A role of central alpha-1 adrenergic mechanism in shaking stress-induced ACTH and noradrenaline secretion.

The role of alpha-1 adrenergic mechanism in the shaking stress-induced adrenocorticotropic hormone (ACTH), and plasma noradrenaline secretion and pressor response were investigated using conscious rats. We also studied whether or not central corticotropin releasing hormone (CRH) is involved in the shaking stress-induced ACTH secretion. The shaking stress caused significant elevations of plasma ACTH, noradrenaline, and systolic blood pressure. Intra-third ventricular administration of alpha-1 adrenergic blocker, bunazosin, inhibited the shaking stress-induced ACTH secretion, but did not alter stress-induced noradrenaline secretion and pressor response. Furthermore, intra-third ventricular administration of CRH antagonist, alpha-helical CRH, significantly attenuated stress-induced ACTH secretion. These results indicate that alpha-1 adrenergic pathway and CRH at least partly mediate the shaking stress-induced ACTH secretion.&#60;/P&#62;</p

Comparison of the Effects of Intra-Third Ventricular Administration of Interleukin-1 or Platelet Activating Factor on ACTH Secretion and the Sympathetic-AdrenomeduIIary System in Conscious Rats

The effects of centrally administered interleukin-1 beta (IL-1) or platelet activating factor (PAF) on adrenocorticotropin (ACTH) and catecholamine secretion, blood pressure and heart rate were examined to determine if these agents stimulate similarly the hypothalamic-pituitary-adrenal (HPA) axis or the sympathetic-adrenomedullary system. Intra-third ventricular administration of IL-1 (50, 200 ng) evoked significant ACTH secretion. Centrally administered IL-1 (50 ng) elevated plasma noradrenaline and adrenaline levels, systolic blood pressure and heart rate. Plasma ACTH, noradrenaline and adrenaline levels were also increased by the higher dose (200 ng) of IL-1 while systolic blood pressure and heart rate were not affected. Intra-third ventricular administration of 9 micrograms of PAF elevated the plasma ACTH level while 3 micrograms of PAF did not stimulate ACTH secretion. Neither dose of centrally administered PAF affected any plasma catecholamine level or systolic blood pressure. These results suggest that central IL-1 stimulates both the HPA axis and the sympathetic-adrenomedullary system, that a higher dose of IL-1 stimulates a mechanism to antagonize the elevation of blood pressure and heart rate and that central PAF is not involved in the control of the sympathetic-adrenomedullary system. Thus, IL-1 and PAF do not interact in the brain, although they interact peripherally.</p

Combined anterior pituitary function test using CRH, GRH, LH-RH, TRH and vasopressin in patients with non-functioning pituitary tumors.

We examined 8 normal subjects and 16 patients with non-functioning pituitary tumors with a combined anterior pituitary test to evaluate the clinical usefulness of the test. Diagnoses included 9 of chromophobe adenoma, 3 of craniopharyngioma, 2 of Rathke's cleft cyst, and 1 each of intrasellar cyst and tuberculum sella meningioma. All subjects received hypothalamic releasing hormones: 1 micrograms/kg corticotropin releasing hormone (CRH), 1 micrograms/kg growth hormone releasing hormone (GRH), 500 micrograms thyrotropin-releasing hormone (TRH), 100 micrograms luteinizing hormone releasing hormone (LH-RH), and a relatively small dose (5 mU/kg) of lysine vasopressin (LVP). In the normal subjects, the addition of LVP potentiated the secretion of adenocorticotropic hormone (ACTH) induced by CRH, but had no significant effect on the secretion of other anterior pituitary hormones. In the combined test with 5 releasing hormones, the plasma ACTH and cortisol responses were not impaired in the majority of the patients before pituitary surgery. Serum thyroid-stimulating hormone (TSH), prolactin (PRL) and follicle-stimulating hormone (FSH) responses were not impaired in 82%, 70% and 67% of the patients, respectively, while the serum LH and GH responses were impaired in 67% and 73% of the patients, respectively. Following pituitary surgery, responses of these hormones to combined testing were similarly impaired in more than 75% of the patients. These results indicate that plasma ACTH, cortisol and serum TSH responses are fairly good before pituitary surgery but are impaired significantly after surgery. No subjects experienced any serious adverse effects related to the testing. These results suggest that combined testing with hypothalamic hormones is a convenient and useful method for evaluating pituitary function.</p