Differential regulation of gonadotropin-releasing hormone (GnRH) receptor expression in the posterior mediobasal hypothalamus by steroid hormones: implication of GnRH neuronal activity
| Autor: | Hyuk Bang Kwon, Sang Soo Kang, Kyungza Ryu, Kyungjin Kim, Jae Young Seong, Kyungyoon Kam, Young Goo Han |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
endocrine system
Pituitary gland medicine.medical_specialty Transcription Genetic medicine.medical_treatment Ovariectomy Hypothalamus Middle Gonadotropin-releasing hormone Biology Polymerase Chain Reaction Rats Sprague-Dawley Cellular and Molecular Neuroscience Internal medicine medicine Animals Molecular Biology Progesterone DNA Primers Drug Implants Neurons Estradiol GNRHR Luteinizing Hormone Oligonucleotides Antisense Preoptic Area Rats Preoptic area Steroid hormone medicine.anatomical_structure Endocrinology Gene Expression Regulation Hypothalamus Pituitary Gland Female Luteinizing hormone hormones hormone substitutes and hormone antagonists Gonadotropin-releasing hormone receptor Receptors LHRH |
| Zdroj: | Brain research. Molecular brain research. 53(1-2) |
| ISSN: | 0169-328X |
| Popis: | The present study is designed to evaluate the relationship between gonadotropin-releasing hormone (GnRH) and GnRH receptor (GnRHR) gene expression during the steroid-induced LH surge. One week after ovariectomy (OVX), a capsule containing 17beta-estradiol (E) or vehicle (V) was implanted into OVX rats, and 2 days later a single injection of progesterone (P) or V was administered s.c. at 10:00 h. Poly(A)-rich RNA samples were isolated from the micropunches of the preoptic area (POA) and the posterior mediobasal hypothalamus (pMBH) from both sides of individual brain slices. Using competitive reverse transcription-polymerase chain reaction (RT-PCR) procedures, three parameters (POA GnRH, pMBH GnRHR) and pituitary GnRHR mRNA levels were simultaneously determined in each individual animal. POA GnRH mRNA and pituitary GnRHR mRNA levels were decreased by treatment with E, but increased by a combination of E and P. In contrast, pMBH GnRHR mRNA levels were clearly augmented by treatment with E, and decreased by the combination of E and P. Temporal changes in such parameters were determined in OVX+E+V- and OVX+E+P-treated rats. P augmented POA GnRH mRNA levels at the time of the LH surge (17:00 h) and the increased GnRH mRNA levels were remained until 22:00 h, while E alone failed to alter POA GnRH mRNA levels. In the pMBH micropunch samples, P substantially decreased E-induced increase in GnRHR mRNA levels at 17:00 h and further lowered those until 22:00 h. Antisense oligonucleotides of GnRHR mRNA administered into the lateral ventricle of OVX+E-treated rats blocked the E-induced increase in pMBH GnRHR mRNA levels. The antisense oligonucleotides also prevented the LH surge as well as the increase in pituitary GnRHR mRNA levels in the OVX+E+P-treated group. However, administration of this antisense oligonucleotides failed to alter POA GnRH mRNA levels. In conclusion, the present study demonstrated that there is an inverse relationship between POA GnRH mRNA levels and pMBH GnRHR mRNA levels in response to E and/or P, and that the blockade of the E-induced increase in pMBH GnRHR mRNA levels effectively nullified the P-induced LH surge. These results indicate that pMBH GnRHR gene expression is involved in synchronizing the GnRH neuronal activity, which is crucial for the generation of the LH surge. |
| Databáze: | OpenAIRE |
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