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Although alcohol and nicotine administration studies have demonstrated that manipulating subjects’ expectancies regarding drug content affects drug response, research with marijuana has not adequately studied drug expectancy effects. The present pilot study was the first to evaluate the credibility and effect of expectancy manipulation on subjective measures and smoking patterns using a marijuana administration balanced-placebo design (BPD). In a 2 × 2 instructional set (told delta-9-tetrahydrocannabinol [THC] vs. told no THC) by drug (smoked marijuana with 2.8% THC vs. placebo) between-subjects design, the authors examined the effect of marijuana expectancy manipulation and the pharmacologic effect on affective and physiologic measures, cigarette ratings, and smoking behavior with 20 marijuana smokers (mean age = 20 years; 25% female). Large main effects of expectancy were found on ratings of cigarette potency, strength, taste, smell, and satisfaction, and observed smoking behavior. Pharmacologic effects were particularly evident for self-reported physical reactions to marijuana and cigarette potency and satisfaction ratings. This study demonstrated the feasibility of the BPD research with marijuana and yielded promising results for future studies examining the independent and combined effects of marijuana pharmacology and expectancies.

This study examined the acute effects of pretreatment with high-dose memantine, an N-methyl-D-aspartate antagonist, on the effects of cocaine in humans. Six African American men completed this laboratory study, in which, following pretreatment with memantine (0 or 60 mg), they had 5 opportunities to smoke cocaine base (0, 12, 25, or 50 mg) or receive an alternative reinforcer ($5.00 merchandise voucher). Cocaine alone produced the well-documented dose-dependent increases in cardiovascular activity and ratings of positive mood. Maximal systolic blood pressure was elevated during memantine pretreatment days. Peak ratings of "I feel stimulated" and "I feel anxious" were also higher with memantine pretreatment. However, memantine pretreatment did not alter the choice to self-administer cocaine. These data suggest that memantine pretreatment may not be helpful in the treatment of cocaine dependence.

The effects of zolpidem, a nonbenzodiazepine hypnotic, on psychomotor task performance, subjective effects, and food intake were examined during simulated shift work. Seven participants completed this 23-day, within-participant design, residential laboratory study. They received a single oral zolpidem dose (0, 5, or 10 mg) 1 hr before bedtime for 3 consecutive days under 2 shift conditions: day shift and night shift. When participants received placebo, next-day performance and subjective effects were disrupted, and food intake was decreased during the night shift. Zolpidem improved subjective reports of sleep quality and, to a lesser extent, next-day performance. Next-day mood, however, was worsened by zolpidem. Food intake was unaffected by zolpidem. These data indicate that shift changes produce performance impairments, mood alterations, and decreases in food intake, and that zolpidem attenuates some shift-change-related disruptions.

Defensive and vocal behaviors of 18 female Long-Evans rats (Rattus norvegicus) in encounters with aggressive, lactating conspecifics were examined in order to determine if female rats emit ultrasounds during agonistic interactions and to characterize any such calls. The subjects, selected during estrus or diestrus, were exposed to 1-min attacks at 25-min intervals. Between attacks the subjects were threatened by the aggressor but protected by a wire-mesh cage. Female rats emitted both high- (32-60 kHz) and low-frequency (20-32 kHz) ultrasonic calls in agonistic encounters, with the rate of high-frequency calls enhanced during estrus. Low-frequency ultrasounds were shorter in duration and higher in frequency than those emitted by male rats in similar conditions. We conclude that female rats emit ultrasonic calls during defensive responding and that the characteristics and rate of calling vary as functions of sex and gonadal hormone state.