The effect of increased ambient temperature on Hsp70, superoxide dismutase, nitric oxide, malondialdehyde, and caspase activity in relation to the intrinsic and extrinsic apoptosis pathway of broiler blood cells.

The objective of this study was to examine the effect of increased ambient temperature on Hsp70 expression, superoxide dismutase (SOD) activity, nitric oxide (NO), malondialdehyde (MDA), caspase 8, caspase 9 and caspase 3 in relation to the intrinsic and extrinsic apoptosis pathway (IAP and EAP) of broiler blood cells (BBC). BBC were maintained at 42 °C and at 5 ranges of temperatures; 42-43, 44-45, 46-47, 48-49, and 50-51 °C. Then Hsp70 expression, SOD activity, NO, MDA, activity of caspase 8, caspase 9 and caspase 3, and living and apoptotic BBC were measured. It was found that Hsp70 expression and SOD were increased at 42-43 °C (P < 0.05), while the activity of caspase 9 and caspase 3 decreased (P < 0.05). At higher temperatures of 44-45 °C, caspase 9 and caspase 3 activities were increased and were higher than at 42 °C (P < 0.05). Apoptosis commenced in the temperature range 46-47 °C; during this range of temperature, NO increased (P < 0.05), but it decreased at 48-49 °C (P < 0.05). At the same time, activity of SOD in BBC was increased, achieving the highest levels (P < 0.05). In addition, activity of caspase 8 and caspase 3 at 48-49 °C was higher than that at 42 °C, and the apoptotic BBC was increased (P < 0.05). Therefore, temperature effects on BBC could be divided into three phases. The first phase was the temperature at 42 °C. The second phase, or pre-apoptotic phase, was in the temperature range from 42 to 45 °C. The third phase was the apoptosis phase, which manifested at 46 °C and above. These phenomena showed that in the pre-apoptosis phase, Hsp70 suppressed the IAP. On the other hand, in the apoptosis phase, apoptotic BBC is caused by the influence of NO, superoxide and MDA through the EAP.