The Metabolic Effects of Surgical Trauma on Growing Rats

Abstract

The metabolic effects of surgical trauma on growing female rats were investigated. In the first experiment three groups of rats were included: a control group (no treatment), an operated group (uteri removed), and a sham-operated (incision only). In a second experiment, including the operated group and sham-operated groups, another group was added; a sham-operated food restricted group (SOFR). The rats in the SOFR group were sham-operated but their food was restricted to the amount of food consumed by the operated group. In the first experiment, rats lost body weight following the surgery, but were able to regain the lost weight. Normal weight levels were achieved by 6 days post operation by increasing the efficiency of food utilization. In the second experiment, the SOFR were unable to maintain normal body weight gain. Nitrogen balance was significantly greater in operated rats compared to unoperated and sham-operated rats on the first day following surgery in the first experiment. In the second experiment nitrogen balance was similar in operated and SOFR rats, but less than in the sham-operated controls. Plasma RNase levels were significantly elevated in the operated rats on the first day following surgery (PO1). Plasma glucose levels on any post operative day were not significantly different from the control groups, but were higher on PO1 than on PO2, PO3, and PO4. The plasma ketone levels were not significantly affected by the surgical trauma. The plasma total amino acid level was lowest on PO3 and was higher than the control on PO6. The increase in amino acid levels in the operated groups correlated with the rapid weight gain from PO3 to PO6. Following surgery total acidic amino acids and ketogenic amino acids were unaltered. The glucogenic, sulfur, and non-essential amino acids contributed more to the increase in the PO6 group of rats than did the basic, essential and acidic amino acids. The mechanism of altered plasma amino acids probably relates to their use as precursors and substrates for gluconeogenesis.