IGF-1 Acts through Kiss1-expressing Cells to Influence Metabolism and Reproduction

Area of Science:

• Neuroendocrinology
• Metabolic Regulation
• Reproductive Biology

Background:

• Kisspeptin (Kiss1) neurons link energy status to reproduction.
• Metabolic control of Kisspeptin neurons remains incompletely understood.
• Insulin-like growth factor 1 (IGF-1) signaling pathways are crucial for development and metabolism.

Purpose of the Study:

• To investigate the role of IGF-1 receptor (IGF1R) in Kisspeptin-expressing cells.
• To determine the combined role of IGF1R and insulin receptor (IR) in Kisspeptin-expressing cells.
• To elucidate the impact on metabolic and reproductive functions.

Main Methods:

• Generated mice with Kiss1-specific deletion of IGF1R (IGF1R^Kiss1).
• Generated mice with Kiss1-specific deletion of both IGF1R and IR (IGF1R/IR^Kiss1).
• Analyzed body length, weight, food intake, energy expenditure, physical activity, puberty onset, fertility, hormone levels, and glucose homeostasis.

Main Results:

• Kiss1-specific IGF1R deletion caused stunted body length, altered metabolism (e.g., increased energy expenditure, POMC expression), delayed puberty, and impaired male fertility.
• IGF1R/IR double deletion resulted in increased fat mass and glucose intolerance.
• These findings highlight sex-specific roles of IGF1R in Kisspeptin cells.

Conclusions:

• IGF1R signaling in Kisspeptin cells is essential for normal body length, metabolic regulation, and reproductive function.
• IGF1R and IR exhibit cooperative roles in maintaining body composition and glucose homeostasis.
• Targeting IGF-1 and insulin signaling in Kisspeptin neurons may offer therapeutic strategies for metabolic and reproductive disorders.