Long-term sensitization of apomorphine-induced rotation behavior in rats with dopamine deafferentation or excitotoxin lesions of the striatum.
Following unilateral 6-hydroxydopamine (6-OHDA)-induced deafferentation or unilateral kainic acid (KA) lesions of the striatum, rats displayed rotation behavior in response to apomorphine (0.25 or 1 mg/kg, SC, for 6-OHDA- and KA-lesioned rats, respectively). Three days following the initial apomorphine injection, rats were challenged under identical conditions with the same dose of apomorphine received previously. A third trial with apomorphine was again repeated after 3 days. Two more sets of behavioral data, each consisting of three trials, were collected under the same conditions as the first. Each set was separated by a period of 5-6 weeks. Following the second trial of the first set, rats showed a significant increase in the maximal number of rotations, demonstrating behavioral sensitization. Following the two 5-week intervals, rats were still sensitized to apomorphine, showing behavioral responses similar to the sensitized. Following the two 5-week intervals, rats were still sensitized to apomorphine, showing behavioral responses similar to the sensitized responses observed after the initial trials. Thus, the postsynaptically mediated sensitization of apomorphine-induced rotation behavior in 6-OHDA- or KA-lesioned rats is a long-lasting phenomenon. That lesions producing postsynaptic dopaminergic hypersensitivity and hyposensitivity can both show long-lasting sensitization may indicate multiple mechanisms underlying the sensitization.
Klug
J M
JM
Department of Psychiatry, University of Cincinnati College of Medicine, OH 45267.
Norman
A B
AB
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D003342:Corpus Striatum / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D003714:Denervation; D004298:Dopamine / Q000502:physiology*; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000633:toxicity; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D016627:Oxidopamine / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D012399:Rotation; D013239:Stereotyped Behavior / Q000187:drug effects*; D014446:Tyrosine 3-Monooxygenase / Q000276:immunology / Q000378:metabolism
D016627:Oxidopamine; D014446:Tyrosine 3-Monooxygenase; D001058:Apomorphine; D007608:Kainic Acid; D004298:Dopamine