Circadian profile of plasma calcitonin gene-related peptide in healthy man

Serum uric acid predicts therapeutic response to midodrine hydrochloride in children with vasovagal syncope: a pilot study

Serum uric acid (UA) level has been proven to be related to several cardiovascular and metabolic diseases. In the present study, we examined if baseline serum UA level could predict the therapeutic efficacy of midodrine hydrochloride on vasovagal syncope (VVS) in children. The pediatric VVS patients who received midodrine hydrochloride from November 2008 to October 2022 were enrolled. After a median treatment duration of 3 months, the therapeutic effect was evaluated. According to the patients' responses to midodrine hydrochloride, which was determined by the recurrence of syncope, they were divided into effective and ineffective groups. The baseline variables were explored using univariable and multivariate logistic analysis. The predictive efficacy was assessed by receiver operating characteristic curve (ROC), precision-recall curve (PR), Hosmer-Lemeshow test, calibration curve, and decision curve analysis (DCA). Totally, 53 participants were included in the study. Among the 51 patients who were successfully followed up, 29 (56.9%) responded to midodrine hydrochloride (effective group), and the other 22 (43.1%) failed to respond to midodrine hydrochloride (ineffective group). The participants in effective group had lower baseline serum UA level than those in ineffective group (276.5 ± 73 μmol/L vs. 332.7 ± 56 μmol/L, p = 0.004). Multivariable logistic analysis showed that serum UA was associated with the therapeutic response (odds ratio (OR): 0.985, 95% confidence interval (CI): 0.974-0.997, p = 0.01). ROC analysis indicated that using baseline serum UA < 299 μmol/L as a threshold value yielded a sensitivity of 77.3% and a specificity of 79.3% in predicting the treatment response to midodrine hydrochloride. The area under the PR curve was 0.833. Hosmer-Lemeshow test yielded a p value of 0.58, and calibration plot indicated that the model was well-fitted. DCA demonstrated that treatment decision depending on the baseline serum UA level resulted in a favorable net benefit.   Conclusion: This pilot study suggested that the baseline serum UA level could be taken as a predictor of therapeutic effect of midodrine hydrochloride on VVS in children. What is Known: • Empirical and unselected use of midodrine hydrochloride has an unfavorable therapeutic effect on VVS in children. Serum uric acid (UA) is closely linked to cardiovascular events. What is New: • A low baseline serum UA level successfully predicts the therapeutic effectiveness of midodrine hydrochloride on VVS in children.

Molecular Mechanisms of Migraine: Nitric Oxide Synthase and Neuropeptides

Migraine is a common condition with disabling attacks that burdens people in the prime of their working lives. Despite years of research into migraine pathophysiology and therapeutics, much remains to be learned about the mechanisms at play in this complex neurovascular condition. Additionally, there remains a relative paucity of specific and targeted therapies available. Many sufferers remain underserved by currently available broad action preventive strategies, which are also complicated by poor tolerance and adverse effects. The development of preclinical migraine models in the laboratory, and the advances in human experimental migraine provocation, have led to the identification of key molecules likely involved in the molecular circuity of migraine, and have provided novel therapeutic targets. Importantly, the identification that vasoconstriction is neither necessary nor required for headache abortion has changed the landscape of migraine treatment and has broadened the therapy targets for patients with vascular risk factors or vascular disease. These targets include nitric oxide synthase (NOS) and several neuropeptides that are involved in migraine. The ability of NO donors and infusion of some of these peptides into humans to trigger typical migraine-like attacks has supported the development of targeted therapies against these molecules. Some of these, such as those targeting calcitonin gene-related peptide (CGRP), have already reached clinical practice and are displaying a positive outcome in migraineurs for the better by offering targeted efficacy without significant adverse effects. Others, such as those targeting pituitary adenylate cyclase activating polypeptide (PACAP), are showing promise and are likely to enter phase 3 clinical trials in the near future. Understanding these nitrergic and peptidergic mechanisms in migraine and their interactions is likely to lead to further therapeutic strategies for migraine in the future.

Acute Increase in Blood αCGRP at Maximal Exercise and Its Association to Cardiorespiratory Fitness, Carbohydrate Oxidation and Work Performed: An Exploratory Study in Young Men

Simple Summary

αCGRP is a neuropeptide that increases in blood during high-intensity exercise in humans. However, the physiological meaning of this molecular response is unknown. Previous experimental works in rodents have related this neuropeptide to several biological processes in the skeletal muscle tissue and cardiorespiratory physiology. Based on the data from these animal studies we hypothesized that in humans αCGRP release during exercise could be similarly associated to metabolic and cardiorespiratory responses. To test this hypothesis, we subjected a sample of physically active young men to an exercise test up to exhaustion while their oxygen uptake (VO_2max), CO₂ production (VCO₂), carbohydrate oxidation and performed work were measured. Blood samples were taken before the exercise test, at maximal intensity and after the volunteers have recovered, and the blood concentration of αCGRP was measured. We found that 2/3 of the volunteers responded to maximal exercise with an increase of their blood αCGRP concentration (responders), while the resting 1/3 did not (non-responders). We also found that VO_2max, VCO₂, carbohydrate oxidation and performed work were higher in the responders when compared to the non-responders. Therefore, our observations support that αCGRP release during exercise may be associated to physiological responses related to physical performance.

Abstract

This study aimed to explore if the acute variations in plasma concentration of α-calcitonin gene-related peptide (αCGRP) induced by a single maximal exercise bout may be associated to cardiorespiratory fitness and carbohydrate oxidation in humans. Twelve young adult Caucasian men (24.3 ± 0.9 years-old; 179.2 ± 1.9 cm of height; 23.9 ± 0.6 kg·m⁻² body mass index) performed a graded exercise test. A venous catheter was placed before testing, and blood samples were taken at baseline, maximal effort and recovery. αCGRP was measured in plasma using a commercial double-sandwich enzyme-linked-immunoassay. A two-way repeated measurements ANOVA was used to compare the values obtained at baseline, maximal effort and recovery. In the whole sample, αCGRP increased at maximal effort and its concentration correlated directly, albeit non-significantly, with the muscle mass normalised VO₂, VCO₂, carbohydrate oxidation and relative power. Two thirds of the participants showed an increase in αCGRP concentration at maximal effort. Post hoc analysis showed that in these individuals, the muscle mass normalised VO₂, VCO₂, carbohydrate oxidation rate and relative power were higher than in the participants lacking this molecular response. Therefore, our data suggest that (a) a majority of young men respond to exercise with an increase in blood αCGRP concentration; and (b) individuals exhibiting this response also show a higher cardiorespiratory fitness, carbohydrate oxidation and work performed. These findings suggest that this neuropeptide could act as an exerkine with potential effects on physical performance.

CGRP and PTX3 as Predictors of Efficacy of Onabotulinumtoxin Type A in Chronic Migraine: An Observational Study

OBJECTIVE

The aim of this study is to find a relation between several biomarkers in peripheral blood and outcome after treatment with onabotulinumtoxin A (OnabotA).

BACKGROUND

OnabotA is an effective treatment in chronic migraine (CM). Different studies have tried to find predictors of response to treatment, either with clinical characteristics, neuroimaging features, or molecular biomarkers; however, it is still not possible to predict the individual outcome.

METHODS

We measured serum levels of biomarkers of inflammation (IL-6, IL-10, TNF-α, and hs-CRP), endothelial dysfunction (PTX3 and sTWEAK), blood-brain barrier disruption (cFN), brain damage (S100b, NSE), and trigemino-vascular activation (CGRP) by ELISA in a group of CM patients treated with OnabotA and healthy controls. After 24 weeks, patients were classified in two groups according to their outcome considering variations in headache frequency: nonresponders (nonimprovement or improvement <50%) and responders (improvement >50%). We compared baseline levels of biomarkers between these groups.

RESULTS

Sixty-two patients diagnosed with CM (IHS 2013 criteria) who fulfilled criteria for treatment with OnabotA and 24 healthy controls were included. Fifteen patients did not respond to treatment (24.2%) and 47 were responders (75.8%). Pentraxin 3 (PTX3) serum levels (1455.4 ± 487.5 pg/mL versus 720.3 ± 334.1 pg/mL, P < .0001) and calcitonin gene-related peptide (CGRP) serum levels (133.1 ± 86.6 ng/mL versus 58.2 ± 91.7 ng/mL, P = .004) were significantly higher in responders than nonresponders. Serum basal levels of PTX3 >1000 pg/mL (AUC 0.908; 95% CI: 0.827-0.990) and CGRP >50 ng/mL (AUC 0.800; 95% CI: 0.652-0.947) were associated with good response to OnabotA treatment.

CONCLUSIONS

These results show that molecular markers of trigeminovascular activation (CGRP) and endothelial dysfunction (PTX3) are associated with response to OnabotA and may act as new biomarkers for the selection of treatment in chronic migraineurs.

Adrenomedullin 2 Enhances Beiging in White Adipose Tissue Directly in an Adipocyte-autonomous Manner and Indirectly through Activation of M2 Macrophages

Adrenomedullin 2 (ADM2) is an endogenous bioactive peptide belonging to the calcitonin gene-related peptide family. Our previous studies showed that overexpression of ADM2 in mice reduced obesity and insulin resistance by increasing thermogenesis in brown adipose tissue. However, the effects of ADM2 in another type of thermogenic adipocyte, beige adipocytes, remain to be understood. The plasma ADM2 levels were inversely correlated with obesity in humans, and adipo-ADM2-transgenic (tg) mice displayed resistance to high-fat diet-induced obesity with increased energy expenditure. Beiging of subcutaneous white adipose tissues (WAT) was more noticeably induced in high-fat diet-fed transgenic mice with adipocyte-ADM2 overexpression (adipo-ADM2-tg mice) than in WT animals. ADM2 treatment in primary rat subcutaneous adipocytes induced beiging with up-regulation of UCP1 and beiging-related marker genes and increased mitochondrial uncoupling respiration, which was mainly mediated by activation of the calcitonin receptor-like receptor (CRLR)·receptor activity-modifying protein 1 (RAMP1) complex and PKA and p38 MAPK signaling pathways. Importantly, this adipocyte-autonomous beiging effect by ADM2 was translatable to human primary adipocytes. In addition, M2 macrophage activation also contributed to the beiging effects of ADM2 through catecholamine secretion. Therefore, our study reveals that ADM2 enhances subcutaneous WAT beiging via a direct effect by activating the CRLR·RAMP1-cAMP/PKA and p38 MAPK pathways in white adipocytes and via an indirect effect by stimulating alternative M2 polarization in macrophages. Through both mechanisms, beiging of WAT by ADM2 results in increased energy expenditure and reduced obesity, suggesting ADM2 as a novel anti-obesity target.

Circadian disruption: New clinical perspective of disease pathology and basis for chronotherapeutic intervention

Biological processes are organized in time as innate rhythms defined by the period (τ), phase (peak [Φ] and trough time), amplitude (A, peak-trough difference) and mean level. The human time structure in its entirety is comprised of ultradian (τ < 20 h), circadian (20 h > τ < 28 h) and infradian (τ > 28 h) bioperiodicities. The circadian time structure (CTS) of human beings, which is more complicated than in lower animals, is orchestrated and staged by a brain central multioscillator system that includes a prominent pacemaker - the suprachiasmatic nuclei of the hypothalamus. Additional pacemaker activities are provided by the pineal hormone melatonin, which circulates during the nighttime, and the left and right cerebral cortices. Under ordinary circumstances this system coordinates the τ and Φ of rhythms driven by subservient peripheral cell, tissue and organ clock networks. Cyclic environmental, feeding and social time cues synchronize the endogenous 24 h clocks and rhythms. Accordingly, processes and functions of the internal environment are integrated in time for maximum biological efficiency, and they are also organized and synchronized in time to the external environment to ensure optimal performance and response to challenge. Artificial light at night (ALAN) exposure can alter the CTS as can night work, which, like rapid transmeridian displacement by air travel, necessitates realignment of the Φ of the multitude of 24 h rhythms. In 2001, Stevens and Rea coined the phrase "circadian disruption" (CD) to label the CTS misalignment induced by ALAN and shift work (SW) as a potential pathologic mechanism of the increased risk for cancer and other medical conditions. Current concerns relating to the effects of ALAN exposure on the CTS motivated us to renew our long-standing interest in the possible role of CD in the etiopathology of common human diseases and patient care. A surprisingly large number of medical conditions involve CD: adrenal insufficiency; nocturia; sleep-time non-dipping and rising blood pressure 24 h patterns (nocturnal hypertension); delayed sleep phase syndrome, non-24 h sleep/wake disorder; recurrent hypersomnia; SW intolerance; delirium; peptic ulcer disease; kidney failure; depression; mania; bipolar disorder; Parkinson's disease; Smith-Magenis syndrome; fatal familial insomnia syndrome; autism spectrum disorder; asthma; byssinosis; cancers; hand, foot and mouth disease; post-operative state; and ICU outcome. Poorly conceived medical interventions, for example nighttime dosing of synthetic corticosteroids and certain β-antagonists and cyclic nocturnal enteral or parenteral nutrition, plus lifestyle habits, including atypical eating times and chronic alcohol consumption, also can be causal of CD. Just as surprisingly are the many proven chronotherapeutic strategies available today to manage the CD of several of these medical conditions. In clinical medicine, CD seems to be a common, yet mostly unrecognized, pathologic mechanism of human disease as are the many effective chronotherapeutic interventions to remedy it.

Differences between men and women in ambulatory blood pressure thresholds for diagnosis of hypertension based on cardiovascular outcomes

Previous studies have reported sex differences in the pathophysiology of hypertension and responses to blood pressure (BP)-lowering medications. Moreover, men exhibit typically higher BP than women, the differences being greater for systolic (SBP) than diastolic (DBP) BP. These differences become apparent during adolescence and remain significant at least until 55-60 yrs of age. Despite such significant sex-related differences in BP regulation, the current recommended ambulatory BP monitoring (ABPM) thresholds for diagnosis of hypertension do not differentiate between men and women. We aimed to derive separate male and female diagnostic thresholds for the awake and asleep SBP and DBP means based upon cardiovascular disease (CVD) outcome. We prospectively studied 3344 subjects (1718 men/1626 women), 52.6 ± 14.5 yrs of age, during a median follow-up of 5.6 yrs. Those with hypertension at baseline were randomized to ingest all their prescribed hypertension medications upon awakening or the entire daily dose of ≥1 of them at bedtime. At baseline, BP was measured at 20-min intervals from 07:00 to 23:00 h and at 30-min intervals at night for 48 h, and physical activity was simultaneously monitored every minute by wrist actigraphy to accurately derive the awake and asleep BP means. Identical assessment was scheduled annually and more frequently (quarterly) if treatment adjustment was required. Cox regression analysis was used to derive outcome-based reference thresholds for ABPM in men and women. Men exhibited greater event rates than women of CVD death, myocardial infarction, angina pectoris, coronary revascularization, and heart failure; however, event rates of non-CVD death and cerebrovascular events were comparable. The relationship between progressively higher ambulatory BP and CVD risk increased more rapidly in women than men for awake SBP/DBP means ≥125/75 mm Hg and asleep means ≥110/70 mm Hg. The derived outcome-based reference thresholds for men were 135/85 mm Hg for the awake and 120/70 mm Hg for the asleep SBP/DBP means. In terms of CVD outcome, the equivalent cutoff threshold values for women were 125/80 mm Hg for the awake and 110/65 mm Hg for the asleep SBP/DBP means. Outcome-based reference thresholds for the diagnosis of hypertension were 10/5 mm Hg lower for ambulatory SBP/DBP in women than men. This marked sex difference indicates the need for revision of current guidelines that propose diagnostic thresholds for ambulatory BP without differentiation between men and women.

Dipper and non-dipper blood pressure 24-hour patterns: circadian rhythm-dependent physiologic and pathophysiologic mechanisms

Neuroendocrine mechanisms are major determinants of the normal 24-h blood pressure (BP) pattern. At the central level, integration of the major driving factors of this temporal variability is mediated by circadian rhythms of monoaminergic systems in conjunction with those of the hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, opioid, renin-angiotensin-aldosterone, plus endothelial systems and specific vasoactive peptides. Humoral secretions are typically episodic, coupled either to sleep and/or the circadian endogenous (suprachiasmatic nucleus) central pacemaker clock, but exhibiting also weekly, monthly, seasonal, and annual periodicities. Sleep induction and arousal are influenced also by many hormones and chemical substances that exhibit 24-h variation, e.g., arginine vasopressin, vasoactive intestinal peptide, melatonin, somatotropin, insulin, steroids, serotonin, corticotropin-releasing factor, adrenocorticotropic hormone, thyrotropin-releasing hormone, endogenous opioids, and prostaglandin E2, all with established effects on the cardiovascular system. As a consequence, physical, mental, and pathologic stimuli that activate or inhibit neuroendocrine effectors of biological rhythmicity may also interfere with, or modify, the temporal BP structure. Moreover, immediate adjustment to exogenous components/environment demands by BP rhythms is modulated by the circadian-time-dependent responsiveness of biological oscillators and their neuroendocrine effectors. This knowledge contributes to a better understanding of the pathophysiology of abnormalities of the 24-h BP pattern and level and their correction through circadian rhythm-based chronotherapeutic strategies.

Twenty-four-hour patterns in occurrence and pathophysiology of acute cardiovascular events and ischemic heart disease

The scientific literature clearly establishes the occurrence of cardiovascular (CV) accidents and myocardial ischemic episodes is unevenly distributed during the 24 h. Such temporal patterns result from corresponding temporal variation in pathophysiologic mechanisms and cyclic environmental triggers that elicit the onset of clinical events. Moreover, both the pharmacokinetics and pharmacodynamics of many, though not all, CV medications have been shown to be influenced by the circadian time of their administration, even though further studies are necessary to better clarify the mechanisms of such influence on different drug classes, drug molecules, and pharmaceutical preparations. Twenty-four-hour rhythmic organization of CV functions is such that defense mechanisms against acute events are incapable of providing the same degree of protection during the day and night. Instead, temporal gates of excessive susceptibility exist, particularly in the morning and to a lesser extent evening (in diurnally active persons), to aggressive mechanisms through which overt clinical manifestations may be triggered. When peak levels of critical physiologic variables, such as blood pressure (BP), heart rate (HR), rate pressure product (systolic BP × HR, surrogate measure of myocardial oxygen demand), sympathetic activation, and plasma levels of endogenous vasoconstricting substances, are aligned together at the same circadian time, the risk of acute events becomes significantly elevated such that even relatively minor and usually harmless physical and mental stress and environmental phenomena can precipitate dramatic life-threatening clinical manifestations. Hence, the delivery of CV medications needs to be synchronized in time, i.e., circadian time, in proportion to need as determined by established temporal patterns in risk of CV events, and in a manner that averts or minimizes undesired side effects.

Gene profiling the response to repeated cocaine self-administration in dorsal striatum: a focus on circadian genes

Alterations in gene expression in the dorsal striatum caused by chronic cocaine exposure have been implicated in the long-term behavioral changes associated with cocaine addiction. To gain further insight into the molecular alterations that occur as a result of cocaine self-administration, we conducted a microarray analysis of gene expression followed by bioinformatic gene network analysis that allowed us to identify adaptations at the level of gene expression as well as into interconnected networks. Changes in gene expression were examined in the dorsal striatum of rats 1 day after they had self-administered cocaine for 7 days under a 24-h access, discrete trial paradigm (averaging 98 mg/kg/day). Here we report the regulation of the circadian genes Clock, Bmal1, Cryptochrome1, Period2, as well as several genes that are regulated by/associated with the circadian system (i.e., early growth response 1, dynorphin). We also observed regulation of other relevant genes (i.e., Nur77, beta catenin). These changes were then linked to curated pathways and formulated networks which identified circadian rhythm processes as affected by cocaine self-administration. These data strongly suggest involvement of circadian-associated genes in the brain's response to cocaine and may contribute to an understanding of addictive behavior including disruptions in sleep and circadian rhythmicity.

Evolution of the CT/CGRP family: comparative study with new data from models of teleosts, the eel, and cephalopod molluscs, the cuttlefish and the nautilus

In mammals, alternative splicing of the calcitonin gene generates two distinct peptides: calcitonin (CT), synthesised in the thyroid C cells and involved in the regulation of calcium metabolism, and calcitonin gene-related peptide (CGRP), brain neuromediator synthesised in the peripheral and central nerves. CGRP is well represented and molecularly conserved during evolution whereas CT has not been detected in any of the invertebrates analysed so far. In order to better understand the evolution of this CT/CGRP peptide family we reviewed the major data concerning its evolution from the literature and our recent data obtained in models of teleosts and cephalopod molluscs. The presence of both CGRP-like molecules and its specific bindings sites in the central nervous system of eel, cuttlefish and nautilus, suggests that the brain neurotransmitter role of CGRP could represent an ancient role in metazoa, already present in cephalopods and conserved among vertebrates, as still observed in mammals. In contrast, the presence of CGRP specific binding sites, and not the peptide itself, in the gills suggests an endocrine role for CGRP, in cephalopods and teleosts, that may have been lost during the evolution of the tetrapod lineage. These data, and the absence of CT-like molecules that we observed in cephalopods, support the hypothesis that CGRP represents the ancestral molecule of the CT/CGRP family, appeared in metazoa before the vertebrate emergence. The distinction between CT and CGRP receptors appears to be an event posterior to the emergence of ecdysozoan and lophotrochozoan protostomes, probably in relation to the CT appearance. The evolution of the CT/CGRP peptide family is probably similar to the evolution of the CT/CGRP receptor family. In fact, the genic duplication that induced the appearance of the two separate molecules, CT and CGRP, may constitute an event close to that, which induced the appearance of the two specific receptors. These events remain to be further studied in order to better understand the peptide and receptor evolution of the CT/CGRP family.

Possible role of calcitonin gene-related peptide in osmoregulation via the endocrine control of the gill in a teleost, the eel, Anguilla anguilla

Osmoregulation is a major challenge in aquatic animals involving a complex endocrine control. We investigated the potential role of calcitonin gene-related peptide (CGRP, a neuromediator in mammals) in the endocrine control of the gill in a teleost, the eel. Transfer from freshwater to seawater induced an hyperosmolality and a concomitant large increase in plasma CGRP levels. Specific CGRP binding sites were characterized in the gill and their number was up-regulated after seawater transfer. This study suggests that the endocrine control of gill function during osmoregulation may represent an ancient role of CGRP in vertebrates.

Evidence for the presence of molecules related to the neuropeptide CGRP in two cephalopods, Sepia officinalis and Nautilus macromphalus: comparison with its target organ distribution

Calcitonin gene-related peptide (CGRP) is a neuropeptide mainly involved in brain and cardiovascular functions in mammals. We investigated its presence and potential roles in two cephalopods, Sepia officinalis and Nautilus macromphalus. CGRP-like, but not calcitonin (CT)-like, molecules were detected by specific radioimmuno- and radioreceptor assays in the brain, optic lobes, branchial heart or afferent branchial vein and kidney. Gel exclusion chromatography of cephalopod brain extracts, followed by SDS-PAGE, indicated that CGRP-like molecules had a molecular weight of around 3 kDa, close to that of human CGRP. The distribution of CGRP target organs was characterized by binding studies in cuttlefish. Specific CGRP binding sites were detected in the brain, optic lobes, and kidney, indicating potential autocrine/paracrine roles of CGRP. Specific CGRP binding sites were also detected in the gills and shell sac that do not contain the peptide itself, indicating potential endocrine roles of CGRP. Accordingly, high circulating levels of CGRP-like molecules were detected in hemolymph of both cuttlefish and nautilus, unlike the situation in mammals. CGRP binding sites were further characterized in the cuttlefish gills by the Scatchard method. Our study indicates that the brain neurotransmitter role of CGRP could represent an ancient role in metazoa, already present in cephalopods and conserved among vertebrates. In contrast, the endocrine role of CGRP, which was suggested in cephalopods and also present in teleosts, may have been lost during the evolution of the tetrapod lineage. Our data support the hypothesis that CGRP represents the ancestral molecule of the CT/CGRP family appeared in metazoa before the vertebrate emergence.

Characterisation and distribution of calcitonin gene-related peptide in a primitive teleost, the eel, Anguilla anguilla and comparison with calcitonin

Radioimmunoassay (RIA), radioreceptor assay and chromatography were used to study the occurrence of calcitonin gene-related peptide (CGRP) in a primitive teleost, the eel, Anguilla anguilla. Immunologically and biologically active CGRP-like molecules were found in brain, heart, kidney, liver, spleen and ultimobranchial body with the higher concentrations in brain, spleen and heart. Gel exclusion chromatography of heart and spleen extracts followed by SDS-PAGE showed that the eel CGRP-like molecules presented a molecular weight between 3.30 and 3.95 kDa similar to that of human CGRP. The wide distribution of CGRP reflects its multiple role as brain neuromediator and peripheral paracrine effector as described in mammals. In comparison, the distribution of calcitonin (CT) was much more restricted, immunologically and biologically active CT-like molecules being localised in the ultimobranchial bodies (UBB) that is the site of CT synthesis in non-mammalian vertebrates. In plasma, CGRP-like concentrations were 10 to 100 higher than those of CT. These high concentrations in a primitive teleost strengthen the possible endocrine role of CGRP in early vertebrates and emphasise the important role of this hormone in evolution.

Circadian variation in portal pressure: appropriate use of non-selective beta blockers in the prevention of variceal bleed

The circadian variation in some biologic functions may have clinical, fiscal and therapeutic implications. The authors discuss circadian variation in portal pressure in cirrhotic patients and nocturnal occurrence of bleeding from varices in these patients. The pathogenesis of the diurnal variation in portal pressure is presented. The authors submit the hypothesis that an optimal dosing regimen for non-selective beta blocker therapy in the prevention of variceal bleed must include an evening dose of beta blocker medication. In studies reporting comparative efficacy of beta blocker therapy with other modalities in the prevention of variceal bleeding, the optimal dosing schedule for beta blocker therapy must be emphasized.

Trigeminal innervation of the mammalian pineal gland

There is evidence that the trigeminal (Gasserian) ganglia innervate the mammalian pineal gland and serve in its regulation in addition to the sympathetic and cholinergic as well as further influences. By means of immunohistochemical methods, previous studies demonstrated fibers containing calcitonin gene-related peptide (CGRP-LI) or substance P (SP) in the superficial pineal of various mammalian species. In addition, SP and the related tachykinin, neurokinin A, were detected by radioimmunoassay and HPLC, respectively, in the rat and human pineal gland. In the present study, retrograde neuronal tracing upon injection of a tracer substance into the superficial pineal gland of rats was used in combination with immunohistochemistry to show that trigeminal ganglionic neurons innervate the gland, and that a considerable amount of these neurons are also CGRP- or SP-immunoreactive. These results reveal that afferent neuropeptidergic entering the superficial pineal gland originate from the trigeminal ganglia. The present paper reviews the evidence for a CGRP- and SP-ergic innervation of the mammalian pineal gland and discusses the possible role of these neuropeptides with regard to pineal function.

Postmenopausal women with vasomotor symptoms have increased urinary excretion of calcitonin gene-related peptide

OBJECTIVES

To establish whether 24 h urinary excretion of the potent vasodilator calcitonin gene-related peptide (CGRP) was higher in postmenopausal women with vasomotor symptoms compared to the level in women without symptoms. We also wanted to establish whether urinary excretion of CGRP changed during the menstrual cycle in women of fertile age.

MATERIAL AND METHODS

Thirteen postmenopausal women with and 13 women without vasomotor symptoms were included. Urine was collected over 24 h and CGRP excretion was measured utilizing radio-immunoassay technique. Twenty-four hour CGRP excretion was also measured in ten fertile women with regular cycles in early follicular, preovulatory and midluteal phase.

RESULTS

Twenty-four hour urinary excretion of CGRP was significantly higher in women with vasomotor symptoms compared to non-flushing women (median 7.16 vs 5.15 pmol/24 h; P = 0.028). CGRP concentrations were stable throughout the ovulatory cycles.

CONCLUSION

The 24 h urinary excretion of CGRP is higher in women with vasomotor symptoms than in women without these symptoms. CGRP may be the mediator of vasodilator signals originating from the thermoregulatory center.

Reversed circadian blood pressure rhythm preserves fetal growth in preeclamptic pregnancy

OBJECTIVE

To determine the clinical trait of hypertension in pregnant women with a reversed circadian blood pressure (BP) rhythm.

STUDY DESIGN

24-h BP monitoring was performed in 56 hypertensive pregnant women, of whom 12 had a reversed systolic BP (SBP) rhythm (day/night mean BP ratio < 1.0). Clinical data, ultrasound fetometry and umbilical artery velocimetry were compared to that in women with a normal rhythm. Statistical analyses were performed with simple linear regression, Mann-Whitney U test, analysis of variance, contingency table analysis and Fisher's test. A two-tailed P value of < 0.05 was considered significant.

RESULTS

In the reversed SBP group, the nighttime BP, fetal weight, albuminuria and S-urate were higher, and the BP variations smaller. The birthweight correlated negatively to the SBP day/night ratio. Higher SBP day/night ratios and larger BP variations were associated with an increased vascular resistance in the umbilical artery and an impaired growth.

CONCLUSION

A reversed SBP rhythm was associated with a more severe degree of preeclampsia, but also with a smaller BP variation, maintenance of fetal growth, and higher birthweight. A sustained high nighttime BP preserved fetal growth. These novel observations challenge the opinion that a reversed circadian BP rhythm is merely an ominous sign.

Changes of plasma calcitonin gene-related peptide levels in postmenopausal women

OBJECTIVE

Our purpose was to investigate whether the secretion of a cardiovascular hormone, calcitonin gene-related peptide, is modified in climateric women according to cardiovascular adaptive responses.

STUDY DESIGN

Plasma calcitonin gene-related peptide levels were measured in climateric women in a basal condition (n = 15), in response to an upright position (n = 8), and during hot flushes (n = 12). The effect of hormonal replacement therapy on plasma calcitonin gene-related peptide was also studied (n = 9). Plasma calcitonin gene-related peptide levels were measured by a specific radioimmunoassay after an acidic extraction.

RESULTS

Plasma calcitonin gene-related peptide levels in postmenopausal women were significantly lower than in the control group (p < 0.01). After the women assumed an upright posture, a lack of plasma calcitonin gene-related peptide increase was observed in control fertile women, who showed the typical significant hormonal increase (p < 0.01). In all patients the occurrence of hot flushes was associated with a significant and rapid increase of plasma calcitonin gene-related peptide levels. After 3 months of hormonal replacement therapy basal plasma calcitonin gene-related peptide levels returned to the range of healthy fertile women.

CONCLUSIONS

The current data show that the secretion of plasma calcitonin gene-related peptide is lower in postmenopausal women and its response to postural stimulus is impaired. Vasomotor changes are associated with an increase of plasma levels of this cardiovascular hormone. An effect of hormonal replacement therapy on calcitonin gene-related peptide secretion has been shown.

Endocrine mechanisms of blood pressure rhythms

The temporal organization of blood pressure is mainly controlled by neuroendocrine mechanisms. The monoaminergic systems appear to integrate the major driving factors of temporal variability, but evidence also indicates a role of the hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, opioid, renin-angiotensin-aldosterone, and endothelial systems as well as other vasoactive peptides. Although their hormonal secretions are typically episodic, the probability of secretory episodes is "gated" by mechanisms that are coupled either to sleep or to an endogenous pacemaker which usually is predominantly (though not only) circadian. Many hormones with established actions on the cardiovascular system (arginine vasopressin, vasoactive intestinal peptide, melatonin, somatotropin, insulin, steroids, serotonin, CRF, ACTH, TRH, endogenous opioids, and prostaglandin E2) are also involved in sleep induction or arousal. Hence, physical, mental, and pathologic stimuli, which may drive activation or inhibition of these neuroendocrine effectors of biologic rhythmicity, may also interfere with the temporal blood pressure structure. On the other hand, the immediate adaptation of the exogenous components of blood pressure rhythms to the demands of the environment are modulated by the circadian-time-dependent responsiveness of the biologic oscillators and their neuroendocrine effectors. These notions may contribute to a better understanding of the pathophysiology and therapeutics of changes in blood pressure.

Interrelationships between calcitonin gene-related peptide and sympathoadrenomedullary system: effects of administration of epinephrine and norepinephrine in healthy man

To investigate the influence of the sympathoadrenomedullary system on the modulation of the circulating levels of calcitonin gene-related peptide (CGRP), the effects of epinephrine (E) and norepinephrine (NE) were studied in 8 normal subjects (4 females and 4 males). The mean basal levels of CGRP in normal subjects were 10.2 +/- 1 pmol/l. After the infusion of E (20 ng/kg per min for 30 min), a significant rise (P < 0.005) in plasma CGRP levels was observed with the expected increases in systolic blood pressure (BP), heart rate (HR) and plasma renin activity (PRA), and decrease in diastolic BP, whereas plasma aldosterone (PA) levels did not significantly change. The infusion of NE (40 ng/kg per min for 30 min) induced an increase in systolic and diastolic BPs, whereas it failed to modify CGRP, HR, PA and PRA. Our data demonstrate that the sympathoadrenomedullary system may modulate CGRP release in man perhaps via the beta-adrenergic pathway. It is likely that the modifications of plasma CGRP levels may be part of the acute vasal response to E.

Effect of parasympathetic and sensory transmitters on human epicardial coronary arteries and veins

Vasomotor effects of various agonists were tested on isolated human epicardial coronary arteries and veins at resting tension and after precontraction with U46619. Acetylcholine relaxed all arteries with intact endothelium but only some endothelium-denuded arteries. Most veins did not relax to acetylcholine. Higher concentrations of acetylcholine induced powerful contractions of all arteries and veins. Preincubation with atropine significantly lowered the pD(2) values but not E(max) values for contractile responses to acetylcholine in arteries and veins (pA(2) value for atropine 9.1 arteries and 9.6 veins). Vasoactive intestinal peptide, human alpha-calcitonin gene-related peptide and substance P potently relaxed all arteries with intact endothelium and all veins. Removal of the arterial endothelium abolished relaxation to substance P in most arteries whereas responses to vasoactive intestinal peptide were unaffected, and for alpha-calcitonin gene-related peptide the pD(2) value but not the E(max) value was significantly lowered. In both arteries and veins, the antagonists alpha-calcitonin gene-related peptide (8-37) and spantide lowered significantly the potency for alpha-calcitonin gene-related peptide and substance P, respectively, without significant changes in E(max) values (pA(2) value for alpha-calcitonin gene-related peptide (8-37) 7.9 arteries and 7.9 veins, for spantide 7.6 arteries and 8.1 veins).

Peripherally administered calcitonin gene-related peptide decreases food intake in mice

Previously, calcitonin gene-related peptide (CGRP) decreased food intake when administered ICV but not when administered peripherally to rats. Amylin, which has a close structural homology to CGRP, reduced food intake administered IP at concentrations higher than those previously tested for CGRP. We examined the effects of higher doses of IP-administered CGRP on food intake. CGRP reduced food intake from 25 to 200 micrograms/kg in mice. CGRP did not reduce water intake and was not aversive in a two-bottle test. Using a lever press, CGRP was more effective at reducing milk consumption in prefed than in nonprefed mice. The effect of CGRP on food intake was not antagonized by the cholecystokinin A receptor antagonist, L364,718. These studies suggest a role for CGRP as a satiating factor.

Calcitonin gene-related peptide-like immunoreactivity in spinal cord and superior cervical ganglion of the Djungarian hamster (Phodopus sungorus)

The indirect immunofluorescent method was employed to investigate the distribution of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in the spinal cord and superior cervical ganglion of the Djungarian hamster Phodopus sungorus. In cross-sections of the spinal cord, immunoreactive fibres and terminals were found in laminae 1 and 2 in high density, in the dorsolateral (Lissauer's) tract, in ventral and lateral horns, and in the area surrounding the central canal. A few CGRP-LI perikarya were seen in the ventral but not the dorsal horn. CGRP-LI was further observed in preganglionic sympathetic neurons which were labelled by retrograde axonal transport of fluoro-gold (FG) following injection of the substance unilaterally into the superior cervical ganglion. Preganglionic sympathetic neurons (PSN) were localized ipsilateral to the injection site mainly in the intermediolateral nucleus and the lateral funiculus of the upper thoracic segments. Most PSN exhibited CGRP-LI. Immunoreactive PSN were not seen contralaterally to the site of FG application nor in animals that did not receive injections. When the preganglionic fibres were ligated 4 days before perfusion, CGRP-LI cell bodies were found in preganglionic sympathetic neurons similar to the situation seen upon FG treatment. In the superior cervical ganglia of untreated hamsters, immunoreactive fibres were seen to enter the ganglion in which they terminated at non-immunoreactive principal ganglion cells. The present study, the first in a hamster species, describes the widespread distribution of CGRP in the spinal cord of P. sungorus and supports the view that considerable interspecies differences exist in occurrence and location of this neuropeptide.

Atrial natriuretic peptide and circadian blood pressure regulation: clues from a chronobiological approach

A critical review of the data available in the literature today permits a better understanding of the multiple actions of atrial natriuretic peptide (ANP) on the cardiovascular system. Moreover, the results of chronobiological studies suggest a role for this peptide in the determination of the circadian rhythm of blood pressure (BP). ANP can affect BP by several mechanisms, including modification of renal function and vascular tone, counteraction of the renin-angiotensin-aldosterone system, and action on brain regulatory sites. A series of interrelated events may follow from very small changes in the plasma levels of ANP. The endpoints are blood volume and BP reduction, but they are rapidly offset (mainly by reactive sympathetic activation) as soon as blood volume or pressure is threatened. The circadian rhythms of BP and ANP are antiphasic under normal conditions and in essential hypertension. The loss in the nocturnal decrease of BP is accompanied by a comparable loss in the nocturnal surge of ANP in hypertensive renal failure and hypotensive heart failure. In the latter condition, BP and ANP variabilities correlate significantly both before and after therapy-induced functional recovery, independently of the mean BP levels. Autonomic function modulates the secretion of ANP, which seems more apt to determine only transient changes in BP levels, as suggested by the short half-life of the peptide and the buffering role of its clearance receptors. There is now sufficient evidence that ANP contributes to short-term control over BP and electrolyte balance, in contrast and in opposition to the renin-angiotensin-aldosterone system, which is involved primarily in long-term BP control. By interfering with other well-established neurohormonal factors, ANP appears to be an additional modulator of the circadian rhythm of BP.