AN ANALOG OF MIF, ALAPTIDE - EFFECT ON SERUM PROLACTIN, DOPAMINE-RECEPTORS AND GROWTH OF RAT ADENOHYPOPHYSIS

Alaptide is a drug chemically derived from prolyl-leucyl-glycin amide (PLG) which is effective after oral administration. We studied the eff ect of long term treatment with alaptide and estradiol-benzoate on ser um prolactin, growth reactivity and dopamine DA-2 receptors in the ant erior pituitary of male rats. Alaptide reduced adenohypophyseal weight when given alone, but only nonsignificantly reduced growth reactivity of the anterior pituitary (AP) raised by estradiol-benzoate (EB). Ala ptide significantly decreased the serum level of prolactin but, on the other hand, significantly increased the binding of H-3-spiperone to d opamine DA-2 receptors in AP membrane preparations, without affecting affinity. The administration of alaptide plus EB together resulted in an additional increase of dopamine DA-2 binding sites. We assume that alaptide has a weak dopaminergic activity on the AP of male rats.