Effect of insulin and clonidine on the evoked release of norepinephrine and serotonin from the nucleus tractus solitarius of the diabetic rat

Pharmacology
J C DunbarG F Anderson

Abstract

Dorsal medullary brain slices containing primarily the nucleus tractus solitarius (NTS) were obtained from normal or 40- to 50-day streptozotocin-diabetic rats and employed for superfusion studies of evoked transmitter release. Electrically stimulated (25 mA, 2-ms pulses, 3 Hz, 1 min) release of [3H]norepinephrine ([3H]NE) or [3H]5-hydroxytryptamine ([3H]5-HT) from 400-microns NTS slices stimulated at 75 min (S1) and 130 min (S2) resulted in S2/S1 release ratios that were not different between normal controls or diabetic control groups. Perfusion of normal [3H]NE-loaded slices with 0.1 mumol/l clonidine reduced the S2/S1 ratio by 23% (p < 0.05) which was uniform in the caudal, subpostremal, and intermediate segment levels of the NTS. In diabetic NTS slices, the S2/S1 ratio was significantly less reduced by clonidine in both the subpostremal (-3%) and intermediate (-11%) slice regions. Blockade of alpha 2-adrenoceptors with yohimbine (0.1 mumol/l) enhanced (p < 0.05) [3H]NE release (S2/S1 ratios) in slices from both normal and diabetic rats. Perfusion of [3H]NE-loaded slices with 5 mU/ml insulin did not affect S2 release. Evoked S2/S1 release ratios from NTS slices loaded with [3H]5-HT did not differ between normal control and d...Continue Reading

Citations

Nov 10, 1998·Biological Psychiatry·S F Leibowitz, J T Alexander
Jul 23, 2003·Regulatory Peptides·Mônica Marques TellesEliane Beraldi Ribeiro

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