Feeding induced by food deprivation is differentially reduced by G-protein α-subunit antisense probes in rats

Abstract

Antisense oligodeoxynucleotide (AS ODN) probes directed against the α-subunit of different G-proteins have been used to differentiate feeding responses in rats elicited by different opioid agonists, including morphine, β-endorphin and dynorphin. Furthermore, antisense probes directed against G oα, but not G sα, G qα or G iα, significantly reduced nocturnal feeding in rats. The present study examined whether food intake and weight changes elicited by 24 h of food deprivation were significantly altered by ventricular administration of antisense probes directed against either G iα 1, G iα 2, G iα 3, G sα, G oα, G qα or G x/zα as well as a control nonsense probe in rats. Deprivation-induced weight loss was significantly enhanced by antisense probes directed against G sα and G x/zα, whereas weight recovery 24 h following reintroduction of food was significantly reduced by antisense probes directed against G iα 2, G qα and G oα. Selective antisense probe effects were noted for deprivation-induced intake with G sα and G qα probes exerting the greatest reductions, G x/zα, G iα 2, and G iα 3 probes exerting lesser effects, and G iα 1 and G oα probes failing to affect deprivation-induced intake. Importantly, the nonsense control probe failed to alter deprivation-induced intake or weight. The reductions in deprivation-induced intake by AS ODN probes directed against G sα or G qα were not accompanied by any evidence of a conditioned taste aversion. These data indicate important distinctions between G-protein mediation of different effector signaling pathways mediating feeding responses elicited under natural (e.g. nocturnal feeding) and regulatory challenge (e.g. food deprivation) conditions.