The sympathetic adrenomedullary system, but not the hypothalamic-pituitary-adrenal axis, participates in aorta adaptive response to stress: nitric oxide involvement

Supplementation with l-arginine and nitrates vs age and individual physiological reactivity

Ageing is a natural ontogenetic phenomenon that entails a decrease in the adaptive capacity of the organism, as a result of which the body becomes less adaptable to stressful conditions. Nitrate and nitrite enter the body from exogenous sources and from nitrification of ammonia nitrogen by intestinal microorganisms. This review considers the mechanisms of action of l-arginine, a known inducer of nitric oxide (NO) biosynthesis, and nitrates as supplements in the processes of ageing and aggravated stress states, in which mechanisms of individual physiological reactivity play an important role. This approach can be used as an element of individual therapy or prevention of premature ageing processes depending on the different levels of initial reactivity of the functional systems. A search was performed of the PubMed, Scopus, and Google Scholar databases (n = 181 articles) and the author's own research (n = 4) up to May 5, 2023. The review presents analyses of data on targeted treatment of NO generation by supplementation with l-arginine or nitrates, which is a promising means for prevention of hypoxic conditions frequently accompanying pathological processes in an ageing organism. The review clarifies the role of the individual state of physiological reactivity, using the example of individuals with a high predominance of cholinergic regulatory mechanisms who already have a significant reserve of adaptive capacity. In studies of the predominance of adrenergic influences, a poorly trained organism as well as an elderly organism correspond to low resistance, which is an additional factor of damage at increased energy expenditure.

CONCLUSION

It is suggested that the role of NO synthesis from supplementation of dietary nitrates and nitrites increases with age rather than from oxygen-dependent biosynthetic reactions from l-arginine supplementation.

Intrauterine and lactation exposure to fluoxetine blunted in the offspring the aortic adaptive response induced by acute restraint stress

Selective serotonin reuptake inhibitors are the most widely prescribed antidepressants to women during pregnancy. Maternal treatment with fluoxetine can expose fetuses and neonates to higher levels of serotonin that plays a role in stress response. Thus, the aim of the study was to evaluate whether maternal treatment with fluoxetine interferes with aorta reactivity of adult male offspring after acute restraint stress. Wistar rats were gavaged with fluoxetine (5mg/kg/day) or water (control) during pregnancy and lactation. The experiments were performed in adult male offspring, treated or not with reserpine (4mg/Kg, ip, 28h before the experimental protocol). Fluoxetine and control rats were submitted to a single restraint stress session (ST) for 1h. Curves to phenylephrine were performed in thoracic aorta with endothelium. Aortic nitric oxide (NOx) were evaluated by the Griess method. The aortic contraction induced by phenylephrine was similar between control and fluoxetine rats. The acute stress reduced contraction in aorta of control ST compared to control, and L-NAME equaled this response. In fluoxetine rats, ST did not change the aortic constriction. Reserpine treatment restored the vasoconstriction in control ST, but did not interfere with aortic contraction in control, fluoxetine or fluoxetine ST. The NOx concentration was higher in aortas from control ST than control rats, and reserpine reduced NOx levels of control ST. The NOx concentration was similar between fluoxetine and fluoxetine ST rats, treated or not with reserpine. In conclusion, maternal treatment with fluoxetine blunted acute restraint stress-induced NO system activation and aortic adaptation in adult offspring.

Blood pressure regulation in stress: focus on nitric oxide-dependent mechanisms

Stress is considered a risk factor associated with the development of various civilization diseases including cardiovascular diseases, malignant tumors and mental disorders. Research investigating mechanisms involved in stress-induced hypertension have attracted much attention of physicians and researchers, however, there are still ambiguous results concerning a causal relationship between stress and long-term elevation of blood pressure (BP). Several studies have observed that mechanisms involved in the development of stress-induced hypertension include increased activity of sympathetic nervous system (SNS), glucocorticoid (GC) overload and altered endothelial function including decreased nitric oxide (NO) bioavailability. Nitric oxide is well known neurotransmitter, neuromodulator and vasodilator involved in regulation of neuroendocrine mechanisms and cardiovascular responses to stressors. Thus NO plays a crucial role in the regulation of the stress systems and thereby in the BP regulation in stress. Elevated NO synthesis, especially in the initial phase of stress, may be considered a stress-limiting mechanism, facilitating the recovery from stress to the resting levels via attenuation of both GC release and SNS activity as well as by increased NO-dependent vasorelaxation. On the other hand, reduced levels of NO were observed in the later phases of stress and in subjects with genetic predisposition to hypertension, irrespectively, in which reduced NO bioavailability may account for disruption of NO-mediated BP regulatory mechanisms and accentuated SNS and GC effects. This review summarizes current knowledge on the role of stress in development of hypertension with a special focus on the interactions among NO and other biological systems affecting blood pressure and vascular function.

Acute Ozone-Induced Pulmonary and Systemic Metabolic Effects Are Diminished in Adrenalectomized Rats

Acute ozone exposure increases circulating stress hormones and induces metabolic alterations in animals. We hypothesized that the increase of adrenal-derived stress hormones is necessary for both ozone-induced metabolic effects and lung injury. Male Wistar-Kyoto rats underwent bilateral adrenal demedullation (DEMED), total bilateral adrenalectomy (ADREX), or sham surgery (SHAM). After a 4 day recovery, rats were exposed to air or ozone (1 ppm), 4 h/day for 1 or 2 days and responses assessed immediately postexposure. Circulating adrenaline levels dropped to nearly zero in DEMED and ADREX rats relative to SHAM. Corticosterone tended to be low in DEMED rats and dropped to nearly zero in ADREX rats. Adrenalectomy in air-exposed rats caused modest changes in metabolites and lung toxicity parameters. Ozone-induced hyperglycemia and glucose intolerance were markedly attenuated in DEMED rats with nearly complete reversal in ADREX rats. Ozone increased circulating epinephrine and corticosterone in SHAM but not in DEMED or ADREX rats. Free fatty acids (P = .15) and branched-chain amino acids increased after ozone exposure in SHAM but not in DEMED or ADREX rats. Lung minute volume was not affected by surgery or ozone but ozone-induced labored breathing was less pronounced in ADREX rats. Ozone-induced increases in lung protein leakage and neutrophilic inflammation were markedly reduced in DEMED and ADREX rats (ADREX > DEMED). Ozone-mediated decreases in circulating white blood cells in SHAM were not observed in DEMED and ADREX rats. We demonstrate that ozone-induced peripheral metabolic effects and lung injury/inflammation are mediated through adrenal-derived stress hormones likely via the activation of stress response pathway.

Reproductive Performance of Native Pulawska and High Productivity Polish Landrace Sows in the Context of Stress During the Period of Early Pregnancy

Experiments revealed that it is necessary to get rid of genotypes RYR1C/T and RYR1T/T because of problems with meat quality and reproduction of gilts and sows. This phenomenon, however, is of individual nature and is characterized by high variability. The aim of the study was to analyse the influence of stressogenic factors in native Puławska and high productivity Polish Landrace breed sows during the period of low pregnancy on reproductive performance and maternal behaviour. Sows in the 2nd reproduction cycle were assigned into groups of five animals as follows: control (C) of RYR1 C/C genotype and experimental (E) of RYR1 C/T genotype. In all, 30 Puławska breed sows and 30 PL breed sows were analysed. During the early stage of pregnancy (days 42-84), experimental groups were subjected to the action of stressogenic factors: elevated temperature, noisy and rough treatment of sows by service personnel and immobilization stress. The effect of stressogenic factors was referred to the reproductive performance of sows. Puławska and PL breed sows from the experimental groups were subjected to the evaluation of maternal traits on the basis of perinatal behaviour determined with the help of an ethogram. Analysis of the results of reproduction and the behaviour of the sows confirmed the higher resistance to stressogenic factors of the Puławska breed. The performed analysis of reproduction and behaviour confirmed that heterozygotic genotypes in the RYR1 locus exhibited less advantageous reproduction, which corroborates the hypothesis about a negative impact of the T allele on swine productivity.

Stress alone or associated with ethanol induces prostanoid release in rat aorta via alpha2-Adrenoceptor

Background

Stress and ethanol are both, independently, important cardiovascular risk factors.

Objective

To evaluate the cardiovascular risk of ethanol consumption and stress exposure, isolated and in association, in male adult rats.

Methods

Rats were separated into 4 groups: Control, ethanol (20% in drinking water for 6 weeks), stress (immobilization 1h day/5 days a week for 6 weeks) and stress/ethanol. Concentration-responses curves to noradrenaline - in the absence and presence of yohimbine, L-NAME or indomethacin - or to phenylephrine were determined in thoracic aortas with and without endothelium. EC50 and maximum response (n=8-12) were compared using two-way ANOVA/Bonferroni method.

Results

Either stress or stress in association with ethanol consumption increased the noradrenaline maximum responses in intact aortas. This hyper-reactivity was eliminated by endothelium removal or by the presence of either indomethacin or yohimbine, but was not altered by the presence of L-NAME. Meanwhile, ethanol consumption did not alter the reactivity to noradrenaline. The phenylephrine responses in aortas both with and without endothelium also remained unaffected regardless of protocol.

Conclusion

Chronic stress increased rat aortic responses to noradrenaline. This effect is dependent upon the vascular endothelium and involves the release of vasoconstrictor prostanoids via stimulation of endothelial alpha-2 adrenoceptors. Moreover, chronic ethanol consumption appeared to neither influence noradrenaline responses in rat thoracic aorta, nor did it modify the increase of such responses observed as a consequence of stress exposure.

Vascular adaptive responses to physical exercise and to stress are affected differently by nandrolone administration

Androgenic anabolic steroid, physical exercise and stress induce cardiovascular adaptations including increased endothelial function. The present study investigated the effects of these conditions alone and in combination on the vascular responses of male Wistar rats. Exercise was started at 8 weeks of life (60-min swimming sessions 5 days per week for 8 weeks, while carrying a 5% body-weight load). One group received nandrolone (5 mg/kg, twice per week for 8 weeks, im). Acute immobilization stress (2 h) was induced immediately before the experimental protocol. Curves for noradrenaline were obtained for thoracic aorta, with and without endothelium from sedentary and trained rats, submitted or not to stress, treated or not with nandrolone. None of the procedures altered the vascular reactivity to noradrenaline in denuded aorta. In intact aorta, stress and exercise produced vascular adaptive responses characterized by endothelium-dependent hyporeactivity to noradrenaline. These conditions in combination did not potentiate the vascular adaptive response. Exercise-induced vascular adaptive response was abolished by nandrolone. In contrast, the aortal reactivity to noradrenaline of sedentary rats and the vascular adaptive response to stress of sedentary and trained rats were not affected by nandrolone. Maximum response for 7-10 rats/group (g): sedentary 3.8 ± 0.2 vs trained 3.0 ± 0.2*; sedentary/stress 2.7 ± 0.2 vs trained/stress 3.1 ± 0.1*; sedentary/nandrolone 3.6 ± 0.1 vs trained/nandrolone 3.8 ± 0.1; sedentary/stress/nandrolone 3.2 ± 0.1 vs trained/stress/nandrolone 2.5 ± 0.1*; *P < 0.05 compared to its respective control. Stress and physical exercise determine similar vascular adaptive response involving distinct mechanisms as indicated by the observation that only the physical exercise-induced adaptive response was abolished by nandrolone.

Gender-based reciprocal expression of transforming growth factor-beta1 and the inducible nitric oxide synthase in a rat model of cyclophosphamide-induced cystitis

BACKGROUND

The pluripotent cytokine transforming growth factor-beta1 (TGF-beta1) is the central regulator of inducible Nitric Oxide Synthase (iNOS) that is responsible for nitric oxide (NO) production in inflammatory settings. Previous studies have implicated a role for NO, presumably derived from iNOS, in cyclophosphamide (CYP)-induced cystitis in the bladder. TGF-beta1 is produced in latent form and requires dissociation from the latency-associated peptide (LAP) to act as primary anti-inflammatory and pro-healing modulator following tissue injury in the upper urinary tract. Since the role of TGF-beta1 in lower urinary tract inflammation is currently unknown, and since gender-based differences exist in the setting of interstitial cystitis (IC), the present study examined the relationship between TGF-beta1 and iNOS/NO in the pathogenesis of CYP-induced cystitis in both male and female rats.

METHODS

Sprague-Dawley rats, 4 months of age, of either gender were given 150 mg/kg CYP intraperitoneally. Urinary and bladder tissue TGF-beta1 and NO reaction products (NO2-/NO3-) were quantified as a function of time following CYP. Expression of active and latent TGF-beta1 as well as iNOS in harvested bladder tissue was assessed by immunohistochemistry.

RESULTS

Female rats had significantly higher levels of NO2-/NO3- in urine even at baseline as compared to male rats (p < 0.001), whereas there was no gender based significant difference in urine levels of active or latent TGF-beta1 prior to CYP injection. Inflammatory and cytotoxic changes were induced by CYP in the bladder of both sexes that were accompanied by differences in the urine levels of NO2-/NO3- and TGF-beta1. Male rats responded to CYP with significantly lower levels of NO2-/NO3- and significantly higher levels of TGF-beta1 in urine (p < 0.05) as compared to females at all time points after CYP. The urine levels of NO2-/NO3- after CYP were inversely correlated to latent and active TGF-beta1 (Pearson coefficient of -0.72 and -0.69 in females and -0.89 and -0.76 in males, respectively; p < 0.01). Bladder tissue of male rats exhibited significantly higher levels of both latent and active TGF-beta1 (p < 0.01) compared to female rats after CYP. TGF-beta1 and iNOS protein was mostly localized in the urothelium.

CONCLUSION

The results of this study suggest that there exists an inverse relationship between the expression of TGF-beta1 and iNOS/NO2-/NO3- in CYP-inflamed bladder. The gender of the animal appears to magnify the differences in urine levels of TGF-beta1 and NO2-/NO3- in this inflammatory setting. These results support the hypothesis that TGF-beta1 can suppress iNOS expression associated with bladder inflammation and reduce systemic levels of NO2-/NO3-, and further suggest that this feature of TGF-beta1 can be harnessed for therapy and diagnosis of interstitial cystitis.

Effects of valsartan on stress-induced changes of serum vascular endothelial growth factor and nitric oxide in mice

This study investigated the effects of renin-angiotensin system (RAS) blockade on stress-induced changes of serum vascular endothelial growth factor (VEGF) and nitric oxide (NO) in mice. Chronic stress increased the serum NO levels significantly compared to control group (p = .0172). Valsartan, an angiotensin II receptor antagonist, alone, did not make significant difference versus control group. In chronic stress + valsartan group, serum NO levels decreased nonsignificantly compared to chronic stress group. There was a nonsignificant increase in serum VEGF levels after chronic stress. Valsartan alone or with chronic stress did not significantly affect the serum VEGF levels. In conclusion, there was no correlation between NO and VEGF changes during the stress response. In this respect, there may be other mechanisms to explain the stress-induced NO increase.

Altered diurnal variation of nitric oxide production in patients with panic disorder

The aim of this prospective study was to investigate the diurnal change in serum nitric oxide (NO) levels in active and remission phases of patients with panic disorder. This study included 15 patients fulfilling the criteria for panic disorder of Diagnostic and Statistical Manual of Mental Disorders--Fourth Edition and 15 healthy controls matched for age and sex. All patients were receiving a selective serotonin reuptake inhibitor at therapeutic doses. The serum nitrite and nitrate levels of subjects were determined at 10:00 a.m. after overnight fasting and at 3:00 p.m. 2 hours after lunch. NO levels of all patients measured in the morning were significantly higher than those of controls. The patients were also divided into active and remission groups according to clinical status and Panic Agoraphobia Scale's cut-off point. There were no statistically significant differences in serum nitrite and nitrate levels of the active group between the 10:00 a.m. and 3:00 p.m. measurements. In contrast, statistically significant differences were found in the serum levels of nitrite (p<0.05) and nitrate (p<0.05) in the remission group. Notably, the afternoon nitrite and nitrate levels of the remission group were higher than those of the morning levels as seen in control subjects. Thus, diurnal variation of NO production is altered in patients with panic disorder but is resumed in the remission phase. The present study suggests that serum NO levels are a good marker for evaluation of panic disorder.