Surface wetting strategy prevents acute heat exposure–induced alterations of hypothalamic stress– and metabolic-related genes in broiler chickens1

Abstract

Heat stress (HS) is devastating to poultry production worldwide, yet its biology and molecular responses are not well defined. Although advances in management strategy have partially alleviated the negative impact of HS, productivity still continues to decline when the ambient temperature rises. Therefore, identifying mechanism-based approaches to decrease HS susceptibility while improving production traits is critical. Recently, we made a breakthrough by applying a surface wetting strategy and showing that it improves growth performance compared with the current conventional cooling system. In the present study, we aimed to further define molecular mechanisms associated with surface wetting in ameliorating HS productivity loss in broilers. Five-week-old broiler chickens were exposed to acute HS (35°C for 2 h) alone or in combination with surface wetting. A control group was maintained at thermoneutral conditions (25°C). Core body temperature (BT) and feed intake were recorded. Blood was collected and hypothalamic tissues (main site involved in the regulation of energy homeostasis) were harvested to determine the expression profile of stress- and metabolic-related genes. Surface wetting prevents HS from increasing BT and plasma corticosterone levels ( < 0.05) and improves feeding and drinking behaviors. At molecular levels, surface wetting blocks the activation of hypothalamic heat shock protein and adenosine monophosphate-activated protein-induced by HS and significantly modulates the expression of feeding-related hypothalamic neuropeptides (agouti-related protein, proopiomelanocortin, orexin, orexin receptor, and leptin receptor). Taken together, our data represent the first evidence that surface wetting alleviates systemic and intracellular stress induced by HS and preserves the intracellular energy status, which, in turn, may result in improved broiler well-being and growth performance.

Sprinkler Technology Improves Broiler Production Sustainability: From Stress Alleviation to Water Usage Conservation: A Mini Review

“…insignificant difference of body core temperature monitored continuously between birds raised under either SPRINK or PAD cooled houses over 48 h. In a recent study using broiler chickens, Dridi's group showed that the SPRINK technology reduced body core temperature induced by heat stress by ∼0.5-1 • C (Figure 2A) (31). Similarly, the SPRINK lowered the overall surface temperature than those with dry surface (Figure 2B).…”

“…AMP, adenosine monophosphate; AMPK, AMP-activated protein kinase; ATP, adenosine triphosphate; HS, heat stress; TN, thermoneutral. Figure 4B was adapted from Rajaei-Sharifabadi et al (31) and used with permission.…”

Effect of Morinda citrifolia (Noni)-Enriched Diet on Hepatic Heat Shock Protein and Lipid Metabolism-Related Genes in Heat Stressed Broiler Chickens

“…RNA integrity and quality was assessed using 1% agarose gel electrophoresis and RNA concentrations and purity were determined for each sample by Take 3 Micro-Volume Plate using Synergy HT multi-mode micro plate reader (BioTek,Winooski, VT). The RNA samples were DNase treated and 1 μg RNA was reverse transcribed using qScript cDNA Synthesis Kit (Quanta Biosciences, Gaithersburg, MD) as we previously described (Rajaei-Sharifabadi H. et al, 2017 ). Real-time quantitative PCR (Applied Biosystems 7500 Real-Time PCR system) was performed as described previously (Rajaei-Sharifabadi H. et al, 2017 ) using 5 μL of 10X diluted cDNA, 0.5 μM of each forward and reverse specific primer, and SYBR Green Master Mix (ThermoFisher Scientific, Rockford, IL) in a total 20 μL reaction.…”

“…The RNA samples were DNase treated and 1 μg RNA was reverse transcribed using qScript cDNA Synthesis Kit (Quanta Biosciences, Gaithersburg, MD) as we previously described (Rajaei-Sharifabadi H. et al, 2017 ). Real-time quantitative PCR (Applied Biosystems 7500 Real-Time PCR system) was performed as described previously (Rajaei-Sharifabadi H. et al, 2017 ) using 5 μL of 10X diluted cDNA, 0.5 μM of each forward and reverse specific primer, and SYBR Green Master Mix (ThermoFisher Scientific, Rockford, IL) in a total 20 μL reaction. Oligonucleotide primers used for chicken ATP citrate lyase (ACLY), acetyl-CoA carboxylase alpha (ACCα), fatty acid synthase (FASN), stearoyl-CoA desaturase (SCD-1), malic enzyme (ME), sterol regulatory element-binding protein 1 and 2 (SREBP-1/2), SREBP Cleavage-Activating Protein (SCAP), insulin induced gene 2 (INSIG2), lipoprotein lipase (LPL), hepatic triglyceride lipase (LIPC), adipose triglyceride lipase (ATGL), fatty acid translocase (CD36), peroxisome proliferator-activated receptor alpha and gamma (PPARα/γ), and ribosomal 18S as housekeeping gene were summarized in Table 1 .…”

“…Plasma glucose, triglyceride, cholesterol, lactate dehydrogenase (LDH), and uric acid levels were measured using an automated spectrophotometer as we previously described (Nguyen et al, 2015 ). Plasma levels of total 3, 5, 3′-triiodothyronine (T 3 ) and thyroxine (T 4 ) were determined using coated tube radioimmunoassay kits (MP Biomedicals, Solon, OH) as we previously described (Rajaei-Sharifabadi H. et al, 2017 ).…”