Brain nitric oxide production by a proline-rich decapeptide from Bothrops jararaca venom improves baroreflex sensitivity of spontaneously hypertensive rats

Abstract

Baroreflex sensitivity is disturbed in many people with cardiovascular diseases such as hypertension. Brain deficiency of nitric oxide (NO), which is synthesized by NO synthase (NOS) in the citrulline-NO cycle (with argininosuccinate synthase (ASS) activity being the rate-limiting step), contributes to impaired baroreflex. We recently showed that a decapeptide isolated from Bothrops jararaca snake venom, denoted Bj-PRO-10c, exerts powerful and sustained antihypertensive activity. Bj-PRO-10c promoted vasodilatation dependent on the positive modulation of ASS activity and NO production in the endothelium, and also acted on the central nervous system, inducing the release of GABA and glutamate, two important neurotransmitters in the regulation of autonomic systems. We evaluated baroreflex function using the regression line obtained by the best-fit points of measured heart rate (HR) and mean arterial pressure (MAP) data from spontaneously hypertensive rats (SHRs) treated with Bj-PRO-10c. We also investigated molecular mechanisms involved in this effect, both in vitro and in vivo. Bj-PRO-10c mediated an increase in baroreflex sensitivity and a decrease in MAP and HR. The effects exerted by the peptide include an increase in the gene expression of endothelial NOS and ASS. Bj-PRO-10c-induced NO production depended on intracellular calcium fluxes and the activation of a G i/o -protein-coupled metabotropic receptor. Bj-PRO-10c induced NO production and the gene expression of ASS and endothelial NOS in the brains of SHRs, thereby improving baroreflex sensitivity. Bj-PRO-10c may reveal novel approaches for treating diseases with impaired baroreflex function. Hypertension Research (2010Research ( ) 33, 1283Research ( -1288 doi:10.1038/hr.2010 Keywords: argininosuccinate synthase; baroreflex sensitivity; Bothrops jararaca venom; nitric oxide; proline-rich oligopeptide INTRODUCTIONThe gaseous messenger NO is involved mainly in the regulation of local and systemic vascular resistance, sodium balance and, consequently, blood pressure control, 1 but it is also a signaling molecule and modulator of brain function. 2 Recent studies relate NO with central cardiovascular control through the regulation of the cardiac and vascular autonomic system via the modulation of the central sites of cardiovascular autonomic neural integration. 3,4 NO is generated in the citrulline-NO cycle by NO synthase (NOS) using L-arginine as a substrate. Three isoforms of NOS have been described: calcium-dependent endothelial (eNOS) and neuronal (nNOS) isoforms and inducible NOS. The expression and activity

Identification of snake bradykinin-potentiating peptides (BPPs)-simile sequences in rat brain – Potential BPP-like precursor protein?

“…A significant decrease in mean arterial pressure (MAP) accompanied by a significant decrease in heart rate (HR) was observed for both SODa and SODb, in a similar way as recently described also for the snake BPPs [31,32,36,57,66], but with a slower and long lasting effect for SODb compared to the faster effect of SODa (data not shown). Considering that the rat SOD enzyme has a key role in regulating the BP, acting as an endogenous antioxidant [67], it would be expected that peptide fragments derived from SOD protein sequence could be biologically effective only in conditions suitable for the antioxidant system's triggering.…”

“…In addition, the cloning and sequencing of the BPPs precursor cDNA from Bj brain not only confirmed the co-expression of the CNP in the same precursor protein in the CNS in the same was as in the venom gland, as well as in situ hybridization studies showed the expression of BPPs/CNP precursor in snake CNS regions associated to the regulation of neuroendocrine functions [30]. In addition, we believe that the recent demonstration of the effects of snake BPPs on central BP control of rats reinforces the hypothesis of the BPPs/CNP roles as neuropeptide hormones [31][32][33].…”

“…Therefore, it would be conceivable that after this primary action, SOD could also be the source of bioactive peptides that could further decrease the BP by a mechanism of action that still need to be unraveled. Although the potential involvement of NO synthesis and Ca2+ influx should also be considered for BPP-like peptides [31][32][33]57].…”

Interactions between the NO-Citrulline Cycle and Brain-derived Neurotrophic Factor in Differentiation of Neural Stem Cells

“…Intracellular media were obtained following cell lysis with radioimmune precipitation assay buffer (50 mM Tris, pH 7.5, 150 mM NaCl, 1% (v/v) Nonidet P-40, 0.5% (w/v) sodium deoxycholate, 0.1% (w/v) SDS, 1 mM diethylene triamine pentaacetic acid (DTPA), and 10 mM N-ethylmaleimide) and centrifugation as previously described (25). Extra-and intracellular media of NSC were directly injected into a vessel containing a saturated solution of vanadium (III) chloride in 1 M HCl at 90°C.…”

Bothrops jararaca Peptide with Anti-Hypertensive Action Normalizes Endothelium Dysfunction Involved in Physiopathology of Preeclampsia

“…Recent results indicated the targets of Bj -PRO-10c, resulting in neurotransmitter release, NO production and alteration of baroreflex control, resulting in alteration of arterial pressure and heart rate [18], [19].…”