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Neonatal PACAP administration in rats delays puberty through the influence of the LHRH neuronal system
F Szabó1, J Horváth, A Heinzlmann
1Department of Human Morphology and Developmental Biology, Faculty of Medicine, Semmelweis University, Tuzolto u. 58, H-1094, Budapest, Hungary.
Insights
Neonatal administration of pituitary adenylate cyclase activating polypeptide (PACAP) delays puberty onset in female rats. This occurs by influencing the gonadotropin-releasing hormone (GnRH) neuronal system, affecting reproductive development.
Area of Science:
- Neuroendocrinology
- Reproductive Biology
- Developmental Neuroscience
Background:
- Puberty onset involves complex hormonal regulation, including cyclic Luteinizing Hormone-Releasing Hormone (LHRH) release.
- Pituitary adenylate cyclase activating polypeptide (PACAP) plays a role in central nervous system differentiation, similar to vasoactive intestinal polypeptide (VIP).
- Previous studies indicated that a single PACAP injection in neonatal female rats delays puberty.
Purpose of the Study:
- To investigate the effect of neonatal PACAP administration on the onset of puberty in female rats.
- To determine the impact of PACAP on key reproductive parameters and LHRH system activity.
Main Methods:
- Neonatal female rats received PACAP administration.
- Vaginal opening, anterior pituitary weight, and first ovulation parameters were assessed.
- LHRH immunostaining intensity in the septo-preoptico-infundibular system was evaluated.
- PACAP antiserum was used to investigate its effect on LHRH immunoreactivity.
Main Results:
- Neonatal PACAP administration significantly delayed vaginal opening.
- A decrease in anterior pituitary weight and the number of expelled ova at first ovulation was observed.
- PACAP treatment reduced LHRH immunostaining intensity in the relevant brain regions.
- PACAP antiserum administration reversed the effect on LHRH immunoreactivity.
Conclusions:
- Neonatal PACAP administration delays the onset of puberty in female rats.
- The delay in puberty is mediated through the influence of PACAP on the LHRH neuronal system.
- PACAP is a key factor in the neuroendocrine regulation of pubertal timing.
Abstract:
The onset of puberty is a concerted action of many factors which leads to cyclic LHRH release in rats. It has been demonstrated that; in common with vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase activating polypeptide (PACAP) is also involved in the differentiation of the central nervous system. In our previous work, it was shown that a single PACAP injection into neonatal female rats delayed puberty. In the present work, neonatal administration of PACAP delayed the vaginal opening and decreased the weight of anterior pituitaries, the number of expelled ova at the first ovulation and the intensity of LHRH immunostaining in the septo-preoptico-infundibular system. PACAP antiserum had a reverse effect on LHRH immunoreactivity. The other studied parameters in the latter group remained unchanged compared to control rats. It was concluded that neonatal PACAP administration delayed the onset of puberty through the influence of the LHRH neuronal system.
