S. Saito et al., EFFECTS OF 2-BUTEN-4-OLIDE, AN ENDOGENOUS FEEDING SUPPRESSANT, ON THEPULSATILE SECRETION OF LUTEINIZING-HORMONE IN OVARIECTOMIZED RATS, Acta endocrinologica, 129(5), 1993, pp. 467-472
The effects of 2-buten-4-olide (2-B4O). an endogenous feeding suppress
ant. on the secretion of luteinizing hormone (LH) were studied in ovar
iectomized rats. Intraperitoneal (ip) administration of 2-B4O: adult f
emale ovariectomized Wistar rats were given daily ip injections of sol
ution containing 2-B4O at 0, 50 or 100 mg/kg body wt for 14 days. This
ip treatment with 2-B4O significantly decreased the mean LH concentra
tion and pulse frequency of LH. Intravenous (iv) administration of 2-B
4O: a solution of 2-B4O (50 or 100 mg/kg body wt) was slowly injected
through an intra-atrium catheter and blood samples were taken every 6
min for 2 h. This iv treatment significantly suppressed the LH pulse f
requency but had no significant effect on the LH amplitude or mean LH.
Injection of 2-B4O into the third cerebroventricle: the injection of
2-B4O into the third cerebroventricle of freely moving rats decreased
the mean LH concentration and the frequency and amplitude of LH pulses
. Third cerebroventricle injection of a corticotropin-releasing factor
(CRF) receptor antagonist before third cerebroventricle injection of
2-B4O: the specific CRF receptor antagonist alpha-helical-CRF (9-41) w
as injected into the third cerebroventricle of ovariectomized rats bef
ore injection of 2-B4O. Administration of 2-B4O into the third cerebro
ventricle significantly decreased the mean LH, concentration and pulse
frequency. Third cerebroventricle injection of the CRF antagonist at
50 mug/rat and then 2-B4O also resulted in significant suppression of
the mean LH concentration and pulse frequency. These findings suggest
that 2-B4O may suppress gonadotropin-releasing hormone secretion in ov
ariectomized rats and that its effect in decreasing LH pulses may not
be caused through the CRF pathway.