The participation of serotoninergic system in the regulation of emotional-defensive behavior evoked by intrahypothalamic carbachol injections in the cat.
The influence of bilateral injections of serotonin (5-HT) and methysergide (MET) to antero-medial hypothalamus (HA) on carbachol-induced emotional-defensive behavior was investigated. Earlier (15 min) stimulation of 5-HT receptors in HA region by 5-HT injections evoked a decrease in the level of vocal response (number and time of growling), while previous blocking of these receptors by means of MET brought about a considerable increase of vocalization level evoked by carbachol (Cch) injections (10 pg) to the same loci of HA. Intrahypothalamic injections of 5-HT alone or MET did not evoke any observable changes in the animals behavior. The alterations of the level of Cch-induced vocal response 3 to 35 days after chemical damage of 5-HT neurons in HA or in the middle forebrain bundle (MFB) in posterolateral hypothalamus caused by 5,7-dihydroxytryptamine were examined. Local neurotoxin injections both to MFB and to HA evoked a long lasting increase in the level of Cch-induced vocalization, which began on the 5th-7th day after lesioning and lasted till the completion of the experiment (35 days). Results data indicate that the 5-HT system exerts an inhibiting influence on the emotional-defensive behavior induced by the cholinergic system.
D000374:Aggression / Q000502:physiology*; D000378:Agonistic Behavior / Q000502:physiology*; D000818:Animals; D002415:Cats; D002799:Cholinergic Fibers / Q000502:physiology; D004644:Emotions / Q000502:physiology*; D006801:Humans; D007031:Hypothalamus / Q000502:physiology*; D008474:Medial Forebrain Bundle / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*
D012701:Serotonin