title: Maintenance of estrous cycle in female rats with anterior or posterior deafferentation of the suprachiasmatic nucleus.
abstract: The aim of the present study was to determine which of the anterior or posterior efferents of the suprachiasmatic nucleus (SCN) predominantly act for the maintenance of estrous cycle in female rats. A small knife (0.8 mm in radius) was used for anterior (ASD), posterior (PSD) and complete suprachiasmatic deafferentations (CSD). The rats subjected to CSD were divided into two groups, the first group bearing lesions on the medial preoptic nucleus (MPN; group CSD-MPN-L) and the other group bearing no lesions on the MPN (group CSD). For reference, anterior hypothalamic deafferentation (AHD) was carried out using a large knife (2.0 mm in radius). All rats with AHD or CSD-MPN-L and some of CSD rats showed persistent estrus, but all animals with ASD or PSD resumed regular estrous cycles after transient irregular periods. Ovaries of AHD, CSD and CSD-MPN-L rats contained very few, if any, corpora lutea, while the number of corpora lutea in ASD or PSD rats was not significantly different from that of sham-operated controls. Immunohistochemical examination revealed that in AHD rats LHRH immunoreactivity in the median eminence was markedly reduced as compared with that of sham-operated controls. In contrast, in ASD, PSD, CSD and CSD-MPN-L rats, the LHRH immunoreactivity in the median eminence was similar to that of sham-operated controls.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D003714:Denervation; D004971:Estrus / Q000502:physiology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis; D007032:Hypothalamus, Anterior; D007150:Immunohistochemistry; D051381:Rats; D011919:Rats, Inbred Strains; D013493:Suprachiasmatic Nucleus / Q000502:physiology*
chemical_list: D007987:Gonadotropin-Releasing Hormone