125 THE GROWTH HORMONE SECRETAGOGUE RECEPTOR (GHSR) GENE POLYMORPHISMS ARE ASSOCIATED WITH RENAL FUNCTION OF THE JAPANESE ELDERLIES

Abstract

Background: The growth hormone secretagogue receptor (GHSR) gene lies on human chromosome 3q26, and GHSR has been identified in the myocardium, brain stem, blood vessels and kidney. GHSR also plays an important role in the regulation of energy metabolisms, heart protective effects, and renal protective effects by binding ghrelin that is mainly secreted by the gastric endocrine cells. We hypothesized that the GHSR gene is one of candidates for susceptibility to healthy aging. Methods: We tested the relation between three single nucleotide polymorphisms (SNPs) genotyping in the GHSR gene (rs535438, rs495225, rs1403637) and clinical phenotypes (height, weight, body mass index (BMI), systol blood pressure (SBP), diastol blood pressure (DBP), bone mineral density (BMD), blood urea nitrogen (BUN), creatinine (Cr), estimated glomerular filtration rate (eGFR), total cholesterol(T-cho), serum cortisol (F), and walking speed) in 316 Japanese healthy elderly people (average age is 77.9 years, 155 men, 161 women). To calculate eGFR, we used the “Equation for estimating glomerular filtration rate in Japanese people”, issued by the Japanese Society of Nephrology. Result: In association analysis of genotype frequencies of the SNPs and eGFR, rs535438 and rs495225 showed a significant association with eGFR (rs535438; p = 0.009, rs495225; p = 0.009). The frequencies of rs1403637 were not associated with eGFR (p = 0.384). We did not find any significant associations between the GHSR gene polymorphisms and height, weight, BMI, SBP, DBP, BMD, BUN, Cr, T-cho, F, and walking speed. Conclusion: The GHSR gene may affect renal function of Japanese healthy elderlies.