The role of P2Y₁ receptor-mediated purinergic signaling in regulating neurotransmission and astrocytic function in mouse brain

Abstract

Purinergic signaling, mediated by purine and pyrimidine nucleosides, regulates various cellular functions in central nervous system (CNS). Adenosine 5’-triphosphate (ATP), as the dominant purinergic signal molecule, acts a neurotransmitter and a neuromodulator and activate downstream purinergic receptors. The signal of extracellular ATP is predominantly mediated by P2Y₁ receptor (P2Y₁R), the most abundant purinergic receptor expressed in CNS. Previous studies demonstrated that stimulation of ATP/P2Y₁R regulated down-stream gene expression and multiple neuronal process, including cholinergic and glutamatergic neurotransmission, as well as neurite outgrowth. However, the effects of P2Y₁R deficiency in the brain have not been revealed. In this study, by using P2Y1R gene knockout (P2Y1R^-/-) mouse as a model, we aimed to investigate the regulation of neuronal functions that could be mediated by ATP/P2Y₁R signaling. To evaluate the function of cholinergic system in P2Y₁R-deficient mouse brain, the expression of globular form acetylcholinesterase (AChE) was tested in P2Y1R^-/- mouse. In P2Y1R^-/- mouse brain, the amounts of AChE activity, AChE catalytic subunit and structure subunit PRiMA, as well as the amount of acetylcholine (Ach), were not significantly altered, suggesting an unchanged function of cholinergic system in P2Y₁R-deficient brain. In addition, the expressions of a series of neuronal development markers, i.e. neurofilaments, were reduced in P2Y1R^-/- mouse brain, indicating P2Y₁R might be involved in neuronal development process and regulate axon elongation. On the other hand, we found that the amount of a series of neurotransmitters, including glutamate, GABA, dopamine and serotonin, were decreased in P2Y1R^-/- mouse brain by HPLC-MS/MS technique, probably due to the down-regulated expression of metabolic enzymes in transcriptional level. Thus, these results indicated a series of novel gene could be targeted by P2Y₁R-meidated purinergic signal. Specifically, reduced expression of glial fibrillary acidic protein (GFAP) indicated a hypo-activity of P2Y1R^-/- astrocytes. Dysregulated expressions of neurotrophic factors suggested the abnormal neurotrophic effect in P2Y1R^-/- mouse brain. Finally, P2Y1R^-/- mice exhibited anti-depressant-like and anti-anxiety-like behavior, with a lower horizontal activity. Taken together, these findings provided evidences for ATP/P2Y1R signal regulating multiple gene expression and further revealed its role in regulating neuronal activities.

Date of Award	2016
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology