Fiber connections in the hypothalamus and some autonomic functions.

The ventromedial hypothalamic nucleus (VMH) belongs to area sympathica B of the SPH-System and its fibers to make up the dorsal longitudinal fasciculus and the hypothalamicotegmental tract. Blood glucose increases by rapid increase in active phosphorylase and G-6-Pase activities in liver following VMH stimulation. From the changes of ultrastructure of the hypophysis and the pancreas, GH, ACTH, LH, FSH and TSH (but not prolactin) are thought to be released by each releasing hormone increased by VMH stimulation. D cell hormone is also released and insulin is not released following VMH stimulation. The lateral hypothalamic nucleus (LH) belongs to area parasympathica C of the SPH-System and its fibers to make up the medial forebrain bundle and stria medullaris. Blood glucose decreases by relatively rapid increase in glycogen synthetase activity in the liver following LH stimulation. From the changes of ultrastructure, GH, ACTH, LH, FSH, TSH and D cell hormone are not released, but prolaction and insulin are released following LH stimulation. By giving lesions in VMH or LH, some degenerated fibers could be seen in LH or VMH, homolaterally.