ETHANOL ENHANCES MEDIAL AMYGDALOID INDUCED-INHIBITION OF PREDATORY ATTACK BEHAVIOR IN THE CAT - ROLE OF GABA(A) RECEPTORS IN THE LATERAL HYPOTHALAMUS

Citation
Yc. Han et al., ETHANOL ENHANCES MEDIAL AMYGDALOID INDUCED-INHIBITION OF PREDATORY ATTACK BEHAVIOR IN THE CAT - ROLE OF GABA(A) RECEPTORS IN THE LATERAL HYPOTHALAMUS, Alcohol and alcoholism, 32(6), 1997, pp. 657-670
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Substance Abuse
Journal title
ISSN journal
0735-0414
Volume
32
Issue
6
Year of publication
1997
Pages
657 - 670
Database
ISI
SICI code
0735-0414(1997)32:6<657:EEMAIO>2.0.ZU;2-A
Abstract
The present study tested the hypothesis that the suppressive effects o f ethanol upon predatory attack behaviour in the cat involve a pathway from the medial amygdala to the lateral hypothalamus, and that these suppressive effects are mediated by gamma-aminobutyric acid (GABA(A)) receptors located in the lateral hypothalamus. Cannula electrodes were implanted into the lateral hypothalamus for elicitation of predatory attack behaviour and for microinjections of the GABA(A) receptor antag onist, bicuculline. Monopolar stimulating electrodes were implanted in to the medial amygdala from which subseizure levels of electrical stim ulation suppressed predatory aback behaviour. In the first phase of th e study, we compared response latencies for predatory attack behaviour following single stimulation of the lateral hypothalamus alone with t hose following paired trials of dual stimulation of the medial amygdal a plus lateral hypothalamus. Dual stimulation significantly suppressed predatory attack. In the second phase of the study, peripheral ethano l administration (in doses of 0.01, 0.5 and 1.0 g/kg, i.p.) enhanced t he suppressive effects of medial amygdaloid stimulation in a dose-and time-dependent manner in which peak effects were obtained 60 min post- injection. In the third phase of the study, bicuculline (0.15 nmol) wa s microinjected into the lateral hypothalamus both prior to and follow ing paired trials of dual stimulation. Drug infusion blocked the suppr essive effects of medial amygdaloid stimulation upon predatory attack behaviour elicited from the lateral hypothalamus, indicating the impor tance of GABA(A) receptors in mediating this suppression. In the fourt h phase of the study, bicuculline, microinjected into the lateral hypo thalamus at the time when ethanol's effects were maximal (i.e. 60-80 m in post-ethanol administration), totally blocked the suppressive effec ts of medial amygdaloid stimulation as well as the enhancing effects o f ethanol upon medial amygdaloid suppression of this form of aggressiv e behaviour. In the last phase of the study, bicuculline (0.15 nmol) i nfusion into the lateral hypothalamus significantly reduced the suppre ssive effects of ethanol (1.0 g/kg, i.p.) upon predatory attack behavi our elicited from the lateral hypothalamus. These results support the hypothesis that ethanol's suppressive effects upon predatory attack be haviour in the cat are mediated, at least in pari, by GABA(A) receptor s in the lateral hypothalamus. The present and recent findings in our laboratory support the view that GABA(A) receptors in the lateral hypo thalamus are activated, in turn, by a GABAergic pathway which arises f rom the medial hypothalamus whose neurons receive inputs from the medi al amygdala.