Читать книгу Neurology - Charles H. Clarke - Страница 56

These are mentioned briefly. In the anterior pituitary, ACTH (corticotrophin), FSH/LH, GH, prolactin and thyrotropin have peptide releasing hormones. GH and prolactin also have inhibiting hormones – prolactin IH is dopamine.

For the posterior pituitary, the hypothalamo‐hypophyseal tracts pass from large (magnocellular) neurones of the supraoptic nucleus and paraventricular nucleus. There are also contributions from periventricular neurones (opiate and peptide neurotransmission) and brainstem (aminergic) neurones. Vasopressin (antidiuretic hormone) and oxytocin are secreted by the supraoptic and paraventricular nuclei – hormones are housed in axonal secretory granules (Herring bodies) before release into the capillary system within the posterior pituitary.

The circumventricular organs are neurones and glia adjacent to the ventricular system, each with an intimate relation to fenestrated capillaries:

 Neurohypophysis – ADH secretion

 Median eminence – anterior pituitary hormone release and inhibition

 VOLT (Vascular Organ of Lamina Terminalis) – feedback loop: low blood volume→renin→angiotensin II→VOLT/SFO→ADH

 SFO (SubFornical Organ)

 Area postrema – emetic centre, obex of 4th ventricle

 Pineal gland – melatonin, sleep‐wake cycles.