Steroid hormones regulate post-translational modification of neural cell adhesion molecule: Implication for the neuroendocrine control of GnRH [Nöral hücre adezyon molekülünün post-translasyonal modifikasyonunu steroid hormonlari{dotless} regüle eder: GnRH'un nöroendokrin kontrolüne kari{dotless}şmasi{dotless}]

In rodents,the cell bodies of gonadotrophin- releasing hormone (gnrh) neurones are diffusely distributed in the preoptic region of the hypothalamus. the aim of this study was to examine the effect of estradiol on the neuroanatomical relationship between gnrh neurons and polysialylated form of neural cell adhesion molecule (psa-ncam) a known marker of neuronal plasticity. in the present study,we have demonstrated changes in the gnrh cell bodies and their terminals in estradiol and progesterone treated ovariectomised rats and their correlation with expression of some neuronal plasticity markers such as neural cell adhesion molecule (ncam),and psa-ncam). by immunohistofluorescent dual labeling,we have also determined that gnrh cell bodies in the medial preoptic area (mpoa) as well as their axon terminals in external zone of me region of hypothalamus are intimately associated with psa-ncam in the proestrous phase of estrous cycle. to further examine whether psa-ncam expression associated with gnrh neuron terminals varies in conjugation with cyclic changes in the ovarian-steroid hormone level,we examined gnrh and psa-ncam dual expression in ovariectomized (ovx) and estrogen-progesterone primed ovx (ebp-ovx) rats. dynamic changes were observed in astrocytes around gnrh perikarya in the mpoa as well as me regions of the hypothalamus and also increase in the expression of ncam and psa-ncam was observed after ebp induced gonadotropin surge in ovariectomised rat model. these results support that steroid hormones regulates formation and extrusion of hydrophilic psa-ncam into poa as well as me as a part of the mechanism of steroids induced synaptic plasticity.