naloxone and diallylnormorphinium-bromide

The ventral tegmental area has been suggested as a possible site of action for the rewarding effect of opiates on the basis of the fact that local morphine injections in this but not other regions are rewarding. That this is a necessary and not just a sufficient site of opiate rewarding action was suggested by the fact that diallyl-normorphinium bromide, a hydrophilic opiate blocker, caused compensatory increases in intravenous heroin self-administration when injected into the ventral tegmental area but not other brain regions.

Topics: Analgesics, Opioid; Animals; Drug Interactions; Male; Microinjections; Morphine; Nalorphine; Naloxone; Narcotic Antagonists; Rats; Rats, Long-Evans; Receptors, Opioid; Reward; Ventral Tegmental Area

Opiate antagonists were tested for their effects upon either drinking or eating in eight experiments. Naloxone, nalorphine, and the active isomer of WIN 44,441 all reduce drinking. Neither an analog of nalorphine that does not cross the blood-brain barrier, nor the inactive isomer of WIN 44,441 is effective in reducing water intake. These data provide support for the conclusion that these antagonists ahve stereospecific effects within the central nervous system. Naloxone suppresses drinking following procedures inducing osmotic, volemic, or hormonal thirst. Naloxone suppresses eating following procedures inducing glucoprivation but does not alter eating elicited by tail-pressure. Collectively, these data lead to the conclusion that endorphins play a role in the organization of ingestive behavior following challenges to homeostasis.

Topics: Angiotensin II; Animals; Consummatory Behavior; Deoxyglucose; Drinking; Eating; Female; Male; Morphine; Nalorphine; Naloxone; Polyethylene Glycols; Rats; Receptors, Opioid; Sodium Chloride; Thirst

Topics: Animals; Avoidance Learning; Conditioning, Operant; Dose-Response Relationship, Drug; Drug Tolerance; Electroshock; Haplorhini; Male; Morphine; Nalorphine; Naloxone; Saimiri