Pulsatile secretion

A pulsatile secretion pattern is critical to the function of many hormones in order to maintain the delicate homeostatic balance necessary for essential life processes, such as development and reproduction.

Pulsatility may function to sensitize target tissues to the hormone of interest and upregulate receptors, leading to improved responses.

Pulsatile secretion in its various forms is observed in: Nervous system control over hormone release is based in the hypothalamus, from which the neurons that populate the pariventricular and arcuate nuclei originate.

[1] These neurons project to the median eminence, where they secrete releasing hormones into the hypophysial portal system connecting the hypothalamus with the pituitary gland.

[9] Studies done in humans, rats, and sheep have also observed a similar circadian pattern of release of adrenocorticotropin (ACTH) shortly preceding the pulse in the resulting corticosteroid.

[16][17] Contemporary theories assume that autocrine and paracrine (ultrashort) feedback mechanisms controlling TSH secretion within the anterior pituitary gland are a major factor contributing to the evolution of its pulsatility.

However, within an islet of Langerhans, the oscillations become synchronized by electrical coupling between closely located beta cells that are connected by gap junctions, and the periodicity is more uniform (3–6 min).