Growth hormone / insulin-like growth factor-1 axis during puberty.

Puberty is a dynamic, transitional period of life which is characterized by the acquisition of secondary sexual characteristics leading to the development of fertility. Puberty is accompanied by sexually dimorphic changes in linear growth, body proportions and body composition. The pubertal growth spurt is influenced by a number of factors such as hormones, nutrition, physical activity and general health, acting mostly in concert in order to modify a genetic potential for growth. Growth hormone (GH) is traditionally considered to be the main regulator of growth. During puberty, elevated sex steroid concentrations (especially oestrogens) stimulate GH production, leading to an activation of the whole GH/Insulinlike growth factor-1 (IGF-1) axis. This activation is mostly characterized by an increase in the amplitude of GH pulses rather than an increase in frequency or in duration. Interactions between GH and sex steroids (especially androgens) express an anabolic effect on muscle mass, bone mineralization and body proportion which constitutes the male and the female adult body composition.