Blood pressure
The Fig 1 showed DOCA-salt induction increased systole and diastole blood pressure in the SHR (p<0.05) compared to normal rats. Induction of DOCA-salt caused an increase in systole 23.61% and diastole 31.57%. Hypertension blood pressure, which is systole above 140 mmHg and diastole above 100 mmHg
(Badyal et al., 2003). DOCA-salt increased in reabsorption of sodium ions and water from renal distal nephron epithelial cells. It affected blood volume and causing an increase in blood pressure.
Fig 1 showed captopril and VisBC (150 mg/kg) therapy could reduce blood pressure in the SHR. VisBC could reduce systole 19.64% and diastole 29.15%, while captopril reduces systole 21.17% and diastole 30.17%. VisBC 150 mg/kg could reduce blood pressure almost the same as captopril as a positive control. From literature studies, it was suspected that VisBC contains some bioactive peptides which act as anti-hypertensive agents
(Wu et al., 2006). In vivo studies of bioactive peptides from viscera as an inhibitor of angiotensin-converting enzyme
(Fahmi et al., 2004). Riyadi et al., (2019) characterized amino acids contained in tilapia visceral protein hydrolysates. Amino acids are the smallest unit that forms bioactive peptides.
TNF-α expression
TNF-a is a Pro-inflammatory cytokine synthesized by monocytes or macrophages (
Tasgin and Haliloglu, 2018). The results with flow cytometry showed the relative amount of TNF-a increased in SHR induced by DOCA-salt compared with normal rats (P<0.05). Whereas, rats with captopril and VisBC (150 mg/kg) therapy could reduce the relative amount of TNF-a (P<0.05) (Fig 2).
TNF-a expression increased in response to the condition of spontaneous hypertension due to DOCA-Salt
(Elmarakby et al., 2008). The role of TNF-a in regulating blood pressure has been studied using a rat model
(Alexander et al., 2002 and
Bae et al., 2010). TNF-a could support an increase in blood pressure mediated by ANG II (
Ramseyer and Garviscera, 2013). The inflammation caused by increased TNF-a
(Venegas-pont et al., 2010). Suppressing TNF-a could inhibit the development of hypertension
(Chatziantoniou et al., 2004). Elmarakby et al., (2008) showed suppression of TNF-a could reduce renal inflammation in hypertensive models. Inhibition of TNF-a can reduce most of the inflammatory index and cause the effect of decreasing blood pressure.
Fig 2 showed VisBC with dose 150 mg/kg able to inhibit the TNF-a (8.08%) increase, which has implications for a decrease in blood pressure. This decrease is related to hypertension mediated by ANG II (
Ramseyer and Garviscera, 2013). TNF-a caused vasodilation, increased vascular permeability and platelet activated (
Navarro and Mora-ferna, 2006). The action mechanism of VisBC suspected by binding to TNF-α and prevented it from interacting with TNF-a receptors (
Goffe and Cather, 2003). These data indicate that TNF-a involved in the inflammatory response and related hypertension cause by DOCA-salt. Therefore, by inhibiting TNF-a can be a potential therapy for lowering blood pressure and reducing inflammation in the blood vessels caused by hypertension.
IL-6 expression
IL-6 is a pro-inflammatory cytokine and showed to be associated with an increased risk of myocardial infarction
(Ridker et al., 2000), prognostic markers of coronary risk and mortality with acute coronary syndrome
(Tan et al., 2009). IL-6 plays a major role in animal model hypertension
(Coles et al., 2007).
The results with flow cytometry showed the relative amount of IL-6 increased in SHR due to DOCA-Salt compared to normal rats (P<0.05). The SHR group, with the therapy of captopril and VisBC with dose 150 mg/kg, could reduce the relative amount of IL-6 by 8.39% (P<0.05) (Fig 3). Hypertension condition due to DOCA-salt can cause an increase in IL-6, TNF-a and ROS (
Wang and Wang, 2009). IL-6 suppression can prevent the diastole dysfunction and is thought to reduce myocardial fibrosis.
IL-6 plays a role in the pathogenesis of hypertension mediated by ANG II. By suppressing IL-6 levels, it could reduce the increase in blood pressure mediated by ANG II
(Brands et al., 2010). The condition of hypertension also increases chronic inflammation
(Bautista et al., 2005). The Renin-angiotensin system (RAS) acts as a pro-inflammatory mediator and could cause organ damage due to hypertension (
Mehta and Griendling, 2007). IL-6 was released from blood vessel tissue in response to ANG II
(Funakoshi et al., 1999). VisBc with a dose of 150 mg/kg was thought to block the effects of ANG II and prevent the release of IL-6. VisBC with a dose of 150 mg/kg demonstrates the ability to suppress the amount of TNF-α and IL-6, to reduce the increase in systole and diastole in spontaneously hypertensive rats induced by DOCA salts.