Anti-apoptotic Actions of Allopregnanolone and Ganaxolone Mediated Through Membrane Progesterone Receptors (PAQRs) in Neuronal Cells
FRONTIERS IN ENDOCRINOLOGY
Authors: Thomas, Peter; Pang, Yefei
Abstract
The neurosteroids progesterone and allopregnanolone regulate numerous neuroprotective functions in neural tissues including inhibition of epileptic seizures and cell death. Many of progesterone's actions are mediated through the nuclear progesterone receptor (PR), while allopregnanolone is widely considered to be devoid of hormonal activity and instead acts through modulation of GABA-(A)receptor activity. However, allopregnanolone can also exert hormonal actions in neuronal cells through binding and activating membrane progesterone receptors (mPRs) belonging to the progestin and adipoQ receptor (PAQR) family. The distribution and functions of the five mPR subtypes (alpha, beta, gamma, delta, epsilon) in neural tissues are briefly reviewed. mPR delta has the highest binding affinity for allopregnanolone and is highly expressed throughout the human brain. Low concentrations (20 nM) of allopregnanolone act through mPR delta to stimulate G protein (G(s))-dependent signaling pathways resulting in reduced cell death and apoptosis in mPR delta-transfected cells. The 3-methylated synthetic analog of allopregnanolone, ganaxolone, is currently undergoing clinical trials as a promising GABA-(A)receptor-selective antiepileptic drug (AED). New data show that low concentrations (20 nM) of ganaxolone also activate mPR delta signaling and exert anti-apoptotic actions through this receptor. Preliminary evidence suggests that ganaxolone can also exert neuroprotective effects by activating inhibitory G protein (G(i))-dependent signaling through mPR alpha and/or mPR beta in neuronal cells. The results indicate that mPRs are likely intermediaries in multiple actions of natural and synthetic neurosteroids in the brain. Potential off-target effects of ganaxolone through activation of mPRs in patients receiving long-term treatment for epilepsy and other disorders should be considered and warrant further investigation.
Genetic association of ADIPOQ gene variants (-3971A > G and+276G > T) with obesity and metabolic syndrome in North Indian Punjabi population
PLOS ONE
Authors: Kaur, Harjit; Badaruddoza, Badaruddoza; Bains, Veena; Kaur, Anupam
Abstract
Background and aims At present obesity and metabolic syndrome (MetS) in India are the most challenging health problems. It is also well accepted that obesity is a significant risk factor for the development of metabolic syndrome and other degenerative diseases. Many studies have reported that single-nucleotide polymorphisms (SNPs) of the adiponectin (ADIPOQ) gene have been associated with obesity and its related disorders. Here, we aimed to investigate the association of two intronic variants in ADIPOQ gene, -3971A>G (rs822396) and +276G>T (rs1501299) with obesity and metabolic syndrome. Methods Biochemical and anthropometric measurements were obtained from a total of 550 unrelated subjects (obese = 250 and non-obese = 300) of North Indian Punjabi population. Genotyping for the intron variants were performed by polymerase chain reaction based restriction fragment length polymorphism (PCR-RFLP) methods. After genotyping, as a quality control measure 10% of the samples for each polymorphism were confirmed by Sanger Sequencing method. The distributions of genotypic and allelic frequencies among obese and non-obese groups were compared by chi-square test and the corresponding risk was calculated using binary logistic regression. The effects of multiple testing were controlled by applying Bonferroni corrections. Results All the anthropometric and biochemical parameters except triglycerides (TG) and very low-density lipoproteins cholesterol (VLDL-C) have shown significant association with both GG and TT genotypes of -3971A>G (rs822396) and +276G>T (rs1501299) polymorphisms respectively. The frequencies of GG (-3971A>G) and TT (+276G>T) genotypes were higher among obese cases (p = 0.008 and p = 0.035 respectively). However, no significant association was found between allelic frequencies of ADIPOQ rs822396 and obesity, whereas the 16 association of ADIPOQ rs1501299 attenuated and became marginally significant after Bonferroni correction (p>0.025). Both the variant genotypes of ADIPOQ gene polymorphisms (-3971GG and +276TT) significantly increased the risk of development of obesity (OR: 1.52, p = 0.03; OR: 1.58, p = 0.04 respectively) and MetS (OR: 1.42, p = 0.03; OR: 1.57, p = 0.01 respectively) in the present population, after adjusting the various covariates. The G-T haplotype model (possessing -3971G and +276T alleles) was shown to provide similar to 3 fold risk towards the obesity susceptibility (OR: 2.69, p = 0.009) and MetS risk (OR: 2.73, p = 0.009) and the association persisted after adjusting for different confounding variables. Conclusion The present study has confirmed that ADIPOQ -3971A>G (rs822396) and +276G>T (rs1501299) polymorphism may be clinically helpful to estimate obesity and MetS risk in North Indian Punjabi population.