The Effects of Obesity, Six Weeks of Aerobic Training, and Cold Water Exposure on the Expression of FNDC5 and UCP1 Genes in Male Wistar Rats.

Background: Obesity is a complex disease that has become increasingly prevalent. While obesity itself is not new, its widespread occurrence is a more recent concern. Stimulating brown adipose tissue (BAT) and promoting the browning of white adipose tissue (bWAT) have shown promise as therapeutic targets to increase energy expenditure and counteract weight gain.

Objectives: This study aimed to investigate two main aspects. First, we examined how obesity affects the expression of the fibronectin type-III domain containing 5 (FNDC5) and uncoupling protein 1 (UCP1) genes in male Wistar rats. Second, we assessed the effects of six weeks of aerobic exercise, exposure to cold water, and the combination of both on the expression of the FNDC5 and UCP1 genes in obese male Wistar rats.

Methods: In this experiment, 25 male Wistar rats were randomly assigned to five groups (5 rats per group) after inducing obesity. The groups included: A control group (C), an obesity group (O), an obesity group exposed to cold water (OC), an obesity group engaged in aerobic exercise (OE), and an obesity group exposed to both cold water and aerobic exercise (OCE). The aerobic exercise sessions lasted 30 - 60 minutes, with a speed of 15 - 25 meters per minute. The cold water exposure protocol involved shallow water (2 - 4 cm) with a temperature of 14 - 18°C. The OCE group performed both aerobic and cold water exercises in each session. The expression of the FNDC5 gene in the soleus muscle and the FNDC5 and UCP1 genes in subcutaneous fat was evaluated using Real-Time PCR. All statistical analyses were performed using SPSS software version 16, with a significance level set at P ≤ 0.05.

Results: Obesity significantly increased the expression of the FNDC5 gene (P = 0.008). After six weeks of aerobic exercise (P = 0.016) or cold water exposure (P = 0.016), there was a significant decrease in FNDC5 gene expression. Surprisingly, the combination of both interventions did not result in a significant effect (P = 0.75). On the other hand, none of the interventions-whether aerobic exercise, cold water exposure, or their combination-had a significant effect on the expression of the UCP1 gene (P > 0.05).

Conclusions: The increase in FNDC5 gene expression caused by obesity may serve as a compensatory mechanism to cope with the condition. However, both cold water exposure and aerobic exercise appear to mitigate this increase in FNDC5 gene expression through enhanced thermogenesis.