Carbohydrate metabolism in rats after partial or total isolation of the medial hypothalamus.

After medial hypothalamic deafferentation at complete (CD), frontal (FD), or frontolateral (FL) levels, at the same time with adrenocortical hormone determination, sensitivity to insulin and insulinemia were determined at a postoperative time, when adenohypophyseal hormonogenetic process concerned to ACTH and growth hormone, is reverted to the normal. The glucose assimilation coefficient (K) was followed weekly for a month postoperatively. Insulin sensitivity decreased after CD and increased after FD. FL and CD rats had significantly elevated plasma insulin level, despite normoglycemia. The changes recorded in plasma insulin level and sensitivity to insulin are attributed primarily to the CNS defect. After hypothalamic isolation, K is unchanged. This might point to the creation of new set point for hypo- and hyperglycemiating system, respectively. We concluded that the presence of nervous connections of the medial hypothalamus with surrounding nervous structures is necessary for a normal carbohydrate metabolism control.