Influence of yohimbine on release of anterior pituitary hormones.
We used a double-blind crossover design to study the effects of alpha 2 adrenoreceptor blockade with yohimbine on levels of anterior pituitary hormones. A dose of yohimbine was used which raised plasma norepinephrine from 379 +/- 74 (S.E.) to 730 +/- 143 pg/ml and mean arterial pressure from 83 +/- 4 to 92 +/- 5 torr (p less than 0.025). This dose (125 micrograms/kg, then 1 microgram/kg/min) also altered mood when compared to saline infusion. In spite of these changes, when prolactin, cortisol, ACTH, beta-endorphin, TSH and growth hormone were measured after 45 minutes of yohimbine infusion, no changes from baseline were noted. These data suggest that in normal man, at rest, alpha 2 adrenoreceptors in the hypothalamus, adenohypophysis or other brain areas do not tonically modulate release of these hormones into the blood.
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D004311:Double-Blind Method; D004723:Endorphins / Q000097:blood; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010908:Pituitary Hormones, Anterior / Q000097:blood*; D011388:Prolactin / Q000097:blood; D011897:Random Allocation; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D015016:Yohimbine / Q000494:pharmacology; D001615:beta-Endorphin
D004723:Endorphins; D010908:Pituitary Hormones, Anterior; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D013972:Thyrotropin; D013006:Growth Hormone; D006854:Hydrocortisone; D009638:Norepinephrine