Abstract
We examined the role of dopamine in neurons of the rat dorsolateral septal nucleus(DLSN) by intracellular recording methods. Dopamine(DA,1-100μM) was administrated by the bath-application. DA(100μM) induced a hyperpolarization(4.9±0.6mV;n=17). In some neurons, the DA-induced hyperpolarization was gradually decreased during the application of DA. The DA-induced hyperpolarization was associated with a decrease in input membrane resistance and reversed polarity at –90mV, suggesting an increase in the potassium conductance. This hyperpolarization was not affected by TTX(1μM). We investigated the effects of DA on the EPSP and the slow IPSP in the presence of bicuculline(15µM). As a result, DA(100µM) reversibly inhibited slow IPSP in all the cells tested(63±8％;n=6), while DA(100µM) inhibited the EPSP in some neurons(26±7％;5 of 6cells). This inhibition was observed in the neurons which did not show any change in input membrane resistance. During a long-term administration(1hour), DA(1µM) progressively facilitated EPSP (~30％) in half of the neurons tested. D1 type receptor agonist SKF38393(50µM) inhibited slow IPSP in the DLSN(21±4％;n=11), while D2 type receptor agonist quinpirole(50µM) produced facilitation of the EPSP in majority of the neurons(20±3％;10 of 15 cells). However, neither D1 nor D2 type receptor agonists produced membrane hyperpolarization. These results suggest that DA causes multiple effects on the efficacy of synaptic transmission in the DLSN. [Jpn J Physiol 54 Suppl:S150 (2004)]
