Central nervous system insulin receptors in normal and diabetic rats.

The presence of specific insulin receptors in homogenates of various parts of the rat brain was demonstrated. Hypothalamic preparations exhibited the greatest insulin binding. Scatchard plots of the binding data were typically curvilinear. Insulin binding to the brain homogenates was influenced by pH, incubation time, temperature, and ionic milieu. The specificity of insulin binding to the brain homogenates was demonstrated by partial displacement of labeled insulin by insulin analogs according to their biological activities and by inhibition of insulin binding by serum containing an antibody to insulin receptors. Insulin binding to brain homogenates from streptozotocin-induced diabetic rats was similar to that from control animals and failed to indicate up-regulation of these receptors.