Tetrachlorodibenzo-p-dioxin alters rat hypothalamic endorphin and mu opioid receptors.
The present study was undertaken to assess if hypothalamic beta-endorphin (beta E) and/or brain mu opioid receptors are associated with 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) (50 micrograms/kg)-induced hypophagia and body weight decline in rats. Hypothalamic beta E concentrations were initially increased to 166% of controls on day 1, and then were depressed to 39% and 49% of control values on days 2 and 3, respectively. Brain mu opioid receptor number was increased 60% in TCDD-treated rats at day 3 without a change in the binding affinity. Food-restricted rats did not exhibit changes in hypothalamic beta E concentrations or brain mu opioid receptor number. These results indicate that TCDD causes early perturbations in hypothalamic beta E concentrations and brain mu receptor number, which may contribute to the mechanisms by which TCDD leads to decreased food intake and progressive weight loss.
Bestervelt
L L
LL
Toxicology Program, School of Public Health, University of Michigan, Ann Arbor 48109-2029.
Nolan
C J
CJ
Cai
Y
Y
Maimansomsuk
P
P
Mousigian
C A
CA
Piper
W N
WN
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000378:metabolism; D005508:Food Deprivation; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism*; D017450:Receptors, Opioid, mu; D012016:Reference Values
D004745:Enkephalins; D000072317:Polychlorinated Dibenzodioxins; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-