title: Distribution and seasonal variation in hypothalamic RF-amide peptides in a semi-desert rodent, the jerboa.
abstract: The jerboa is a semi-desert rodent, in which reproductive activity depends on the seasons, being sexually active in the spring-summer. The present study aimed to determine whether the expression of two RF-amide peptides recently described to regulate gonadotrophin-releasing hormone neurone activity, kisspeptin (Kp) and RF-amide-related peptide (RFRP)-3, displays seasonal variation in jerboa. Kp and/or RFRP-3 immunoreactivity was investigated in the hypothalamus of jerboas captured in the field of the Middle Atlas mountain (Morocco), either in the spring or autumn. As in other rodents, the Kp-immunoreactive (-IR) neurones were found in the anteroventro-periventricular and arcuate nuclei. RFRP-3 neurones were noted within the dorso/ventromedial hypothalamus. A marked sexual dimorphism in the expression of Kp (but not RFRP-3) was observed. The number of Kp-IR neurones was nine-fold higher, and the density of Kp-IR fibres and terminal-like elements in the median eminence was two-fold higher in females than in males. Furthermore, a significant seasonal variation in peptide expression was obtained with an increase in both Kp- and RFRP-3-IR cell bodies in sexually active male jerboas captured in the spring compared to sexually inactive autumn animals. In the arcuate nucleus, the level of Kp-IR cells and fibres was significant higher during the sexually active period in the spring than during the autumnal sexual quiescence. Similarly, the number of RFRP-3-IR neurones in the ventro/dorsomedial hypothalamus was approximately three-fold higher in sexually active jerboa captured in the spring compared to sexually inactive autumn animals. Altogether, the present study reports the distribution of Kp and RFRP-3 neurones in the hypothalamus of a desert species and reveals a seasonal difference in their expression that correlates with sexual activity. These findings suggest that these two RF-amide peptides may act in concert to synchronise the gonadotrophic activity of jerboas with the seasons.
authors.affiliation: Laboratory of Neuroendocrinology and Nutritional and Climatic Environment, Faculty of Sciences, ATLAS-FES, Morocco.
authors.forename: A
authors.initials: A
authors.lastname: Janati
authors.forename: R
authors.initials: R
authors.lastname: Talbi
authors.forename: P
authors.initials: P
authors.lastname: Klosen
authors.forename: J D
authors.initials: JD
authors.lastname: Mikkelsen
authors.forename: R
authors.initials: R
authors.lastname: Magoul
authors.forename: V
authors.initials: V
authors.lastname: Simonneaux
authors.forename: S
authors.initials: S
authors.lastname: El Ouezzani
mesh_terms: D000818:Animals; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D059648:Kisspeptins / Q000378:metabolism*; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D012377:Rodentia; D012621:Seasons; D012727:Sex Characteristics
chemical_list: D059648:Kisspeptins; D009479:Neuropeptides; C416987:RFamide peptide