Gonadotropin releasing hormone (GnRH) centrally plays a role in control of the hypothalamicpituitary- gonadal axis-related hormone secretions in the reproductive neuroendocrine system. In addition, hormone receptors like luteinizing hormone receptor (LHR) are important element for hormones to take effect in target organ. However, ageing-dependent changes in terms of the distribution of GnRH neurons in the brain and LHR expression in the acyclic ovary have not been fully understood yet. Therefore, we comparatively investigated those ageing-dependent changes using young (1-5 months), middle (11-14 months) and old (21-27 months) aged female mice. Whereas a number of GnRH positive fibers and neurons with monopolar or bipolar morphology were abundantly observed in the brain of the young and middle aged mice, a few GnRH positive neurons with multiple dendrites were observed in the old aged mice. In addition, acyclic ovary without repeated development and degeneration of the follicles was shown in the old aged mice than others. LHR expression was localized in theca cells, granulosa cell, corpora lutea and atretic follicle in the ovaries from young and middle aged mice, in contrast, old aged mice had few positive LHR expression on the follicles due to acyclic ovary. However, the whole protein level of LHR was higher in the ovary of old aged mice than others. These results are expected to be used as an important basis on the relationship between GnRH and LHR in old aged animals as well as in further research for reproduction failure.

Abstract
 INTRODUCTION
 MATERIAL AND METHOD
  Animals, ethics and chemicals
  Tissue processing
  Classification of Ovarian follicles
  Immunohistochemistry
  Western blotting
  Statistical analysis
 RESULT
  Distribution of GnRH positive expression in the brain
  Ovarian follicular morphology in old mice
  Immunohistochemical analysis of LHR positive expressionin the ovary
  Western blot analysis of LHR expression in acyclic old mice.
 DISCUSSION
 REFERENCE

• Young-Jong Kim(College of Veterinary Medicine, Kyungpook National University)
• Byung-Joon Park(College of Veterinary Medicine, Kyungpook National University)
• Won-Jae Lee(College of Veterinary Medicine, Kyungpook National University)
• Seung-Joon Kim(College of Veterinary Medicine, Kyungpook National University) Correspondence