Suppressed serum prolactin in sinoaortic-denervated rats

Area of Science:

• Neuroendocrinology
• Cardiovascular Physiology
• Hormone Regulation

Background:

• Arterial baroreceptors play a crucial role in cardiovascular regulation.
• Prolactin (PRL) secretion is influenced by various neural and hormonal factors.
• Catecholamines in the median eminence are key regulators of pituitary hormone release.

Purpose of the Study:

• To investigate the impact of arterial baroreceptor deafferentation on serum and pituitary prolactin (PRL).
• To examine the effects on catecholamine levels in the median eminence and pituitary gland.
• To establish a potential link between baroreceptor function and PRL regulation.

Main Methods:

• Sinoaortic denervation (SAD) or sham operation (SO) in male Wistar rats.
• Measurement of serum PRL using radioimmunoassay.
• Quantification of catecholamines (dopamine and norepinephrine) in the median eminence and pituitary using radioenzymatic or HPLC methods.
• Assessment of mean arterial pressure (MAP) and heart rate responses to bromocriptine.

Main Results:

• SAD rats exhibited suppressed serum PRL levels three days post-surgery.
• Significant reductions in norepinephrine and dopamine were observed in the median eminence of SAD rats.
• Anterior pituitaries of SAD rats showed increased catecholamine concentrations, while posterior pituitaries remained unchanged.
• Bromocriptine administration suppressed PRL and reduced MAP in both SAD and SO rats.

Conclusions:

• The SAD rat serves as a model for hypertension with suppressed serum PRL.
• Interruption of arterial baroreceptor nerves suppresses PRL secretion.
• This suppression is likely mediated by modulation of tuberoinfundibular catecholamine turnover.