Food and temperature change photoperiodic responses in two vole species:
different roles for Tshβ, Kisspeptin and Rfrp3
Abstract
Seasonal timing of reproduction in voles is driven by photoperiod. Here
we hypothesize that a negative energy balance can modify
spring-programmed photoperiodic responses in the hypothalamus,
controlling reproductive organ development. We reveal that Common
(Microtus arvalis) and Tundra voles (Microtus oeconomus),
reduce photoperiodic induced pars tuberalis thyroid-stimulating hormone
β-subunit (Tshβ) expression to inhibit gonadal development when food is
scarce. Reduction in gonadal size is more pronounced in tundra voles, in
which the hypothalamic Kisspeptin (Kiss1) system seems involved in
downregulating gonadal development, especially in males. Low temperature
additionally leads to decreased hypothalamic RF-amide related peptide
(Rfrp3) levels, which may facilitate further suppression of gonadal
growth. Shutting off the photoperiodic-axis when food is scarce in
spring may be an adaptive response to save energy, leading to delayed
reproductive organ development until food resources are sufficient for
reproduction, lactation and offspring survival.