The glycine receptor alpha 3 subunit mRNA expression shows sex-dependent differences in the adult mouse brain.

BACKGROUND: The glycinergic system plays an important inhibitory role in the mouse central nervous system, where glycine controls the excitability of spinal itch- and pain-mediating neurons. Impairments of the glycine receptors can cause motor and sensory deficits. Glycine exerts inhibition through interaction with ligand-gated ion channels composed of alpha and beta subunits. We have investigated the mRNA expression of the glycine receptor alpha 3 (Glra3) subunit in the nervous system as well as in several peripheral organs of female and male mice. RESULTS: Single-cell RNA sequencing (scRNA-seq) data analysis on the Zeisel et al. (2018) dataset indicated widespread but low expression of Glra3 in vesicular glutamate transporter 2 (Vglut2, Slc17a6) positive and vesicular inhibitory amino acid transporter (Viaat, Slc32a1)positive neurons of the mouse central nervous system. Highest occurrence of Glra3 expression was identified in the cortex, amygdala, and striatal regions, as well as in the hypothalamus, brainstem and spinal cord. Bulk quantitative real-time-PCR (qRT-PCR) analysis demonstrated Glra3 expression in cortex, amygdala, striatum, hypothalamus, thalamus, pituitary gland, hippocampus, cerebellum, brainstem, and spinal cord. Additionally, male mice expressed higher levels of Glra3 in all investigated brain areas compared with female mice. Lastly, RNAscope spatially validated Glra3 expression in the areas indicated by the single-cell and bulk analyses. Moreover, RNAscope analysis confirmed co-localization of Glra3 with Slc17a6 or Slc32a1 in the central nervous system areas suggested from the single-cell data. CONCLUSIONS: Glra3 expression is low but widespread in the mouse central nervous system. Clear sex-dependent differences have been identified, indicating higher levels of Glra3 in several telencephalic and diencephalic areas, as well as in cerebellum and brainstem, in male mice compared with female mice.

6-OHDA-Induced Changes in Colonic Segment Contractility in the Rat Model of Parkinson's Disease.

Background: Gastrointestinal dysfunction is one of the most common non-motor symptoms in Parkinson's disease (PD). The exact mechanisms behind these symptoms are not clearly understood. Studies in the well-established 6-hydroxydopamine (6-OHDA) lesioned rats of PD have shown altered contractility in isolated circular and longitudinal smooth muscle strips of distal colon. Contractile changes in proximal colon and distal ileum are nevertheless poorly studied. Moreover, segments may serve as better tissue preparations to understand the interplay between circular and longitudinal smooth muscle. This study aimed to compare changes in contractility between isolated full-thickness distal colon muscle strips and segments, and extend the investigation to proximal colon and distal ileum in the 6-OHDA rat model. Methods: Spontaneous contractions and contractions induced by electrical field stimulation (EFS) and by the non-selective muscarinic agonist methacholine were investigated in strip and/or segment preparations of smooth muscle tissue from distal and proximal colon and distal ileum in an in vitro organ bath comparing 6-OHDA-lesioned rats with Sham-operated animals. Key Results. Our data showed increased contractility evoked by EFS and methacholine in segments, but not in circular and longitudinal tissue strips of distal colon after central 6-OHDA-induced dopamine denervation. Changes in proximal colon segments were also displayed in high K+ Krebs-induced contractility and spontaneous contractions. Conclusions: This study further confirms changes in smooth muscle contractility in distal colon and to some extent in proximal colon, but not in distal ileum in the 6-OHDA rat model of PD. However, the changes depended on tissue preparation.