Neuroanatomical and functional characterization of the ghrelin-responsive neurons of the lateral hypothalamic area

MARIA PAULA CORNEJO; MIRTA REYNALDO; FRANCO BARRILE; GUADALUPE GARCÍA-ROMERO; NICOLAS DE FRANCESCO; MARIO PERELLO

Congreso; Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2018

Ghrelin is a stomach-derived hormone that regulates a variety of biological functions via the growth hormone secretagogue receptor (GHSR), a receptor located in key brain areas that mediate the actions of the hormone. GHSR is highly expressed in the lateral hypothalamic area (LHA), which controls essential functions, including food intake, locomotor activity and reward-related behavioral responses. Here, we used a mouse model, in which the expression of enhanced green fluorescent protein (eGFP) is controlled by the promoter of GHSR (GHSR-eGFP mice), to gain neuroanatomical and functional insights of the GHSR-expressing neurons of the LHA. We found that GHSR neurons of the LHA are present from bregma X to bregma X en the antero-posterior axis, and particularly enriched in the XX (perifornical region?). GHSR neurons of the LHA increase the level of the marker of neuronal activation c-Fos in response to centrally injected ghrelin and fail to increase c-Fos in response to systemically injected ghrelin. We also identified that a subset of GHSR neurons of the LHA are GABAergic and that no GHSR neurons of the LHA express orexin. Finally, we found that local intra-LHA rostral infusions of ghrelin increase food intake. Thus, current data provide evidence that ghrelin receptor signaling seems to target a subset of GABA neurons of the LHA that, in turn, affect food intake.