The maturation of exploratory behavior in adolescent Mus spicilegus on two photoperiods

Le résumé fourni par la source

Dispersal from the natal site or familial group is a core milestone of adolescent development in many species. A wild species of mouse,Mus spicilegus, presents an exciting model in which to study adolescent development and dispersal because it shows different life history trajectory depending on season of birth.M. spicilegusborn in spring and summer on long days (LD) disperse in the first 3 months of life, whileM. spicilegusborn on shorter autumnal days (SD) delay dispersal through the wintertime. We were interested in using these mice in a laboratory context to compare age-matched mice with differential motivation to disperse. To first test if we could find a proxy for dispersal related behavior in the laboratory environment, we measured open field and novel object investigation across development inM. spicilegusraised on a LD 12 h:12 h light:dark cycle. We found that between the first and second month of life, distance traveled and time in center of the open field increased significantly with age inM. spicilegus. Robust novel object investigation was observed in all age groups and decreased between the 2nd and 3rd month of life in LD males. Compared to male C57BL/6 mice, maleM. spicilegustraveled significantly longer distances in the open field but spent less time in the center of the field. However, when a novel object was placed in the center of the open field, MaleM. spicilegus, were significantly more willing to contact and mount it. To test if autumnal photoperiod affects exploratory behavior inM. spicilegusin a laboratory environment, we reared a cohort ofM. spicileguson a SD 10 h:14 h photoperiod and tested their exploratory behavior at P60-70. At this timepoint, we found SD rearing had no effect on open field metrics, but led to reduced novel object investigation. We also observed that in P60-70 males, SD rearedM. spicilegusweighed less than LD rearedM. spicilegus. These observations establish that SD photoperiod can delay weight gain and blunt some, but not all forms of exploratory behavior in adolescentM. spicilegus.

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