Involvement of lateral habenula α1 subunit-containing GABA receptor-mediated inhibitory transmission in the regulation of depression-related behaviors in experimental Parkinson's disease.

Neuropharmacology

Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education of China, Xi'an 710061, China. Electronic address:

Published: April 2017

The lateral habenula (LHb) plays an important role in the regulation of depression. At present, it is not clear whether GABA receptor-mediated inhibitory transmission in the LHb is involved in Parkinson's disease (PD)-associated depression. In this study, unilateral 6-hydroxydopamine lesions of the substantia nigra in rats induced depressive-like behaviors and led to hyperactivity of LHb neurons compared to sham-operated rats, which attribute to depletion of dopamine, and decreased synthesis and release of GABA and increased release of glutamate in the LHb. Intra-LHb injection of GABA receptor agonist muscimol produced antidepressant-like effects, while the injection of GABA receptor antagonist picrotoxin induced or increased the expression of depressive-like behaviors in sham-operated and the lesioned rats. However, the doses producing these behavioral effects in the lesioned rats were lower than those in sham-operated rats. Intra-LHb injection of muscimol decreased the firing rate of LHb neurons and increased the medial prefrontal cortex serotonin (5-HT) release; conversely, picrotoxin increased the firing rate of the neurons and decreased 5-HT release in two groups of rats. Compared to sham-operated rats, the duration of muscimol and picrotoxin action on the firing rate of the neurons and 5-HT release was prolonged in the lesioned rats. These changes in the lesioned rats were associated with up-regulation of the expression of α1 subunit-containing GABA receptors and reduction of GABA release in the LHb. Collectively, our findings suggest that degeneration of the nigrostriatal pathway impairs GABA receptor-mediated inhibitory transmission in the LHb, and the transmission is important for regulating PD-associated depression.

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Source
http://dx.doi.org/10.1016/j.neuropharm.2017.01.015DOI Listing

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