Involvement of dopamine receptors in diethylpropion-induced conditioning place preference

Diethylpropion (DEP) is an amphetamine-like agent used as an anorectic drug. Abuse of DEP has been reported and some restrictions of its use have been recently imposed. The conditioning place preference (CPP) paradigm was used to evaluate the reinforcing properties of DEP in adult male Wistar rats. After initial preferences were determined, animals weighing 250-300 g (N = 7 per group) were conditioned with DEP (10, 15 or 20 mg/kg). Only the dose of 15 mg/kg produced a significant place preference (358 ± 39 vs 565 ± 48 s). Pretreatment with the D1 antagonist SCH 23390 (0.05 mg/kg, sc) 10 min before DEP (15 mg/kg, ip) blocked DEP-induced CPP (418 ± 37 vs 389 ± 31 s) while haloperidol (0.5 mg/kg, ip), a D2 antagonist, 15 min before DEP was ineffective in modifying place conditioning produced by DEP (385 ± 36 vs 536 ± 41 s). These results suggest that dopamine D1 receptors mediate the reinforcing effect of DE

FREE-RUNNING RHYTHMS OF COCAINE SELF-ADMINISTRATION IN RATS HELD UNDER CONSTANT LIGHTING CONDITIONS

Using a discrete trials (DT) procedure we have previously shown that rats exhibit variations in their pattern of cocaine self-administration relative to the time-of-day, often producing a daily rhythm of intake in which the majority of infusions occur during the dark phase of the light cycle. We have sought to determine if cocaine self-administration demonstrates free-running circadian characteristics when held under constant lighting conditions in the absence of external environmental cues. Rats self-administering cocaine (1.5 mg/kg/infusion) under a DT3 procedure (three trials per hour) were kept in constant dim (<5lux, DIM) conditions and the pattern of intake analyzed for free-running behavior. We show that cocaine self-administration has a period length (TAU) of 24.13 ± 0.07 hours in standard 12-hr light-dark conditions, which is maintained for at least five days in constant dim conditions. With longer duration DIM exposure cocaine self-administration free-runs with a TAU of approximately 24.92 ± 0.16 hours. Exposure to constant light conditions (1000lux, LL) lengthened TAU to 26.46 ± 0.23 hours; this was accompanied by a significant decrease in total cocaine obtained during each period. The pattern of cocaine self-administration, at the dose and availability used in this experiment, is circadian and is likely generated by an endogenous central oscillator. The DT procedure is therefore a useful model to examine the substrates underlying the relationship between circadian rhythms and cocaine intake

The genetic and ecophysiological diversity of Microcystis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/171576/1/emi15615.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/171576/2/emi15615-sup-0002-FigureS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/171576/3/emi15615_am.pd