[Effects of neurotensin microinjected into ventral tegmental area on spontaneous motor activity in neonatal 6-hydroxydopamine-treated rats].
Intracerebroventricular treatment of the catecholamine neurotoxin, 6-hydroxydopamine (6-OHDA) after desmethylimipramine pretreatment results in semipermanent brain dopamine (DA) depletion. It has been shown that rats neonatally treated with 6-OHDA show hyperactivity in an open-field test. The purpose of this study was to investigate the spontaneous motor activity in neonatal 6-OHDA-treated rats following bilateral saline (SAL; 0.25 microliter) or neurotensin (NT; 1.25, 2.50, 5.00 micrograms/0.25 microliter/side) microinjection into the ventral tegmental area. Each dose of NT significantly augmented locomotor activity in 6-OHDA-treated rats. On the other hand, controls did not show significant increase in lower dose of NT. Effect of NT microinjection on number of rearings in the 6-OHDA-treated group was not significantly altered compared to the vehicle-treated group. These results suggest that the responses in locomotor activity to NT the ventral tegmental area increase in neonatal 6-OHDA-treated rats, and imply that residual activity in mesolimbic DA neurons which is mediated by NT receptors contributes to a part of the hyperactivity seen after neonatal 6-OHDA lesion.
Ikegami
Masanaga
M
Institute of Psychology, University of Tsukuba, Tsukuba, 305-8572, Japan.
Iwasaki
Tsuneo
T
D000818:Animals; D000831:Animals, Newborn; D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology; D004195:Disease Models, Animal; D004298:Dopamine / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D008297:Male; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects*; D009496:Neurotensin / Q000008:administration & dosage / Q000494:pharmacology*; D016627:Oxidopamine; D051381:Rats; D018028:Receptors, Neurotensin / Q000502:physiology; D017557:Ventral Tegmental Area
D018028:Receptors, Neurotensin; D009496:Neurotensin; D016627:Oxidopamine; D004298:Dopamine