Cold commonly affects growth and reproductive development in small mammals.Here,we test the hypothesis that low ambient temperature will affect growth and puberty onset,associated with altered hypothalamic Kiss-1 gene expression and serum leptin concentration in wild rodents.Male Brandts voles (Lasiopodomys brandtii) were exposed to cold (4±1℃) and warm (23 ± 1℃) conditions from birth,and killed at different developmental stages based on body mass growth: Day 26,Day40; Day 60 and Day 90) .Brandts voles increased thermogenic capacity of brown adipose tissue,mobilized body fat,decreased serum leptin levels and delayed the reproductive development especially at 40 days of age under cold conditions.They increased food intake to compensate for the high energy demands in the cold.The hypothalamic Kiss-1 gene expression on Day 26 was decreased,associated with lower wet testis mass and testis testosterone concentration on Day 40,in the cold-exposed voles compared with those in the warm conditions.Serum leptin concentration was positively correlated with body fat,testis mass and testosterone concentration.These data suggested that the reduced Kiss-1 expression may be an early major gatekeeper for delaying the onset of puberty,and the decrease in serum leptin concentration during the early stage of development may act as a signal to link metabolic and reproductive status in the cold environment.