Opiate antagonists: central sites of action in suppressing water intake of the rat.
The pure opiate antagonists, naloxone and naltrexone (0.1-10 mg/kg), dose-dependently suppressed water intake of 24 h water-deprived rats upon subcutaneous administration; their quaternary derivatives, methyl-naloxone and methyl-naltrexone, which are impermeable to the blood-brain barrier, failed to affect drinking. Upon intracerebroventricular administration, both quaternary analogs attenuated drinking at a dose of only 10 microgram. These results demonstrate that the antidipsogenic effects of opiate antagonists are primarily mediated at sites within the central nervous system.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004327:Drinking Behavior / Q000187:drug effects*; D008297:Male; D009270:Naloxone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds; D051381:Rats; D011919:Rats, Inbred Strains
D000644:Quaternary Ammonium Compounds; C032257:methylnaltrexone; D009270:Naloxone; D009271:Naltrexone