Apoptosis in the adult goldfish pituitary

Abstract

This thesis research characterized apoptosis in the adult goldfish pituitary. Apoptosis is a form of programmed cell death that plays key roles in many biological processes by selectively removing old or unwanted cells. Morphological and biochemical signs of apoptosis established its presence within the gland. The pituitary gonadotrophs secrete gonadotropin-II to regulate sex steroid production, ovulation and sperm production. It was possible to combine TUNEL with immunocytochemistry and demonstrate apoptosis in gonadotropin-II positive cells in the pars distalis of the pituitary, allowing for the fist time the identification of apoptotic gonadotrophs in situ. Other studies suggest that pituitary cell populations and function fluctuate through the seasonal reproductive cycle. Apoptosis could play a role in regulating secretion by regulating the cell number. Treatments with the dopamine agonist apomorphine, and with a gonadotropin-releasing hormone agonist failed to modulate the apoptosis levels measured by DNA laddering or by TUNEL. Finally, this study demonstrated that the calcium ionophore A23187, significantly increases apoptosis in whole pituitary gland cultures. These studies established a new method to identify apoptotic hormone-secreting cells.