AJP - Regulatory, Integrative and Comparative Physiology, Vol 244, Issue 3 363-R367, Copyright © 1983 by American Physiological Society
Paraventricular nucleus region controls pituitary-adrenal function in Brattleboro rats
A. J. Baertschi, J. L. Beny and G. B. Makara
To study the role of the paraventricular nucleus and of neurohypophysial
hormones in the control of ACTH secretion, the paraventricular nuclei (PV)
of Brattleboro diabetes insipidus rats (DI) were lesioned (L) with a knife;
sham-lesioned DI (S) served as controls. Four days later, the rats were
stressed by ether inhalation, and blood samples were taken during and 30-40
min after stress for the determination of corticosterone. The median
eminence (ME) and neural lobe (NL) were homogenized in 50 microliters of
0.1 N HCl and frozen pending bioassay of corticotropin-releasing factor
(CRF). PV lesion almost abolished the corticosterone secretion to ether and
reduced the ME CRF content three- to sevenfold. The NL CRF content in S was
about twice that of ME, and oxytocin accounted for more than 60% of NL CRF.
However, PV lesion had no effect on NL CRF activity. Low amounts of
oxytocin (2 mU/ml) had no significant CRF activity but potentiated the ME
CRF effect in L. The results suggest that 1) PV is one of the most
important sites for CRF synthesis or CRF fiber transit in DI; 2)
corticosterone secretion to ether stress is governed mainly by ME CRF; and
3) a large proportion of CRF fibers to NL probably originates outside PV.
