Antagonism between pineal peptides and catecholamines. II. The action of a pineal peptide extract on the process of endogenous catecholamines secretion-excretion.

To determine the processes of adrenaline and noradrenaline secretion-excretion in rats and rabbits with/without associated insulin lente administration (20 U.I./kg rat b.w. and 6 U.I./kg rabbit b.w.), the authors used a pineal peptide extract that has now become available under the trade name of "Crinofizin". Under conditions of natural light, environmental temperature of 18-20 degrees C and fed ad libitum, Crinofizin did not cause significant alterations in the rat 24 hrs urinary excretion of catecholamines. Administration of insulin induced a more than two-fold increase in the two catecholamines both in the rabbit and the rat. Administration of Crinofizin one hour before insulin prevented totally or partially these effects of insulin. The drug acted as a blocking agent in the processes of endogenous adrenaline and noradrenaline secretion-excretion under hormonal stimulation, but not under basal conditions.