RESUMEN
We have recently found that prostaglandin (PG) D(2) stimulates food intake via DP(1) receptor. Here we show that complement C5a stimulates food intake by activating the orexigenic PGD(2) system. C5a (30-100 pmol/mouse), after intracerebroventricular administration, stimulated food intake in non-food-deprived mice. The orexigenic activity of C5a was blocked by co-administration of a DP(1) receptor antagonist, BWA868C. Central administration of C5a elevated the hypothalamic mRNA expression of COX-2 but not COX-1, and the food intake stimulation of C5a was inhibited by pretreatment with a COX-2 inhibitor, celecoxib, suggesting that C5a activates COX-2 upstream of the PGD(2)-DP(1) system. The orexigenic activity of C5a was also inhibited by an antagonist for neuropeptide Y (NPY) Y(1) receptor, which was activated downstream of the PGD(2)-DP(1) system. These results suggest that C5a stimulates food intake via a PGD(2)- and NPY-dependent mechanism. C5a is the first example of orexigenic peptides acting through the PGD(2)-NPY system in the central nervous system.
Asunto(s)
Complemento C5a/farmacología , Ingestión de Alimentos/efectos de los fármacos , Hidantoínas/farmacología , Neuropéptido Y/fisiología , Prostaglandina D2/fisiología , Animales , Ciclooxigenasa 1/genética , Ciclooxigenasa 1/metabolismo , Ciclooxigenasa 2/genética , Ciclooxigenasa 2/metabolismo , Ingestión de Alimentos/fisiología , Hipotálamo/efectos de los fármacos , Hipotálamo/enzimología , Masculino , Ratones , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Receptores de Prostaglandina/antagonistas & inhibidores , Receptores de Prostaglandina/fisiología , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
We found that prostaglandin (PG) D(2), the most abundant PG in the central nervous system, stimulates food intake after intracerebroventricular administration in mice. The orexigenic effect of PGD(2) was mimicked by a selective agonist for the DP(1) receptor among two receptor subtypes for PGD(2), and abolished by its antagonist. Central administration of an antagonist or antisense oligodeoxynucleotide for the DP(1) receptor remarkably decreased food intake, body weight and fat mass. Hypothalamic mRNA levels of lipocalin-type PGD synthase were up-regulated after fasting. The orexigenic activity of PGD(2) was also abolished by an antagonist for neuropeptide Y (NPY) Y(1) receptor. Taken together, PGD(2) may stimulate food intake through central DP(1) receptor coupled to the NPY system.