Comparative analysis of kisspeptin-immunoreactivity reveals genuine differences in the hypothalamic Kiss1 systems between rats and mice

Peptides. 2013 Jul;45:85-90. doi: 10.1016/j.peptides.2013.04.013. Epub 2013 May 4.


Kiss1 mRNA and its corresponding peptide products, kisspeptins, are expressed in two restricted brain areas of rodents, the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC). The concentration of mature kisspeptins may not directly correlate with Kiss1 mRNA levels, because mRNA translation and/or posttranslational modification, degradation, transportation and release of kisspeptins could be regulated independently of gene expression, and there may thus be differences in kisspeptin expression even in species with similar Kiss1 mRNA profiles. We measured and compared kisspeptin-immunoreactivity in both nuclei and both sexes of rats and mice and quantified kisspeptin-immunoreactive nerve fibers. We also determined Kiss1 mRNA levels and measured kisspeptin-immunoreactivity in colchicine pretreated rats. Overall, we find higher levels of kisspeptin-immunoreactivity in the mouse compared to the rat, independently of brain region and gender. In the female mouse AVPV high numbers of kisspeptin-immunoreactive neurons were present, while in the rat, the female AVPV displays a similar number of kisspeptin-immunoreactive neurons compared to the level of Kiss1 mRNA expressing cells, only after axonal transport inhibition. Interestingly, the density of kisspeptin innervation in the anterior periventricular area was higher in female compared to male in both species. Species differences in the ARC were evident, with the mouse ARC containing dense fibers, while the rat ARC contains clearly discernable cells. In addition, we show a marked sex difference in the ARC, with higher kisspeptin levels in females. These findings show that the translation of Kiss1 mRNA and/or the degradation/transportation/release of kisspeptins are different in mice and rats.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anterior Thalamic Nuclei / cytology
  • Anterior Thalamic Nuclei / drug effects
  • Anterior Thalamic Nuclei / metabolism
  • Arcuate Nucleus of Hypothalamus / cytology
  • Arcuate Nucleus of Hypothalamus / drug effects
  • Arcuate Nucleus of Hypothalamus / metabolism
  • Colchicine / pharmacology
  • Female
  • Gene Expression Regulation
  • Immunohistochemistry
  • Kisspeptins / genetics*
  • Kisspeptins / metabolism
  • Male
  • Mice
  • Nerve Fibers / drug effects
  • Nerve Fibers / metabolism
  • Neurons / cytology
  • Neurons / drug effects
  • Neurons / metabolism
  • Protein Biosynthesis
  • Protein Transport
  • RNA, Messenger / genetics*
  • RNA, Messenger / metabolism
  • Rats
  • Sex Factors
  • Species Specificity


  • Kiss1 protein, mouse
  • Kiss1 protein, rat
  • Kisspeptins
  • RNA, Messenger
  • Colchicine