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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of acute and chronic treatment of rats with the tricyclic antidepressant imipramine, the 5-HT1A receptor partial agonist tandospirone, or its metabolite 1-PP were compared on behavioral responses produced by the activation of 5-HT receptors and on brain monoamine receptors. The behaviors examined were the 5-HT behavioral syndrome elicited by the 5-HT1A receptor agonist 8-OH-DPAT and the head shake response produced by the 5-HT2 receptor agonist DOB. Drug treatments were administered either by subcutaneous infusion from implanted minipumps or by repeated injection and the effects of chronic drug treatment were assessed when the drug was present and absent at the time of testing. The infusion of tandospirone blocked elicitation of the 5-HT behavioral syndrome when tested after 1 or 14 days of drug treatment (drug present) and 24 hr after the drug was withdrawn (drug absent). When administered by injection, tandospirone blocked the production of the 5-HT syndrome 1 hr (drug present), but not 24 hr (drug absent), following either 1 day or 14 days of drug treatment. Chronic infusion of imipramine did not alter the 5-HT syndrome. Chronic, but not acute, injections of imipramine blocked the 5-HT syndrome when tested 1 hr but not 24 hr, after the final injection. Treatment with 1-PP did not alter the 5-HT syndrome. The head shake response was attenuated by acute and chronic injection of tandospirone either 1 or 24 hr after treatment, although chronic infusion of tandospirone did not alter this behavior. Head shaking was attenuated by the infusion and injection of imipramine after acute treatment, chronic treatment, or following drug withdrawal. Chronic injection of 1-PP also inhibited the head shake response 24 hr after injection, although 1-PP was ineffective at all other times and when given by infusion. The density of hippocampal 5-HT1A receptors was unaltered by the chronic drug treatments. 5-HT2 receptor density in frontal cortex was reduced by the chronic infusion of either tandospirone, imipramine, and 1-PP, but only by chronic injections of imipramine. The density of cortical beta-adrenergic receptors was reduced following chronic imipramine injections or infusion. The results suggest that both tandospirone and imipramine may regulate 5-HT-mediated responses and 5-HT2 receptor density, which may contribute to their efficacy as antidepressants, although their effects were dependent upon the method of administration and may involve different neuropharmacological mechanisms.
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PMID:Effect of chronic treatments with tandospirone and imipramine on serotonin-mediated behavioral responses and monoamine receptors. 839 53

The effect of repeated cocaine administration on serotonin2 (5-HT2) receptor function was examined in male rats. Rats were fitted with indwelling jugular catheters and subsequently received cocaine (15 mg/kg, i.p., b.i.d.) or saline for 7 days. Rats were challenged with the 5-HT2 agonist DOI (25, 100, 400 micrograms/kg, i.v.) or saline 42 hr and 8 days after cessation of chronic treatment. Serial blood samples were collected at various times after DOI challenge and analyzed for prolactin levels. DOI-induced head shakes and skin jerks were examined concurrently in the same subjects. After 42 hr of withdrawal, the stimulatory effects of DOI on prolactin release and shaking behavior were significantly enhanced in cocaine-treated rats. Conversely, the skin jerk response to DOI was not altered by prior cocaine exposure. After 8 days of withdrawal, the prolactin and head shake responses to DOI were still potentiated in cocaine-treated rats, but this effect was no longer statistically significant. The data indicate that chronic cocaine enhances the sensitivity of 5-HT2 receptor mechanisms. Our findings further suggest the possibility that altered 5-HT2 receptor function may be involved in the mood disturbances experienced by abstinent cocaine addicts.
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PMID:Chronic cocaine exposure potentiates prolactin and head shake responses to 5-HT2 receptor stimulation in rats. 878 4

2,5-Dimethoxy-4-iodoamphetamine (DOI), a serotonin (5-HT)2A/2C receptor agonist, elicits shaking behaviors in rodents, which have been reliably quantified as behavioral correlates of 5-HT2A receptor activation. Such studies are lacking in the rabbit. As part of our research examining the role of the 5-HT2 receptor in rabbits, we analyzed the behavioral effects of systemically administered DOI in rabbits. DOI (0.01-3 micromol/kg) or vehicle was injected, and two distinct behaviors, head bobs (vertical head movements) and body shakes (wet dog shakes), were counted for 90 min following the injection. DOI dose-dependently increased the number of head bobs and body shakes. The selective 5-HT2A receptor antagonist ketanserin (1-3 micromol/kg), 1 h before DOI (0.3 micromol/kg) challenge, significantly attenuated head bobs, but not body shakes. In contrast, the selective 5-HT2C receptor antagonists SDZ SER 082 (1-3 micromol/kg) and SB 206553 (1 micromol/kg) 30 min before challenge, significantly reduced body shakes but not head bobs produced by the same dose of DOI. This study establishes that, in rabbits, DOI mediates head bobs via 5-HT2A receptors and body shakes via 5-HT2C receptors. Thus, the rabbit provides a novel behavioral assay that discriminates between 5-HT2A and 5-HT2C receptor activation.
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PMID:A novel behavioral model that discriminates between 5-HT2A and 5-HT2C receptor activation. 1190 Aug 8


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