GPR50 Distribution in the Mouse Cortex and Hippocampus

Exploring orphan GPCRs in neurodegenerative diseases

Neurodegenerative disorders represent a significant and growing health burden worldwide. Unfortunately, limited therapeutic options are currently available despite ongoing efforts. Over the past decades, research efforts have increasingly focused on understanding the molecular mechanisms underlying these devastating conditions. Orphan receptors, a class of receptors with no known endogenous ligands, emerge as promising druggable targets for diverse diseases. This review aims to direct attention to a subgroup of orphan GPCRs, in particular class A orphans that have roles in neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and Multiple sclerosis. We highlight the diverse roles orphan receptors play in regulating critical cellular processes such as synaptic transmission, neuronal survival and neuro-inflammation. Moreover, we discuss the therapeutic potential of targeting orphan receptors for the treatment of neurodegenerative disorders, emphasizing recent advances in drug discovery and preclinical studies. Finally, we outline future directions and challenges in orphan receptor research.

Association between single nucleotide variants and severe chronic pain in older adult patients after lower extremity arthroplasty

BACKGROUND

Hip or knee osteoarthritis (OA) is one of the main causes of disability worldwide and occurs mostly in the older adults. Total hip or knee arthroplasty is the most effective method to treat OA. However, severe postsurgical pain leading to a poor prognosis. So, investigating the population genetics and genes related to severe chronic pain in older adult patients after lower extremity arthroplasty is helpful to improve the quality of treatment.

METHODS

We collected blood samples from elderly patients who underwent lower extremity arthroplasty from September 2020 to February 2021 at the Drum Tower Hospital Affiliated to Nanjing University Medical School. The enrolled patients provided measures of pain intensity using the numerical rating scale on the 90th day after surgery. Patients were divided into the case group (Group A) and the control group (Group B) including 10 patients respectively by the numerical rating scale. DNA was isolated from the blood samples of the two groups for whole-exome sequencing.

RESULTS

In total, 661 variants were identified in the 507 gene regions that were significantly different between both groups (P < 0.05), including CASP5, RASGEF1A, CYP4B1, etc. These genes are mainly involved in biological processes, including cell-cell adhesion, ECM-receptor interaction, metabolism, secretion of bioactive substances, ion binding and transport, regulation of DNA methylation, and chromatin assembly.

CONCLUSIONS

The current study shows some variants within genes are significantly associated with severe postsurgical chronic pain in older adult patients after lower extremity arthroplasty, indicating a genetic predisposition for chronic postsurgical pain. The study was registered according to ICMJE guidelines. The trial registration number is ChiCTR2000031655 and registration date is April 6th, 2020.

SRC-1 Deficiency Increases Susceptibility of Mice to Depressive-Like Behavior After Exposure to CUMS

Steroid receptor coactivator 1 (SRC-1) is one of the coactivators recruited by the nuclear receptors (NRs) when NRs are activated by steroid hormones, such as glucocorticoid. SRC-1 is abundant in hippocampus and hypothalamus and is also related to some major risk factors for depression, implicated by its reduced expression after stress and its effect on hypothalamus-pituitary-adrenal gland axis function. However, whether SRC-1 is involved in the formation of depression remains unclear. In this study, we firstly established chronic unpredictable stress (CUS) to induce depressive-like behaviors in mice and found that SRC-1 expression was reduced by CUS. A large number of studies have shown that neuroinflammation is associated with stress-induced depression and lipopolysaccharide (LPS) injection can lead to neuroinflammation and depressive-like behaviors in mice. Our result indicated that LPS treatment also decreased SRC-1 expression in mouse brain, implying the involvement of SRC-1 in the process of inflammation and depression. Next, we showed that the chronic unpredictable mild stress (CUMS) failed to elicit the depressive-like behaviors and dramatically promoted the expression of SRC-1 in brain of wild type mice. What's more, the SRC-1 knockout mice were more susceptible to CUMS to develop depressive-like behaviors and presented the changed expression of glucocorticoid receptor. However, SRC-1 deficiency did not affect the microglia activation induced by CUMS. Altogether, these results indicate a correlation between SRC-1 level and depressive-like behaviors, suggesting that SRC-1 might be involved in the development of depression induced by stress.