Final Activity Report Summary - CLOCK IN PITUITARY (Role of the circadian clockwork in the anterior pituitary gland) The pituitary gland is the master gland of the endocrine system that regulates a number of physiological functions such as growth or reproduction. The release of its hormones in the bloodstream is under the control of hypothalamic oscillators that pace the pulsatile pattern of each pituitary hormone. In this project, we proposed to investigate the circadian clock gene in the pituitary gland. We described their temporal pattern of expression, which permitted us to define this gland as a peripheral clock. However, we found that the regulation of clock genes is much more complex in the pituitary than in other peripheral organs, revealing an integration of different cues, such as light influence through the suprachiasmatic nuclei and feeding schedule. The use of mutant mice that lack a functional circadian clock disclosed a dramatic dampening in pituitary pulsatility, namely of the highly patterned secretion of growth hormone (GH) in males. Interestingly, this change of GH pattern has unexpected consequences at the metabolic level since expression of hepatic enzymes involved in xenobiotic detoxification is altered.
