Influence of social isolation and 6-OHDA lesion on the effects of quinelorane

The sensitivity of the response to the preferential dopaminergic D3 (DAD3) receptor agonist, quinelorane, was compared in mice housed socially and in mice isolated for 4 weeks. Quinelorane (1, 5, 10, 50 and 100 mug/kg) was ad ministered intraperitoneally. Motor activity was measured for 60 min posttr eatment. Rectal temperature was measured prior to and 1 h following the adm inistration of quinelorane (10, 50 and 100 mug/kg ip). Quinelorane signific antly and dose-dependently decreased locomotor activity in social and in is olated mice. The locomotor activity of isolated mice was significantly lowe r than that of social mice, but isolation had no effect on quinelorane-indu ced hypomotility. Quinelorane decreased dose-dependently rectal temperature in isolated and social mice, but isolation had no effect on quinelorane-in duced decrease in rectal temperature. The lesions of dopaminergic terminals with intracerebroventricular administration of 6-OHDA decreased the dopami ne (DA) level by 93% in the nucleus accumbens and by 91% in the corpus stri atum; these lesions impaired neither the hypolocomotion nor the hypothermia induced by quinelorane. Thus, it may be concluded that social isolation ha s no influence on the quinelorane-induced decreases in rectal temperature a nd in locomotor activity and that the DA receptors involved in these effect s of quinelorane are located postsynaptically. (C) 2001 Elsevier Science In c. All rights reserved.