Differential Expression Of GABA_A Receptor A Subunits MRNA In Hypothalamus Of Precocious Puberty Female Rat Modulated By Nourishing "Yin"-Removing "Fire" Chinese Herb Mixture

Background:GABAergic input to Gonadotropin-releasing hormone (GnRH) neurons is necessary to initiate the onset of puberty and its action mainly depends on GABAA receptor of which the subunit composition, properties and consequently function varies during the period. Since evidences supported that pubertal initiation delayed and development slowed down under the effects of Nourishing "Yin"-Removing "Fire" Chinese herb mixture in the cases of precocious puberty, we hypothesized whether the herb mixture affect the expression of GABAA receptor subunits and contribute to retarding the process of sexual development.Methods:To examine the expression of GABAA receptor a subunits in hypothalamus, we selected precocious puberty female rat models induced by danazol. An subcutaneous single dose (300?g) of danazol was administered on day5after birth, and daily intragastric dose of Nourishing "Yin"-Removing "Fire" Chinese herb mixture (containing natural medicament power3.3g per ml) from day15to the day it was sacrificed. GABAA receptor a subunits mRNA levels were assessed by semiquantitive RT-PCR normalized to ?-actin levels and realtime quantitive PCR, and the protein level was checked by western blot. The parameters of pubertal development were monitored as following:the timing of vaginal opening, the organs coefficient and levels of serum estrodial (E2), luteinizing hormone (LH) and follicule-stimulating hormone (FSH).Results:The day of vaginal opening and development of uterus and ovary showed significant advancement in M compared with N and V (P<0.05, respectively). And RT-PCR results indicated that mRNA expression of GABAA receptor al and ?3subunits decreased in M compared with N and V (P<0.05, respectively), but no statistical differences in a2were observed between M and N. After the treatment of Chinese herb mixture, the reproductive organs coefficients decreased compared with M and M+S (P<0.05, respectively); the serum level of E2and LH showed significantly depressed in TCM respectively compared with M and M+S (P<0.01), and FSH also showed depressed (P<0.05); realtime PCR results revealed that only the expression of al and ?3subunits in six a subunits showed increased in TCM compared with M and M+S (P<0.01). And the protein expression of al subunit showed the same trend as mRNA.Conclusions:This study demonstrated that our Nourishing "Yin"-Removing "Fire" Chinese herb mixture could have profound effects on the precocious pubertal rats and the al and ?3mRNA expression of GABAA receptor subunits changed during the treatment that might participate in timing of puberty.