Excitatory regulative effect of nerve fibers on LH secretion in rat anterior pituitary

    LIU Ling1, GAO Liª²Zhi1,2, JU Gong1

    1PLA Institute of Neurosciences, Fourth Military Medical University, Xi¬ðan 710033, China, 2Institute of Neurosciences, College of Life Science & Biotechnology, Shanghai Jiaotong University, Shanghai 200240, China

    ¡¾Abstract¡¿ AIM: To investigate the direct regulative effect of nerve fibers on luteinizing hormone (LH) secretion in rat anterior pituitary. METHODS: Eighty diestrus rats determined by vaginal smear were randomly divided into sham operation (SO) and ovariectomy (OVX) groups. Seven days after operations, the anterior pituitary was harvested and superfused with Krebs solution (Krebsª²Ringerª²bicabonateª²BSA buffer, KRBGA) with or without tetrodotoxin (TTX). Electrical field stimulation (EFS) was performed at 10 Hz or 2 Hz for 10 min or 2 min, respectively, and the perfusate was continuously collected every 10 min for 130 min from the time 10 min before EFS and measured for LH by radioimmunoassay. RESULTS: In the anterior pituitary superfused with KRBGA without EFS, LH concentration were in a steady basal level with difference between the 2 groups, (4.8¡À0.5) IU/L in SO group, and (7.1¡À1.3) IU/L in OVX group (P<0.05). EFS at 10 Hz for 10 min significantly increased LH secretion in the time 10 min after cease of stimulation, from (4.9¡À0.1) IU/L to (15.7¡À0.8) IU/L in SO group and from (7.5¡À4.7) IU/L to (20.0¡À1.4) IU/L in OVX group, respectively (P<0.05). However, the effect of the same parameter of EFS was abolished if the TTX was added into the perfusate, and LH concentration decreased to (5.4¡À0.5) IU/L in SO group and (7.7¡À0.9) IU/L in OVX group 10 min after cease of stimulation. Other variables of EFS have no effect on LH secretion. CONCLUSION: The nerve fibers in the anterior pituitary may have a direct regulative effect on LH secretion. ......