pituicyyttejä

Pituicytes are specialized glial cells found in the posterior pituitary gland, also known as the neurohypophysis. They are the most abundant cell type in this region of the brain. Historically, pituicytes were thought to be simple supporting cells for the axons of neurosecretory neurons that originate in the hypothalamus and terminate in the posterior pituitary. These neurons produce and release hormones such as antidiuretic hormone (ADH) and oxytocin into the bloodstream.

However, research over the past few decades has revealed that pituicytes are far more dynamic and play a more active role than previously understood. They are not merely structural components but actively interact with the axon terminals of the neurosecretory neurons. Pituicytes possess processes that ensheath the nerve terminals, and their morphology can change in response to physiological stimuli, such as dehydration or lactation.

These cellular changes in pituicytes are thought to influence the release of ADH and oxytocin. For instance, during states of dehydration, pituicytes retract their processes, allowing for more direct access of the axon terminals to the perivascular space and thus facilitating hormone release. Conversely, during rehydration, they extend their processes to cover the terminals. This dynamic interaction suggests that pituicytes act as regulators of neurohormone secretion, contributing to the fine-tuning of fluid balance and social behaviors regulated by the posterior pituitary.