Lower vascular conductance responses to handgrip exercise are improved following acute antioxidant supplementation in young individuals with post-traumatic stress disorder

Young individuals with post-traumatic stress disorder (PTSD) display peripheral vascular and autonomic nervous system dysfunction, two factors potentially stemming from a redox imbalance. It is currently unclear if these aforementioned factors, observed at rest, alter peripheral haemodynamic responses to exercise in this population. This study examined haemodynamic responses to handgrip exercise in young individuals with PTSD following acute antioxidant (AO) supplementation. Thirteen young individuals with PTSD (age 23 ± 3 years), and 13 age- and sex-matched controls (CTRL) participated in the study. Exercise-induced changes to arm blood flow (BF), mean arterial pressure (MAP) and vascular conductance (VC) were evaluated across two workloads of rhythmic handgrip exercise (3 and 6 kg). The PTSD group participated in two visits, consuming either a placebo (PL) or AO prior to their visits. The PTSD group demonstrated significantly lower VC (P = 0.04) across all exercise workloads (vs. CTRL), which was significantly improved following AO supplementation. In the PTSD group, AO supplementation improved VC in participants possessing the lowest VC responses to handgrip exercise, with AO supplementation significantly improving VC responses (3 and 6 kg: P < 0.01) by blunting elevated exercise-induced MAP responses (3 kg: P = 0.01; 6 kg: P < 0.01). Lower VC responses during handgrip exercise were improved following AO supplementation in young individuals with PTSD. AO supplementation was associated with a blunting of exercise-induced MAP responses in individuals with PTSD displaying elevated MAP responses. This study revealed that young individuals with PTSD exhibit abnormal, peripherally mediated exercise responses that may be linked to a redox imbalance.

Cardiac autonomic function is preserved in young adults with major depressive disorder

The prevalence of major depressive disorder (MDD) is highest in young adults and contributes to an increased risk of developing future cardiovascular disease (CVD). However, the underlying mechanisms remain unclear. The studies examining cardiac autonomic function that have included young unmedicated adults with MDD report equivocal findings, and few have considered the potential influence of disease severity or duration. We hypothesized that heart rate variability (HRV) and cardiac baroreflex sensitivity (BRS) would be reduced in young unmedicated adults with MDD (18-30 yr old) compared with healthy nondepressed young adults (HA). We further hypothesized that greater symptom severity would be related to poorer cardiac autonomic function in young adults with MDD. Heart rate and beat-to-beat blood pressure were continuously recorded during 10 min of supine rest to assess HRV and cardiac BRS in 28 HA (17 female, 22 ± 3 yr old) and 37 adults with MDD experiencing current symptoms of mild-to-moderate severity (unmedicated; 28 female, 20 ± 3 yr old). Neither HRV [root mean square of successive differences between normal heartbeats (RMSSD): 63 ± 34 HA vs. 79 ± 36 ms MDD; P = 0.14] nor cardiac BRS (overall gain, 21 ± 10 HA vs. 23 ± 7 ms/mmHg MDD; P = 0.59) were different between groups. In young adults with MDD, there was no association between current depressive symptom severity and either HRV (RMSSD, R2 = 0.004, P = 0.73) or cardiac BRS (overall gain, R2 = 0.02, P = 0.85). Taken together, these data suggest that cardiac autonomic dysfunction may not contribute to elevated cardiovascular risk factor profiles in young unmedicated adults with MDD of mild-to-moderate severity.NEW & NOTEWORTHY This study investigated cardiac autonomic function in young unmedicated adults with major depressive disorder (MDD). The results demonstrated that both heart rate variability and cardiac baroreflex sensitivity were preserved in young unmedicated adults with MDD compared with healthy nondepressed young adults. Furthermore, in young adults with MDD, current depressive symptom severity was not associated with any indices of cardiac autonomic function.

Vascular Responses to Passive and Active Movement in Premenopausal Females: Comparisons across Sex and Menstrual Cycle Phase

PURPOSE

Adequate, robust vascular responses to passive and active movement represent two distinct components linked to normal, healthy cardiovascular function. Currently, limited research exists determining if these vascular responses are altered in premenopausal females (PMF) when compared across sex or menstrual cycle phase.

METHODS

Vascular responses to passive leg movement (PLM) and handgrip (HG) exercise were assessed in PMF ( n = 21) and age-matched men ( n = 21). A subset of PMF subjects ( n = 11) completed both assessments during the early and late follicular phase of their menstrual cycle. Microvascular function was assessed during PLM via changes in leg blood flow, and during HG exercise, via steady-state arm vascular conductance. Macrovascular (brachial artery [BA]) function was assessed during HG exercise via BA dilation responses as well as BA shear rate-dilation slopes.

RESULTS

Leg microvascular function, determined by PLM, was not different between sexes or across menstrual cycle phase. However, arm microvascular function, demonstrated by arm vascular conductance, was lower in PMF compared with men at rest and during HG exercise. Macrovascular function was not different between sexes or across menstrual cycle phase.

CONCLUSIONS

This study identified similar vascular function across sex and menstrual cycle phase seen in microvasculature of the leg and macrovascular (BA) of the arm. Although arm microvascular function was unaltered by menstrual cycle phase in PMF, it was revealed to be significantly lower when compared with age-matched men highlighting a sex difference in vascular/blood flow regulation during small muscle mass exercise.

High sodium intake differentially impacts brachial artery dilation when evaluated with reactive versus active hyperemia in salt resistant individuals

This study sought to determine if high sodium (HS) intake in salt resistant (SR) individuals attenuates upper limb arterial dilation in response to reactive (occlusion) and active (exercise) hyperemia, two stimuli with varying vasodilatory mechanisms, and the role of oxidative stress in this response. Ten young, SR participants (9 males, 1 female) consumed a 7-day HS (6,900 mg/day) and a 7-day recommended sodium intake (RI: 2,300 mg/day) diet in a randomized order. On the last day of each diet, brachial artery (BA) function was evaluated via reactive (RH-FMD: 5 min of cuff occlusion) and active [handgrip (HG) exercise] hyperemia after consumption of both placebo (PL) and antioxidants (AO). The HS diet significantly elevated sodium excretion (P < 0.05), but mean arterial blood pressure was unchanged. During the PL condition, the HS diet significantly reduced RH-FMD when compared with RI diet (P = 0.01), but this reduction was significantly restored (P = 0.01) when supplemented with AO (HS + PL: 5.9 ± 3.4; HS + AO: 8.2 ± 2.7; RI + PL: 8.9 ± 4.7; RI + AO: 7.0 ± 2.1%). BA shear-to-dilation slopes, evaluated across all HG exercise workloads, were not significantly different across sodium intervention or AO supplementation. In SR individuals, HS intake impaired BA function when assessed via RH-FMD, but was restored with acute AO consumption suggesting oxidative stress as a contributor to this dysfunction. However, exercise-induced BA dilation was unaltered, potentially implicating an inability of HS intake to influence the mechanisms responsible for effectively maintaining skeletal muscle perfusion during exercise.NEW & NOTEWORTHY This study examined if high sodium (HS) intake in salt resistant (SR) individuals attenuates brachial artery (BA) flow-mediated dilation in response to reactive (occlusion) and active (exercise) hyperemia. In SR individuals, HS intake impaired reactive hyperemia-induced BA dilation, but not exercise-induced BA dilation. This finding suggests that although brachial artery nitric oxide bioavailability may be reduced following HS intake, the redundant mechanisms associated with adequate upper limb blood flow regulation during exercise are maintained.

Daily Stress and Microvascular Dysfunction: The Buffering Effect of Physical Activity

Although often short-lived, emotional responsiveness to daily stressors ( i.e. , routine and sometimes unexpected everyday hassles) is associated with increased cardiovascular disease (CVD), morbidity, and mortality. Here, we present the novel hypothesis that a disruption of microvascular homeostasis is a key antecedent. In addition, we postulate that physical activity may mitigate the psychobiological consequences of daily stress, thereby limiting pathophysiological CVD-related sequelae.

Exaggerated pressor responses, but unaltered blood flow regulation and functional sympatholysis during lower limb exercise in young, non-Hispanic black males

PURPOSE

Young non-Hispanic black (BL) males have displayed lower blood flow (BF) and vascular conductance (VC), but intact functional sympatholysis, during upper limb exercise when compared to non-Hispanic white (WH) males. This study sought to explore if similar differences were also present in the lower limbs.

METHODS

Thirteen young BL males and thirteen WH males completed one visit comprised of rhythmic lower limb (plantar flexion) exercise as well as upper limb (handgrip) exercise for a limb-specific comparison. Limb BF, mean arterial pressure (MAP), and VC were evaluated at three submaximal workloads (8, 16, and 24 kg). To determine potential limb differences in functional sympatholysis, the impact of sympathetic nervous system activation (via cold-pressor test (CPT)) was evaluated at rest and during steady state exercise (30 % of maximal voluntary contraction) on a subsequent visit.

RESULTS

MAP responses to lower and upper limb exercise were elevated in young BL males (vs WH males), resulting in significantly lower VC responses in the upper limb, but not the lower limb. Further, BL males, when compared to WH males, revealed no differences in functional sympatholysis, evident by similar responses in both the exercising leg and arm VC during CPT.

CONCLUSION

The findings of the current study indicate that although elevated MAP responses were observed during both lower and upper limb exercise in young BL males, vascular conductance was only hindered in the upper limbs. This may potentially highlight enhanced compensatory mechanisms in the lower limb (vs upper limb) to maintain perfusion in young BL males.

Microvascular β-Adrenergic Receptor-Mediated Vasodilation Is Attenuated in Adults With Major Depressive Disorder

BACKGROUND

Major depressive disorder (MDD) is associated with sympathetic overactivity and alterations in peripheral adrenergic receptor function; however, no studies have directly assessed vasoconstrictor responsiveness in adults with MDD. We tested the hypotheses that β-adrenergic receptor-mediated vasodilation would be blunted in adults with MDD compared with healthy nondepressed adults (HA) and would functionally contribute to exaggerated norepinephrine-induced vasoconstriction.

METHODS

In 13 HA (8 female; 24±4 years) and in 12 adults with MDD (8 female; 22±3 yrs), red blood cell flux was measured during graded intradermal microdialysis perfusion of the β-adrenergic receptor agonist isoproterenol (10-10 to 10-4 mol/L) and, separately, during the perfusion of norepinephrine (10-12 to 10-2 mol/L), alone and in combination with the β-adrenergic receptor antagonist propranolol (2 mmol/L). Nonadrenergic vasoconstriction was assessed via perfusion of angiotensin II (10-12 to 10-4 mol/L).

RESULTS

Isoproterenol-induced vasodilation was blunted in adults with MDD (188.9±70.1 HA versus 128.3±39.4 au MDD, P=0.025). Net norepinephrine-induced vasoconstriction was exaggerated in adults with MDD (-0.16±0.54 HA versus -0.75±0.56 au MDD, P=0.014); however, there were no group differences in angiotensin II-induced vasoconstriction. Propranolol potentiated norepinephrine-induced vasoconstriction in HA (-0.16±0.54 norepinephrine versus -1.60±1.40 au propranolol, P<0.01) but had no effect in adults with MDD (-0.75±0.56 norepinephrine versus -1.58±1.56 au propranolol, P=0.08).

CONCLUSIONS

β-adrenergic receptor-mediated microvascular vasodilation was blunted in adults with MDD and contributed to exaggerated adrenergic vasoconstriction. The relative loss of the vasoprotective effect of β-adrenergic receptor-mediated vasodilation may contribute to increased peripheral resistance, thereby driving the development of hypertension in adults with MDD.

Augmented T-cell mitochondrial reactive oxygen species in adults with major depressive disorder

The prevalence of major depressive disorder (MDD) is highest in young adulthood, an effect that has been magnified by the COVID-19 pandemic. Importantly, individuals with MDD are at a greater risk of developing cardiovascular disease (CVD). Accumulating evidence supports immune system dysregulation as a major contributor to the elevated CVD risk in older adults with MDD; however, whether this is present in young adults with MDD without comorbid disease remains unclear. Interestingly, recent data suggest augmented T-cell mitochondrial reactive oxygen species (T-cell mitoROS) as a potent driver of immune dysregulation in animal models of psychiatric disease. With this background in mind, we tested the hypothesis that young adults with MDD would have augmented T-cell mitoROS and circulating proinflammatory cytokines compared with healthy young adults without MDD (HA). Whole blood was drawn from 14 young adults with MDD (age: 23 ± 2 yr) and 11 HA (age: 22 ± 1 yr). T-cell mitoROS (MitoSOX red; total: CD3+, T-helper: CD4+, T cytotoxic: CD8+) and serum cytokines were assessed by flow cytometry. Total T-cell mitoROS was significantly greater in adults with MDD compared with HA [median: 14,089 arbitrary units (AU); median: 1,362 AU, P = 0.01]. Likewise, both T-helper and T-cytotoxic cell mitoROS were significantly greater in adults with MDD compared with HA (both: P < 0.05). There were no differences in circulating cytokines between groups (all cytokines: P > 0.05). Collectively, these findings suggest that elevated T-cell mitoROS may represent an early marker of immune system dysregulation in young, otherwise healthy, adults with MDD.NEW & NOTEWORTHY To our knowledge, we provide the first evidence of augmented T-cell mitochondrial reactive oxygen species (T-cell mitoROS) in young, otherwise healthy adults with MDD. Although the elevated T-cell mitoROS did not correspond to a proinflammatory profile, these findings suggest that elevated T-cell mitoROS may be an early marker of immune system dysregulation in young adults with MDD.

Cerebrovascular reactivity is blunted in young adults with major depressive disorder: The influence of current depressive symptomology

BACKGROUND

In middle-aged adults with depression, cerebral vasodilatory reactivity is blunted; however, this has not been examined in treatment-naïve young adults with major depressive disorder (MDD). We tested the hypothesis that cerebrovascular reactivity would be blunted in young adults (18-30 yrs) with MDD compared to healthy non-depressed adults (HA) and would be attenuated to a greater extent in adults with symptomatic MDD (sMDD) compared to adults with MDD in remission (euthymic MDD; eMDD).

METHODS

Sixteen adults with MDD [21±3yrs; n = 8 sMDD (6 women); n = 8 eMDD (5 women)] and 14 HA (22±3yrs; 9 women) participated. End-tidal carbon dioxide concentration (P_ETCO₂; capnograph), beat-to-beat mean arterial pressure (MAP; finger photoplethysmography), middle cerebral artery blood velocity (MCAv; transcranial Doppler ultrasound), and internal carotid artery (ICA) diameter and blood velocity (Doppler ultrasound) were continuously measured during baseline and rebreathing-induced hypercapnia. Cerebrovascular reactivity was calculated as the relative increase in vascular conductance during hypercapnia.

RESULTS

In adults with MDD, cerebrovascular reactivity in the MCA (∆39±9 HA vs. ∆31±13% MDD, p = 0.04), but not the ICA (∆36±24 HA vs. ∆34±18% MDD, p = 0.84), was blunted compared to HA. In the MCA, cerebrovascular reactivity was reduced in adults with sMDD compared to adults with eMDD (∆36±11 eMDD vs. ∆25±13% sMDD, p = 0.02).

LIMITATIONS

The cross-sectional nature approach limits conclusions regarding the temporal nature of this link.

CONCLUSION

These data indicate that MCA cerebrovascular reactivity is blunted in young adults with MDD and further modulated by current depressive symptomology, suggesting that the management of depressive symptomology may secondarily improve cerebrovascular health.

COVID-19-Related Daily Stress Processes in College-Aged Adults: Examining the Role of Depressive Symptom Severity

Exposure to daily stressors specific to the COVID-19 pandemic (e.g., threat of infection) is associated with emotional distress, heightened stress reactivity, and increased depressive symptomology. Herein, we examined whether current depressive symptomology modulates the association between COVID-19-related daily stressor exposure and negative affective reactivity in young, otherwise healthy, college-aged adults. Fifty-eight adults (21 men; 22±3years) completed a daily web-based interview for eight consecutive days to assess COVID-19-related daily stress exposure and emotional responsiveness (September–November 2020). Depressive symptom severity was assessed using the Patient Health Questionnaire-9 (PHQ-9), and a score of ≥10 (range: 0–27) was used to define adults with a depressive episode (n=20). Participants reported at least one COVID-19-related stressor on 35.8% of interview days. Depressive symptomology did not predict the likelihood of exposure to a COVID-19-related stressor (p=0.46; OR=1.52; 95% CI: 0.492–4.718). However, negative affect (NA) was greater on days with an exposure to any COVID-19-specific daily stressor in adults with moderate-to-severe depressive symptoms (b=0.28, SE=0.093, p=0.003) but not in those without (b=0.009, SE=0.074, p=0.90), such that negative affective reactivity to COVID-19-related stressors was amplified in adults with a current depressive episode (p=0.019). Depressive symptomology did not moderate positive affective reactivity (p=0.686). Taken together, these data suggest that exposure to daily stressors related to COVID-19 further worsens NA in adults with a current depressive episode, potentially rendering them more susceptible to adverse mental health outcomes during the pandemic.

Impact of acute antioxidant supplementation on vascular function and autonomic nervous system modulation in young adults with PTSD

Posttraumatic stress disorder (PTSD) has been associated with an increase in risk of cardiovascular disease (CVD). The goal of this study was to determine if peripheral vascular dysfunction, a precursor to CVD, was present in young adults with PTSD, and if an acute antioxidant (AO) supplementation could modify this potential PTSD-induced vascular dysfunction. Thirteen individuals with PTSD were recruited for this investigation and were compared with 35 age- and sex-matched controls (CTRL). The PTSD group participated in two visits, consuming either a placebo (PTSD-PL) or antioxidants (PTSD-AO; vitamins C and E; α-lipoic acid) before their visits, whereas the CTRL subjects only participated in one visit. Upper and lower limb vascular functions were assessed via flow-mediated dilation and passive leg movement technique. Heart rate variability was utilized to assess autonomic nervous system modulation. The PTSD-PL condition, when compared with the CTRL group, reported lower arm and leg microvascular function as well as sympathetic nervous system (SNS) predominance. After acute AO supplementation, arm, but not leg, microvascular function was improved and SNS predominance was lowered to which the prior difference between PTSD group and CTRL was no longer significant. Young individuals with PTSD demonstrated lower arm and leg microvascular function as well as greater SNS predominance when compared with age- and sex-matched controls. Furthermore, this lower vascular/autonomic function was augmented by an acute AO supplementation to the level of the healthy controls, potentially implicating oxidative stress as a contributor to this blunted vascular/autonomic function.

Examining sex differences in sitting-induced microvascular dysfunction: Insight from acute vitamin C supplementation

PURPOSE

Lower limb microvascular dysfunction resulting from prolonged sitting (PS) bouts has been revealed to occur independent of sex. Although acute antioxidant supplementation has been reported to blunt conduit artery dysfunction following PS in young males, it is unknown if this protective effect extends to the microvasculature or is relevant in young females, who possess intrinsic vascular protective mechanisms specific to antioxidant defense. Therefore, this study employed an acute antioxidant supplementation to further examine sex differences during PS with a specific focus on microvascular function.

METHODS

On two separate visits, 14 females (23 ± 3 years) and 12 males (25 ± 4 years) had leg microvascular function (LMVF) assessed (via the passive leg movement technique) before and after 1.5 h of sitting. Prior to each visit, one gram of vitamin C (VC) or placebo (PL) was consumed.

RESULTS

PS significantly reduced LMVF [PL: (M: -34 ± 20; F: -23 ± 18%; p < 0.01) independent of sex (p = 0.7)], but the VC condition only blunted this reduction in males (VC: -3 ± 20%; p < 0.01), but not females (VC: -18 ± 25%; p = 0.5).

CONCLUSION

Young males and females reported similar reductions LMVF following PS, but only the young males reported a preservation of LMVF following the VC supplementation. This finding in young females was highlighted by substantial variability in LMVF measures in response to the VC condition that was unrelated to changes in the potential contributors to sitting-induced reductions in LMVF (e.g. lower limb venous pooling, reduced arterial shear rate).

NEW AND NOTEWORTHY

In this study, we employed an acute Vitamin C (VC) supplementation to examine sex differences in leg microvascular function (LMVF) following a bout of prolonged sitting. This study revealed that prolonged sitting reduced LMVF independent of sex, but only young males reported an attenuation to this lowered LMVF following VC supplementation. The young females revealed substantial variability in sitting-induced changes to LMVF that could not be explained by the potential contributors to sitting-induced reductions in LMVF (e.g. lower limb venous pooling, reduced arterial shear rate).

Image compression and restoration incorporating prior knowledge

It is shown how to incorporate prior knowledge into the restoration of an image from a finite number of its expansion coefficients in some basis. The significant image enhancement obtained for simple prior knowledge suggests an application to image-transform coding. A computer simulation is presented that demonstrates that compression ratios greater than 13:1 are possible.