The effect of CART on pituitary hormones release from cultured pituitary cells harvested from fasted and fed ad libitum male rats
Cocaine and Amphetamine-Regulated Transcript (CART) is widely expressed in the central nervous system and in several endocrine organs. CART is an important factor in the regulation of energy homeostasis. The aim of the study was to assess the role of CART in physiological response of pituitary cells in a course of starvation. The pituitary cells harvested from starved and fed ad libitum male rats were cultured for 48 h and treated with: 0.1 nM, 1 nM, 10 nM or 100 nM doses of CART. The medium was collected after 60 min and stored at −70 °C until samples were further assayed for: LH, FSH, PRL, GH, TSH and ACTH. We revealed that in cultures of pituitary cells collected from fasted rats the basal levels of the examined hormones were reduced. Incubation of pituitary cells of non-starved rats with any dose of CART reduced the concentration of LH and TSH, while the levels of the other hormones were decreased after administration only specific doses of CART. In cells of fasted rats no change in the concentration of gonadotrophins was observed. The PRL level was increased only in the 1 nM dose of CART, while the 10 nM and 100 nM CART doses markedly enhanced GH and TSH. Moreover, administration of 1 nM, 10 nM and 100 nM of CART to cultured cells of fasted rats resulted in a significant rise of the ACTH.
Our results indicate that CART can directly affect the physiological release of PRL, ACTH, TSH and GH in pituitary cells of starved animals. Moreover, CART did not alter the LH and FSH suppression level, which is correlated with food deprivation. This data stays in contrast with the already proposed role of CART as an anorexigenic hypothalamic factor.