노화흰쥐의 시상하부에서 vasopressin-면역반응 신경세포의 형태학적 변화
Morphological Changes in Vasopressin- immunoreactive Neurons in the Hypothalamus of the Aged Rats
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노화는 중추신경계의 구조를 변화시킬 뿐 아니라 여러 신경인자들의 분포에 영향을 미쳐 생체리듬에 많 은 변화를 초래한다. vasopressin (VP)은 시상하부에서 분비되는 펩타이드의 일종으로서, 주로 혈압을 상승시키고 항이뇨호르몬 작용을 가진다. 본 연구는 여러 생체리듬조절에 관여하는 시상하부에 분포하는 VP-면역반응 신경세포의 형태학적 변화를 노화 흰쥐에서 관찰함으로써 노화로 인한 신경세포 변화를 관찰하고자 하였다. Sprague-Dawley계의 약 12주령인 젊은 흰쥐와 약 18월령의 노화흰쥐에 통상의 조직처리를 한 후 VP 일차항체를 사용하여 면역조직화학염색을 시행한 후 광학현미경으로 비교 관찰하였다. VP의 염색결과, VP-면역반응 신경세포는 주로 시상하부의 뇌실곁핵과 시각로위핵에서 두드러지게 관찰되었으 며 노화흰쥐의 VP-면역반응 신경세포에서 핵과 세포체 크기가 젊은흰쥐에 비해 매우 크게 관찰되었으나 노화흰 쥐의 VP-면역반응 신경세포의 수는 감소하였다. 그리고 시각교차위핵에서 노화흰쥐에서 VP-면역반응 신경세포의 수는 젊은흰쥐보다 약 2배정도 많이 나타났다. 따라서 노화가 진행됨에 따라 시상하부에서 VP 분비의 변화를 초래하여 다양한 기본생활주기가 달라지고 하루 주기행동의 주간리듬(diurnal rhythm)의 변화에 영향을 미칠 것으로 사료된다.
Abstract
The role of neuropeptides in the central nervous system (CNS) has received increasing attention. Numerous peptide molecules are found in the mammalian CNS and many of them are thought to act as either neurotransmitters or neuromodulators. The neuropeptides found in high concentration in the hypothalamus include vasopressin (VP), vasoactive intestinal polypeptide, somatostatin, and oxytocin. The main approches to assess the involvement of neuropeptides can be focused on functions affecting the aging of the brain. Morphological aging of the CNS has been characterized by degenerative changes of fiber connections and cell loss, although degeneration does not always occur to the same extent throughout various parts of the brain and, moreover, varies for different cell types. Despite of many studies in VP containing neurons , there exist discrepancies in results about the changes of aged rat brain. The aim of the present study is, therefore, to investigative possible changes in the number and morphology of VPimmunoreactive neurons with aging in each area of the hypothalmus of the aged rats. As a result, the number of VP-immunoreactive neurons was decreased in hypothalamus nucleus of aged group. Especially, in VP-immunoreactive neurons of hypothalamus, the size of neuronal cell body and nuclei in aged group is larger than in young group and the fiber density of immunoreactivity neurons of median eminance (ME) in aged group is stronger than in young group. But, the total number of VP-immunoreactive neurons in the suprachiasmatic nucleus (SCN) of the aged group is larger than in the young group. These studies indicate the involvement of VP-immunoreactive neurons in aging process of hypothalamus, and aging process may affect the synthesis of VP in the neurons of hypothalamic nuclei. Whereas, in VP expression, aging process induces an enlargement of the cell size of surviving neurons to compensate.
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