Sustained GnRH Agonism Alters Endocrine Dynamics and Pubertal Progression in Juvenile Rats.

Area of Science:

• Reproductive Endocrinology
• Developmental Biology
• Pharmacology

Background:

• Puberty onset is regulated by the hypothalamic-pituitary-gonadal (HPG) axis.
• Gonadotropin-releasing hormone (GnRH) agonists are used to suppress the HPG axis and delay puberty.
• The developmental effects of sustained HPG axis suppression during puberty are not fully understood.

Purpose of the Study:

• To investigate the effects of GnRH receptor agonism on HPG axis function and pubertal development in juvenile rats.
• To characterize the developmental consequences of sustained HPG axis suppression.

Main Methods:

• Juvenile male and female Sprague-Dawley rats received leuprolide acetate (LA) or vehicle control.
• Assessments included body mass, gonadal size, peripheral pubertal markers, pituitary gene expression, and serum hormone concentrations.

Main Results:

• LA treatment reduced gonad size in both sexes and blunted peripheral puberty signs in females more than males.
• Pituitary gonadotropin-releasing hormone receptor (Gnrhr), follicle-stimulating hormone beta (Fshb), and luteinizing hormone beta (Lhb) mRNA levels decreased.
• Serum FSH and ACTH levels were lower, with sex-specific alterations in LH and progestin levels in females.

Conclusions:

• Leuprolide acetate (LA) treatment inhibits pubertal maturation and alters HPG axis output in a sex-specific manner.
• Findings underscore the need for multi-level analyses to comprehend altered GnRH signaling impacts on physiology.
• Further research is required to understand the long-term physiological consequences.