Alterations in Kidney Structures Caused by Age Vary According to Sex and Dehydration Condition

Abstract

Aging is a complex biological process, resulting in gradual and progressive decline in structure and function in many organ systems. Our objective is to determine if structural changes produced by aging vary with sex in a stressful situation such as dehydration. The expression of Slc12a3 mRNA in the renal cortex, α-smooth muscle actin (α-SMA), and fibronectin was evaluated in male and female rats, aged 3 and 18 months, submitted and not submitted to water deprivation (WD) for 48 h, respectively. When comparing ages, 18-month-old males showed a lower expression of Slc12a3 mRNA than 3-month-old males, and control and WD 18-month-old male and female rats exhibited a higher expression of α-SMA than the respective 3-month-old rats. Fibronectin was higher in both control and WD 18-month-old males than the respective 3-month-old males. In females, only the control 18-month-old rats showed higher fibronectin than the control 3-month-old rats. When we compared sex, control and WD 3-month-old female rats had a lower expression of Slc12a3 mRNA than the respective males. The WD 18-month-old male rats presented a higher expression of fibronectin and α-SMA than the WD 18-month-old female rats. When we compared hydric conditions, the WD 18-month-old males displayed a lower relative expression of Slc12a3 mRNA and higher α-SMA expression than the control 18-month-old males. Aging, sex, and dehydration lead to alterations in kidney structure.

Molecular Mechanisms Associated with Aging Kidneys and Future Perspectives

“…Kidney function declines with age for several structural and clinical reasons. Structural changes, such as a decrease in the number of functional units and reduced kidney blood flow, limit the capacity of the kidneys to eliminate waste products efficiently, which manifests as a constant decrease in filtration rate after 40 years of age [8,22,23]. Intraglomerular hypertension caused by the loss of glomeruli results in the hypertrophy and hyperfiltration of the remaining nephrons [24], which can begin a vicious cycle of insults that culminates in further nephron loss and irreversible kidney damage.…”