Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Microdialysis was used to characterize the effect of serotonergic input on cholinergic interneurons in the nucleus accumbens (NAC) of freely moving rats. Local infusion of 5-hydroxytryptamine (5-HT) or the serotonin reuptake blocker fluoxetine significantly decreased extracellular acetylcholine (ACh) in the NAC. This decrease in ACh was blocked by the 5-HT1 (and beta-adrenergic) antagonist propranolol. To test suggests that 5-HT inhibits ACh interneurons via one of the 5-HT1 receptor types. The 5HT1A agonist 8-OH-DPAT given systemically again decreased extracellular levels of ACh, and the effect was dose-dependent. The 5-HT1A effect was probably exerted in the NAC, because local infusion of 8-OH-DPAT mimicked systemic injections. These microdialysis results are similar to in vitro studies which suggest an inhibitory impact of 5-HT on ACh release in basal ganglia slices and homogenates. The decrease in extracellular ACh as measured in vivo is apparently mediated, at least in part, through a 5-HT1A receptor in the accumbens. Given the role of the NAC in behavior reinforcement, this 5-HT-ACh interaction may be involved in serotonergic treatment of depression.
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PMID:In vivo modulation of acetylcholine in the nucleus accumbens of freely moving rats: I. Inhibition by serotonin. 837 97

Serotonin (5-HT) reuptake inhibitors (SSRIs) such as fluvoxamine are interesting compounds. Initially launched as antidepressants, they have been found to be active in various psychiatric disorders besides depression, including obsessive-compulsive disorder, panic disorder, and eating disturbances. Preliminary data suggest their efficacy in alcohol and drug abuse, aggression, and posttraumatic stress disorder as well. Along with those clinical findings, new preclinical data have emerged. For example, fluvoxamine has demonstrated activity in various models of anxiety in rodents. Its anxiolytic activity can be clearly discriminated from that of the benzodiazepines. In the DRL 72-sec paradigm, fluvoxamine exhibits a good antidepressant profile, similar to those of imipramine and flesinoxan. Studies have shown that fluvoxamine does not down-regulate beta-adrenoceptors; apparently, that property is not a conditio sine qua non for antidepressant activity. Results of studies of the mechanism of action of fluvoxamine in which drug discrimination tests were performed with rats and pigeons suggest that the fluvoxamine stimulus is not (or is only to a very limited degree) dependent on activation of 5-HT1A receptors or 5-HT1B/1D receptors, or both. Experimentation is ongoing in those animal models.
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PMID:Preclinical evidence on the psychotropic profile of fluvoxamine. 837 18

The effect of repeated administration of (+)-OXA (a noradrenaline (NA) uptake inhibitor) and (-)-OXA (devoid of an effect on the NA uptake, but a clinically active antidepressant drug) on central 5-HT receptor subpopulations was studied. (-)-OXA given repeatedly, but not acutely, attenuated the 8-OH-DPAT-induced hypothermia in mice. (+)-OXA administered acutely, as well as repeatedly, was inactive in that test. The 8-OH-DPAT-induced syndrome in rats was attenuated by both OXA isomers administered either acutely or repeatedly. The hypothermia induced by m-CPP in mice was attenuated by single-dose administration of (+)-OXA and (-)-OXA; when given repeatedly, (+)-OXA increased the action of m-CPP. (-)-OXA administered repeatedly was inactive in that test. Either single or repeated administration of (+)-OXA had practically no effect on the depression of exploratory activity induced by m-CPP. (-)-OXA administered acutely or repeatedly attenuated the effect of m-CPP in the same manner. Acute, but not chronic, administration of (-)-OXA reduced the number of head-twitch episodes induced by 5-HTP in mice. Repeated, but not acute, treatment with (+)-OXA attenuated the effect of 5-HTP. The obtained results indicate that (+)-OXA administered repeatedly increases the reactivity of 5-HT1B receptors, decreases the reactivity of 5-HT2 receptors, and has no effect on the reactivity of 5-HT1A- (pre- and postsynaptic) and 5-HT1C-receptors. (-)-OXA given repeatedly decreases the reactivity of presynaptic 5-HT1A receptors and has no influence on the reactivity of postsynaptic 5-HT1A-, 5-HT1B-, 5-HT1C- and 5-HT2-receptors.
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PMID:The effect of repeated treatment with oxaprotiline enantiomers on central 5-HT receptor subpopulations. 840 66

1. Preclinical and clinical studies suggest that 5-HT1A receptor agonists are a new class of mixed anxiolytics/antidepressants with, possibly, impulsivity reducing properties. 2. The anxiolytic effects of 5-HT1A receptor agonists result predominantly from an interaction with presynaptic 5-HT1A receptors (resulting in a decrease of serotonergic transmission), whereas the antidepressive and, possibly, the impulse control enhancing effects, result predominantly from an interaction with postsynaptic 5-HT1A receptors. 3. These proposed mechanism(s) of action fit well with the generally held view that anxiety is the result of a hypersensitive 5-HT system; whereas impulsivity and depression is the result of a hyposensitive 5-HT system. 4. However, it appears very likely that activation of pre- and postsynaptic 5-HT1A receptors is additionally involved in the antidepressive and impulse control enhancing effects, on the one hand, and in the anxiolytic effects of these compounds, on the other hand. 5. These latter, seemingly paradoxical, findings can be explained by assuming that (1) the presynaptic mechanism reflects an anxiolytic component in the animal models of impulsivity and depression, (2) antagonism of postsynaptic 5-HT1A receptors by these compounds contributes to their anxiolytic effects, (3) postsynaptic 5-HT1A and 5-HT2 receptors have functionally opposing effects or, alternatively, that (4) downregulation of postsynaptic 5-HT2 receptors contributes to the therapeutic effects of these compounds.
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PMID:5-HT1A receptor ligands in animal models of anxiety, impulsivity and depression: multiple mechanisms of action? 841 3

The effects of the selective 5-HT1A receptor agonist (R)-8-hydroxy-2(di-n-propylamino)tetralin [(R)-8-OH-DPAT] and the novel 5-HT1A antagonist (S)-5-fluoro-8-hydroxy-2-(dipropylamino)-tetralin [(S)-UH-301] were studied with regard to the firing pattern of single mesencephalic dopamine (DA) neurons with extracellular recording techniques in chloral hydrate anesthetized male rats. Neuronal activity was studied with respect to firing rate, burst firing and regularity of firing. In the ventral tegmental area (VTA) low doses of (R)-8-OH-DPAT (2-32 micrograms/kg i.v.) caused an increase in all three parameters. The effect on firing rate of DA neurons was more pronounced in the parabrachial pigmentosus nucleus than in the paranigral nucleus, the two major subdivisions of VTA. In the substantia nigra zona compacta (SN-ZC), (R)-8-OH-DPAT (2-256 micrograms/kg i.v.) had no effect on firing rate and regularity of firing and only slightly increased burst firing. High doses of (R)-8-OH-DPAT (512-1024 micrograms/kg i.v.) decreased the activity of DA cells in both areas, an effect that was prevented by pretreatment with the selective DA D2 receptor antagonist raclopride. (S)-UH-301 (100-800 micrograms/kg i.v.) decreased both firing rate and burst firing without affecting regularity of DA neurons in the VTA. In the SN-ZC, (S)-UH-301 decreased the firing rate but failed to affect burst firing and regularity of firing. These effects of (S)-UH-301 were blocked by raclopride pretreatment. Local application by pneumatic ejection of 8-OH-DPAT excited the DA cells in both the VTA and the SN-ZC, whereas (S)-UH-301 inhibited these cells when given locally. These results show that 5-HT1A receptor related compounds differentially affect the electrophysiological activity of central DA neurons. The DA receptor agonistic properties of these compound appear to contribute to the inhibitory effects of high doses of (R)-8-OH-DPAT and (S)-UH-301 on DA neuronal activity. Given the potential use of 5-HT1A receptor selective compounds in the treatment of anxiety and depression their effects on central DA systems involved in mood regulation and reward related processes are of considerable importance.
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PMID:The 5-HT1A receptor selective ligands, (R)-8-OH-DPAT and (S)-UH-301, differentially affect the activity of midbrain dopamine neurons. 851 Jul 63

The effects of a challenge dose of the 5-HT1A agonist, ipsapirone (0.3 mg per kg body weight), or placebo on body temperature and on adrenocorticotrophic hormone (ACTH) and cortisol release, were examined in 30 normal subjects (14 males, 19-74 years and 16 females, 22-69 years) using a randomized, double blind design. Irrespective of age or gender, ipsapirone induced a significant reduction in body temperature relative to placebo and a significant increase in ACTH and cortisol release. Maximal temperature reduction by ipsapirone was significantly blunted in older subjects and was inversely related to age. There was no gender difference in the hypothermic response to ipsapirone. ACTH and cortisol responses showed an opposite impact of aging in males and females. Whereas both responses diminished with age in male subjects, they increased with age in females. The cortisol response of older females was significantly larger than that of all the other subjects. Adverse effects of ipsapirone were also more marked in elderly females and were correlated with ACTH and cortisol responses. These findings should be taken into consideration in the use of ipsapirone and other 5-HT1A agonists as challenge procedures for studying central serotonergic function in depression and other disorders. Careful matching of control and experimental subjects is indicated so as to avoid spurious results which reflect the effects of age and gender rather than the pathophysiology of the disorders being investigated.
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PMID:Complex effects of age and gender on hypothermic, adrenocorticotrophic hormone and cortisol responses to ipsapirone challenge in normal subjects. 852 84

Psychopharmacotherapy of the elderly must take into account the effects of age-related changes in the structure and function of the brain and various organs. In general, older people are more sensitive than young people to both the therapeutic and toxic effects of psychotropic medications, necessitating lower doses and longer dosage intervals. This holds true for the treatment of 5 major types of psychiatric illness (depression, bipolar disorder, anxiety, psychotic disorders and dementia). The tricyclic antidepressants, although efficacious, inexpensive, and backed by 30 years of experience, are less well tolerated by the elderly than are newer antidepressants such as the selective serotonin uptake inhibitors. Problems with monoamine oxidase (MAO) inhibitors, including orthostatic hypotension and restrictions in diet and other medication use, have been overcome by the advent of reversible selective inhibitors of MAO-A, but the efficacy of these in the elderly has yet to be proven in clinical trials. Lithium remains the mainstay for the treatment of bipolar disorder. However, careful dosing and monitoring of plasma lithium concentrations are required in the elderly due to changes in pharmacokinetics and pharmacodynamics which make older patients very sensitive to the toxic effects of this medication. Similarly, age-related changes in the pharmacokinetics and pharmacodynamics of the benzodiazepines, the most frequently prescribed medications for anxiety in the elderly, result in recommendations for lower doses and preferential use of those agents metabolised by conjugation (e.g. oxazepam). Buspirone, a partial serotonin 5-HT1A-agonist which is better tolerated than benzodiazepines in the elderly, may be used as an alternative. The elderly are extremely sensitive to extrapyramidal adverse effects which the typical antipsychotics (neuroleptics) exhibit to varying extents. The selection of a suitable agent for the treatment of a psychotic disorder should be based upon the adverse effect profile of the drug and the specific symptoms and situation of the patient. The newer atypical antipsychotics, clozapine and risperidone, have yet to be well-studied in the elderly. Dementia, exemplified by Alzheimer's disease, is almost exclusively an illness of the elderly. Only one medication, tacrine, has been approved for its treatment, based on extensive basic research and positive results of several clinical trials. Its long-term benefits have yet to be determined and it has several adverse effects, including a tendency to increase liver enzymes to the extent that the medication has to be discontinued.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Recent advances in geriatric psychopharmacology. 853 49

Antidepressant properties of 5-HT1A receptor ligands (the full agonist 8-OH-DPAT, the partial agonists ipsapirone and buspirone, and the selective antagonist WAY 100135) were studied in a chronic mild stress model of depression. In this model, rats subjected to a variety of mild stressors for a prolonged period of time show a substantial decrease in the consumption of a 1% sucrose solution (anhedonia), an effect being sensitive to repeated treatment with antidepressant drugs. In the present study we found that the stress-induced deficit in the sucrose intake was gradually reversed by chronic (3-5 weeks) administration of buspirone (2.5 and 5 mg/kg, i.p., b.i.d.) or WAY 100135 (10 mg/kg, s.c., b.i.d.), but not 8-OH-DPAT (0.5 mg/kg, s.c., b.i.d.) or ipsapirone (5 mg/kg i.p., b.i.d.). The magnitude of the effect of buspirone and WAY 100135 was comparable to that observed following similar administration of the antidepressant drugs imipramine (10 mg/kg i.p.) or citalopram (10 mg/kg i.p.). Increases in the sucrose intake following chronic treatment with buspirone, WAY 100135, imipramine and citalopram were specific to the stressed animals; the behaviour of control non-stressed animals was unchanged by any drug. These results suggest that buspirone and WAY 100135 may have antidepressant properties. Possible links between the anti-anhedonic effect of these drugs and their interaction with 5-HT1A receptors and/or the dopamine system are discussed.
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PMID:The effect of 5-HT1A receptor ligands in a chronic mild stress model of depression. 857 28

These studies demonstrate that prenatal cocaine produces differential changes in neuroendocrine responses following challenge with a 5-HT releaser versus a 5-HT1A agonist and suggest differential functional alterations in both pre- and postsynaptic components of 5-HT pathways. The attenuated neuroendocrine responses in adult male progeny following challenge with a 5-HT releaser, in the absence of reductions in 5-HT receptors, provide additional evidence in support of a presynaptic 5-HT deficit in adult male cocaine-exposed progeny. Furthermore, since prenatal cocaine produced a differential profile of alterations in 5-HT-mediated neuroendocrine responses in adult male (i.e., decreases ACTH and renin) versus prepubescent female (i.e., decreases ACTH and corticosterone) progeny following challenge with a 5-HT releaser, these data indicate that the differences could be due to gender and/or postnatal developmental ages. Gender differences in prenatal cocaine effects on postsynaptic receptor function were more clearly shown in study II, which demonstrated that at the same postnatal age, 5-HT1A-mediated neuroendocrine responses were significantly potentiated in male but not female cocaine-exposed progeny. In summary, the data presented in this chapter indicate that the biochemical and functional changes in 5-HT systems observed following prenatal exposure to cocaine are unique with respect to pre- versus postsynaptic alterations, pre- versus postpubescent developmental times, and differences between genders. A number of general conclusions can be drawn from the data presented. The presence of marked neurochemical deficits at both pre- and postpubescent timepoints, in the absence of any visually apparent physical terata, emphasizes the importance of investigating the neurochemical teratogenic potential of cocaine and other psychostimulants. Furthermore, data from these studies demonstrate the importance of investigating male and female progeny separately, as prenatal cocaine exposure may produce gender-specific alterations in some, but not all, aspects of brain neurotransmitter systems. Another important point that can be discerned from the present data is the necessity of subjecting cocaine-treated animals to challenge tests in order to reveal alterations that might not be readily apparent from measuring basal values for specific biochemical or functional parameters (e.g., basal hormone levels). In addition, the differential biochemical and functional changes in 5-HT systems, manifested at pre- versus postpubescent times, suggests that prenatal cocaine may adversely affect the normal maturational changes occurring in 5-HT systems. This may be of consequence in evaluating developmental stages in human offspring exposed to cocaine in utero. Furthermore, the ability of prenatal cocaine to alter 5-HT-mediated ACTH and renin responses in progeny suggest that offspring may exhibit alterations in their response to physiologic stimuli such as stress. Since neuroendocrine challenge tests can be performed in humans, the present data indicate the potential clinical utility of this approach to provide peripheral markers that can be used to identify changes in brain 5-HT pathways in human offspring exposed in utero to cocaine. Prenatal cocaine-induced alterations in brain 5-HT systems may be of significant clinical importance as dysfunction of 5-HT systems has been implicated in various psychiatric disorders including depression, anxiety, aggression, and drug-seeking behavior.
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PMID:Prenatal cocaine produces biochemical and functional changes in brain serotonin systems in rat progeny. 859 82

A common action of many antidepressants is the inhibition of the reuptake of the biogenic amines norepinephrine, serotonin (5-HT) and/or dopamine into nerve terminals. Another postulated mechanism of action for many antidepressants is the downregulation of beta-adrenergic receptors postsynaptically after chronic administration. Many antidepressants have been reported to produce changes in the regulation of 5-HT1 and 5-HT2 receptors chronically. None of these mechanisms is completely satisfactory as a common antidepressant mechanism of action. Is it possible to unify these hypotheses of antidepressant action? A number of receptor changes have been recognized in depression. Usually, these implicated receptors are linked to a G protein. Thus, it could be hypothesized that depression may be the result of a disorder of the large family of receptor-linked G proteins. Depression, a disorder in which there seems to be an important genetic component, could be expressed in either the receptor or in the G proteins, leading to a defective linkage between the receptor and the G protein, resulting in abnormal transduction mechanisms. The concept of antidepressants is changing rapidly as these agents appear with new therapeutic indications other than depression, such as panic disorder, obsessive compulsive disorder, etc. It can be expected that the presently available antidepressants might eventually be considered anxiolytics or that benzodiazepines and 5-HT1A agonists could come to be viewed as disinhibiting substances.
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PMID:The future of antidepressants. 867 34


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