Naloxone blocks the effect of diazepam and meprobamate on conflict behaviour in rats

Periodic postpartum separation from the offspring results in long-lasting changes in anxiety-related behaviors and sensitivity to morphine in Long-Evans mother rats

“…Benzodiazepines, by acting on their receptors in basal ganglia, augment the agonist potency of morphine (Horvath et al 2000). The anxiolytic effects of benzodiazepines can be blocked (or augmented; see Frussa-Filho et al 1999) by opioid antagonists in animals and humans (Billingsley and Kubena 1978;Koob et al 1980;Duka et al 1981Duka et al , 1982Agmo et al 1995;Tsuda et al 1996). For example, infusion of the opioid antagonist naltrexone into the amygdala attenuates the anxiolytic action of diazepam in the plus-maze test (Kang et al 2000).…”

Overexpression of Proenkephalin in the Amygdala Potentiates the Anxiolytic Effects of Benzodiazepines

“…While others have found that opioid antagonists have no intrinsic effects on anxietylike behaviors, a few reports show an anxiogenic action of opioid antagonists in the social interaction test and conflict paradigm (Agmo et al 1995;Tsuda et al 1996;Zhang et al 1996). Opioid antagonists have been shown to block the anxiolytic or anti-conflict effects of benzodiazepines in humans and laboratory animals (Billingsley and Kubena 1978; Koob et al 1980;Duka et al 1981Duka et al , 1982Agmo et al 1995;Tsuda et al 1996), although some reports fail to show influences of opioid antagonists on the anticonflict properties of benzodiazepines (Britton et al 1981). The underlying mechanisms and site of action for these effects remain unknown.…”

“…Interestingly, clinical studies suggest interactions between responses to benzodiazepines and opioids in humans (Darke et al 1993). The anxiolytic effects of benzodiazepines can be blocked by opioid antagonists in both humans and laboratory animals (Billingsley and Kubena 1978;Koob et al 1980;Duka et al 1981Duka et al , 1982Agmo et al 1995;Tsuda et al 1996).…”

“…Interestingly, clinical studies suggest interactions between responses to benzodiazepines and opioids in humans (Darke et al 1993). The anxiolytic effects of benzodiazepines can be blocked by opioid antagonists in both humans and laboratory animals (Billingsley and Kubena 1978;Koob et al 1980;Duka et al 1981Duka et al , 1982Agmo et al 1995;Tsuda et al 1996).Prior studies using herpes virus-mediated gene transfer demonstrated that overexpression of proenkephalin in amygdala produced antinociceptive effects, and illustrated the usefulness of this methodology for examining the role of neuropeptides in behavioral responses (Kang et al 1998). To investigate if modifying opioid peptides in the amygdala altered anxiety-like behavior or the anxiolytic effects of benzodiazepines, a herpes virus vector (SHPE) expressing human preproenkephalin was delivered to the rat amygdala.…”

Drug discrimination and drug stimulus generalization with anxiolytics

“…Because some behavioral effects of BZ and other sedativeianxiolytics have been blocked by opioid antagonists [e.g., Duka et al, 1981;Soubrie et al, 19801, the opioid receptor antagonist naltrexone was studied in combination with doses of lorazepam and pentobarbital that alone occasioned 100% drug lever responding. No decrease in percentage of drug lever responding occurred with any dose of naltrexone (1 .O, 3.2, 10 mg/kg p.0.)…”