Contractile protein synthesis rates in vivo in the rat jejunum: Modulating role of adrenalectomy and thyroidectomy on ethanol-induced changes

Acute ethanol toxicity has many deleterious effects on the gastrointestinal tract and, in particular, inhibits small intestinal protein synthesis. The mechanism(s) of the ethanol-induced inhibition of protein synthesis are unknown. This study was designed to investigate the role of adrenal and thyroid hormones on the ethanol-induced inhibition of whole jejunal protein synthesis in adrenalectomised and thyroidectomised male Wistar rats. Acute ethanol dosage significantly reduced protein synthesis in all subcellular protein fractions of the whole jejunum, in sham-thyroidectomized, thyroidectomized, sham-ardrenalectomized and adrenalectomized rats. Synthesis rates relative to RNA and DNA were also highly significantly reduced in all treatment groups in ethanol-dosed rats. However in most protein fractions the inhibition of protein synthesis was greater in thyroidectomized compared to sham-thyroidectomized rats, whereas the reverse was true in adrenalectomized rats. Neither adrenalectomy or thyroidectomy completely abolished ethanol-induced inhibition in protein synthesis, suggesting that ethanol or its metabolites, e.g. acetaldehyde, acts directly on the tissue. However, the ethanol-induced inhibition of protein synthesis was greater in thyroidectomized rats demonstrating that contractile and non-contractile proteins synthesis in the jejunum is under control of complex regulatory processes.