Elevation of Plasma Thyrotropin (TSH) During Electrical Stimulation in the Rabbit Hypothalamus

Plasma thyrotropin (TSH) levels increased by 90 to 600% on one or more occasions in 8 out of 13 conscious rabbits during electrical stimulation applied through platinum electrodes previously implanted in the ventral anterior hypothalamus. Plasma TSH levels had increased 15–20 min from the onset of stimulation, reaching peak values after 30 min of excitation in 6 out of 10 trials. This rapid response to hypothalamic stimulation, probably due to release of TSH from the pituitary, was elicited in rabbits in which resting TSH levels were increased or decreased by prior dietary and hormonal treatment. (Endocrinology81: 173, 1967)