Effects of prolactin and glycosylated prolactin on (pro)insulin synthesis and insulin release from cultured rat pancreatic islets.
In order to study the possible differential effects of the nonglycosylated and glycosylated forms of prolactin on insulin content and secretion in pancreatic islets, neonatal rat pancreatic islets were exposed for 6 days in vitro to 2 micrograms/ml of nonglycosylated ovine prolactin (oPRL), or to 2 micrograms/ml of glycosylated oPRL (G-oPRL). oPRL stimulated a significant increase (p less than 0.01) in the total amount of insulin released into the medium over the 6 day culture period; however, G-oPRL had no effect. Islets cultured for 6 days in the presence of oPRL showed no increase in the amount of DNA per islet. However, there was a significant (p less than 0.007) increase in the amount of total protein synthesized by the islets exposed to oPRL. These findings suggest that the effect of oPRL on neonatal rat pancreatic islet cells is a nonspecific effect. The nonglycosylated form of PRL may play a role in B-cell function by promoting protein synthesis, which results in augmented insulin synthesis.
Lutcher Brown Department of Biochemistry, Whittier Institute for Diabetes and Endocrinology, La Jolla, CA 92037.
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E
Markoff
G M
GM
Beattie
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A
Hayek
U J
UJ
Lewis
D000818:Animals; D005947:Glucose / Q000494:pharmacology; D006001:Glycoconjugates; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D011384:Proinsulin / Q000096:biosynthesis*; D011388:Prolactin / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew; D013329:Structure-Activity Relationship
D006001:Glycoconjugates; D007328:Insulin; D011388:Prolactin; D011384:Proinsulin; D005947:Glucose