Diabetes alters mu and kappa opioid binding in rat brain regions: comparison with effects of food restriction.
Diabetic rats display changes in opioid pharmacology and brain regional levels of opioid peptides and prodynorphin mRNA. Previous investigations of opioid receptor binding, carried out in whole-brain homogenates, have, however, failed to detect changes. In the present study, quantitative autoradiography was used to measure mu and kappa opioid receptor binding in discrete brain regions of streptozotocin-treated diabetic rats. Measurement was limited to regions that previously displayed opioid binding changes in chronically food-restricted rats, since our primary aim is to identify brain mechanisms that mediate adaptive responses to persistent metabolic need and adipose depletion. Diabetics displayed strong trends or statistically significant changes which matched seven of the thirteen binding changes observed in food-restricted rats. In no case did diabetics display changes in the opposite direction. The two statistically significant changes common to food-restricted and diabetic rats are increased kappa binding in the medial preoptic area and decreased mu binding in the lateral habenula. The possible functional significance of these changes is discussed.
Wolinsky
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TD
Millhauser Laboratories, Department of Psychiatry, New York University Medical Center, NY 10016, USA.
Abrahamsen
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GC
Carr
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KD
D000818:Animals; D001345:Autoradiography; D001575:Benzomorphans / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000378:metabolism; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017473:Receptors, Opioid, kappa / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D014018:Tissue Distribution
D001575:Benzomorphans; D004745:Enkephalins; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; C027248:bremazocine