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Chronic use of cocaine in high doses can produce tolerance as assessed by various behavioral, neurochemical, cellular and molecular measures in specific brain regions. Tolerance to cocaine is indicated by drug discrimination and intracranial self-stimulation models, which show the development of tolerance after approximately 1 week of frequent cocaine(More)
The effects of four m-cholinoceptor antagonists and d-tubocurarine on carbachol- or nicotine-induced contractions of frog rectus abdominus muscle were investigated. The n-cholinoceptor-mediated contractile responses of frog rectus abdominis muscles were inhibited competitively by d-tubocurarine whereas m-cholinoceptor antagonists inhibited them(More)
This experiment tested the hypotheses that: (1) self-administration of cocaine would produce an increase in dopamine (DA) oxidation current in the nucleus accumbens (n. acc.); and (2) a faster rate of cocaine intake in the presence of a D1 receptor antagonist would produce a greater increase in DA levels. Rats trained to self-administer cocaine under a(More)
Coaxial bioassay system (guinea-pig trachea and rat anococcygeus muscle as donor and bioassay organs, respectively) and tracheal open ring preparations from ovalbumin-sensitized guinea-pigs were used to investigate the role of the epithelium in response to the antigen challenge. Ovalbumin induced concentration-dependent relaxations in the phenylephrine(More)
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