Repeated administration of triiodothyronine (T3) to rats enhances nigrostriatal and mesolimbic dopaminergic behavioural responses.
A once daily injection to rats of triiodothyronine (T3; 100 micrograms/kg s.c.) for 10 days enhanced the locomotor responses of rats pretreated with tranylcypromine (5 mg/kg) to an injection into the nucleus accumbens of dopamine (5 micrograms bilaterally), when tested 24 hr after the last T3 administration. This treatment did not, however, alter the control responses of tranylcypromine-pretreated rats to injection of saline (1 microliter bilaterally). Injection of T3 for 10 days enhanced the circling responses of unilateral nigrostriatal-lesioned rats to apomorphine (0.5 mg/kg) but not to methamphetamine (0.5 mg/kg). The probable explanation for the latter result was the finding that repeated T3 administration lowered basal striatal dopamine concentrations. The treatment also produced a trend towards reduced dopamine concentrations in the n. accumbens, although the difference did not reach statistical significance. These data suggest that repeated T3 injection causes an increased post-synaptic function of both the nigrostriatal and mesolimbic dopamine systems in rat brain.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000378:metabolism; D003342:Corpus Striatum / Q000502:physiology; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D008032:Limbic System / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013378:Substantia Nigra / Q000502:physiology; D014284:Triiodothyronine / Q000494:pharmacology*
D014284:Triiodothyronine; D004298:Dopamine