Kisspeptin neurones in the posterodorsal medial amygdala modulate sexual partner preference and anxiety in male mice

Abstract

The posterodorsal medial amygdala (MePD) is a neural site in the limbic brain involved in regulating emotional and sexual behaviours. There is however limited information on the specific neuronal cell type in the MePD functionally mediating these behaviours in rodents. The recent discovery of a significant kisspeptin neurone population in the MePD has raised interest in the possible role of kisspeptin and its cognate receptor in sexual behaviour. This study therefore tested the hypothesis that the MePD kisspeptin neurone population is involved in regulating attraction towards opposite sex conspecifics, sexual behaviour, social interaction and anxiety response by selectively stimulating these neurones using the novel pharmacosynthetic DREADDs (designer receptors exclusively activated by designer drugs) technique. Adult male Kiss-Cre mice received bilateral stereotaxic injections of a stimulatory DREADD viral construct (AAV-hSyn-DIO-hM₃D(Gq)-mCherry) targeted to the MePD which were activated by intraperitoneal (i.p.) injection of clozapine-N-oxide (CNO). Socio-sexual behaviours were assessed in a counter-balanced fashion after i.p. injection of either saline or CNO (5mg/kg). Selective activation of MePD kisspeptin neurones by CNO significantly increased the time spent by male mice in investigating an oestrous female as well as duration of social interaction. Additionally, after CNO injection the mice appeared less anxious; evidenced by longer exploratory time in the open arms of the elevated plus maze. However, levels of copulatory behaviour were comparable between CNO and saline treated controls. These data indicate that DREADD-induced activation of MePD kisspeptin neurones enhances sexual partner preference in males and social interaction and decreases anxiety, suggesting a key role played by MePD kisspeptin in sexual motivation and social behaviour.

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