Possible role of prostaglandins in the regulation of food intake in the newborn rat.

The effect of fatty acids (prostaglandins, arachidonic and linoleic acids) and prostaglandin synthetase inhibitors on food intake (measured as change in weight) were studied in newborn and young rats. PGE2 (0.1, 0.5 mg/kg) and PGF2 alpha (0.5 mg/kg) inhibited feeding in the 6 hr deprived 1 day old rat. Under the same deprivation PGF2 alpha (0.5, 1 mg/kg) also caused anorexia in 5, 10 and 15 day old rats. S.C. injection of arachidonic acid (2.5-20 mg/kg) and linoleic acid (150 mg/kg) depressed while aspirin (200-400 mg/kg) and indomethacin 8-32 mg/kg) increased feeding in the non-deprived 1 day old rat. The anorectic activity of arachidonic acid is antagonized by prior (1 hr) administration of aspirin (100 mg/kg) and indomethacin (4 mg/kg) indicating the involvement of prostaglandins in arachidonic acid-induced anorexia. S.C. injection of aspirin (400 mg/kg), indomethacin (4,8 mg/kg) and flurbiprofen (3.12-25 mg/kg) to 1.5 hr deprived 5 day old rats also increased food intake. It is hypothesized that the prostaglandin-generating system and endogenous aspirin (endospirin)-like substances, which inhibit such a generation, play an important physiological role in the regulation of hunger-satiety in the newborn rat.