Pituitary secretes to brain. Experiments in sheep

Area of Science:

• Endocrinology
• Neuroscience
• Vascular Biology

Background:

• The pituitary gland's vascular connections are crucial for hormone transport.
• Previous studies suggested venous drainage from the adenohypophysis to the cavernous sinus.
• A hypothesis proposed retrograde blood flow from the adenohypophysis to the neurohypophysis.

Purpose of the Study:

• To investigate the direction of blood flow within the pituitary gland.
• To determine if adenohypophyseal hormones are transported directly to the brain.

Main Methods:

• Vascular casting of the pituitary gland.
• Physiological studies measuring blood flow.
• Analysis of hormone concentrations in intracranial blood samples.

Main Results:

• Confirmed retrograde blood flow from the adenohypophysis to the neurohypophysis.
• Observed increased prolactin and growth hormone in the internal carotid artery and sagittal sinus.
• Demonstrated that the neurohypophyseal capillary bed can deliver adenohypophyseal hormones directly to the brain.

Conclusions:

• The neurohypophyseal capillary bed receives trophic hormones from the adenohypophysis.
• Under specific physiological conditions, these hormones are directly supplied to the brain.
• This finding has implications for understanding pituitary-brain communication and hormone regulation.