Abstract
BackgroundPhysiological responses to cold exhibit individual variation that can be affected by various factors, such as morphological characteristics, seasonal changes, and lifestyle; however, the genetic factors associated with this variation remain unclear. Recent studies have identified mtDNA as a potential genetic factor affecting cold adaptation. In addition, non-shivering thermogenesis (NST), a process closely related to mitochondrial dynamics, has also been suggested as an important factor affecting human response to cold. The present study aimed to clarify the relationship between mitochondrial haplogroup and NST during periods of mild cold exposure.MethodsSeventeen healthy university students (D: n = 8, non-D: n = 9) participated in the present study during summer and winter. A climate chamber was programmed so that ambient temperature inside dropped from 28°C to 16°C over the course of an 80-minute period. Physiological parameters were recorded throughout the course of the experiments.ResultsIncreases in VO2 were significantly greater during periods of cold exposure in winter than they were during periods of cold exposure in summer, and individuals from the D group exhibited greater winter values of ΔVO2 than individuals from the non-D group.Tre was significantly lower during periods of rest and cold exposure in winter; however, no significant difference was observed between Tre values of individuals in the D and non-D groups. In addition, although was significantly lower during periods of rest in winter than it was during those same periods in summer, no significant seasonal differences in values of were observed during periods of cold exposure.ConclusionsResults of the present study indicated that NST was greater in winter, and that the D group exhibited greater NST than the non-D group during winter. Despite the differences between groups in NST, no significant differences in rectal and skin temperatures were found between groups in either season. Therefore, it was supposed that mitochondrial DNA haplogroups had a greater effect on variation in energy expenditure involving NST than they had on insulative responses. Future studies are necessary in order to investigate more multiple candidate genes related to human cold adaptation and to elucidate the relationship between gene polymorphism and physiological polytypism.
Highlights
Physiological responses to cold exhibit individual variation that can be affected by various factors, such as morphological characteristics, seasonal changes, and lifestyle; the genetic factors associated with this variation remain unclear
In a post-hoc test carried out in winter, changes in VO2 (ΔVO2) of haplogroup D was significantly greater during the period ranging from 90 to 100 minutes compared with ΔVO2 of haplogroup non-D during that same period
ΔVO2 of haplogroup D was significantly greater during the period ranging from 40 to 100 minutes in winter than it was during that period in summer
Summary
Physiological responses to cold exhibit individual variation that can be affected by various factors, such as morphological characteristics, seasonal changes, and lifestyle; the genetic factors associated with this variation remain unclear. Physiological adaptations to cold, such as the metabolic adaptation of the Inuit [3] and the insulative adaptation of Australian aborigines [4], are well known. Adaptations such as these might have involved genetic adaptations, since these groups were settled in their respective environments for long periods of time. Thermogenesis can be divided into shivering thermogenesis (ST) and non-shivering thermogenesis (NST) These physiological responses to cold are affected by various environmental or individual factors such as season [6,7,8], lifestyle [9], and physical characteristics [10]. Genetic factors must exist, few studies examining the effects of genetic factors on physiological responses to cold have been undertaken
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
