Two hours after injection, d-amphetamine sulfate (10 mg/kg, i.p.) lowered thyrotropin-releasing hormone (TRH) levels in rat striatum by 50%, but produced no significant changes in the TRH contents of hypothalamus, septum, brain stem or preoptic area. The effect peaked 2 h after amphetamine injection and declined slowly thereafter. The amphetamine-induced decrease in striatal TRH could be blocked by pretreatment with haloperidol or α-methyltyrosine, or by production of a 6-hydroxydopamine lesion in the ipsilateral substantia nigra. Amphetamine did not act by inhibiting protein synthesis in as much as cycloheximide did not similarly decrease striatal TRH. Kainic acid injected into the striatum lowered TRH by 30% after 5 days. In contrast, partial deafferentation of the striatum (by cerebral hemitransection at mid-hypothalamic level) increased striatal TRH 2-3-fold, while lesions of the dorsal raphe did not significantly change striatal TRH. Thus TRH levels in rat striatum are closely regulated by dopaminergic and other neurotransmitter systems.
- thyrotropin-releasing hormone
ASJC Scopus subject areas
- Molecular Biology
- Clinical Neurology
- Developmental Biology