Brain and hepatic Hsp70 protein levels in heat-acclimated broiler chickens during heat stress

Abstract

In the present study we have investigated the effects of heat acclimation on brain and hepatic Hsp70 protein levels and body temperature of broiler chickens in response to gradual heat stress. Two groups of broilers were raised up to 47 days of age under distinct temperature conditions: thermoneutral (TN, according to bird age) or hot environmental (HS, 31-33°C). At 46 days of age, the birds reared at high ambient temperature were transferred to thermoneutrality conditions. After 18 h, these birds and the birds reared at thermoneutral temperature were submitted to gradual heat stress in a climatic chamber so that environment temperature was increased from 28 to 40ºC at a rate of 2ºC/h. Colonic temperature was measured using a thermometer sensor probe at each two hours, and hepatic and brain tissues were collected immediately after slaughter in order to assess Hsp70 protein level by Western blotting analysis. The colonic temperatures of birds reared at high temperature increased steeply during the first 2 h of heat stress (1.06ºC/h) and more slowly thereafter (0.59ºC/h). Broilers reared at thermoneutral temperature showed a small increase in the first 4 h of heat stress (0.18ºC/h) and then colonic temperature increased sharply (0.72ºC/h). Nevertheless, both groups presented similar final colonic temperature by the end of the stress period. Hsp70 levels (ng Hsp70 µg total protein-1) did not change in the liver or brain of the birds reared at high temperature. On the other hand, both liver and brain Hsp70 levels increased significantly during heat stress in the animals reared at thermoneutrality, with a higher expression of this peptide in brain tissue

Hsp70 Genotypes and Heat Tolerance of Commercial and Native Chickens Reared in Hot and Humid Conditions

“…In the poultry industry, heat stress is responsible for the morbidity and mortality of one million broilers per month (Guerreiro et al, 2004). Several recent reports show that heat stress adversely affects feed intake (Cooper & Washburn, 1998), water intake (Bruno et al, 2011), growth performance (Altan et al, 2000;Abu-Dieyeh, 2006), blood variables (Altan et al, 2000;Aengwanich, 2007), electrolytes (Borges et al, 2004), and the immune system (Zulkifli et al, 2000b;Mashaly et al, 2004;Tirawattanawanich et al, 2011), increasing mortality (AlFataftah et al, 2007).The optimal temperature range for commercial broilers is about 21-26 o C (Ewing et al, 1999), and a temperature of 32 o C causes heat stress (Daghir, 1995).…”

Promoter methylation negatively correlated with mRNA expression but not tissue differential expression after heat stress

“…Compared with normally feathered birds, heat-resistance birds (naked-neck Label Rouge) display lower HSP70 levels in hepatic cells when gradual heat stress is induced (Mazzi et al, 2002). Guerreiro et al (2004) measured brain and hepatic HSP70 protein levels using Western blot after gradual heat stress and found that brain HSP70 levels are 3-4 times higher than those in the hepatic tissue of heat-stressed birds reared at thermoneutrality. Much research has been performed to illuminate the cause of HSP70 expression differences in individuals and tissue-dependent expression.…”

Research Note: Metabolic changes and physiological responses of broilers in the final stage of growth exposed to different environmental temperatures

“…In addition, HS is known to delay the synthesis of most proteins except for heat shock proteins ( Wang et al., 2018a , Wang et al., 2018b ). It has been reported that HS induced an increase in the levels of HSP 70 protein and mRNA in the heart, liver, and kidney of broiler chickens ( Guerreiro et al., 2004 ). The HSP 70 level increased significantly in broilers under HS, with a relatively higher expression in the heart ( Mahmoud et al., 2004 ), liver, brain ( Gabriel et al., 1996 , Guerreiro et al., 2004 ), and immune organs (the bursa of Fabricius, thymus, and spleen) ( Liu et al., 2013 ).…”