Fig. 4: Hypothalamic kisspeptin-immunoreactivity in KiDKO mice along postnatal maturation.

Detection of kisspeptin content in situ was conducted using immunohistochemistry. Due to the features of immunoreactivity (IR) of kisspeptin in the mouse hypothalamus, this procedure allowed the detection of fibers in the ARC, while permitting the counting of numbers of kisspeptin-IR cells in AVPV. Representative images and quantitative data on kisspeptin-IR fibers (area) or cells in the ARC of males (a–c) and the AVPV (d–f) and ARC (g–i) of females of control and KiDKO genotypes are presented. Data were collected at three postnatal ages: 2 weeks (corresponding to mini-puberty), 4 weeks (corresponding to early pubertal transition), and adulthood (4 months). Group sizes for ARC densitometry: n = 4 control males, n = 4 KiDKO males for 2 week, 4 week, and adults; n = 4 control females; n = 4 KiDKO females for 2 week and adults; and n = 3 control females; n = 4 KiDKO females for 4 week. Of note, for quantification of kisspeptin cell numbers in the AVPV, higher number of animals at 2- and 4-weeks was included due to the greater variability: n = 7 control females, n = 6 KiDKO females for 2 weeks, and n = 7 control females, n = 7 KiDKO females for 4 week. The values are represented as the mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001 vs. corresponding control groups. n/d not detectable. Scale bars correspond to 200 µm.