Aging exacerbates hypertension related testicular injury in rats

Introduction The average age of paternity is rising in developed world. Hypertension is the most common chronic disease among adult males, affecting male fertility. Aging is an important risk factor for the development of atherosclerosis and hypertension. However, involvements of aging on hypertension related testicular injury are not fully clarified. Objective In this study, we investigated the involvements of aging on testes in spontaneously hypertensive rats (SHRs). Methods Male SHRs and Wistar Kyoto rats (WKYs; normotensive control) at the age of 36, 54 or 72 weeks (wk) were used (n=6, each age). At each age, body weight, testicular weight and blood pressure were measured. Serum testosterone and testicular tissue levels of malondialdehyde (MDA: a maker of lipid peroxide) were also measured by colorimetric assay and ELISA assay. Morphological changes in the testis were evaluated by hematoxylin and eosin staining. TUNEL staining was performed to quantify the apoptosis in testis. Results SHRs at 36, 54 o 72 wk showed a significant increase in mean blood pressure compared to WKYs at each age. SHRs at 54 or 72 but not 36 wk demonstrated a significant decrease in body weight and increase in testicular weight/body weight ratio compared to WKYs at each age. Testicular tissue levels of MDA in SHRs at all ages were significantly higher than those in WKYs at all ages. Serum testosterone in SHRs at 54 or 72 but not 36 wk was lower than that in WKYs at each age. SHRs at 54 or 72 but not 36 wk demonstrated obvious morphological changes such as thickening of blood vessel wall in testis, and seminiferous tubules with degeneration compared to the WKYs at each age. Number of TUNEL positive cells in testicular seminiferous tubules in SHRs at 36 wk was significantly greater than those in WKYs at 36 wk. While number of TUNEL positive cells in testicular seminiferous tubules in SHRs at 72 wk was significantly lower than those in WKYs at 72 wk. Conclusion Aged SHRs showed significant increases in oxidative damage and vacuolation in testes, and decrease in serum testosterone compared to age matched WKYs. Aging could exacerbate hypertension related testicular injury in rats. Disclosure Work supported by industry: no.