Microinjection of vasopressin and two related peptides into the amygdala: enhancing effect on local dopamine neurotransmission

Abstract

The effects of local microinjection of Arg 8-vasopression, cyclo[Lys-Gly] and l-Pro- l-Leu-GlyNH 2 (PLG) were studied on the α-MPT-induced disappearance of dopamine and noradrenaline in the amygdala and in a number of other brain regions. A dose-dependent increase in dopamine utilization was found in the amygdala after local microinjection of Arg 8-vasopressin, cyclo[Lys-Gly] and PLG at doses of 0.1, 2.7 and 18 pmol respectively. No effects were found on noradrenaline utilization in this brain region. Using a microdissection method, it was found that cyclo[Lys-Gly] enhanced dopamine utilization in the nucl. amygdaloideus centralis, whereas the effect of PLG was mainly located in the nucl. amgydaloideus corticalis. These effects of Arg 8-vasopressin, cyclo[Lys-Gly] and PLG on dopamine utilization in the amygdala are correlated with those on avoidance behavior and can be interpreted as in support of the role of dopamine as neurotransmitter involved in retrieval processes.