CHANGES IN REGIONAL PROTEIN-SYNTHESIS IN RAT-BRAIN AND PITUITARY AFTER SYSTEMIC INTERLEUKIN-1-BETA ADMINISTRATION

A convenient and sensitive method has been developed for measuring cha nges in protein synthesis in discrete areas of the brain and pituitary of conscious freely moving rats. A single injection of high-concentra tion low-specific activity L-[S-35]methionine is given to flood amino acid precursor pools, thereby equalizing the specific activity of the L-[S-35]methionine throughout the tissue. Unincorporated L[S-35]methio nine is removed from cryostat sections by treatment with perchloric ac id (2%) before quantitative autoradiography. The sensitivity of this t echnique is demonstrated by the detection of changes in protein synthe sis in regions of the brain and pituitary after systemic administratio n of interleukin-1 beta, a cytokine that has centrally mediated effect s but which is not thought to cross the blood-brain barrier, Areas of the brain found to exhibit significant increases in protein synthesis were the subfornical organ, the choroid plexus, the medial habenular, the dentate gyrus, and the anterior and posterior lobes of the pituita ry. In the brain, the cingulate cortex and the pineal gland showed sig nificant decreases in the rate of protein synthesis.