The Effects of Vasoactive Intestinal Peptide on Adrenal Steroid Hormone Secretion

Vasoactive intestinal peptide (VIP)-immunoreactive nerve fibers have been demonstrated in the rat adrenal cortex in close association with zona glomerulosa cells (Holzwarth, 1984). We have studied the effects of VIP on steroid hormone secretion from the outer zones of the normal rat adrenal cortex. Intact capsule-glomerulosa preparations, consisting of the capsule, zona glomerulosa, and a small portion of the zona fasciculata were perifused in vitro. The secretory responsiveness was assessed by measuring aldosterone and corticosterone release following stimulation with the physiological secretagogues ACTH and angiotensin II. ACTH (10$\sp{-12}$ to 10$\sp{-8}$ M) stimulated dose-dependent increases in aldosterone secretion (1.9 to 36.9 fold over basal secretion) and corticosterone secretion (1.4 to 14.0 fold over basal secretion). VIP (10$\sp{-6}$ to 10$\sp{-4}$ M) stimulated dose-dependent increases of both aldosterone (1.7 to 41.0 fold) and corticosterone secretion (1.8 to 5.3 fold). However, glucagon and (N-Ac-Tyr$\sp1$-D-Phe$\sp2$)-GRF(1-29)-NH$\sb2$, peptides structurally related to VIP, stimulated neither aldosterone nor corticosterone secretion indicating that VIP effects were specific for this peptide. In addition, VIP (10$\sp{-5}$ M) potentiated the aldosterone but not the corticosterone secretory response to subthreshold concentrations of ACTH (10$\sp{-13}$ and 10$\sp{-12}$ M) by approximately 65-70% whereas it had no effect on the secretory response to angiotensin II. The distribution of adrenal VIP receptors was assessed by in vitro autoradiography of $\sp{125}$I-VIP binding. $\sp{125}$I-VIP (0.75 and 2.0 nM) binding was concentrated in the capsule and zona glomerulosa, coincident with the distribution of VIP nerve fibers which aborize extensively in this region. The specificity of this binding was demonstrated using unlabelled VIP, ACTH and angiotensin II.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Cunningham, Lee Anna

Contributors dc:contributor

• Holzwarth, Matilde

• Biology, General
• Biology, Neuroscience
• Biology, Animal Physiology

Language dc:language

eng

Identifier

(UMI)AAI8908660

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/77651