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Three experiments examined the effects of centrally and peripherally acting scopolamine (scopolamine hydrochloride-SHC) or only peripherally acting scopolamine (scopolamine methyl nitrate-SMN), on motor activity levels and the ability of these agents to induce taste aversions. In Experiment 1 rats were injected with isotonic saline, 1 mg/kg SHC, or 1 mg/kg SMN. SHC produced significant increases in stabilimeter activity (p less than 0.025) and in rearing response frequency (p less than 0.01), whereas SMN resulted in significantly less activity (p less than 0.025). Both agents induced strong conditioned taste aversions to saccharin (p less than 0.01). Experiment 2 examined the role of the area postrema in mediating these drug induced behavioral changes. Sham lesioned and area postrema lesioned rats were given saline, SHC or SMN (1 mg/kg for both drugs) and examined for changes in activity, rearing response frequency and induction of taste aversions to saccharin. SHC again produced significant increases in activity (p less than 0.01), whereas SMN produced decrements in activity (p less than 0.05). However, the brain lesion did not consistently alter the effects of these drugs on activity but it did reduce the amount of the decrement observed in rearing responses in SMN treated rats. The brain lesion also altered the ability of the drugs to induce taste aversions. Both SMN and SHC produced strong taste aversions in the sham lesioned rats (p less than 0.01) but no significant aversions were observed in the area postrema lesioned rats. Experiment 3 examined the ability of the brain lesion to alter the effects of SMN by using a within groups design. Area postrema lesions were found to attenuate but not abolish, the inhibitory effects of SMN on both activity levels and rearing responses (p less than 0.03). The results of these experiments suggest that in the absence of the chemically-sensitive area postrema both SMN and SHC fail to induce taste aversions and the inhibitory effect of SMN on spontaneous activity is attenuated.
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
January 1986,
Neuropharmacology,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
February 1994,
Pharmacology, biochemistry, and behavior,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
August 1997,
Behavioral neuroscience,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
March 1983,
Behavioural brain research,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
July 1990,
Pharmacology, biochemistry, and behavior,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
May 1983,
Behavioral and neural biology,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
November 1994,
Brain research,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
February 1987,
Toxicology and applied pharmacology,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
January 1997,
Behavioural brain research,
K P Ossenkopp, and
C Sutherland, and
R L Ladowsky
October 1985,
Brain research,
