Effects of streptozotocin diabetes on amylase release and cAMP accumulation in rat parotid acinar cells.
Rat parotid responses to sympathetic nerve stimulation in vivo are impaired 2-4 weeks after the induction of streptozotocin diabetes. In this study, the effects of experimental diabetes of similar duration and severity on noradrenaline-stimulated amylase release and cAMP accumulation were examined in vitro. Amylase levels were significantly lower in acinar cells isolated from diabetic animals than in controls, and cellular amylase increased after treatment of the diabetic animals with either thyroxine (T4) or insulin. Diabetes and T4 had no apparent affect on amylase release measured as a percentage of the total. In contrast, giving insulin resulted in a significant reduction in maximal secretion (20.4 +/- 2.4% compared with 43.6 +/- 7.6%). Similar results were observed when amylase release was stimulated with forskolin. Basal cAMP levels were unaffected by diabetes or T4 (7.8 +/- 2.3 pmol/mg protein), but stimulated cAMP levels were significantly greater in diabetic acinar cells than in controls. Insulin reversed the effects of diabetes on cAMP accumulation, whereas T4 had no effect. Thus, diabetes (2-4 weeks) and insulin in vivo appear to have paradoxical effects on parotid amylase release and cAMP accumulation in vitro. Further, the effects of diabetes appear to be unrelated to thyroid status.
Anderson
L C
LC
Department of Oral Biology, University of Washington, Seattle 98195.
Bevan
C A
CA
D000681:Amylases / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000032:analysis / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010306:Parotid Gland / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine / Q000494:pharmacology
D007328:Insulin; D005576:Colforsin; D000242:Cyclic AMP; D000681:Amylases; D013974:Thyroxine; D009638:Norepinephrine