Diabetes, Vol 36, Issue 10 1173-1177, Copyright © 1987 by American Diabetes Association
Effects of glucose and diabetes on binding of naloxone and dihydromorphine to opiate receptors in mouse brain
DA Brase, YH Han and WL Dewey
Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond.
The effects of glucose and diabetes on the high-affinity
lofentanil-displaceable opiate-receptor binding in mouse brain membranes
were studied to determine if the attenuation of opiate actions by
hyperglycemia previously observed in our laboratory was due to a
modification of receptor affinity or number. With membranes from normal ICR
mice, glucose (100-400 mg/dl) caused small but significant
concentration-dependent decreases in receptor affinities for [3H]naloxone
and [3H]dihydromorphine, both in the absence and presence of 20 mM NaCl,
without changing the maximum number of binding sites. Fructose and the
nonmetabolizable sugar 3-O-methylglucose had intermediate effects on
naloxone affinity in the presence of NaCl that were not significantly
different from control or from the effect of glucose. Similar results were
obtained with brain membranes from streptozocin-induced diabetic mice. The
binding affinity for [3H]naloxone in the presence of NaCl was not affected
by the induction of diabetes in ICR mice via streptozocin or in
spontaneously diabetic (db/db) C57BL/KsJ mice compared with their
nondiabetic (m+/m+) littermates. These results indicate that the previously
observed attenuation of opiate effects by glucose may be partly due to a
glucose-induced decrease in opiate-receptor affinity. However, the much
greater attenuation of morphine by fructose in vivo cannot be explained by
this mechanism.