Immunohistochemical research on the insulin-sensitive elements of the hypothalamic median eminence

The indirect peroxidase-labeled antibody method was used to localize insulin receptors in the median eminence of rat hypothalamus. For experiments the rabbit antisera against synthetic peptides correspond to the deduced amino acid sequences of alpha- and beta-subunits of human placenta insulin receptor used as the first sera. The antisera were produced by prof. N. Yanaihara. Results have shown that after intraventricular injection of 1 U insulin the electron dense particles of DAB reaction were distributed on the surface membrane of tanycytes and axon terminals in the median eminence of hypothalamus. The functional properties of revealed receptors corresponded to IGF-1 receptors. Results support the hypothesis of central regulatory action of insulin in brain by its interaction with central IGF-1 receptors on the membrane of neuroependymal elements in the median eminence of hypothalamus.