Effects of vaso-inactive doses of PGA1 and PGE1 on insulin secretion in the rat

Theophylline prevents the inhibitory effect of prostaglandin E 2 on glucose-induced insulin secretion in man

“…The inhibitory effect of prostaglandin E2 on glucoseinduced insulin secretion was prevented by theophylline (100 mg as a loading dose followed by a 5 mg/min infusion), a drug that increases the intracellular cAMP concentrations by inhibiting phosphodiesterase activity. Our data suggest the involvement of the adenylate cyclase system in the inhibitory action of prostaglandin E2 on glucose-induced insulin secretion in man.The initial confusion about the effects of prostaglandins (PG) on insulin secretion, arising for the main part from the conflicting results of the in vitro studies performed in different animal spe¬ cies (Robertson 1979), was followed by an unceas¬ ing increase in experimental in vivo data indicat¬ ing that PG of the E series (PGE) inhibit the insulin response to glucose in several species, including rats (D'Onofrio et al 1977; Sacca et al 1975), dogs (Robertson et al 1974) and humans (Giugliano et al 1978; Robertson & Chen 1977). The available data in humans indicate that both PGE and PGE2 can inhibit glucose-induced insu¬ lin secretion in a dose-dependent manner (Giug¬ liano & Torella 1978; Giugliano et al 1978; Ro¬ bertson & Chen 1977) and that this effect is probably direct, because it is not reversed by alpha-adrenergic antagonists, which block the in¬ hibiting effect of catecholamines on insulin se¬ cretion (Giugliano et al 1979).…”

“…The initial confusion about the effects of prostaglandins (PG) on insulin secretion, arising for the main part from the conflicting results of the in vitro studies performed in different animal spe¬ cies (Robertson 1979), was followed by an unceas¬ ing increase in experimental in vivo data indicat¬ ing that PG of the E series (PGE) inhibit the insulin response to glucose in several species, including rats (D'Onofrio et al 1977;Sacca et al 1975), dogs (Robertson et al 1974) and humans Robertson & Chen 1977).…”