[Effect of biogenic amines on rat anterior pituitary cyclic AMP]

The effects of biogenic amines on the formation of adenosine-3',5' monophosphate (cAMP) in the anterior pituitary of rats were investigated. Pituitary halves were preincubated in a Krebs-Ringer bicarbonate buffer (pH 7.4) containing theophylline (10(-2)M) at 37 degrees C for 30 minutes and incubated in a fresh buffer for 15 minutes after the addition of test substances. Noradrenaline at 4 X 10(-4)M and serotonin at 3.3 X 10(-4)M were effective in elevating cAMP, but dopamine at 2 X 20(-4)M was ineffective. The beta adrenergic blocking agent, propranolol, effectively antagonized the cAMP response to noradrenaline, but the alpha adrenergic blocking agent, phentolamine, did not. The serotonin antagonist, methysergide, remarkably antagonized the cAMP response to serotonin, but the alpha and beta adrenergic agents did not.