Interaction of naloxone and sodium chloride intake on body weight gain in WKY and SHR rats.
Although a possible role for endogenous opioids in the regulation of feeding behavior has been proposed, little direct information is available concerning the impact of long term opiate antagonist treatment on body weight. Therefore, the effect of chronic exposure to naloxone on body weight was examined in WKY and SHR rats. Since the affinity of opiate antagonists for the receptor is increased by the presence of sodium ions, body weight was also determined in animals receiving a diet containing either 0.48% or 4% sodium chloride. Naloxone does not affect body weight in either strain of animals fed a normal (0.48% NaCl, Purina) diet. However, WKY rats fed the diet elevated in sodium chloride showed an increase in body weight which is blocked by treatment with naloxone. In contrast, SHR rats fed this diet weighed less than control animals receiving the normal diet, and naloxone did not decrease their weights further. These results suggest that naloxone may impact on mechanisms which regulate body weight, but is not capable of decreasing weight below a set point in either WKY or SHR rats.
D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D004032:Diet; D004347:Drug Interactions; D005260:Female; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D009270:Naloxone / Q000008:administration & dosage*; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride / Q000008:administration & dosage*
D009270:Naloxone; D012965:Sodium Chloride