Puberty is defined by the attainment of reproductive maturity and rapid linear growth. These events are largely orchestrated through the maturation of the hypothalamic-pituitary-gonadal axis (HPG) and Growth Hormone (GH) axis, respectively. To define mechanisms that modulate healthy pubertal maturation and growth, assessment of pulsatile Luteinizing Hormone (LH) and GH secretion is routinely performed from a number of species, and following interventions known to modify sexual maturation and growth. These observations provide valuable information for the extrapolation of hypothalamic control of hormone release. Given size and technical constraints, extrapolation of pulsatile hormone release across puberty in female mice does not exist. Thus sex-specific alterations in pubertal development of the HPG and GH-axis remain largely undefined.

In this study, we characterized LH and GH profiles in early-pubertal (5-weeks-old) female C57Bl/6 mice, and repeated observations in the same mice in early-adulthood (10 to 11-weeks-old). Measures were collected relative to the 4-day estrous cycle. Data demonstrate the emergence of the preovulatory LH surge by 5 weeks of age, and estrus stage specific alterations in pulsatile LH secretion. These observations demonstrated marked changes in the pattern of LH secretion prior to ovulation in early-pubertal and early adult female mice.  Moreover, we observed striking differences in the pulsatile pattern of GH secretion over the 4 day estrous cycle. Herein, we demonstrated sex-specific differences in the pulsatile GH secretion in the mouse. Data suggests mechanistic alterations in the pulse generators for LH and GH secretion in the maturing and cycling female mouse.

This work was supported by the University of Queensland and Otago University. Y Wanreceives a postgraduate scholarship from The University of Queensland.