Effects of acute cold exposure on oxidative balance and total antioxidant capacity in juvenile Chinese soft‐shelled turtle, Pelodiscus sinensis

Abstract

Acute cold exposure may disturb the physiological homeostasis of the body in ectotherms. To date, there has been no information on the effects of cold exposure on homeostasis of reactive oxygen species (ROS) or antioxidant defense response in the Chinese soft-shelled turtle, Pelodiscus sinensis. In this study, P. sinensis juveniles were acclimated at 28 °C, transferred to 8 °C as cold exposure for 12 h, then moved back to 28 °C rewarming for 24 h. We measured the ROS level and total antioxidant capacity (TAC) in the brain, liver, kidney and spleen at 2 and 12 h cold exposure, and at the end of the rewarming period. Malonaldehyde (MDA) and carbonyl protein were used as markers of oxidative damage. Turtles being maintained simultaneously at 28 °C were used as the control group. Cold exposure did not disturb the ROS balance in all 4 tissues, while rewarming raised the ROS level in the brain and kidney of P. sinensis. Cold exposure and rewarming decreased the TAC in the brain, liver and spleen but did not change the TAC in the kidney. MDA and carbonyl protein levels did not increase during the treatment, indicating no oxidative damage in all 4 tissues of P. sinensis. Our results indicated that extreme cold exposure did not impact the inner oxidative balance of P. sinensis, but more ROS was produced during rewarming. P. sinensis showed good tolerance to the harsh temperature change through effective protection of its antioxidant defense system to oxidative damage. This study provides basic data on the stress biology of P. sinensis.

Effects of both cold and heat stresses on the liver of giant spiny frog Quasipaa spinosa: stress response and histological changes

“…The liver is known to be a hub for metabolism, and mitochondria are considered to be the major site for cellular production of ROS (Kiss et al, 2011;Paital, 2016;Zhang et al, 2013). Results showed that both cold and heat stress can significantly increase the generation of mitochondrial ROS, which was consistent with results in other ectotherms, such as the euryhaline fish Takifugu obscurus (Cheng et al, 2015(Cheng et al, , 2017, the eurythermal bivalve Mya arenaria from a low-shore intertidal population (Abele et al, 2002) and the Chinese soft-shelled turtle Pelodiscus sinensis (Zhang et al, 2017b). To counteract the adverse effects of ROS, antioxidant enzymes can be activated to cope with oxidative stress (Cui et al, 2014).…”

Antioxidant response to acute cold exposure and following recovery in juvenile Chinese soft-shelled turtles, Pelodiscus sinensis

“…However, freezing can lead to physical damage, cell dehydration and whole body ischemia that can cause severe tissue damage and oxidative stress (Dinkelacker et al, 2005;Storey, 2006;Voituron et al, 2002), resulting in activation of Nrf2 and its downstream antioxidant enzymes when temperatures were reduced below 0°C. Furthermore, it has been reported that the ROS did not increase during acute cold exposure in P. sinensis (Zhang et al, 2017b), indicating a stable balance between ROS production and antioxidant defense, which indicates that cold exposure for 12 h did not produce oxidative stress sufficient to trigger Nrf2 pathway activation of antioxidant defenses.…”

“…After enduring severe cold stress, and even whole body freezing, no signs of physiological damage was detected in turtle species (Baker et al, 2007;Storey, 2006). Our previous studies of the subtropical Chinese soft-shelled turtle Pelodiscus sinensis also indicated no increase in oxidative damage after severe cold exposure (a reduction from 28°C to 8°C in less than 5 min that was then maintained for 2-12 h) (Chen et al, 2015;Zhang et al, 2017b). All these results indicate a unique ROS balancing capacity, which may promote the excellent cold stress tolerance in freshwater turtles.…”

“…S1). However, significant changes in total antioxidant capacity was observed in the brain and liver of P. sinensis after 12 h of cold stress (Zhang et al, 2017b). Therefore, a duration of 12 h was selected for measuring the antioxidant response to acute cold stress.…”

Effect of cold stress on ovarian & uterine microcirculation in rats and the role of endothelin system

“…In addition, cold not only induces menstrual disorders and dysmenorrhea [5,6], it can also trigger ovarian insulin resistance, reproductive hormone disorders, and polycystic ovary phenotype [7][8][9]. Cold exposure can not only induce gynecological diseases via sympathetic neuroendocrine and endocrine systems, oxidative damage, and energy metabolism pathway [10][11][12][13], but it can also influence on reproductive system, through blood circulation changes. For instance, research by Meidan et al showed that cold stress can cause uterine artery contraction, thereby resulting in the reduction of placental blood flow [14].…”