Temperature Sensitivity of Dopaminergic Neurons of the Substantia Nigra Pars Compacta: Involvement of Transient Receptor Potential Channels

Changes in temperature of up to several degrees have been reported in different brain regions during various behaviors or in response to environmental stimuli. We investigated temperature sensitivity of dopaminergic neurons of the rat substantia nigra pars compacta (SNc), an area important for motor and emotional control, using a combination of electrophysiological techniques, microfluorometry, and RT-PCR in brain slices. Spontaneous neuron firing, cell membrane potential/currents, and intracellular Ca2+ level ([Ca2+]i) were measured during cooling by ≤10° and warming by ≤5° from 34°C. Cooling evoked slowing of firing, cell membrane hyperpolarization, increase in cell input resistance, an outward current under voltage clamp, and a decrease of [Ca2+]i. Warming induced an increase in firing frequency, a decrease in input resistance, an inward current, and a rise in [Ca2+]i. The cooling-induced current, which reversed in polarity between −5 and −17 mV, was dependent on extracellular Na+. Cooling-induced whol...