Glucometabolic effects of single and repeated exposure to forced-swimming stressor in Sprague-Dawley rats

Adverse effects of noise stress on glucose homeostasis and insulin resistance in Sprague-Dawley rats

Noise pollution remains a pervasive health hazard that people encounter especially in large commercial metropolis and has been implicated in many adverse non-auditory health conditions such as hypertension, atherosclerosis, vascular (endothelial) dysfunction and metabolic disorders. There is a growing body of evidence showing that chronic noise exposure is associated with an increased risk of hypercholesterol, adiposity and development of type 2 diabetes. The present study investigated the effect of noise stress on parameters of glucose homeostasis in male rats and possible recovery after noise cessation. Twenty-four (24) adult male Sprague-Dawley rats were designated into four groups (n = 6 per group). All rats except the control group were exposed to 95dB noise using a noise generator for 28 consecutive days. A group of rats was investigated immediately after 28 days of noise exposure (NE28), while others were left to recover from noise stress for 7 days (NER7) or 14 days (NER14). OGTT and ITT were performed using standard methods. Plasma levels of triglyceride (TRIG), total cholesterol (CHOL), low density lipoprotein (LDL) and high-density lipoprotein (HDL) were determined. Serum level of insulin, corticosterone (CORT) and corticosterone-releasing-factor (CRF) were determined using ELISA. Homeostasis model assessment-insulin resistance (HOMA-IR) and glycogen content in liver as well as gastrocnemius muscle were also determined.

Although glucose tolerance remained unchanged in the noise-exposed groups, insulin sensitivity was however significantly reduced compared with control. There was significant increase (P < 0.05) in the level of CHOL, LDL and HDL. Noise also increased (P < 0.05) both insulin and CORT levels; and elicited a higher HOMA-IR index in NE28 rats. Hepatic and myocytic glycogen content were lower (P < 0.05) in NE28 rats relative to control. The reported changes above were reversed following a 14-day noise withdrawal period. Noise-induced insulin resistance may result from dysregulation of the stress axis and appears to be reversible with noise cessation.

Effects of Rhodiola rosea and Panax ginseng on the Metabolic Parameters of Rats Submitted to Swimming

Adaptogen-based plant formulations play an important role in traditional medicine and have been used in medical practice to increase the resistance of individuals. Rhodiola rosea (RR) and Panax ginseng (PG) exhibit adaptogenic properties and are related to the recovery of homeostasis and strengthen systems impaired by stress. This study aimed to evaluate the effects of RR and PG on metabolic profile and muscle damage parameters in Wistar rats submitted to swimming. Animals were divided according to the following: G1: control group; G2: group that was submitted to swimming; G3: group treated with PG; G4: group treated with PG and submitted to swimming; G5: treated with RR; and G6: treated with RR and submitted to swimming. At the end of the experimental protocol, groups G2, G4, and G6 practiced swimming for a period five times longer than during the previous 30 days. Anthropometric and biochemical parameters were investigated, and no significant results were found in the groups. Nevertheless, animals treated with PG and RR reduced the levels of creatine phosphokinase (CPK) and lactic dehydrogenase (LDH). Our findings demonstrate that both PG and RR produced a significant reduction in the levels of CPK and LDH after physical stress, suggesting that they can be used to improve physical performance. For these reasons, we may say that these plants may be used to minimize the stress promoted by the practice of physical exercises.