ESTROGEN-RECEPTOR AND PROGESTERONE RECEPTOR-IMMUNOREACTIVE CELLS ARE NOT CO-LOCALIZED WITH GONADOTROPIN-RELEASING-HORMONE IN THE BRAIN OF THE FEMALE MINK (MUSTELA-VISON)

The distribution of gonadal steroid (estrogen, progesterone) receptors in the brain of the adult female mink was mapped by immunocytochemist ry. Using a monoclonal rat antibody raised against human estrogen rece ptor (ER), the most dense collections of ER-immunoreactive (LR) cells were found in the preoptic/anterior hypothalamic area, the mediobasal hypothalamus (arcuate and ventromedial nuclei), and the limbic nuclei (amygdala, bed nucleus of the stria terminalis, lateral septum). Immun oreactivity was mainly observed in the cell nucleus and a marked heter ogeneity of staining appeared from one region to another. A monoclonal mouse antibody raised against rabbit uterine progesterone receptor (P R) was used to identify the PR-IR cells in the preoptic/anterior hypot halamic area and the mediobasal hypothalamus (arcuate and ventromedial nuclei). This study also focused on the relationship between cells co ntaining sex-steroid receptors and gonadotropin-releasing hormone (GnR H) neurons on the same sections of the mink brain using a sequential d ouble-staining immunocytochemistry procedure. Although preoptic and hy pothalamic GnRH neurons were frequently in close proximity to perikary a containing ER or PR, they did not themselves possess receptor Immuno reactivity. The present study provides neuroanatomical evidence that G nRH cells are not the major direct targets for gonadal steroids and co nfirms for the first time in mustelids the results previously obtained in other mammalian species.