INTRANIGRAL TRANSPLANTS OF FETAL VENTRAL MESENCEPHALIC TISSUE ATTENUATE D1-AGONIST-INDUCED ROTATIONAL BEHAVIOR

Rats were given unilateral B-hydroxydopamine lesions and tested 4 week s later for rotational behavior elicited by either systemic or intrani gral injections of dopamine agonists. Subsequently, transplants of fet al (E14) ventral mesencephalic (VM) or cortical tissue were implanted into the lesioned substantia nigra and allowed to develop and integrat e within the parenchyma of the host midbrain for a 4-week period befor e rotational behavior was retested. In animals receiving transplants o f fetal VM: tissue, systemic injections of amphetamine (5.0 mg/kg, ip) or the DB-agonist, quinpirole (0.2 mg/kg, sc), elicited rotational be havior that was quantitatively similar to rotational behavior observed (1) before animals received transplants of fetal VM tissue or (2) in animals with midbrain transplants of fetal cortical tissue. Intranigra l administration of quinpirole (10.0 mu g) immobilized most animals an d did not elicit rotational behavior in any animals regardless of trea tment, Rotational behavior elicited by systemic administration of the D1-agonist, SKF 82958 (0.01 mg/kg, sc), was slightly attenuated by VM transplants placed into the midbrain. Rotational behavior elicited by intranigral injections of SKF 82958 (7.5 mu g) was markedly reduced in animals with VM transplants. These data support the hypothesis that m idbrain D1-receptors modulate the expression of dopamine agonist-induc ed rotational behavior. (C) 1997 Academic Press