Decreased sympatho-adrenal activity in diabetic patients with autonomic dysfunction following mental stress

Diurnal salivary cortisol and urinary catecholamines are associated with diabetes mellitus: the Multi-Ethnic Study of Atherosclerosis

The objective was to examine the cross-sectional association of diurnal salivary cortisol curve components and urinary catecholamines with diabetes status. Up to 18 salivary cortisol samples over 3 days and overnight urinary catecholamines were collected from 1002 participants in the Multi-Ethnic Study of Atherosclerosis. Diabetes was defined as a fasting blood glucose of at least 126 mg/dL or medication use. Cortisol curve measures included awakening cortisol, cortisol awakening response, early decline, late decline, and cortisol area under the curve (AUC). Urinary catecholamines included epinephrine, norepinephrine, and dopamine. Participants with diabetes had significantly lower cortisol awakening response (β = -0.19; 95% confidence interval [CI], -0.34 to -0.04) than those without diabetes in multivariable models. Whereas men with diabetes had a nonsignificant trend toward lower total AUC (β = -1.56; 95% CI, -3.93 to 0.80), women with diabetes had significantly higher total AUC (β = 2.62; 95% CI, 0.72 to 4.51) (P = .02 for interaction) compared with those without diabetes. Men but not women with diabetes had significantly lower urinary catecholamines compared with those without diabetes (P < .05). Diabetes is associated with neuroendocrine dysregulation, which may differ by sex. Further studies are needed to determine the role of the neuroendocrine system in the pathophysiology of diabetes.

Cardiovascular reactivity to mental stress is not affected by alpha2-adrenoreceptor activation or inhibition

RATIONALE

It has been postulated that cardiovascular reactivity to mental stress varies with tonic central sympathetic nervous system activity, but pharmacological evidence is missing.

OBJECTIVE

To test whether modulation of central sympathetic nervous system activity by alpha2-adrenergic agonism and antagonism affects cardiovascular reactivity to mental stress.

MATERIALS AND METHODS

On three five-stepped dose/concentration-response study days, 12 healthy male volunteers received intravenous infusions of dexmedetomidine (alpha2-agonist, target plasma concentrations: 0.04-0.32 ng/ml), yohimbine (alpha2-antagonist, doses: 0.016-0.125 mg/kg), and placebo, respectively. During each dose step, subjects performed a 5-Choice Reaction Time Task (CRTT) and a Paced Auditory Serial Addition Task (PASAT) to induce moderate mental stress. Prestress baseline, as well as stress-induced responses of heart rate, and noninvasive finger arterial blood pressure (Finapres) were assessed.

RESULTS

Prestress baseline heart rate and blood pressure decreased with increasing doses of dexmedetomidine and increased with increasing doses of yohimbine. However, dexmedetomidine and yohimbine did not affect stress-induced heart-rate and blood-pressure changes.

CONCLUSIONS

Cardiovascular reactivity to mental stress is not related to pharmacologically manipulated tonic central sympathetic nervous system activity by alpha2-adrenergic agonists and antagonists. These results do not support the assumption that cardiovascular reactivity is an index of tonic central sympathetic nervous system activity.

A new test for autonomic cardiovascular and neuroendocrine responses in diabetes mellitus: evidence for early vagal dysfunction

AIMS/HYPOTHESIS

Diabetic autonomic neuropathy affects many physiological systems, producing a variety of important clinical manifestations. It is associated with high morbidity and mortality, particularly during times of stress. This is thought to be due to an increased risk of cardiac arrhythmias, although the exact mechanisms involved have yet to be fully elucidated. The aim of the present study was to investigate the endocrine, cardiac autonomic and psychological responses of diabetic patients with and without autonomic neuropathy to a single breath of 35% CO(2).

METHODS

The 35% CO(2) challenge was performed in 20 male diabetic subjects, 11 of whom had autonomic neuropathy.

RESULTS

Baseline and stimulated cortisol, prolactin, systolic blood pressure and emotional arousal were similar in the two groups. However, subjects with autonomic neuropathy failed to demonstrate the expected CO(2)-induced bradycardia seen in the non-neuropathic patients (p<0.0001).

CONCLUSIONS/INTERPRETATION

The CO(2) challenge can be safely and easily administered to produce hypothalamic-pituitary-adrenal axis and cardiac autonomic activation, as well as emotional arousal. The test clearly distinguishes between subjects with and without cardiac autonomic neuropathy and could be an important adjunct to the methods currently available for the investigation and diagnosis of diabetic autonomic neuropathy.

Characteristic patterns of circadian variation in plasma catecholamine levels, blood pressure and heart rate variability in Type 2 diabetic patients

AIMS

To investigate whether Type 2 diabetic patients exhibit characteristic patterns of circadian variation in plasma levels of catecholamines, blood pressure (BP) and heart rate variability (HRV).

METHODS

Ten Type 2 diabetic and eight control in-patients were studied. Blood for catecholamine measurement was collected every 4 h, and non-invasive ambulatory BP and heart rate were monitored throughout the day. HRV was determined using frequency domain methods.

RESULTS

Diabetic patients showed a different pattern of circadian variation in BP and HRV from that of controls, the diurnal-nocturnal differences (D-N) being significantly smaller. The mean 24-h HRV levels were reduced in diabetic subjects. The mean 24-h plasma noradrenaline level of 1.36 +/- 0.12 nmol/l in diabetic patients was significantly lower than the 2.03 +/- 0.20 nmol/l in controls (P < 0.01). In contrast, no significant difference in adrenaline levels was observed. The mean 24-h plasma noradrenaline level demonstrated a significant positive correlation with D-N in systolic BP (r = 0.49, P = 0.0153).

CONCLUSIONS

The present study demonstrated distinctive patterns of circadian variation in plasma noradrenaline level, BP and HRV in Type 2 diabetic patients, associated with an abnormal circadian pattern of sympathovagal modulation.

Sympathetic nervous system and experimental diabetes: role of adrenal medullary hormones

The sympathetic nervous system is of major importance in the regulation of various physiological functions. The present review discusses the mechanisms which control glucose homeostasis and the role of the sympathetic nervous system in experimental diabetes with special emphasis on the role of adrenal medullary hormones, over-activity of the sympathetic nervous system and its relationship to hypertension in the diabetic state and the effect of stress. The chapter also reviews the ability of various drugs and pharmacological agents to produce hyperglycemia in experimental animals and how this information can be used in screening new chemical entities and in differentiating the mode of action of these agents.

Cardiac and plasma catecholamine responses to exercise in patients with type 2 diabetes: prognostic implications for cardiac-cerebrovascular events

BACKGROUND

Patients with diabetes mellitus have an altered exercise plasma catecholamine response, which may be related to the abnormal sympathoadrenal function and autonomic neuropathy. Presence of autonomic neuropathy is associated with poor prognosis, but relationship between exercise plasma catecholamine and prognosis has not been investigated. This study determined if altered plasma catecholamine response to exercise was associated with cardiac-cerebrovascular events.

METHODS

Forty patients with type 2 diabetes without apparent macrovascular complications and 30 control subjects performed treadmill exercise with serial measurements of plasma norepinephrine and epinephrine. Clinical, exercise, and catecholaminergic variables considered relevant to the cardiac-cerebrovascular events were examined by Cox regression model. Analysis of 24-hour heart rate variability was performed in a subgroup of patients.

RESULTS

During 7.2 years, 8 patients, but no control subjects, had events (3 myocardial and 5 cerebral infarctions). Compared with Event(-) patients, Event(+) patients had: (1) orthostatic hypotension; (2) lower peak exercise heart rate; (3) lower plasma norepinephrine immediately after exercise; and (4) lower plasma epinephrine at peak exercise. High frequency components in heart rate variability analysis were diminished in Event(+) patients. Multivariate analysis showed that peak heart rate (P = 0.04) and plasma epinephrine at peak exercise (P = 0.03) were independent predictors of subsequent events.

CONCLUSIONS

These data suggest that chronotropic incompetence and lower plasma epinephrine response to exercise are associated with high risk of cardiac-cerebrovascular events in patients with type 2 diabetes.

Cilnidipine, the N- and L-type calcium channel antagonist, reduced on 24-h urinary catecholamines and C-peptide in hypertensive non-insulin-dependent diabetes mellitus

To evaluate the effects of cilnidipine (CNP), L- and N-type calcium channel blocker and nilvadipine (NVP) on 24-h urinary epinephrine (U-EP), norepinephrine (U-NE), dopamine (U-DA) and C-peptide (U-CPR) in patients associated with hypertension and non-insulin-dependent diabetes mellitus (HT-NIDDM), a randomized crossover study was performed with 35 HT-NIDDM patients. The patients were given CNP (10 mg/day) and NVP (8 mg/day), separately, for 4 weeks each. After CNP treatment, U-NE, U-DA and U-CPR levels were significantly reduced compared with pre-treatment levels: 160.4 +/- 12.7 to 111.7 +/- 8.9 microg/day (mean +/- S.E., P < 0.005); 934.8 +/- 163.4 to 590.3 +/- 33.4 microg/day (P < 0.05); 86.7 +/- 9.9 to 57.6 +/- 7.4 microg/day (P < 0.05), respectively. Although no significant differences were observed in U-EP, U-NE, U-DA and U-CPR levels by NVP treatment, U-NE, U-DA and U-CPR levels after CNP treatment were significantly lower than those after NVP treatment: 111.7 +/- 8.9 versus 155.0 +/- 13.7 microg/day (P < 0.02); 590.3 + 33.4 versus 822.2 +/- 104.3 microg/day (P < 0.05); 57.6 +/- 7.4 versus 80.6 +/- 8.1 microg/day (P < 0.05), respectively. In conclusion, it was demonstrated that CNP treatment significantly reduced U-NE, U-DA and U-CPR excretion compared with NVP treatment in HT-NIDDM patients.