New analogs of somatostatin: inhibiting effectively GH, glucagon and insulin levels.

: The in vivo effects of three new analogs of somatostatin (ASS-51, ASS-52 and ASS-53 analogs) on GH, insulin and glucagon were studied in WKY rats. The solid phase method was used for the synthesis of ASS. Octreotide and ASS were given iv. in a dose of 0.05 &mgr;g/kg per animal in a time-dependent manner. ASS-52 and ASS-53 were longer acting and more potent somatostatin analogs when compared to octreotide in producing the inhibition of GH. ASS-51 was found to be the most potent and selective inhibitor of insulin and glucagon release. Our results show that the increased inhibitory effect and the higher selectivity of the new somatostatin analogs may result from the differences in their chemical structure. ASS-52 is most active in inhibiting GH release. The mechanism by which ASS-52 inhibits preferentially GH release may involve the opioid system and the activation of GABA-ergic receptors. In studies in vitro ASS-52 inhibited GH release from pituitary cells" culture.