Differences in Number of Midbrain Dopamine Neurons Associated with Summer and Winter Photoperiods in HumansReportar como inadecuado




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Recent evidence indicates the number of dopaminergic neurons in the adult rodent hypothalamus and midbrain is regulated by environmental cues, including photoperiod, and that this occurs via up- or down-regulation of expression of genes and proteins that are important for dopamine DA synthesis in extant neurons ‘DA neurotransmitter switching’. If the same occurs in humans, it may have implications for neurological symptoms associated with DA imbalances. Here we tested whether there are differences in the number of tyrosine hydroxylase TH, the rate-limiting enzyme in DA synthesis and DA transporter DAT immunoreactive neurons in the midbrain of people who died in summer long-day photoperiod, n = 5 versus winter short-day photoperiod, n = 5. TH and DAT immunoreactivity in neurons and their processes was qualitatively higher in summer compared with winter. The density of TH immunopositive TH+ neurons was significantly ~6-fold higher whereas the density of TH immunonegative TH- neurons was significantly ~2.5-fold lower in summer compared with winter. The density of total neurons TH+ and TH- combined was not different. The density of DAT+ neurons was ~2-fold higher whereas the density of DAT- neurons was ~2-fold lower in summer compared with winter, although these differences were not statistically significant. In contrast, midbrain nuclear volume, the density of supposed glia small TH- cells, and the amount of TUNEL staining were the same in summer compared with winter. This study provides the first evidence of an association between environmental stimuli photoperiod and the number of midbrain DA neurons in humans, and suggests DA neurotransmitter switching underlies this association.



Autor: Tim D. Aumann , Mai Raabus, Doris Tomas, Agustinus Prijanto, Leonid Churilov, Nicholas C. Spitzer, Malcolm K. Horne

Fuente: http://plos.srce.hr/



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