Swiss-Webster mice selectively bred for high swim stress-induced analgesia (SSIA) were exposed to continuous ambient cold (5 degrees C) for 6 weeks or to daily 3-min swims for 14 consecutive days either in 20 or 32 degrees C water. Thereafter, mice subjected to the particular procedure were injected intraperitoneally with 10 mg/kg of naltrexone HCl and were tested for modification of the opioid...

Quaternary derivatives of naloxone and naltrexone, methyl naloxonium chloride(ORG 10908) and naltrexone methobromide ( MRZ 2663BR ), respectively, were compared with the parent compounds for their ability to antagonize the reinforcing properties of heroin as measured in an operant, i.v., self-administration paradigm. As expected, lower doses (up to 0.2 mg/kg) of naloxone and naltrexone produced...

There are mixed results on the effects of opioid antagonists on acute nicotine response in humans. The present study examined the effects of a single dose of 50 mg oral naltrexone relative to placebo on smoking response in 22 chronic smokers during short-term nicotine abstinence, after acute smoking and subsequent smoking deprivation, and on smoking behavior in a choice paradigm. The results sh...

Opiates have been used historically for the treatment of depression. Renewed interest in the use of opiates as antidepressants has focused on the development of kappa opioid receptor (κ-receptor) antagonists. Buprenorphine acts as a partial µ-opioid receptor agonist and a κ-receptor antagonist. By combining buprenorphine with the opioid antagonist naltrexone, the activation of µ-opioid receptor...

Naltrexone, an opiate antagonist, and bupropion, a noradrenergic/dopaminergic antidepressant, have many effects on the reward systems of the brain. These medications impact eating behavior, presumably via their impact on food reward. However, only bupropion induces weight loss in obese individuals, while naltrexone does not have any appreciable effect. The combination of 32 mg of naltrexone and...

Pretreatment with morphine-like agonists potentiates the behavioral effects of opioid antagonists, possibly reflecting a state of acute physical dependence. Several studies have used operant behavior to quantify these effects. However, little research has been done using unconditioned behavior. One objective of this study was to determine whether opioid agonist pretreatment (e.g., morphine, fen...

BACKGROUND Alcoholism, which is a disabling addiction disorder, is a major public health problem worldwide. The present study was designed to determine whether the application of acupuncture at the Shenmen (HT7) point suppresses voluntary alcohol consumption in addicted rats and whether this suppressive effect is potentiated by the administration of naltrexone. METHODS Rats were initially tra...

The purpose of this study was to investigate the differences in subjective acute effects of alcohol and naltrexone among those who prefer spicy food to varying degrees. Acute biphasic alcohol effects scale (BAES), visual analogue scale for craving (VAS-C), blood alcohol concentration (BAC) and food preference scale were measured in 26 men. Repeated measures ANOVA (2 preference groups×4 time blo...

Overweight and obese individuals differ in their degree of hedonic eating. This may reflect adaptations in reward-related neural circuits, regulated in part by opioidergic activity. We examined an indirect, functional measure of central opioidergic activity by assessing cortisol and nausea responses to acute opioid blockade using the opioid antagonist naltrexone in overweight/obese women (mean ...

The effects of naltrexone on the in vitro luteinizing hormone (LH) secretion from whole pituitary glands as well as from dispersed pituitary cells of common carp (Cyprinus carpio L.) in primary cell culture were studied. The perifusion of whole pituitary glands with naltrexone at a concentration of 10 M caused a significant increase of LH secretion compared to the control. This finding suggests...