Biochemistry and physiology of gastrointestinal somatostatin

Somatostatin, a tetradecapeptide initially isolated from the ovine hypothalamus, is widely distributed throughout the gastrointestinal tract where it may act as a hormone, local chemical messenger, or neurotransmitter to elicit many physiological actions. Release of somatostatin from D cells in the gut is regulated by mechanisms that are both dependent on and independent of cAMP. In most cases somatostatin acts to inhibit the function of its target cells. It performs this action in part via pertussis-toxin-sensitive inhibitory guanine nucleotide-binding proteins that regulate adenylate cyclase activity. Other mechanisms may involve sites of action distal to intracellular second messenger systems .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44411/1/10620_2005_Article_BF01536041.pd

Plasminogen activator and nuclear androgen receptor in rat prostate tumors after treatment with D-Trp-6-LH-RH.

Plasminogen activator and nonspecific proteolytic activity in transplantable squamous cell rat prostate tumor 11095 were measured by a fluorometric method. Prostate tumors which regressed after treatment with D-Trp-6-LH-RH had 10-fold lower concentrations of plasminogen activator(s) per mg of protein, and considerably higher levels of nuclear androgen receptor. On the other hand, there were no significant changes in nonspecific proteolytic activity in tumor tissue between untreated and D-Trp-6-LH-RH treated rats. The prostate tumor had at least three different plasminogen activator-like bands, as determined by polyacrylamide gel electrophoresis with plasminogen as substrate. The decreased activity of plasminogen activator(s) and considerably higher levels of nuclear androgen receptors correlate with the regression of prostate tumors induced by the treatment of rats with D-Trp-6-LH-RH