Response of Hypothalamic Hypophyseal Hormones to Stimulation and Lesion in the Thalamus and Hypothalamus

ABSTRACT

Plasma levels of growth hormone(GH), luteinizing hormone(LH) and cortisol were determined by radioimmunoassay following radiofrequency(RF) stimulation or coagulation of various nuclei in thalamus and hypothalamus. RF stimulation or coagulation of many nuclei in thalamus and hypothalamus consisted of pulvinar and dorsomedial nucleus in thalamus and anterior and posterior hypothalamic nuclei in hypothalamus. Anterior thalamic stimulation resulted in highly significant increase of plasma LH, GH, cortisol and TH levels. However thalamic stimulation resulted no change in the level of various plasma hormones. Hypothalamic lesion produced significantly decreased plasma LH, GH and cortisol levels. Plasma cortisol and LH levels were highest 2 hours after stimulation while GH levels did not increased until 6 hours and TH until 72 hours respectively after stimulation. The significant difference in latency for beginning of hormone secretion suggests that GH, cortisol and LH may be controlled by several separate neuronal networks. Plasma GH and cortisol levels were lowest 72 hrs after coagulation of the anterior hypothalamic area, while GH, cortisol and LH levels did not change following stimulation or coagulation of posterior hypothalamic nucleus and thalamic nucldi. It was also noted that the anterior hypothalamic stimulation or coagulation caused increased or decreased in GH, cortisol, and LH than that observed from stimulation or coagulation of other hypothalamic and thalamic nuclei respectively.