UMLS:C0011570 - FACTA Search

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

Guanine nucleotide binding (G) proteins play a pivotal role in postreceptor information transduction. An important characteristic of G proteins is their increased guanine nucleotide binding following agonist stimulation, which in turn leads to their activation. We have developed a method that enables the measurement of early events in signal transduction beyond receptors, through activated receptor-coupled guanine nucleotide exchange on G proteins. Using this method, lithium was recently demonstrated to inhibit the coupling of both muscarinic cholinergic and beta-adrenergic receptors to pertussis toxin-sensitive and cholera toxin-sensitive G proteins, respectively, thus suggesting alteration of the function of G protein by lithium, as the single site for both the antimanic and antidepressant effects of this drug. One of the most puzzling aspects of the ability of lithium to ameliorate the manic-depressive condition is its relatively selective action upon the central nervous system (CNS). It was previously shown that lithium selectively attenuated the function of Gs proteins in the CNS. In the present study, we show that inhibition by lithium of muscarinic receptor-coupled G protein function is also selective to the CNS. The clinical profile of lithium, carbamazepine, and electroconvulsive treatment (ECT), agents that are effective in the prevention and treatment of bipolar affective disorder, differs from that of purely antidepressant drugs. Antidepressant drugs are effective in the acute treatment and prevention of depression only, and can even precipitate hypomanic or manic "switches," or "rapid cycling" between mania and depression. We have investigated and compared the effects of chronic antibipolar and antidepressant treatments on receptor-coupled G protein function. Antibipolar treatments (lithium, carbamazepine, ECT) attenuate both receptor-coupled Gs and non-Gs (i.e., Gi, Go) proteins function; in contrast, only Gs protein function is inhibited by antidepressant drugs [either tricyclics or monoamine oxidase (MAO) inhibitors]. Moreover, an integral adrenergic neuronal system is required for antidepressant inhibition of Gs protein function, as pretreatment with the noradrenergic neurotoxin DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine) specifically abolishes the effects of antidepressant drugs on Gs protein, whereas antibipolar drug effects on G protein function are unaffected by DSP-4. Our results suggest that attenuation of beta-adrenergic receptor-coupled Gs protein function, which is common to both antidepressant and antibipolar treatments, may be the mechanism underlying their antidepressant therapeutic efficacy.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Ziskind-Somerfeld research Award. The involvement of guanine nucleotide binding proteins in the pathogenesis and treatment of affective disorders. 158 23

Exploratory behavior, measured by the time an animal spends investigating objects in a novel environment, has been shown to be sensitive to prior exposure of the animal to stressors. Using this paradigm, it was demonstrated previously that both corticotropin-releasing factor (CRF) and the alpha 2-adrenoreceptor antagonist, idazoxan, elicited stress-like decreases in exploratory behavior. Because an activation of cerebral noradrenergic systems is observed during stress, following intracerebroventricular (i.c.v.) administration of CRF, or following peripheral administration of idazoxan, the involvement of noradrenergic systems in the behavioral effect of restraint and CRF was examined. Inhibition of norepinephrine (NE) release using the alpha 2-agonist clonidine (25 micrograms/kg, i.p.) or the noradrenergic-selective neurotoxin DSP-4 antagonized the restraint-induced decrease in exploratory behavior. The combination of these 2 treatments completely prevented this effect of restraint. The alpha 1-receptor antagonist prazosin (200 micrograms/kg) also prevented the behavioral effect of restraint, whereas the alpha 1-agonist phenylephrine (50 or 100 ng, i.c.v.) decreased exploratory behavior. None of these treatments consistently altered locomotor activity as measured by the number of entries into the different compartments or the number of rears. These results implicate noradrenergic systems in the stress-related changes in this behavior, consistent with our parallel measures on the production of NE catabolites. Thus, both CRF and noradrenergic systems appear to be involved in the effect of restraint on exploratory behavior in this task. Neither DSP-4 nor prazosin had any effect on the CRF-induced decrease in exploratory behavior. However, the CRF antagonist alpha-helical CRF (20 micrograms, i.c.v.) reversed the decrease in exploratory behavior induced by phenylephrine. The most likely explanation is that the 2 systems act in tandem such that noradrenergic systems regulate the release of brain CRF via an alpha 1-adrenoreceptor. This arrangement parallels that involved in the release of hypothalamic CRF to activate the pituitary-adrenal axis. The implications of these results for research on stress-related behaviors and for the etiology of depression are discussed.
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PMID:Restraint-stress-induced changes in exploratory behavior appear to be mediated by norepinephrine-stimulated release of CRF. 279 37

An experimental model, including novel and fearful stimuli, has been used to study the effect of noradrenaline, serotonin, and dopamine depletion on hippocampal electrical activity and behavior in freely moving rabbits. DSP-4 (N-(2-chloroethyl)-N-ethyl-2- bromobenzylamine hydrochloride, 40 mg/kg ip), a selective hippocampal noradrenaline depletor, decreased the overall exploratory activity and significantly increased RSA (rhythmic slow activity) percentage. The high frequencies of the hippocampal RSA were significantly reduced. When this noradrenaline depletion was coupled with a serotonin depression by p-chlorophenylalanine (pCPA), the above described effect was potentiated. In particular, the frequency distribution of RSA was characterized by a further reduction of the high values with a concomitant increase of the low frequency band. Moreover, a more evident decrease of the exploratory activity and a similar increase of RSA percentage was observed. These results show that the hippocampal electrical activity is modulated by noradrenaline and serotonin by an inhibitory effect on RSA occurrence and a frequency selection. The block of dopamine receptors by chronic haloperidol administration (5 mg/kg ip/day) did not seem to exert any effect on RSA parameters. Results are discussed in the light of attentional and emotional theories.
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PMID:Effect of DSP-4, pCPA, and haloperidol on hippocampal electrical activity and behavior in rabbits. 623 63

Chronic mild unpredictable stress, which reduces rewarded behaviour in rats, is becoming increasingly popular as an animal model of depression. The effect of chronic mild stress (applied to animals housed five per cage for 15 days) on forced swimming and open field behaviour, and on beta-adrenoceptor binding was studied in naive rats and after the denervation of the locus coeruleus projections by DSP-4 (50 mg kg(-1)) treatment. In the forced swimming test, chronic mild stress reduced the immobility time on the second day of testing in both vehicle- and DSP-4-treated rats, indicating rather an antidepressant-like effect. This antidepressant-like effect of chronic mild stress in the forced swimming test was not present in individually housed rats which suggests that this paradigm is sensitive to housing conditions. Stress had no clear effect on the open field locomotion in naive animals (but caused a reduction in defecations), but completely blocked the DSP-4-induced decrease in the exploratory activity. As measured by 3H-dihydroalprenolol binding, DSP-4 treatment increased the beta-adrenoceptor affinity in the frontal cortex and the number of binding sites in the hippocampus and in the cerebral cortex (total-frontal cortex). Stress had no effect on the beta-adrenoceptor binding in the frontal cortex and cerebral cortex, but prevented the increase in affinity caused by DSP-4 treatment in the frontal cortex. In the hippocampus, chronic mild stress and DSP-4 treatment increased the number of beta-adrenoceptor binding sites. Neither chronic mild stress nor DSP-4 treatment had any effect on CCK(B) receptor binding in the cerebral cortex and striatum. These results show that chronic mild stress applied to group-housed rats can prevent the development of certain behavioural and biochemical changes caused by the denervation of the locus coeruleus projection areas.
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PMID:Chronic mild unpredictable stress after noradrenergic denervation: attenuation of behavioural and biochemical effects of DSP-4 treatment. 1064 90

The effect of inositol as an antidepressant was previously demonstrated in both animal models of depression-like behavior and in clinical trials. Unlike most antidepressant drugs, inositol does not have a clear target in the synapse and was not demonstrated to alter monoamine levels in the brain. The present study attempted to draw a psychopharmacological profile of inositol's behavioral effects by exploring the interactions between the drug and specific receptor agonists and antagonists in the forced swim test. Rats received inositol treatment (or control) in combination with the serotonergic metabolism inhibitor PCPA or with the noradrenergic neurotoxin DSP-4. Results indicated that PCPA but not DSP-4 abolished the ability of inositol to cause a reduction in immobility time in the forced swim test. In mice, the specific 5-HT(2A)/5-HT(2C) antagonist ritanserin, but not the 5-HT(1A)/5-HT(1B)/beta adrenergic antagonist pindolol, abolished inositol's effect in the forced swim test. The 5-HT(2A)/5-HT(2C) agonist DOI and the 5-HT(1A) agonist 8-OH-DPAT did not have any significant effects on inositol's activity. The present data indicates that the antidepressant effect of inositol may involve 5-HT(2) receptors. It is thus possible that the effects of reuptake antidepressant drugs and the effects of inositol may have a common final pathway.
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PMID:The antidepressant activity of inositol in the forced swim test involves 5-HT(2) receptors. 1116 36

Changes in the control of dopaminergic neurotransmission by noradrenergic locus coeruleus (LC) projections has been implicated in such disorders as depression, drug addiction, and Parkinson's disease. In the present study, the effect of DSP-4, a neurotoxin highly selective for LC projections, on D(2) receptor abundance as assessed by [3H]-raclopride binding in the striatum was studied in rats after administration in doses of 10 and 50 mg/kg either 3 days or 1 month before decapitation. Three days after DSP-4 the levels of noradrenaline in the frontal cortex were dose-dependently reduced; after 1 month, noradrenaline levels were lowered only by the higher dose. DOPAC levels were dose-dependently reduced in the frontal cortex and striatum 3 days but not 1 month after DSP-4 treatment. Cortical 5-HIAA levels were reduced 3 days but not 1 month after DSP-4. The apparent number of D(2) receptor binding sites in the striatum was higher 1 month after either dose of DSP-4. DSP-4 treatment had no effect on [3H]-raclopride binding affinity, the ability of dopamine (DA) to compete with [3H]-raclopride binding and to activate [35S]GTPgammaS binding or on the binding affinities of GDP and [35S]GTPgammaS for corresponding G proteins 1 month after administration of the neurotoxin. These data suggest that after administration of DSP-4, short-term reduction in DA and 5-HT metabolism occurs. Subsequently, an upregulation of D(2) receptor binding sites develops in the striatum even after a minor denervation of the LC projections. Thus, alterations in the LC projection systems elicit lasting adaptive changes in DA-ergic neurotransmission that can serve as a substrate for psychiatric disorders.
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PMID:Effect of denervation of the locus coeruleus projections by DSP-4 treatment on [3H]-raclopride binding to dopamine D(2) receptors and D(2) receptor-G protein interaction in the rat striatum. 1276 55

(-)-Deprenyl (selegiline) is an irreversible inhibitor of monoamine oxidase (MAO) B, which was discovered in 1962 and become the "golden standard" of MAO research. Like the other MAO-B inhibitors, it was synthesized as an antidepressant, but in a selective MAO-B inhibitory dose it does not act in depression. It is used in the treatment of Parkinson's disease. (-)-Deprenyl potentiates the effect of dopamine, it has antioxidant activity and prevents the toxicity of the dopaminergic (6-OH-dopamine; 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP)), the noradrenergic (DSP-4) and cholinergic (AF64A) neurotoxins after pre-treatment. When (-)-deprenyl was administered with levodopa in a long-term treatment of Parkinsonian patients, it induces adverse events (nausea, dizziness, confusion, hallucination, insomnia and cardiovascular changes), which could be due to dopamine potentiation in dopaminergic systems (limbic system), other than the nigrostriatal pathway. (-)-Deprenyl in much lower concentrations needed to induce MAO-B inhibition (10(-9) to 10(-13) M) potently inhibits MPTP or serum withdrawal induced apoptosis in tissue cultures of neuro-ectodermal origin (PC12, M1, M2058). The (+)-enantiomer of deprenyl lacks of this property. The anti-apoptotic activity of (-)-deprenyl can be prevented by inhibiting the metabolism of the drug with SKF-525A pre-treatment, which suggests that some of the presently unknown metabolites could be responsible for the anti-apoptotic activity. In high concentration (10(-3) M), (-)-deprenyl and its metabolites induce apoptosis in tissue cultures without serum withdrawal (biphasic action). Our findings support the view that 100, or even 1000 times lower dose of (-)-deprenyl can be offered in human therapy to protect, or slow down neuronal degeneration, than it is presently used. With low dose of the drug the dopaminergic adverse events could be avoided, while anti-apoptotic activity might be preserved.
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PMID:(-)-Deprenyl, a selective MAO-B inhibitor, with apoptotic and anti-apoptotic properties. 1469 98

Individual differences in novelty-related behavior are associated with sensitivity to various neurochemical manipulations. In the present study the amphetamine-induced locomotor activity and behavioral sensitization to amphetamine (0.5 mg/kg) was investigated in rats with high or low spontaneous exploratory activity (HE- and LE-rats, respectively) after partial denervation of the locus coeruleus (LC) projections with a low dose of the selective neurotoxin DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine; 10 mg/kg). DSP-4 produced a partial depletion (about 30%) of noradrenaline in the frontal cortex of both HE- and LE-rats; additionally the levels of metabolites of dopamine and 5-HT were reduced in the frontal cortex and nucleus accumbens of the LE-rats. Amphetamine-stimulated locomotor activity was attenuated by the DSP-4 pretreatment only in the HE-rats and this effect persisted over repeated testing. Behavioral sensitization to repeated amphetamine was evident only in the LE-rats with intact LC projections. Repeated amphetamine treatment reduced D(2) receptor mediated stimulation of [(35)S]GTPgammaS-binding and dopamine-dependent change in GDP-binding affinity in the striatum, but only in HE-rats. The absence of amphetamine sensitization in HE-rats could thus be related to the downregulation by amphetamine of the G protein stimulation through D(2) receptors. Conclusively, acute and sensitized effects of amphetamine depend on the integrity of LC projections but are differently regulated in animals with high or low trait of exploratory activity. These findings have implications to the neurobiology of depression, drug addiction, and attention deficit hyperactivity disorder.
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PMID:Amphetamine-induced locomotion, behavioral sensitization to amphetamine, and striatal D2 receptor function in rats with high or low spontaneous exploratory activity: differences in the role of locus coeruleus. 1715 51

The aim of this study was to assess the 5-HT1A receptor reactivity after neonatal noradrenergic neurons' lesion. DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine), 50 mg/kg, was administered 30 min after a selective serotonin reuptake inhibitor (SSRI)--zimelidine (10 mg/kg) on the 1st and 3rd day of life. Zimelidine was used to prevent serotonin (5-HT) depletion. 5-HT1A autoreceptor is involved in the regulation of 5-HT release as well as the pathogenesis of depression. During a microdialysis study of anaesthetized rats, the 5-HT1A receptor agonist, R-(+)-8-OH-DPAT (0.1 mg/kg), decreased 5-HT release in the medial prefrontal cortex of control rats but this effect was significantly attenuated in DSP-4-treated animals (10-12 weeks old). To further determine which type of receptor, either pre or postsynaptically located, is involved in the attenuated response to the 5-HT1A receptor agonist in lesioned rats, behavioral tests were conducted. In the forced swimming test, DSP-4 treated rats after saline injection, displayed shorter immobility time in comparison to control rats. R-(+)-8-OH-DPAT (0.5 mg/kg) evoked an antidepressant-like effect in control and DSP-4 treated rats in a learned helplessness paradigm as well as the forced swimming test. The results of this study provided further support for the exclusive desensitization of 5-HT1A autoreceptor in adult rats with neonatal lesion of the central noradrenergic system.
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PMID:Reactivity of 5-HT1A receptor in adult rats after neonatal noradrenergic neurons' lesion--implications for antidepressant-like action. 1878 11

Monoamines are implicated in the modulation of adult hippocampal neurogenesis in depression models and following chronic antidepressant treatment. Given the key role of Sonic hedgehog (Shh) in adult neurogenesis, we examined whether monoaminergic perturbations regulate the expression of Shh or its co-receptors Smoothened (Smo) and Patched (Ptc). Combined depletion of both serotonin and norepinephrine with para-chlorophenylalanine (PCPA) resulted in a significant decrease in Smo and Ptc mRNA within the dentate gyrus subfield of the hippocampus. However, selective depletion of serotonin, using the serotonergic neurotoxin 5,7-dihyrdroxytryptamine (5,7-DHT), or norepinephrine, using the noradrenergic neurotoxin DSP-4, did not alter expression of Shh and its co-receptors, Smo and Ptc. Acute treatment with the monoamine releasing agent, para-chloroamphetamine (PCA) significantly upregulated Smo mRNA within the dentate gyrus. However, acute or chronic treatment with pharmacological antidepressants that modulate monoaminergic neurotransmission did not regulate Shh cascade expression. These results indicate that robust changes in monoamine levels can regulate the expression of the Shh signaling cascade in the adult rodent brain.
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PMID:Monoaminergic regulation of Sonic hedgehog signaling cascade expression in the adult rat hippocampus. 1942 33

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