The response of apomorphine administered into the accumbens in rats with bilateral lesions of the nucleus accumbens, induced with 6-hydroxydopamine.
Bilateral lesions of the nucleus accumbens, induced with 6-hydroxydopamine, reduced motor activity and produced a 20-35% depletion of the concentrations of dopamine (DA) and its main metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). Small doses of apomorphine (1-10 ng), injected into the nucleus accumbens of sham-lesioned rats, decreased motor activity, while larger doses (1-10 micrograms) produced hyperactivity. In rats lesioned with 6-hydroxydopamine, apomorphine caused hyperactivity only, and this apomorphine-induced response was more pronounced than in sham-lesioned rats. Large doses of apomorphine decreased, only in sham-lesioned animals, the levels of DOPAC and HVA. These data suggest that the apomorphine-induced hypomotility is mediated by presynaptically located DA receptor systems in the nucleus accumbens, whereas the apomorphine-induced hypermotility is likely to be mediated by postsynaptically located DA receptor systems.
Radhakishun
F S
FS
Rudolf Magnus Institute for Pharmacology, Medical Faculty, University of Utrecht, The Netherlands.
Wolterink
G
G
van Ree
J M
JM
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001058:Apomorphine / Q000008:administration & dosage / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism; D006719:Homovanillic Acid / Q000378:metabolism; D006892:Hydroxydopamines / Q000633:toxicity*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects*; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D012686:Septal Nuclei / Q000187:drug effects*
D006892:Hydroxydopamines; D015102:3,4-Dihydroxyphenylacetic Acid; D016627:Oxidopamine; D001058:Apomorphine; D004298:Dopamine; D006719:Homovanillic Acid