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The running response of B6AF1/J mice to 25 mg/kg of morphine sulfate was increased up to 3-fold when this dose was administered either twice daily for 5 days or once a week for 2 or 3 weeks. The effect of weekly pretreatment was proportional to the dose of morphine and lasted as long as 1 month after pretreatment was stopped. There was no sensitization when(More)
Two progenitor strains, BALB/cBy and C57BL/6By, their reciprocal F1 hybrids, and seven of their recombinant-inbred derived lines were used to examine the genetic basis of the response to thermal pain, and morphine analgesia at doses of 2.5, 5.0 and 10.0mg/kg. Both the latency of response to thermal pain and the analgesic response differed significantly(More)
Cotinine is the major metabolite of nicotine in humans, and the substance greatly outlasts the presence of nicotine in the body. Recently, cotinine has been shown to exert pharmacological properties of its own that include potential cognition enhancement, anti-psychotic activity, and cytoprotection. Since the metabolite is generally less potent than(More)
Pretreatment of B6AF1/J mice with d-amphetamine HCl 10 mg/kg, twice daily for 5 days, produced a 4-fold increase in the running response to a test dose of 5 mg/kg amphetamine. Amphetamine pretreatment decreased whole-brain norepinephrine levels to 50% of control values and whole-brain dopamine to 85%. The test dose of 5 mg/kg amphetamine lowered whole brain(More)
In a situation of social conflict, mice that are defeated by an opponent exhibit a marked analgesia. Microinjections of naloxone (1 or 10 micrograms) into the periaqueductal grey area (PAG) or into the region of the arcuate nucleus prior to the defeat prevented the emergence of analgesia. Microinjections of morphine (5 micrograms) into these sites had(More)
Mice that received five daily injection of methylphenidate HCl, 10-75 mg/kg, showed an increased running response to methylphenidate, cocaine, and amphetamine. Sensitization to methylphenidate persisted for at least 50 days. Repeated IP injections of methylphenidate into mice with unilateral striatal lesions increased ipsilateral turning in response to(More)
Mice subjected to defeat in a social conflict paradigm display an analgesic response that is apparently mediated by endogenous opioids. It is blocked by naloxone and shows full cross-tolerance to and from morphine. The present study investigated the contribution of sources of endogenous opioids outside of the central nervous system, namely the pituitary and(More)
Chronic cocaine administration has been associated with sensitization (an increase in drug effect) rather than the tolerance observed with many psychotropic compounds. Because cocaine acts at the presynaptic dopamine transporter, we evaluated sensitization and striatal dopamine transporter binding in vivo in several mouse strains. All strains of mice(More)