involved the stimulation of postsynaptic rather than presynaptic 5-HT1A receptors.
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PMID:Antidepressant-like action of 8-OH-DPAT, a 5-HT1A agonist, in the learned helplessness paradigm: evidence for a postsynaptic mechanism. 214 88

The azapirone class of anxiolytic drugs is being evaluated for clinical use in the treatment of depression. Buspirone, a serotonin (5-hydroxytryptamine, 5-HT) partial agonist active at the 5-HT1A receptor subtype, was evaluated in the treatment of depression in a series of five placebo-controlled, parallel group studies involving 382 patients with DSM-III major depression and significant associated anxiety symptoms (both Hamilton depression [HAM-D] and Hamilton anxiety [HAM-A] scales greater than or equal to 18). Buspirone therapy was initiated at 15 mg/day with individual dose titration to a maximum of 90 mg/day and resulted in marked improvement in both depressive and anxiety symptoms. Analyses of the composite data base from the five studies show significant (p less than 0.05) improvement in mean HAM-D, HAM-A, and Clinical Global Impression-Global Improvement scale ratings for buspirone-treated compared with placebo-treated patients. Of particular interest was significant improvement in cardinal depression symptoms, e.g., depressed mood, guilt, work and interest, anergia, and diurnal variation of mood. Subset analyses revealed that patients with melancholic-type major depression and patients with more severe symptoms (judged by higher initial HAM-D or HAM-A total scores) responded better to buspirone than did patients who were less ill. The buspirone dose most frequently associated with clinically significant improvement was 40 mg/day. Gepirone, an analogue of buspirone with highly selective binding affinity for the 5-HT1A receptor subtype, also shows promise of antidepressant efficacy in preliminary controlled clinical trials. These data suggest that azapirones, which as partial agonists modulate 5-HT1A receptor function, have clinically important antidepressant properties.
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PMID:Clinical effects of the 5-HT1A partial agonists in depression: a composite analysis of buspirone in the treatment of depression. 219 3

Obsessive-compulsive disorder (OCD) is emerging very clearly as a serotonin specific illness. The evidence for this comes from a variety of clinical sources. Firstly the efficacy of 5-HT uptake inhibitors, especially clomipramine, is consistent and strong. Secondly clomipramine has not merely been found to be effective against placebo in 9 placebo controlled studies, it is also found to be more effective in some studies than reference tricyclic antidepressants and monoamine oxidase inhibitors. In other studies tricyclic antidepressants do not appear to be better than placebo. The lack of efficacy of general antidepressants, neuroleptics and benzodiazepines supports the specificity of the serotonin effect. Thirdly the evidence of the efficacy of clomipramine in OCD without concomitant depression reported by Montgomery 1980 and supported by other studies suggests that 5-HT uptake inhibitors have a specifically anti-obsessional effect. The lack of response of depressive symptoms in OCD to other antidepressants suggests that these depressive symptoms are integral to OCD and will only respond when the OCD is treated. Many of the studies found efficacy for 5-HT uptake inhibitors compared with placebo despite both groups being treated with concomitant behaviour therapy. This argues either for behaviour therapy being relatively ineffective or for there being a synergistic effect with the 5-HT uptake inhibitor which is more likely. Results from studies with selective serotonergic probes with a worsening of OCD symptoms in response to the 5-HT1A agonist, m-chlorophenyl piperazine, add support to the serotonergic hypothesis of OCD but further investigation is needed.
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PMID:[Biological treatments in obsessive-compulsive disorder]. 220 92

Buspirone, an azapirone derivative and a 5-HT1A partial agonist, is the first nonbenzodiazepine anxiolytic introduced into medicine for the treatment of generalized anxiety disorder. A series of well-controlled clinical trials demonstrated that its anxiolytic properties were similar to those of various benzodiazepines and significantly better than placebo. More recently, antidepressant effects were also observed. Patients with clinical indications for which buspirone seems to be particularly appropriate are those with generalized anxiety disorder, those with chronic anxiety, the anxious elderly, and, perhaps, many patients of all ages who suffer from mixed symptoms of anxiety and depression. Studies conducted with patients suffering from panic disorder have so far been inconclusive, and thus buspirone is, for the present at least, not recommended for routine treatment of panic disorder. Buspirone seems to be most helpful in anxious patients who do not demand immediate gratification or the immediate relief they associate with the benzodiazepine response. Slower and more gradual onset of anxiety relief is balanced by the increased safety and lack of dependency-producing aspects of buspirone. Finally, whether or not buspirone may possess "curative" properties, in addition to "anxiety-suppressant" properties, that allow the patient to improve coping skills with time requires further exploration.
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PMID:Buspirone in clinical practice. 221 69


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