Region Specific Effects of Aging and the Nurr1-Null Heterozygous Genotype on Dopamine Neurotransmission
Evangel Kummari, Shirley Guo-Ross and Jeffrey B Eells*
Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
- *Corresponding Author:
- Jeffrey B Eells
Department of Basic Sciences, College of Veterinary Medicine
Mississippi State University, Mississippi State, MS 39762, USA
E-mail: [email protected]
Received Date: March 13, 2017; Accepted Date: March 31, 2017; Published Date: April 05, 2017
Citation: Eells JB, Kummari E, Guo-Ross S (2017) Region Specific Effects of Aging and the Nurr1-Null Heterozygous Genotype on Dopamine Neurotransmission. Neurochem Neuropharm Open Access 3:114. doi: 10.4172/2469-9780.1000114
Copyright: © 2017 Eells JB, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The transcription factor Nurr1 is essential for dopamine neuron differentiation and is important in maintaining dopamine synthesis and neurotransmission in the adult. Reduced Nurr1 function, due to the Nurr1-null heterozygous genotype (+/-), impacts dopamine neuron function in a region specific manner resulting in a decrease in dopamine synthesis in the dorsal and ventral striatum and a decrease in tissue dopamine levels in the ventral striatum. Additionally, maintenance of tissue dopamine levels in the dorsal striatum and survival of nigrostriatal dopamine neurons with aging (>15 months) or after various toxicant treatments are impaired. To further investigate the effects of aging and the Nurr1-null heterozygous genotype, we measured regional tissue dopamine levels, dopamine neuron numbers, body weight, open field activity and rota-rod performance in young (3-5 months) and aged (15-17 months) wild-type +/+ and +/- mice. Behavioral tests revealed no significant differences in rota-rod performance or basal open field activity as a result of aging or genotype. The +/- mice did show a significant increase in open field activity after 3 min of restraint stress. No differences in tissue dopamine levels were found in the dorsal striatum. However, there were significant reductions in tissue dopamine levels in the ventral striatum, which was separated into the nucleus accumbens core and shell, in the aged +/- mice. These data indicate that the mesoaccumbens system is more susceptible to the combination of aging and the +/- genotype than the nigrostriatal system. Additionally, the effects of aging and the +/- genotype may be dependent on genetic background or housing conditions. As Nurr1 mutations have been implicated in a number of diseases associated with dopamine neurotransmission, further data is needed to understand why and how Nurr1 can have differential functions across different dopamine neuron populations in aging.