The correlation between hypothalamic and midbrain biogenic amine content and the intensity of the emotional-defensive arousal in cats.
Changes in levels of noradrenaline (NA), dopamine (DA), serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the medial hypothalamus and the midbrain central grey matter were determined and correlated with various levels of an emotional-defensive arousal in cats, evoked by an intrahypothalamic injection of carbachol. At the initial stage of excitation, 3 min after the injection of carbachol, the levels of NA, DA, and 5-HIAA in the medial hypothalamus increased, whereas in the central grey matter only the 5-HIAA level was elevated. During the maximum excitation (when the vocalization attained the peak level) the level of amines and 5-HIAA decreased in the medial hypothalamus; in the central grey matter only the levels of 5-HT and 5-HIAA declined. In the final phase of response, 5 min after the disappearance of vocalization, the 5-HT level in both structures increased. These results confirm the notion that the noradrenergic, dopaminergic and serotonergic systems participate in the central regulation of the emotional-defensive behavior, and show that the hypothalamus and midbrain play different roles in this regulation. The results also indicate that neurochemical mechanisms are similar in different types of emotional-defensive behavior. It seems that catecholaminergic systems play a stimulating role, while the serotonergic system inhibits the carbachol-induced defensive response.
D000818:Animals; D001143:Arousal / Q000502:physiology*; D001679:Biogenic Amines / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002415:Cats; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007033:Hypothalamus, Middle / Q000378:metabolism*; D008297:Male; D008636:Mesencephalon / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism
D001679:Biogenic Amines; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D002217:Carbachol; D004298:Dopamine; D009638:Norepinephrine