Modulation of pineal activity during the 23rd sunspot cycle: melatonin rise during the ascending phase of the cycle is accompanied by an increase of the sympathetic tone

In two groups of female CD-rats nocturnal urine (19-23 h, 23-3 h, 3-7 h) was collected at monthly intervals over 658 days (I: 1997-1999) and 494 days (II: 1999-2000) coinciding with the ascending limb (1996-2000) of the 23rd sunspot cycle (1996-2008). The excretion of 6-sulfatoxymelatonin (aMT6s: I, II) was determined as well as the ratio of noradrenaline/adrenaline (NA/A: I) reflecting the activity of the sympathetic nervous system. AMT6s was higher in II than I (19-7 h: +24%; P < 0.001; 23-3 h: +30% and 3-7 h: +17%, P < 0.001), and progressively increased (19-23 h) showing linear regressions (1: R = +0.737, P = 0.003; II: R = +0.633, 0.008) which correlated (I) with the Planetary Index (Ap: R = +0.598, P = 0.020), an established estimate of geomagnetic disturbances due to solar activity. NA/A rose at all intervals (I: 46-143%) correlating with Ap (R = +0.554-0.768; P = 0.0399-0.0013). These results indicate that melatonin secretion rises as solar activity increases during the ascending limb of a sunspot cycle accompanied by growing geomagnetic disturbances (Ap) which elevate the sympathetic tone and thus affect the pineal gland, initially stimulating the activity of arylalkylamine N-acetyltransferase and subsequently fostering the expression of N-acetylserotonin O-methyltransferase (rate-limiting enzyme for melatonin biosynthesis) if Ap increases further. The potential (patho) physiological significance of these findings is discussed and the need for a systematic continuation of such studies is emphasized.

[Endovascular radiofrequency denervation of renal arteries as an innovation method of treatment of refractory arterial hypertension. First experience in Russia]

Excessive activation of the sympathetic nervous system forms the basis of pathogenesis of essential arterial hypertension (AH). The present work was aimed at evaluating efficacy and safety of endovascular radiofrequency denervation of renal arteries in patients with AH refractory AH based on the initial first experience in with using this methodology in the Russian Federation. The interventions were carried out on December 14-15th, 2011 in the first five patients presenting with AH refractory to antihypertensive therapy consisting of three and more drugs in therapeutic doses, one of which was a diuretic. The selection criteria were systolic arterial pressure (SAP) ≥160 mm Hg or ≥150 mm Hg in the presence of type 2 diabetes mellitus. The obligatory conditions for selection were the preserved renal function [glomerular filtration rate (GFR) ≥45 ml/min] and the absence of the secondary form of AH. The procedure of denervation was performed in the conditions of roentgen-operating room using special Medtronic Ardian Simplicity Catheter System™. In all cases we managed to perform bilateral denervation of renal arteries with the radiofrequency effect in not less than 4 zones of each of vessels. Efficacy of each of the effect was registered with due regard for reaching certain temperature and values of impedance. The interventions were not accompanied by the development of any complications either in the area of manipulations or the site of puncture. Neither were there any complications from the side of the cardiovascular or excretory systems of the body. Diurnal monitoring of AP (DMAP) registered a significant decrease in SAP averagely from 174±12 to 145±10 mm Hg three days after the intervention. A persistent antihypertensive effect was confirmed by the DMAP findings one month after denervation - the SAP level averagely amounted to 131±6 mm Hg. Endovascular radiofrequency denervation of renal arteries is a safe and efficient method of treatment of AH resistant to multicomponent antihypertensive therapy.

Sympathetic radiofrequency neurolysis for unilateral lumbar hyperhidrosis: a case report

Patients with hyperhidrosis suffer from physical, social and mental discomfort which often cannot be treated sufficiently using conservative measures. A new percutaneous approach to sympathectomy using radiofrequency denervation has seemed to offer longer duration of action and less incidence of post sympathetic neuralgia. This article reports the authors' experience with sympathetic RF neurolysis in a 35 year old male with right unilateral lumbar hyperhidrosis. Under scopy guided localization of the lumbar spine sympathetic blockade with local anesthetics to L2-5 vertebral levels were performed as a diagnostic block. Lesion effectiveness is monitored by bilateral feet skin temperature measurement. Clinical effects produced by the first sympathetic ganglion block were sustained for 1 week and then RF neurolysis of lumbar sympathetic ganglion was performed to the same levels for a longer effect. The procedure was accomplished within 30 minutes and the patient was discharged within 2 hours after the procedure. Hyperhidrosis was relieved after the procedure and there were no postsympathectomy neuralgia and sexual dysfunction. The patient obtained improvement of lumbar hyperhidrosis at his first month of follow- up and was satisfied with the outcome. In conclusion, RF neurolysis of lumbar sympathetic ganglions is a safe and effective palliative procedure with minimal invasiveness for relieving excessive sweat secretion in patients with localized hyperhidrosis.

Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans

Static and pulsed magnetic fields have been reported to have a variety of physiological effects. However, the effect of static magnetic fields on pain perception and sympathetic function is equivocal. To address this question, we measured pain perception during reproducible noxious stimuli during acute exposure to static magnets. Pain perception, muscle sympathetic nerve activity, mean arterial pressure, heart rate, and forearm blood velocity were measured during rest, isometric handgrip, postexercise muscle ischemia, and cold pressor test during magnet and placebo exposure in 15 subjects (25 ± 1 yr; 8 men and 7 women) following 1 h of exposure. During magnet exposure, subjects were placed on a mattress with 95 evenly spaced 0.06-T magnets imbedded in it. During placebo exposure, subjects were placed on an identical mattress without magnets. The order of the two exposure conditions was randomized. At rest, no significant differences were noted in muscle sympathetic nerve activity (8 ± 1 and 7 ± 1 bursts/min for magnet and placebo, respectively), mean arterial pressure (91 ± 3 and 93 ± 3 mmHg), heart rate (63 ± 2 and 62 ± 2 beats/min), and forearm blood velocity (3.0 ± 0.3 and 2.6 ± 0.3 cm/s). Magnets did not alter pain perception during the three stimuli. During all interventions, no significant differences between exposure conditions were found in muscle sympathetic nerve activity and hemodynamic measurements. These results indicate that acute exposure to static magnetic fields does not alter pain perception, sympathetic function, and hemodynamics at rest or during noxious stimuli.

Effects of 12 mT static magnetic field on sympathetic agonist-induced hypertension in wistar rats

We investigated the combined effects of a moderate-intensity static magnetic field (SMF) and two different sympathetic agonists, an alpha(1)-adrenoceptor agonist, phenylephrine and a beta(1)-adrenoceptor agonist, dobutamine, which induced hypertension and different hemodynamics in Wistar rats. Five-week-old male rats were continuously exposed to the SMF intensity of 12 mT (B(max)) with the peak spatial gradient of 3 mT/mm for 10 weeks. A loop-shaped flexible rubber magnet was adjusted to fit snugly around the neck region of a rat (diameter-adjustable to an animal size). Sham exposure was performed using a dummy magnet. Six experimental groups of six animals each were examined: (1) sham exposure with intraperitoneal (ip) saline injection (control); (2) SMF exposure with ip saline injection (SMF); (3) sham exposure with ip phenylephrine (1.0 microg/g) injection (PE); (4) SMF exposure with ip phenylephrine injection (SMF + PE); (5) sham exposure with ip dobutamine (4.0 microg/g) injection (DOB); (6) SMF exposure with ip dobutamine injection (SMF + DOB). Fifteen minutes after the injection of each agent, the first set of parameters, arterial blood pressure (BP) and heart rate (HR), the second set of parameters, skin blood flow (SBF) and skin blood velocity (SBV), or the third set of parameters, the number of rearing (exploratory behavior) responses and body weight was monitored. Each agent was administered three times a week for 10 weeks, and each set of parameters was monitored on different days, once a week. The dose of phenylephrine significantly increased BP and decreased HR, SBF, SBV, and the number of rearing responses in the PE group compared with those in the respective age-matched control group. The dose of dobutamine significantly increased BP and HR, increased SBF, SBV, and the number of rearing responses in the DOB group compared with those in the control group. Continuous neck exposure to the SMF alone for up to 10 weeks induced no significant changes in any of the measured cardiovascular and behavioral parameters. The SMF exposure for at least 2 weeks (1) significantly depressed phenylephrine effects on BP, SBF, SBV, and rearing activity (SMF + PE group vs. PE group); (2) significantly depressed dobutamine effects on BP, SBF, and SBV, and suppressed dobutamine-induced increase in the rearing activity (SMF + DOB group vs. DOB group). These results suggest that continuous neck exposure to 12 mT SMF for at least 2 weeks may depress or suppress sympathetic agonists-induced hypertension, hemodynamics, and behavioral changes by modulating sympathetic nerve activity.

Neurostimulation for refractory angina pectoris

Spinal cord stimulation (SCS) has been shown to be particularly useful, safe and effective treatment in the management of patients with refractory angina pectoris and those unsuitable for percutaneous or surgical revascularisation. Clinical and experimental research has shown that it decreases myocardial ischemia without masking the clinical symptoms of its imminent development. In addition to providing pain relief, neurostimulation has also been shown to improve microcirculatory blood flow and increase the myocardial threshold for ischaemia. The anti-ischaemic effects of SCS have been evaluated by: (a) exercise testing, (b) ambulatory electrocardiogram (ECG), and (c) invasive measurements of lactate from coronary sinus blood samples. Patients have reported not only significantly fewer angina attacks but also decreased consumption of glyceryl trinitrate and improved quality of life. A number of mechanisms have been proposed including placebo effects, primary anti-nociceptive effects, involvement of endogenous opiates, anti sympathetic nervous system effects, increases in coronary blood flow, and redistribution of myocardial blood flow.

Evaluation of sympathetic skin response in Parkinson's disease

There is no clear definition on the role of sympathetic skin response (SSR) in the evaluation of patients with Parkinson's disease (PD). We recorded the SSR of the palms of 64 controls and 46 patients with PD to electrical stimulation of the median nerve at the wrist. We analyzed onset latency and peak-to-peak amplitude. A study of parasympathetic function (R-R interval analysis) was also undertaken. We found that patients with PD had more absent SSRs than controls. The mean amplitude of the SSR was significantly reduced in both lower and upper limbs of PD patients in comparison with control subjects (p<0.001). The onset latency was longer in the lower limbs of these patients in respect to the control group (p<0.003). There was a significant inverse correlation between SSR amplitudes and age, severity and late onset of the disease. There was no association of these parameters with dysautonomic symptoms or R-R interval variation. In conclusion, there is a significant association between altered SSR and PD and an inverse correlation in this group of patients between SSR values and older age, greater severity and later onset of disease. Therefore, the study of SSR may provide valuable information on cholinergic sympathetic function in patients with PD.

Responses of neurons containing VGLUT3/nNOS-cGMP in the rVLM to cardiac stimulation

Responses of glutamatergic neurons in the rostral ventrolateral medulla to stimulation of cardiac sympathetic afferents have not been defined. Nitric oxide influences neural function of glutamate. We evaluated the relationship between vesicular glutamate transporter 3, c-Fos and neuronal nitric oxide synthase/soluble guanylyl cyclase in the rostral ventrolateral medulla following cardiac stimulation. In anesthetized cats with barodenervation and vagotomy, epicardial application of bradykinin, but not its vehicle, caused pressor responses. More vesicular glutamate transporter 3-containing neurons colocalized with c-Fos or c-Fos and neuronal nitric oxide synthase in the rostral ventrolateral medulla in bradykinin-treated cats (n = 6; P < 0.05) than in control animals (n = 4). Colocalization of neuronal nitric oxide synthase, soluble guanylyl cyclase and c-Fos or vesicular glutamate transporter 3 was noted following bradykinin stimulation. Findings indicate activation of rostral ventrolateral medulla glutamatergic neurons by cardiac stimulation, which may be influenced by nitric oxide via cGMP.

Electrical activation of the human vestibulo-sympathetic reflex

Muscle sympathetic nerve activity (MSNA) is modulated on a beat-to-beat basis by the baroreflex. Vestibular input from the otolith organs also modulates MSNA, but characteristics of the vestibulo-sympathetic reflex (VSR) are largely unknown. The purpose of this study was to elicit the VSR with electrical stimulation to estimate its latency in generating MSNA. The vestibular nerves of seven subjects were stimulated across the mastoids with short trains of high frequency, constant current pulses. Pulse trains were delivered every fourth heartbeat at delays of 300-700 ms after the R wave of the electrocardiogram. Vestibular nerve stimulation given 500 ms after the R wave significantly increased baroreflex-driven MSNA, as well as the diastolic blood pressure threshold at which bursts of MSNA occurred. These changes were specific to beats in which vestibular stimulation was applied. Electrical stimulation across the shoulders provided a control condition. When trans-shoulder trials were subtracted from trials with vestibular nerve stimulation, eliminating the background baroreflex-driven sympathetic activity, there was a sharp increase in MSNA beginning 660 ms after the vestibular nerve stimulus and lasting for about 60 ms. The increase in the MSNA produced by vestibular nerve stimulation, and the associated increase in the diastolic blood pressure threshold at which the baroreflex-driven bursts occurred, provide evidence for the presence of a short-latency VSR in humans that is likely to be important for the maintenance of blood pressure during rapid changes in head and body position with respect to gravity.

Light activates the adrenal gland: timing of gene expression and glucocorticoid release

Light is a powerful synchronizer of the circadian rhythms, and bright light therapy is known to improve metabolic and hormonal status of circadian rhythm sleep disorders, although its mechanism is poorly understood. In the present study, we revealed that light induces gene expression in the adrenal gland via the suprachiasmatic nucleus (SCN)-sympathetic nervous system. Moreover, this gene expression accompanies the surge of plasma and brain corticosterone levels without accompanying activation of the hypothalamo-adenohypophysial axis. The abolishment after SCN lesioning, and the day-night difference of light-induced adrenal gene expression and corticosterone release, clearly indicate that this phenomenon is closely linked to the circadian clock. The magnitude of corticostereone response is dose dependently correlated with the light intensity. The light-induced clock-dependent secretion of glucocorticoids adjusts cellular metabolisms to the new light-on environment.

Enlightening the adrenal gland

The secretion of glucocorticoid hormones is tightly regulated by the circadian clock and by negative humoral feedback loops, both acting on the hypothalamic-pituitary gland-adrenal axis. However, a new study Ishida et al., 2005 [this issue of Cell Metabolism) shows that light can influence the adrenal's glucocorticoid output by a more direct pathway.

Light and diurnal cycle affect autonomic cardiac balance in human; possible role for the biological clock

The morning shift in cardiac sympatho-vagal balance seems involved in the increased risk of cardiovascular incidents at that time. To investigate the contribution of the biological clock in autonomic cardiac control, we investigated the presence of a diurnal rhythm independent of external factors, and of a circadian phase-dependent effect of moderate light in healthy volunteers. Recordings of heart rate (HR) and vagal and sympathetic cardiac tone were performed at different times over the day-night cycle during supine, awake, resting conditions, during exposure to different light intensities. The similarity between the diurnal rhythm in resting HR and that during previous constant routine conditions, demonstrated that our setup allowed accurate estimation of the endogenous circadian rhythm in HR. The present study suggests that, while a circadian rhythm in vagal cardiac tone is the main cause for the circadian rhythm in resting heart rate, the increase in sympathetic cardiac tone participates in the HR increase caused by early morning light.

α-Adrenoceptor subtypes mediating regional kidney blood flow responses to renal nerve stimulation

The mechanisms underlying the relative insensitivity of the renal medullary circulation to renal sympathetic nerve stimulation (RNS) remain unknown. Therefore, we tested the effects of systemic alpha(1)- and alpha(2)-adrenoceptor blockade on responses to electrical RNS in pentobarbitone anaesthetized rabbits. Renal blood flow (RBF), cortical laser Doppler flux (CLDF), and to a lesser extent medullary LDF (MLDF) were reduced by RNS in a frequency-dependent manner. Prazosin decreased responses of RBF and CLDF, but not MLDF, to RNS. For example, during the control period 4 Hz stimulation reduced RBF, CLDF and MLDF by 85+/-3%, 89+/-2%, and 20+/-12%, respectively, but after prazosin, corresponding responses were 39+/-3%, 42+/-5% and 28+/-7%, respectively. Prazosin markedly blunted pressor and renal vasoconstrictor responses to intravenous phenylephrine, without altering pressor responses to intravenous xylazine. Rauwolscine enhanced renal vasoconstrictor responses to RNS, although this was statistically significant for RBF and CLDF but not MLDF. For example, during the control period 2 Hz stimulation reduced RBF, CLDF and MLDF by 63+/-7%, 58+/-7%, and 29+/-17%, respectively, and after rauwolscine, corresponding responses were 83+/-4%, 87+/-1%, and 53+/-12%, respectively. Rauwolscine markedly blunted renal vasoconstrictor responses to renal arterial guanabenz, but not phenylephrine. These data suggest that alpha(1)-adrenoceptors contribute to RNS-induced vasoconstriction in the renal cortex, but contribute less in vascular elements controlling medullary perfusion. Activation of alpha(2)-adrenoceptors appears to blunt RNS-induced renal vasoconstriction, but this mechanism does not underlie the relative insensitivity of medullary perfusion to RNS.

Changes in cardiac adrenergic nervous system after transmyocardial laser revascularisation assessed by I-123-MIBG SPECT. A preliminary report

BACKGROUND

Metaiodobenzylguanidine (MIBG), a noradrenaline analogue which may be labelled with I-123, has been used in the assessment of pre-synaptic activity of the cardiac adrenergic nervous system (Syst(adren)) in several diseases. The effects of transmyocardial laser revascularisation (TMLR) on Syst(adren) have not yet been established.

AIM

To examine whether TMLR-induced changes in Syst(adren) may be one of the mechanisms responsible for clinical improvement in patients undergoing this method of revascularisation.

METHODS

The study group consisted of 19 patients (mean age 63+/-9 years) who underwent TMLR, by using high-power CO(2) laser; as a single method of cardiac revascularisation. Syst(adren) was assessed before TMLR (STUDY-0), soon after the procedure (mean 13+/-5 days, STUDY-I), and in 12 patients six months after TMLR (STUDY-II). In total, 50 studies using I-123-MIBG SPECT were performed. The regional distribution of tracer was assessed qualitatively, using a 17-segment model of the left ventricle.

RESULTS

In 16% of examinations the assessment of the I-123-MIBG uptake was not possible due to the poor quality of images. Thus, 41 SPECT studies (16 - STUDY-0, 16 - STUDY-I, and 9 - STUDY-II) were analysed and compared. In STUDY-0, an impaired uptake of I-123-MIBG was found in 193 of 272 analysed segments. In STUDY-I, the I-123-MIBG uptake increased in 5% of defects (CI(0,95)=3-9%) and deteriorated in 55% (CI(0,95)=48-62%). When STUDY-II was compared with baseline, the uptake was increased in 25% of defects (CI(0,95)=17-34%) and decreased in further 25% of defects. When STUDY-II was compared with STUDY-I, the uptake increased in 67% (CI(0,95)=58-75%) of defects and did not deteriorate in any. The global MIBG uptake in STUDY-I decreased in 15 patients (94%, CI(0,95)=70-100%) when compared with baseline, and increased in all 9 patients with long-term follow-up data available, when STUDY-II to STUDY-I was compared.

CONCLUSIONS

TMLR significantly deteriorates Syst(adren) activity which, however, improves 6 months after the procedure to the values similar to those assessed pre-operatively. TMLR-induced impairment of Syst(adren) may contribute to the clinical improvement observed shortly (<6 months) after the procedure.

Radiofrequency lesioning of the sympathetic chain at different levels

The interruption of sympathetic pathways is a commonly used modality for the treatment of many painful conditions and some other problems like vascular disorders. Radiofrequency (RF) techniques have gained popularity in this field in the recent years. The major advantages of RF techniques over other neurodestructive methods are; the formation of controlled lesion, low complication rates and low perioperative discomfort. In this paper, RF applications of the different sympathetic regions are described, together with the indications, risks and comments of the author.

Influence of stimulus intensity on waveform of sympathetic skin response evoked by magnetic stimulation

OBJECTIVE

The aim of this study was to investigate the influence of stimulus intensity on the waveform of sympathetic skin response (SSR). The origin of the SSR waveform was discussed.

METHODS

A total of 12 SSRs from palm skin were analyzed in 40 normal subjects. SSR was evoked by magnetic stimulation to the neck at 3 different intensities (10, 35, and 70% of the maximum output). The 3 stimuli were repeatedly applied in 4 separate sets. Waveforms were classified as either the P type, in which the positive component was larger than the negative one, or the N type, in which the negative component was larger than the positive one. Amplitude values of peak-to-peak, the first negative (N1), and subsequent positive (P1) components were compared among the 12 responses.

RESULTS

When the stimulation was increased, the SSR size became larger. The P type SSR was most frequently found in the maximum stimulation. Strong stimulation generally produced a large P1. Only the N type SSR exhibited a large N1 response to the maximum stimulation. There was a significant, negative correlation between N1 peak duration (difference between the SSR onset and N1 peak latencies) and P1 amplitude.

CONCLUSIONS

These results suggested that strong responses probably produced a P type SSR with a large P1 component. In this condition, a rapid change of potential from negative to positive prevented any correlation between N1 amplitude and the magnitude of the response. In the N type SSR, however, a large N1 was associated with a strong response. These findings can be explained by a newly presented theory on the neurophysiological origin of the negative and positive components, based on a model of equivalent current dipole dependent on the Na+ concentration gradient.

SIGNIFICANCE

The present study provided some suggestions on the neurophysiological mechanism of SSR waveform.

Effect of photic stimuli on rat salivary glands. Role of sympathetic nervous system

Saliva secretion during feeding facilitates chewing, swallowing and other oral functions. Between meals, a "resting saliva" is elicited to allow speaking and contribute to maintain soft and hard tissues health. Chewing is the main stimulus for "stimulated saliva" secretion. Mouth dryness and other less well known stimuli control "resting saliva". In humans the stimulus of the light increases the parotid saliva flow rate. Saliva secretion occurs in response to a reflex. Both motor branches of the autonomous nervous system drive efferent outputs to the salivary glands. Cellular bodies of sympathetic motor fibers innervating salivary glands are located in the superior cervical ganglia. A multisynaptic pathway couples the superior cervical ganglia to hypothalamic areas related to the control of autonomous and endocrine functions. Projections from suprachiasmatic nuclei involved in circadian rhythms control reach those areas. Salivary glands postsynaptic beta-adrenoceptors control synthesis and secretion of proteins. Postsynaptic alpha 2-adrenoceptors modulate salivary responses mediated by alpha 1 and beta-adrenoceptors. Parotid alpha-amylase circadian rhythm in suckling rats, suggest that the sympathetic nervous system mediates an effect of light on saliva secretion. Analysis of: 1) parotid fine structure, 2) submandibular secretory response to adrenergic agonists, and 3) submandibular 3H-clonidine binding to alpha 2-adrenoceptors, demonstrated that an increase of sympathetic reflex activity occurs in salivary glands of rats chronically exposed to constant light. Similar effects were observed in rats chronically exposed to immobilization stress. Catecholamine biosynthetic enzyme mRNA levels in adrenal glands and superior cervical ganglia suggest that changes induced by light on salivary sympathetic reflex activity are mediated by plasma catecholamines released by adrenal glands. Post and presynaptic alpha 2 adrenoceptors could play an important role in saliva secretion control when light or stress stimuli modify the sympathoadrenal system.

Potential of iodine-123 metaiodobenzylguanidine single-photon emission tomography to detect abnormal functional status of the pulmonary neuroadrenergic system in irradiated lung

The potential of iodine-123 metaiodobenzylguanidine (MIBG) to detect functional abnormalities of the pulmonary neuroadrenergic system (PNS) in irradiated lung areas (ILAS) was preliminarily explored using single-photon emission tomography (SPET). The subjects included five healthy subjects and a total of 31 patients with peripheral-type lung cancer treated by radiation; 15 patients (group A) had received a dose of less than 36 Gy (mean +/- SD: 28.2 +/-6.2 Gy), and 16 patients (group B) had received a higher dose (mean +/- SD: 51.2 +/- 3.5 Gy) at the time of examination. MIBG SPET scans acquired 15 min and 3 h after injection were used to measure the MIBG uptake ratio (count ratio of the ILA to the contralateral non-ILA) and the clearance rate [percentage of (early counts - delayed counts)/early counts] from the ILAs without noticeable abnormal opacities on chest computed tomography scan. Lung perfusion changes were also assessed by technetium-99m macroaggregated albumin SPET. By contrast to the homogeneous MIBG uptake in the lungs of the healthy subjects, MIBG uptake was folcally decreased in correspondence with the ILAs in all patients, including 11 patients (73.3%) of group A with relatively preserved lung perfusion. The reduction MIBG uptake was significant (P<0.0001), and the MIBG clearance rate from the ILAs was also significantly faster than the clearance rates from the normal lungs and contralateral non-ILAs (both P<0.01). Group B patients showed significantly lower MIBG uptake and faster clearance from the ILAs than group A patients (P<0. 001 and P<0.05, respectively), although there was no significant difference in the clearance from the non-ILAs. Overall, MIBG uptake/clearance from the ILAs correlated significantly with the radiation dose in the 31 patients (r = -0.656; P<0.0001 and r = 0. 387; P<0.05, respectively). Perfusion changes were inversely correlated with the clearance from the ILAs (r = -0.432, P<0.05), but did not correlate with MIBG uptake. These preliminary results suggest that MIBG may have the potential to be a marker of abnormal functional status of the PNS produced by irradiation and may facilitate investigation of irradiation lung injury independently of morphological or lung perfusion changes.

Effect of bright light exposure on muscle sympathetic nerve activity in human

To evaluate the effect of bright light on the sympathetic nervous system in human, muscle sympathetic nerve activity (MSNA) was recorded from the peroneal nerve in five healthy subjects. Each subject was exposed to bright light of 5000 lx for 20 min. After the bright light exposure, MSNA became significantly enhanced. The heart rate increased transiently only during the bright light exposure. The blood pressure did not change significantly during and after the bright light exposure. The result is the first direct evidence showing that bright light modulates the activity of the sympathetic nervous system in normal human.

Heart rate variability in workers exposed to medium-frequency electromagnetic fields

This study was undertaken to evaluate the neurovegetative regulation of the heart in workers occupationally exposed to medium frequency (MF) electromagnetic (EM) fields. The subjects were 71 workers of MF broadcast stations, aged 20-68 (mean 47.1) with the duration of work under exposure ranging from 2-40 years and 22 workers of radio link stations, aged 21-65 (mean 46.9) who were not exposed to MF EM fields. The distribution of age and work tenure in both groups did not differ significantly. Heart rate variability (HRV) was analysed basing on 512 normal heart evolutions registered in resting, from the body surface, using the Medea-HRV system. The analysis concerned time-domain and frequency-domain parameters of HRV using fast fourier transformation. Power spectrum in the low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency bands (LF and HF, respectively) was determined. Statistically insignificant differences found between exposed and non-exposed groups were found either in time- or in frequency-domain parameters of HRV. No correlation between the power spectrum and the subjects age was noted. Such a relationship, however, could be observed in the control group. In the study group a statistically significant negative correlation was found between the maximum intensity of EM fields and HF power spectrum. Thus it was concluded that occupational exposure to EM fields brings about impairments in the neurovegetative regulation of the cardiovascular function.

Pretreatment with [131I] metaiodobenzylguanidine and surgical resection of advanced neuroblastoma

Pretreatment with [131I] metaiodobenzylguanidine (MIBG) followed by surgical resection in advanced neuroblastoma (stage 3 and 4) has been studied in relation to resectability, morbidity and mortality, survival rate after two years, control of distant metastasis and serum levels of LDH as prognostic factors. Twenty-one patients with advanced neuroblastoma were primarily treated with MIBG radiotherapy, followed by surgical resection. Sixteen patients had stage 4 disease. Between 2 and 6 courses of MIBG treatment were given per patient. In 17 patients gross complete resection was achieved. Two patients developed complications directly related to the operation, one died as a result of this. The overall mortality was 38%. MIBG therapy resulted in partial response in 13 patients and in stable disease in 8 patients. Two years survival in the group with partial response was 86% and in the group with stable disease 28%. Because of the resulting excellent general condition of the patients the interval between pretreatment with MIBG and surgery could be very short. Follow-up till December 1994 showed that 13 children were alive for 3 to 47 months. Seven had no evidence of disease. Preoperative MIBG de novo treatment in advanced neuroblastoma is equal to induction chemotherapy, but less toxic.

Changes in cardiac performance and sympathetic stimulation during and after fractionated radiotherapy in a rat model

The consequences of fractionated irradiation on the number of cardiac alpha- and beta-adrenergic receptors, myocardial norepinephrine concentration and in vitro assessed heart function were studied in Sprague-Dawley rats. Animals were locally irradiated on the thorax with a total dose of 50 Gy, in 5 weeks, using two different fractionation schemes (5 x 2.0 Gy/week and 3 x 3.3 Gy/week). Functional and biochemical assays were performed during treatment and at 6 months after initiation of treatment. During fractionated irradiation, the numbers of alpha- and beta-adrenergic receptors tended to rise. During this period, myocardial norepinephrine concentration remained fairly constant and no decrease in cardiac output was observed. At 6 months, a significant increase of the numbers of alpha- and beta-adrenergic receptors was observed in the 3.3 Gy/fraction group compared to age-matched controls, p = 0.012 and p = 0.02, respectively. At this time point, the myocardial norepinephrine concentration had decreased below control levels (p = 0.008 for the 3.3. Gy/fraction schedule, and p = 0.03 for the 2.0 Gy/fraction schedule). At 6 months, the cardiac output declined to 61% (p = 0.009) and 69% (p = 0.04) of control values for the 3.3 and 2.0 Gy/fraction schedules, respectively. The present data clearly show development of late cardiac sequelae caused by fractionated thorax irradiation with a total dose of 50 Gy. Moreover, this study lends support to the importance of fraction size with regard to the severity of the radiation-induced cardiac damage.

Effects of MR exposure on axonal outgrowth in the sympathetic nervous system of the chick

The effects of MR exposure on the rate and specificity of sympathetic preganglionic axonal outgrowth were examined in the chick embryo. Embryos were exposed to a static magnetic field of 1.5 T for 6 hours, 64 MHz RF field pulses, and a switched magnetic field gradient of amplitude 0.6 G/cm for 4 hours. No significant difference in axonal outgrowth was observed between MR-exposed and control embryos. In addition, the distributions of several major extracellular matrix (ECM) molecules, laminin, fibronectin, and collagen IV, were examined. Immunostaining patterns of these ECM molecules during axonal outgrowth showed no difference between MR-exposed and control embryos. Our results suggest that the MR exposure conditions used in this study do not affect axonal outgrowth in the sympathetic nervous system of the chick.

Age-related changes in the noradrenergic pattern and receptor responses of the rat cardiovascular system after repeated microwave exposure

In the present research the effect of repeated microwave exposure on the noradrenergic pattern by histofluorescence method and on receptor-mediated responses using alpha and beta agonists in myocardium and aorta of young-adult and aged rats was studied. Young-adult irradiated rats showed an increase in noradrenergic innervation more marked in myocardial tissue, while an increase in maximal response to the agonist was found only at aortic level. Aged stressed rats exhibited an increase in fluorescent fibres at atrial and aortic level, but in the atrial section this increase was found to be less evident than in young-adult animals. Functional data in aged rats revealed a more marked decrease in maximal response ratio (M.R.R.) of myocardial tissue than in young-adult rats, together with a noticeable decrease in maximal response at aortic level. These results indicate no direct correlation between morphological and functional data. Participation of both central and peripheral mechanisms is suggested.

Light-induced arousal affects simultaneously EEG and heart rate variability in the rat

In awaken rats, ECG and EEG were simultaneously analysed in order to quantify the cortical EEG and beat-to-beat heart rate variability (HRV) in response to light onset. The HRV bands LF (40-200 mHz), MF (200-600 mHz) and HF (600-2500 mHz) and the EEG bands delta (1-4 Hz), theta (4-8 Hz), alpha (8-13 Hz) and beta (13-32 Hz) were assessed. Light onset induced a significant arousal reaction in the EEG, manifested by a global decrease in total spectral power and a shift towards theta and beta bands, while total HRV spectral power increased, with a shift to the sympathetic-related MF band. This simultaneous changes in HRV and EEG induced by light onset could be triggered by the same common factor that controls both oscillatory responses.

[The effect of ionizing radiation on the nervous mechanisms regulating cardiac activity]

Functional state of cardiac nervous links and pattern of cardiogenic reflectory responses to radiation (4 Gy) were studied in acute experiments on anesthetized rats at various periods after single radiation. The control level of nervous activity significantly varies in different terms after radiation. Intensification of parasympathetic effects and domination of depressor reactions are typical of the initial period (the 1st day). A decrease in the sympathetic tone and weakening of adrenergic influences are observed in all terms after radiation (from the 1st till the 14th day). Interrelationships between sympathetic and parasympathetic links of heart regulation as well as cardiogenic reflectory responses are not restored to the control level in remote terms after radiation (the 14th-20th days). So, single radiation of animals in a dose of 4 Gy has induced a disorder in the nervous heart regulation, which may be a cause of different pathological states.

Noradrenergic innervation and receptor responses of cardiovascular tissues from young and aged rats after acute microwave exposure

Young and senescent rats were exposed to 2,450 GHz microwaves for 45' and the effects of this treatment on the noradrenergic pattern and beta-cardiac and alpha-aortic receptorial functions were evaluated. In young animals, an increase in noradrenergic innervation was observed, while no functional modification was shown. In aged rats the increase in fluorescent fibers was almost the same as that observed in young rats, but significant variations in functional responses were found. Both at atrial and ventricular levels responses to the beta-agonist isoprenaline were unmodified in their affinity indices, but showed a marked decrease in the maximal responses; by contrast the activity of noradrenaline on the aortic alpha-adrenoceptors showed a great increase in maximal response without changes in the pD2 values. These results suggest that the predominant effect of microwave exposure consists in an increase in the noradrenergic pattern, and this effect is not related to the functional modifications.

Biochemical characterization of programmed cell death in NGF-deprived sympathetic neurons

Young sympathetic neurons die when deprived of nerve growth factor (NGF). Under such circumstances, cell death is appropriate to the developing nervous system and requires RNA and protein synthesis. We have hypothesized the existence of an endogenous death program within neurons that is suppressed by trophic factors. The extent and timing of required changes in the synthetic events that comprise the death program are unknown. In an effort to characterize the biochemical events that mediate the death program further, we performed several experiments on embryonic rat sympathetic neurons in vitro. The death program was blocked with cycloheximide when total protein synthesis was inhibited > or = 80%. When protein synthesis was inhibited within 22 +/- 4 h of NGF deprivation, death was prevented in half the neurons. Hence, we define the commitment point for protein synthesis to be 22 +/- 4 h. Analogously, the commitment point for RNA synthesis was 26 +/- 4 h and that for NGF rescue, 24 +/- 4 h. We tested the ability of a wide variety of chemicals to interfere with the death program. Most compounds tested were unable to prevent neuronal death. Some treatments, however, did save NGF-deprived neurons and were subsequently characterized. These included ultraviolet light and agents that raise intracellular concentrations of cAMP. Finally, we looked for the neuronal expression in vitro and in vivo of genes that have been associated with programmed death in other cell types, including TRPM-2/SGP-2, polyubiquitin, TGF beta-1, c-fos, and c-myc. None of these genes showed significant activation associated with neuronal death.

Effect of ionizing radiation on sympathetic nerve function in rat parotid glands

Ionizing radiation (IR) irreversibly damages salivary glands. The pathologic mechanism is unknown. Previously we reported that parotid serous acinar cells may not be the primary site of damage by IR. The purpose of this study was to determine if IR alters sympathetic nerve function in rat parotid glands. Male adult rats received a single dose of radiation (20 Gy) to the head and neck. Three days after IR, parotid saliva secretion induced by norepinephrine (NE) was completely blocked. Catecholamine uptake and metabolism were studied by injecting [3H] dopamine ([3H]DA) into irradiated rats, as a bolus. After 60 min, animals were sacrificed and the parotid gland, submandibular gland, and left ventricle removed. Tissue contents of [3H]DA and [3H]NE, identified by HPLC, were unaffected by IR. The results indicate that IR abolishes acinar responsiveness to NE without affecting parotid sympathetic nerve function.

[The characteristics of the radiation lesion in exposure of the anterior abdomen in dogs and the effect of modifying factors]

A comparative study was made of the effect of gamma/neutron and X-radiation on the forepart of dog abdomen. The RBE coefficient was found to depend upon body mass and to range from 1.3 to 1.5. The exclusion of the sympathetic nervous system before irradiation was shown to aggravate the clinical condition and to increase the death rate. On the contrary, the exclusion of the parasympathetic nervous system before irradiation and gastric lavage after irradiation improved the clinical picture of radiation sickness and increased the radioresistance of dogs.

Sympathetic neurotransmission in the rabbit isolated central ear artery is affected as early as one week following a single dose of X-irradiation

1. The short-term effect of a single dose of 4500 rad X-irradiation on sympathetic neurotransmission (involving both noradrenergic and purinergic components) was assessed in the rabbit central ear artery, 1, 4 and 6 weeks post-irradiation. 2. Neurally mediated contractions were reduced as early as 1 week post-irradiation, with responses to lower frequency stimulation being initially most affected. This suggest that the purinergic component of the contractile response is affected earlier than the adrenergic component. 3. There was no change in the amplitude or sensitivity of treated preparations to the cumulative application of noradrenaline when compared with untreated preparations. In contrast, contractions to alpha, beta-methylene ATP (1 microM), a P2-purinoceptor agonist, were significantly increased at 4 and 6 weeks post-irradiation, although not at 1 week post-irradiation. 4. There were no apparent changes in the pattern of catecholamine fluorescence as a result of irradiation. However, the tissue content of noradrenaline was significantly reduced 6 weeks post-irradiation when compared with control preparations. 5. It is concluded that damage to sympathetic cotransmission is one of the early effects of irradiation, with initial impairment predominantly of the purinergic component.

[Neurogenic arterial hypertension in humans]

The purpose of this study was to investigate baroreflex activity in hypertensive patients with orthostatic hypotension (OH) due to sinoaortic baroreceptor denervation. The study concerned 3 patients (pts), 58-63 years, mean age 60.6 +/- 2 with both arterial hypertension (paroxysms recorded at 250/130 mmHg) and OH. They received radiation therapy to the entire cervical area for neoplasm, 9.6 +/- 2.8 years ago and had a carotid murmur without significant stenosis. Every pt had a severe and symptomatic OH: blood pressure (BP) and heart rate (HR) were respectively 163 +/- 17/105 +/- 7, 82 +/- 5 b/mn in lying position and 82 +/- 16/53 +/- 9 mmHg, 99 +/- 1 b/mm in standing position. The standing-induced increase in HR was lower (delta HR = + 17.3 b/mn) than expected; atropine (0.02 mg/kg) infusion and cold pressor test were ineffective; the massage of sinocarotid receptors induced a slight decrease in HR (delta HR = - 8 b/mn) and BP was not modified by Valsalva's maneuver. Infusion of norepinephrine (0.016 mg/mn) performed in one pt, increased BP without effect on HR. Platelet alpha 2-adrenoreceptors (alpha 2AR) evaluated by (3H) Yohimbine binding showed a significant increase in alpha 2AR number (Bmax), without any significant change in affinity (KD) when compared with normotensive and essential hypertensive pts: (table; see text) This study described an unusual etiology of a paroxysmal hypertension with orthostatic hypotension, demonstrated the impairment of baroreflex activity and suggested the potential interest of platelet alpha 2 adrenoceptors measurement to evaluate sympathetic tone in these patients.

[Effect of laser radiation on the posttraumatic recovery of the interneuronal connections in the sympathetic trunk]

Low energetic laser radiation produces stimulating influence on posttraumatic regeneration of interneuronal connections of the sympathetic trunk. Local effect of the low energetic laser with exposition of 25 sec., power of the incident ray 16 mVt/cm2 increases the cause of reparative regeneration of sympathetic preganglionic fibers. Restoration of the cranial cervical ganglion (CCG) connections with the spinal cord takes place 5-6 days earlier comparing with the control. Localization and structural organization of the spinal initial neurons is stated, their processes reach the CCG.

[The sympathetic-adrenal and hypophyseal-adrenal systems in the preoperative irradiation of patients with cancer of the esophagus and cardia]

A study was made of 74 patients with esophageal and cardiac cancer, Stages II and IV. The excretion of catecholamines, corticosteroids and their precursors was studied, tests with adrenalin before and after preoperative irradiation at a summary dose of 30 Gy were done. It has been shown that before the start of radiation therapy the excretion of catecholamines and corticosteroids is lowered, the reaction to adrenalin administration is negative in most patients, the phase syndrome of cardiac hypodynamics associated with disturbed function of the sympathoadrenal system was revealed. After irradiation DOPA and dopamine excretion gets still lower whereas adrenalin excretion remains at the initial reduced level, the level of noradrenalin increases but does not achieve the normal level, i. e. a predominant decrease of catecholamine synthesis is observed. Adrenalin tests after irradiation revealed the depletion of the reaction of the cardiovascular system interrelated, to a great extent, with the activity of the sympathoadrenal system. Preoperative irradiation in patients with esophageal and cardiac cancer results in an increased excretion of 17-ketosteroids (17-KS) and 17-ketogenic steroids, however 17-KS excretion does not reach the normal level. For better tolerance of irradiation and for a radiosensitization effect testenate is administered to patients before and during radiation therapy. The administration of testenate 7-10 days before the start and during radiotherapy proved to be effective which was confirmed by noticeable necrobiotic and necrotic changes of cancer cells.

The fine structure of sympathetic neurons in x-irradiated frogs

The effects of whole body x-irradiation on the fine structure of sympathetic neurons were studied in 15 unanesthetized adult frogs (Rana pipiens), as seen at intervals ranging from 1 hour to 2 weeks after single exposures to 1000 r and 2000 r. Using standard procedures, the lumbar sympathetic ganglia of experimental and 20 control animals were prepared for electron microscope examination. Radiation produced conspicuous but irregular and variable deterioration, swelling, and clearing of neuronal lysosomes. These changes may have been due to an increased permeability of lysosomal membranes, causing the entry of fluid into lysosomes and their swelling and deterioration, but a pronounced escape of lysosomal enzymes into the cytoplasm was questionable. Less frequent were the dilatation and the parallel layering or complete fusion and tight packing of the rough-edged endoplasmic reticulum. The number of vacuoles, probably derived from Golgi cisternae, was somewhat increased. These vacuoles were conjectured to serve the "sequestration" of damaged cytoplasmic areas. Abnormal amounts of presumptive glycogen granules occupied some axons of myelinated and unmyelinated fibers, especially of presynaptic nerve fibers. This was assumed to be due to a decreased breakdown of glycogen and probably caused the interruption of the transmission of nerve impulses in presynaptic fibers. The maximal incidence of these alterations seemingly occurred 8 days after exposure to 1000 r, and 1 hour after x-irradiation with 2000 r. Signs of recovery appeared 2 weeks after exposure to 2000 r.