Gonadotropin - releasing hormone (GnRH) content in the medial basal hypothalamus after substance P injection into the 3rd cerebral ventricle in female rats.
The effect of substance P (SP) on gonadotropin releasing hormone (GnRH) content in the medial basal hypothalamus (MBH) was studied. To evaluate this effect, 5 microg of SP in saline or saline alone were injected into the 3rd cerebral ventricle in conscious ovariectomized (OVX) and ovariectomized with subcutaneously implanted 17beta-estradiol capsules (OVX+E[_2]) rats. Two hours later the animals were decapitated and GnRH was estimated by radioimmunoassay in the tissue extracts from MBH. SP injected i.c.v. had no effect on the GnRH content in MBH in OVX rats. However, SP significantly decreased GnRH content in OVX+E[_2] rats. These results provide evidence that SP participates in the control of GnRH neurons within MBH. It is suggested that SP may stimulate GnRH release from GnRH neuron terminals and that estrogen may be involved in this process.
Walczewska
A
Department of Physiology, Institute of Physiology and Biochemistry, Medical University of Lodz, Poland.
Dziedzic
B
Jakubowska-Naziemblo
B
Traczyk
WZ