Intraventricular prolactin inhibits hypothalamic vasoactive-intestinal polypeptide-expression in doves

Area of Science:

• Neuroendocrinology
• Animal Behavior
• Reproductive Biology

Background:

• Prolactin's role in crop-sac development in Columbiformes is known.
• Its central nervous system functions remain less understood.
• Investigating prolactin's central effects in ring doves.

Purpose of the Study:

• To examine prolactin's central effects on vasoactive-intestinal polypeptide (VIP) and gonadotropin-releasing hormone (GnRH) expression.
• To assess prolactin's influence on sexual behavior and reproductive physiology.
• To elucidate prolactin's regulatory mechanisms within the brain.

Main Methods:

• Intracerebroventricular (i.c.v.) administration of ovine-prolactin in ring doves.
• Daily injections for six days via chronically implanted cannula.
• Monitoring of sexual behavior, testicular weight, crop weight, and neuronal expression of VIP and GnRH.

Main Results:

• Pre-courtship prolactin reduced sexual behavior and testicular weight.
• Incubation-phase prolactin decreased infundibular VIP-positive neurons and crop weight.
• No significant changes in VIP or GnRH neuronal expression were observed with pre-courtship administration.

Conclusions:

• Prolactin's central administration affects reproductive behaviors and physiology differently depending on the reproductive stage.
• During incubation, prolactin appears to autoregulate its own synthesis/release via VIP modulation in the hypothalamus.
• Further research is needed to fully understand prolactin's complex neuroendocrine roles.