Neonatal exposure to short days and low temperatures blunts stress response and yields low fluctuating asymmetry in Siberian hamsters

Abstract

Fluctuating asymmetry (FA) refers to small, non-directional deviations from perfect bilateral symmetry in morphological characters. Individuals with low FA presumably either developed in a relatively stable environment and/or were better able to buffer against developmental stressors. The present study investigated the effects of seasonal factors measured by day length and ambient temperature manipulations on the development of bilateral characters and concomitant changes in stress responses. Siberian hamsters were exposed to either long days (16 h of light per day) or short days (8 h of light per day) combined with either standard temperatures (21 ± 2°C) or low temperatures (8 ± 2°C) on the day of birth until weaning. Cortisol concentrations at baseline and following acute restraint stress, and FA values were measured in adulthood. Females reared in winter-like conditions with short day lengths and low temperatures had low FA and low cortisol concentrations following restraint stress compared to other females. Females reared in long day lengths and standard temperatures had the highest rate of increase in cortisol concentrations after restraint among other female groups. No group effects were observed in males regarding day length and temperature manipulations. Baseline and post-restraint cortisol concentrations were higher in females than males for all groups except in animals reared in short day lengths and low temperatures. Our results suggest that winter-like conditions during neonatal period evoke hyposensitivity to stress in adult females and this blunted response to stress is a key factor in achieving ideal growth patterns.

The relationship between facial shape asymmetry and attractiveness in Mexican students

“…Some studies have found a significant correlation between fluctuating asymmetry and some environmental stressors in a variety of traits and organisms. These include temperature (Babbitt, ; Benderlioglu et al, ), population density (Serrano et al, ), poor environmental conditions (Teixeira et al, ) or minor morphological abnormalities (Polak and Taylor, ). In addition, some genetic factors like heterozygosity have also been postulated as sources of fluctuating asymmetry (FA) (Hutchison and Cheverud, ; Vangestel et al, ).…”

Perinatal light imprinting of circadian clocks and systems (PLICCS): A signature of photoperiod around birth on circadian system stability and association with cancer

“…This finding also highlights knowledge of photoperiod by the foetus. Siberian hamster neonates (P0-P21) exposed to different photoperiods and temperatures elicited sex differences in basal plasma cortisol levels, cortisol stress response, and bone length symmetry in later life (Benderlioglu et al, 2007). With regard to circadian clocks and systems development, it is interesting to note that light is detectable at the suprachiasmatic nuclei (SCN) level at P0 in wild type but not in melanopsin k/o mice as determined by FOS expression (Lupi et al, 2006).…”

“…Animal experiments suggest that sex differences may be important in PLICCS (Benderlioglu et al, 2007;Pyter & Nelson, 2006;Varcoe et al, 2011) and studies that attempt to demonstrate PLICCS in humans should certainly screen for sex differences where possible. Beyond collecting the usual host of established or suspected risk factors for, and co-variables of, disease developments, maternal activity patterns, breast-feeding, and maternal melatonin (and potentially other hormone) zeitgeber information to the neonate may also be important for PLICCS, although acquiring this information -at least in retrospective human studies -will be a challenge to say the least.…”

Fluctuating Asymmetry and Steroid Hormones: A Review

“…Indeed, female Siberian hamsters reared in winter-like conditions with short day lengths and low temperatures in the laboratory had significantly lower cortisol concentrations in response to acute stressors and lower FA in adulthood compared to the females that were reared in any other temperature and day length groups [61]. An elevated stress response marked by increased glucocorticoids in winter months may compromise growth, immune, and other important functions that require significant energy reserves [62].…”

“…It should also be noted that the target group corresponded to the children who were exposed to the ice storm in utero during 14-22 weeks of gestation. Finger ridge configurations are established before the 19 th week of gestation, however [61][62][63][64]. After this period, injury and caustic substances may reduce the appearance of the ridges, but the original pattern will return unless the skin is damaged considerably [97].…”