Expression Of Vesicular Glutamate Transporter 1 In Mouse Anterior Pituitary

Glutamate is one of the major excitatory neurotransmitters in the mammalian central nervous system and its storage in synaptic vesicles is via VGluTs (vesicular glutamate transporters). VGluTs are located at the vesicle membranes and provide the vesicles with relatively high concentration of glutamate. Three types of VGluTs with similar pharmacological characters have been discovered: VGluTI,VGluT2 and VGluT3.Recent studies have found that VGluTs exist in cells of a number of endocrine organs and their roles are to store glutamate from intracytoplasmic vesicles to endocrine vesicles and form glutamatergic system in these endocrine cells. Although the regulation of mammalian anterior pituitary hormone secretion is the core issue of neuroendocrinology, few studies have focused on the role of glutamate in the anterior pituitary. To find the potential effect of glutamatergic system in anterior pituitary hormone secretion, we started our research in the expression of VGluT1 in anterior pituitary.Kunming mice were selected in this experiment. By way of immunohistochemical staining methods, we observed the VGluT1 expression in mice anterior pituitary. The results are as the following:1. Observed under the light microscope, VGluT1 immuno-reactive cells were small, irregular-shaped and polygonal. Positive cells had apophysis and often clustered together. The positive products were located in the cytoplasm, showing a cell outline.2. Observed under the electron microscope, positive products were found in the cell plasma membrane vesicles of adrenocorticotropic hormone cells.3. The result of VGluT1 expression change after adrenalectomy (ADX) showed that the number of VGluT1 immunoreactive products increased significantly after ADX of 7d compared with normal controls in the male mice.This is the first report of confirming the existence of VGluT1 immuno-reactive products in corticotrophs of mice through morphological methods. Combining the changes of VGluT1 expression after conditioned endocrine status, we postulate there exists the glutamatergic system in anterior pituitary. The results may be helpful to further clarify the Glu regulatory mechanisms of pituitary hormones.