Chicken muscle hydrolysate reduces blood pressure in spontaneously hypertensive rats, upregulates ACE2, and ameliorates vascular inflammation, fibrosis, and oxidative stress

Fan H, Liao W, Spaans F, Pasha M, Davidge ST, Wu J. Chicken muscle hydrolysate reduces blood pressure in spontaneously hypertensive rats, upregulates ACE2, and ameliorates vascular inflammation, fibrosis, and oxidative stress. J Food Sci. 2022 Mar;87(3):1292-1305. doi: 10.1111/1750-3841.16077.

chicken, peer-reviewed, Publication, Research Showcase 2022, Spent hen

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Spent hens are egg-laying chickens reaching the end of their egg-laying cycle and are seen as a by-product to the egg industry. A spent hen muscle protein hydrolysate prepared by food-grade
thermoase PC10F (SPH-T) has previously shown antihypertensive potential. In the present work, we further investigated its antihypertensive effect and underlying mechanisms in spontaneously hypertensive rats.

Approach

Spent hen carcasses were purchased from a local supermarket. Spent hen muscle proteins were extracted using a pH-shift method. Spontaneously hypertensive rats were divided into three groups: untreated, low dose (250 mg SPH-T/kg/day body weight), and high dose (1,000 mg SPH-T/kg/day body weight); each group consisted of six animals. SPH-T was dissolved in 10 ml of Ensure and orally administered to rats once per day from day 1; untreated group was given Ensure only. Systolic/diastolic blood pressure (SBP / DBP), mean arterial pressure (MAP), and heart rate (HR) were recorded.

Analysis of Results

Oral administration of SPH-T over a period of 20 days reduced SBP by 25.7 mm Hg (p < 0.001) and 11.9 mm Hg, respectively, for the high- and low-dose groups. The high-dose treatment decreased the circulating level of angiotensin II (from 25.0 to 5.7 pg/ml) while increased angiotensin-converting enzyme 2 (ACE2) (from 1.3 to 3.3 IU/ml) and angiotensin (1–7) (from 37.0 to 70.1 pg/ml) significantly. Furthermore, the high-dose group doubled the aortic expression of ACE2 while reduced the expression of angiotensin (Ang) II type 1 receptor (by 35%). Circulating inflammatory cytokines including tumor necrosis factor alpha and monocyte chemoattractant protein-1 as well as vascular inflammatory proteins including inducible nitric oxide synthase and vascular cell adhesion molecule-1 were attenuated by ~15%–50% by the treatment; nitrosative stress (35%) and type I collagen synthesis (50%) in the aorta were also attenuated significantly. Moreover, SPH-T possessed an umami taste (no obvious bitter taste) as analyzed by electronic tongue.

Application

Hypertension is a global health concern, afflicting more than 20% of adults worldwide. Uncovering the antihypertensive effect of spent hen protein hydrolysate underpinned its functional food nutraceutical applications for the prevention and treatment of hypertension.
Future research is needed to ascertain whether or not the antioxidant, anti-inflammatory, and anti-fibrotic effects of SPH-T are due to the increased ACE2 and Ang (1–7) levels. Besides, SPH-T was featured with an umami taste and without an obvious bitter taste, supporting its potential functional food and nutraceutical applications.

Abstract

Spent hens are egg-laying chicken reaching the end of their egg-laying cycle and are seen as a by-product to the egg industry. A spent hen muscle protein hydrolysate prepared by food-grade thermoase PC10F (SPH-T) has previously shown antihypertensive potential. In the present work, we further investigated its antihypertensive effect and underlying mechanisms in spontaneously hypertensive rats. There are three groups: untreated, low dose (250 mg SPH-T/kg/day body weight), and high dose (1,000 mg SPH-T/kg/day body weight). Oral administration of SPH-T over a period of 20 days reduced systolic blood pressure by 25.7 mm Hg (p < 0.001) and 11.9 mm Hg (p < 0.05), respectively, for the high- and low-dose groups. The high-dose treatment decreased the circulating level of angiotensin II (from 25.0 to 5.7 pg/ml) while increased angiotensin-converting enzyme 2 (ACE2) (from 1.3 to 3.3 IU/ml) and angiotensin (1–7) (from 37.0 to 70.1 pg/ml) significantly (p < 0.05). Furthermore, the high-dose group doubled the aortic expression of ACE2 while reduced the expression of angiotensin (Ang) II type 1 receptor (by 35%). Circulating inflammatory cytokines including tumor necrosis factor alpha and monocyte chemoattractant protein-1 as well as vascular inflammatory proteins including inducible nitric oxide synthase and vascular cell adhesion molecule-1 were attenuated by ∼15%–50% by the treatment; nitrosative stress (35%) and type I collagen synthesis (50%) in the aorta were also attenuated significantly (p < 0.05). Moreover, SPH-T possessed an umami taste (no obvious bitter taste) as analyzed by electronic tongue.