Age‐Related Dysregulation of Neuronal Activity in Single Dopaminergic Neurons

Aging is a known risk factor for neurodegenerative diseases, including Parkinson's disease (PD) and Alzheimer's disease. Dopamine neurotransmission has been implicated in the etiology of PD and age‐related decline of motor control, motivation, and cognitive functions. Few studies have pursued cellular and synaptic mechanisms to explain the decline in midbrain dopamine neurotransmission with age. Here, we used in vivo single‐cell electrophysiological recordings in anesthetized mice to characterize changes in dopamine neurotransmission related to age. We used mice of 4, 12, 24, 30 months of age to record midbrain dopamine neuronal firing activity. Our preliminary data indicates a steady decrease of dopamine neuron firing activity with age, particularly in 30 month‐old mice. In a parallel experiment, using ex vivo whole cell patch clamp electrophysiology, we assessed excitability and firing pattern in midbrain dopamine neurons. To evaluate excitability, spontaneous firing was measured and step current injections from 20pA up to 400pA were also applied to induce firing. Our results show an increase in firing rate frequency and a decrease in the number of spikes with higher current injections, starting with 18 months of age, possibly indicating increased sensitivity to depolarization block. We are currently studying synaptic transmission by assessing glutamate receptor‐mediated burst firing in dopamine neurons in young and old mice. These results will provide a comprehensive assessment of the effects of age on firing induced by both intrinsic conductances and external synaptic input.Support or Funding InformationR01 from NIA (R01 AG052606) and T32 training grant from NIA (T32 AG052363)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.