The lateral hypothalamus and anterior hypothalamic nucleus differentially contribute to rats' defensive responses in the elevated plus-maze and shock-probe burying tests.
Lesions or pharmacological inhibition of the lateral septum reduce rats' open-arm avoidance in the elevated plus-maze and their burying behavior in the shock-probe test. The current study examined whether hypothalamic areas that receive direct input from the lateral septum also influence open-arm avoidance and defensive burying. Bilateral infusions of the GABA-A receptor agonist muscimol (20 ng) into the lateral hypothalamus selectively increased rats' open-arm avoidance without affecting shock-probe burying. In contrast, infusions of muscimol into the anterior hypothalamic nucleus suppressed burying without affecting rats' open-arm avoidance. These dissociations suggest that the lateral hypothalamus contributes to the exploration of potentially threatening environments, whereas the anterior hypothalamus influences defensive responses to proximal discrete threat stimuli.
Hakvoort Schwerdtfeger
Rebecca M
RM
Centre for Neuroscience Studies, Canada.
Menard
Janet L
JL
D000704:Analysis of Variance; D000818:Animals; D007025:Anterior Hypothalamic Nucleus / Q000293:injuries / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology; D001522:Behavior, Animal / Q000187:drug effects; D003674:Defense Mechanisms; D004597:Electroshock / Q000379:methods; D005106:Exploratory Behavior / Q000502:physiology*; D018755:GABA Agonists / Q000494:pharmacology; D007026:Hypothalamic Area, Lateral / Q000293:injuries / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans
D018755:GABA Agonists; D009118:Muscimol