Abstract

There are few data about early thermal conditioning (TC) and its effect on later life in rabbits. Therefore, the present study aimed to investigate the impact of exposing two rabbit breeds to early age short-term heat stress (EA-STHS) on physiological parameters and hepatic expression levels of some genes. Rabbits from New Zealand White (NZW) and Baladi Black (BB) rabbit breeds were reared in a controlled environmental chamber (28 ± 2 °C and 40 ± 2% RH). At 42 days of age, rabbits from both breeds were equally divided into two groups; control (untreated) and heat exposed groups (kept at 36 ± 1 °C and 62% RH for 6 h). At 13 weeks of age, rabbits of all groups were re-exposed to acute heat stress (36 ± 1 °C and 62% RH for 6 h). At 13 weeks of age, plasma CORT, plasma MDA, and hepatic MDA had significantly lower levels in the rabbits from the two breeds subjected to EA-STHS than untreated control groups. plasma TAC and the relative hepatic expression of all the studied genes like Hsp70, HspA9, Hsp90α and UCP2 had significantly higher levels in EA-STHS treated NZW and BB rabbits compared with the control groups. In conclusion, the results suggest that EA-STHS has a long-lasting effect on the later life response to acute heat stress in NZW and BB breeds, as indicated by the hepatic expression profile of several genes, corticosterone, and antioxidant parameters. Additionally, each breed had characteristic patterns for the tested parameters at each time point and treatment.

• HIGHLIGHTS

• Rabbits are susceptible to thermal stress, which is associated with adverse effects on production and reproduction traits.

• Early-age thermal conditioning is one of the suggested protective treatments to reduce the heat stress adverse effects.

• Early age short-term thermal stress may induce thermotolerance ability to later time heat exposure in both rabbit breeds.

摘要

关于早期热调节（TC）及其对家兔晚年生活的影响的数据很少。因此，本研究旨在研究将两个兔品种暴露于早期短期短期热应激（EA-STHS）对某些基因的生理参数和肝表达水平的影响。将新西兰白（NZW）和巴拉迪黑（BB）兔种的兔子在受控的环境室内（28±2°C和40±2％RH）饲养。在42天大时，将两个品种的兔子平均分为两组。对照组（未治疗）和热暴露组（在36±1°C和62％RH下保持6小时）。在13周龄时，所有组的兔子均再次暴露于急性热应激（36±1°C和62％RH）6小时。在13周龄时，血浆CORT，血浆MDA，与未治疗的对照组相比，接受EA-STHS的两个品种的兔子的肝MDA水平显着降低。与对照组相比，EA-STHS处理的NZW和BB兔的血浆TAC和所有研究的基因（如Hsp70，HspA9，Hsp90α和UCP2）的相对肝表达水平均显着较高。总之，结果表明，EA-STHS对NZW和BB品种对急性热应激的后期反应具有长效影响，如几个基因的肝表达谱，皮质酮和抗氧化剂参数所表明的。此外，每个品种在每个时间点和处理方式下都有所测试参数的特征模式。与对照组相比，在EA-STHS处理的NZW和BB兔中，Hsp90α和UCP2的水平明显更高。总之，结果表明，EA-STHS对NZW和BB品种对急性热应激的后期反应具有长效影响，如几个基因的肝表达谱，皮质酮和抗氧化剂参数所表明的。此外，每个品种在每个时间点和处理方式下都有所测试参数的特征模式。与对照组相比，在EA-STHS处理的NZW和BB兔中，Hsp90α和UCP2的水平明显更高。总之，结果表明，EA-STHS对NZW和BB品种对急性热应激的后期反应具有长效影响，如几个基因的肝表达谱，皮质酮和抗氧化剂参数所表明的。此外，每个品种在每个时间点和处理方式下都有所测试参数的特征模式。

• 强调

• 兔子易受热应激，这与对生产和繁殖性状的不利影响有关。

• 早期热调节是减少热应激不良影响的建议保护措施之一。

• 在两个兔子品种中，早期年龄的短期热应激可能会诱导耐热性，从而在以后的时间暴露于热中。