Brain renin-angiotensin system in broiler chickens with cold-induced pulmonary hypertension

Effects of allicin on ascites syndrome traits and angiotensin II type 1 receptor gene expression in broilers reared in the Mexican highlands

Ascites syndrome (AS) is a deadly condition in fast-growing chickens, preceded by pulmonary arterial hypertension (PAH), where the angiotensin II type 1 receptor (ATR1) plays a role. We investigated whether allicin (ALLI), a garlic derivative, could (a) interact with broiler ATR1, (b) affect ascites-related traits [haematocrit content (Hct%), blood oxygen saturation (SaO2), and the right-to-total ventricular weight ratio (RV:TV)], (c) modify ATR1 expression in the lung, heart, and liver, alongside ascites mortality and growth performance in Ross 308 broilers raised at high altitude and under cold temperatures promoting PAH/AS. Three groups (n = 70 each) were studied: 0-ALLI (untreated), 1-ALLI (allicin 1 mg/kg bodyweight/daily at 14-27 days of age by oral-oesophageal route), and 2.5-ALLI. After 3-6 weeks, Hct%, SaO2, RV:TV ratios, and ATR1 expression in the lung, heart, and liver, were evaluated. Weekly productive performance and AS mortality were recorded. Molecular dockings and dynamic simulations predicted that ALLI might inhibit broiler ATR1 in a transitory manner. At 42 days of age, birds in the 2.5-ALLI group exhibited lower Hct% and lower RV:TV values, while ALLI marginally enhanced SaO2. ATR1 expression in the 1-ALLI and 2.5-ALLI groups was higher (i.e. restored) in the lungs and heart, respectively, but not in the liver compared with the untreated group. Productive performance remained unaffected by ALLI, and 2.5-ALLI provided a protection of 4.3% against ascites mortality. In conclusion, 2.5-ALLI mitigated PAH/AS traits in the lungs and heart without compromising broiler productive performance. Further studies adjusting ALLI doses and combinations are warranted.RESEARCH HIGHLIGHTS Broilers bred at >2000 m OSL and <20°C were treated with 1 or 2.5 mg allicin per os.Allicin at 2.5 mg per os decreased haematocrit and right ventricular hypertrophy.Allicin treatments restored ATR1 expression in the heart and lungs.Productive performance of broilers was not affected by allicin treatments.Allicin is a promising candidate to enhance the quality of poultry production.

Effect of sage (Salvia officinalis L.) extract in antioxidant status and intestinal morphology of pulmonary hypertensive chickens

OBJECTIVES

The effects of dietary sage on the growth performance, antioxidant status, intestinal mucosa morphology, and pulmonary hypertensive response were investigated in broiler chickens with pulmonary hypertension.

METHODS

Chicks (Ross 308) were reared under cold stress for 35 days and treated with 0.05% vitamin C (positive control) and 0 (control), 0.1 or 0.2% sage extracts, then performance, oxidant and antioxidant status, and intestinal morphology were evaluated.

RESULTS

The index of pulmonary hypertension (RV:TV) was decreased, and weight gain (days 22-35) was increased in all treatments (except for sage 0.1%) compared with control (P < 0.05). Lipid peroxidation was decreased, whereas the activity of antioxidant enzymes (GPX, CAT, and SOD) was increased in the sage 0.2% group compared with control (P < 0.05). In the lung, SOD, CAT, and GPX transcripts were decreased in the sage 0.2% group compared with control (P < 0.05). In the right ventricle of the heart, SOD and CAT transcripts were increased in the sage 0.2% group compared with other groups of chickens, whereas GPX transcript was decreased (P < 0.05). The jejunal villus length in the chickens fed sage was significantly lower than in control (P < 0.05). The ileal villus width, villus surface area, and lamina proporia thickness in the chickens fed sage (0.2%) were increased compared with control (P < 0.05).

CONCLUSIONS

Dietary supplementation of sage (0.2%) could modulate pulmonary hypertensive response, improve antioxidant status (enzymatic activity), intestinal morphometry, and absorptive surface in the broiler chickens.

The dopamine receptor D4 regulates the proliferation of pulmonary arteries smooth muscle in broilers by downregulating AT1R

The major cause of pulmonary vascular remodeling in broilers is abnormal proliferation of vascular smooth muscle cells (VSMCs), and one of the main causes of pulmonary hypertension syndrome (PHS) in broilers is pulmonary artery vascular remodeling. Forty Arbor Acres (AA) broilers were randomly divided into four groups (n = 10): a control group (deionized water, 0 g/L NaCl), a freshwater group (FW, deionized water + 1 g/L NaCl), highly salinized freshwater group 1 (H-SFW-1, deionized water + 2.5 g/L NaCl) and highly salinized freshwater group 2 (H-SFW-2, deionized water + 5 g/L NaCl). The results of in vivo experiments showed that vascular smooth muscle of the broilers could be significantly proliferated by intake of high-salinity fresh water (H-SFW-1 & H-SFW-2), which significantly increased the content of angiotensin II (Ang II) and the expression of angiotensin II type 1 (AT1) receptor protein. Meanwhile, it significantly decreased the expression of dopamine receptor D4 (DRD4) protein. The results of in vitro experiments showed that exogenous Ang II induced the proliferation of primary VSMCs in broilers, which could be significantly inhibited by DRD4 agonists (D4A, HY-101384A) and enhanced by DRD4 inhibitors (D4I, HY-B0965). In addition, the results of immunoblotting and fluorescence quantitative PCR showed that AT1 receptors could be negatively regulated by DRD4 in VSMCs of broilers, either at the transcriptional or translational level. At the same time, the expression of AT1 receptor could be increased by DRD4 inhibition by D4I and decreased by DRD4 activation by D4A. The negative regulatory effect of DRD4 on AT1 receptor occurred in a dose-dependent manner. These results indicate that long-term intake of highly salinized fresh water can cause PHS in broilers, accompanied by varying degrees of proliferation of pulmonary artery smooth muscle. This mechanism may involve response of its receptor being induced by increased Ang II, while DRD4 can negatively regulate it.

Pathophysiology and pathological remodelling associated with dilated cardiomyopathy in broiler chickens predisposed to heart pump failure

Broiler chickens selected for rapid growth are highly susceptible to dilated cardiomyopathy (DCM). In order to elucidate the pathophysiology of DCM, the present study examines the fundamental features of pathological remodelling associated with DCM in broiler chickens using light microscopy, transmission electron microscopy (TEM), and synchrotron Fourier Transform Infrared (FTIR) micro-spectroscopy. The morphological features and FTIR spectra of the left ventricular myocardium were compared among broiler chickens affected by DCM with clinical signs of heart pump failure, apparently normal fast-growing broiler chickens showing signs of subclinical DCM (high risk of heart failure), slow-growing broiler chickens (low risk of heart failure) and Leghorn chickens (resistant to heart failure, used here as physiological reference). The findings indicate that DCM and heart pump failure in fast-growing broiler chickens are a result of a complex metabolic syndrome involving multiple catabolic pathways. Our data indicate that a good deal of DCM pathophysiology in chickens selected for rapid growth is associated with conformational changes of cardiac proteins, and pathological changes indicative of accumulation of misfolded and aggregated proteins in the affected cardiomyocytes. From TEM image analysis it is evident that the affected cardiomyocytes demonstrate significant difficulty in the disposal of damaged proteins and maintenance of proteostasis, which leads to pathological remodelling of the heart and contractile dysfunction. It appears that the underlying causes of accumulation of damaged proteins are associated with dysregulated auto phagosome and proteasome systems, which, in susceptible individuals, create a milieu conducive for the development of DCM and heart failure. RESEARCH HIGHLIGHTS The light and electron microscopy image analyses revealed degenerative changes and protein aggregates in the cardiomyocytes of chickens affected by DCM. The analyses of FTIR spectra of the myocardium revealed that DCM and heart pump failure in broiler chickens are associated with conformational changes of myocardial proteins. The morphological changes in cardiomyocytes and conformational changes in myocardial proteins architecture are integral constituents of pathophysiology of DCM in fast-growing broiler chickens.