Fig. 1

Experimental design. The black solid arrow indicates the duration of an LP (long photoperiod) group, and the grey solid arrow shows the duration of an SP (short photoperiod) group. Birth, weaning, and the end of the experiment are marked with dotted lines. The red bracket shows the period for which physiological measurements were taken from postnatal 3–22 weeks, and the blue bracket indicates sample collection from postnatal 0 day to 19 weeks. The hatched area represents the parental exposure period. Parental voles were maintained under long photoperiod conditions, and after 10 days of pairing, half of the pregnant females were transferred to short photoperiod conditions for delivery