Attenuated cardiovascular, neuroendocrine, and behavioral responses after a single footshock in central amygdaloid lesioned male rats.

The effect of bilateral electrolytical CEA lesioning on behavioral, cardiovascular and neuroendocrine changes has been studied in male Wistar rats before, during and shortly after a brief aversive stimulus of an unavoidable footshock. Blood samples were withdrawn via a permanent heart catheter. Lesioning of the CEA abolished completely the immobility response normally seen after a footshock. Lesions failed to affect the early tachycardiac response compared to sham-lesioned controls, but the poststress recovery was attenuated, probably due to diminished vagal activation. Furthermore, the magnitude of the responses of all measured hormones (epinephrine, norepinephrine, corticosterone and prolactin) appeared to be attenuated in the lesioned rats. These results suggest that the CEA plays an important and general role in the behavioral, autonomic and hormonal output during a brief unavoidable, unconditioned footshock. This is in contrast with the selective role of the CEA in vagal (parasympathetic) and on inhibitory (immobility) behavioral responses following conditioning.