Vito De Gennaro Colonna

Growth Hormone-Independent Cardioprotective Effects of Hexarelin in the Rat

We previously reported that induction of selective GH deficiency in the rat exacerbates cardiac dysfunction induced by experimental ischemia and reperfusion performed on the explanted heart. In the same model, short-term treatment with hexarelin, a GH-releasing peptide, reverted this effect, as did GH. To ascertain whether hexarelin had non-GH-mediated protective effects on the heart, we compared hexarelin and GH treatment in hypophysectomized rats. Hexarelin (80 μg/kg sc), given for 7 days, prevented exacerbation of the ischemia-reperfusion damage induced by hypophysectomy. We also demonstrate that hexarelin prevents increases in left ventricular end diastolic pressure, coronary perfusion pressure, reactivity of the coronary vasculature to angiotensin II, and release of creatine kinase in the heart perfusate. Moreover, hexarelin prevents the fall in prostacyclin release and enhances recovery of contractility. Treatment with GH (400 μg/kg sc) produced similar results, whereas administration of EP 51389 (8...

Cardiovascular involvement in systemic autoimmune diseases

Autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), primary antiphospholipid syndrome (APS), systemic sclerosis and systemic vasculitis, affect a large number of people in whom one of the leading causes of morbidity and mortality is cardiovascular disease. Cardiovascular disease is associated with the development of accelerated atherosclerosis. It seems to occur at a younger age than in the general population, is often asymptomatic and, in addition to traditional risk factors, also involves specific risk factors as chronic inflammation, the duration and activity of the autoimmune disease, and immunosuppressive therapy. The early phases of cardiovascular involvement in patients with autoimmune diseases may be clinically silent, with only a microcirculation disorder present. There are various means of detecting morphological cardiac damage: coronary angiography remains the gold standard for diagnosing coronary stenosis, but new, non invasive and more reliable methods have been introduced into clinical practice in order to detect subclinical microcirculation abnormalities.

Cardiac ischemia and impairment of vascular endothelium function in hearts from GH-deficient rats: Protection by hexarelin

The ability of hexarelin, an effective growth hormone (GH)-releasing hexapeptide, to reverse the worsening of cardiac dysfunction in GH-deficient animals was studied in young male rats passively immunized by administration of an anti-GH-releasing hormone (GHRH) serum. Heart preparations from anti-GHRH serum-treated rats, undergoing low-flow ischemia and reperfusion, showed: (1) a progressive increase of left ventricular end-diastolic pressure during the ischemic period and a poor recovery of contractility at reperfusion with a consistent decrease of the left ventricular-developed pressure; (2) a decreased rate of formation of 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), a stable metabolite of prostacyclin, in perfusates from preischemic and reperfusion periods; (3) an increased vasopressor activity of angiotensin II. Hexarelin (80 microg/kg, bid, s.c.), administered for 15 days to anti-GHRH serum-treated rats, restored to normal the impaired somatotropic function and counteracted the ischemic damage, improving postischemic left ventricular developed pressure to values higher than those of controls. Furthermore, both the generation of 6-keto-PGF1alpha and the vasopressor activity of angiotensin II reverted to those of control preparations. Administration of hexarelin to control rats induced a considerable improvement of postischemic ventricular function of the perfused hearts which was similar to that present in preparations from anti-GHRH serum-treated rats given hexarelin. This protective activity was divorced from any further stimulation of somatotropic function. Collectively, these data indicate that, in GH-deficient rats, hexarelin is capable of restoring somatotropic function and has a beneficial effect in myocardial ischemia and reperfusion damage. In addition, the increased responsiveness of the coronary vasculature to angiotensin II and the decreased generation of prostacyclin in hearts from GH-deficient rats would indicate that for prevention of injury and dysfunction of the vascular endothelium a normal somatotropic function is mandatory.

Enalapril and quinapril improve endothelial vasodilator function and aortic eNOS gene expression in l-NAME-treated rats

Endothelial dysfunction ensuing inhibition of nitric oxide synthase (NOS) was investigated in male Sprague-Dawley rats given N(omega)-nitro-L-arginine methyl ester (L-NAME) in drinking water for 8 weeks. Age-matched rats served as controls. L-NAME-treated rats, as compared to control animals, showed: (1) a clear-cut increase in systolic blood pressure; (2) a consistent decrease of endothelial-cell NOS (eNOS) gene expression in aortic tissue; (3) a reduction of the relaxant activity of acetylcholine (ACh, from 10(-10) to 10(-4) M) on norepinephrine-precontracted aortic rings (reduction by 52+/-5%); (4) a marked decrease (-50%) of the basal release of 6-keto-prostaglandin F(1 alpha) (6-keto-PGF(1 alpha)) from aortic rings. In L-NAME-treated rats, administration in the last 2 weeks of either the angiotensin-converting enzyme inhibitor enalapril (1 mg/kg/day) or the cognate drug quinapril (1 mg/kg/day) decreased systolic blood pressure levels, completely restored eNOS mRNA levels in aortic tissue, and allowed a consistent recovery of both the relaxant activity of ACh and the generation of 6-keto-PGF(1 alpha). No difference was present in the ability of the two angiotensin-converting enzyme inhibitors to reverse NAME-induced endothelial dysfunction. These findings indicate that L-NAME-induced hypertension in the rat relies on the marked impairment of the endothelial vasodilator function, with an ensuing contribution by a decreased production of prostacyclin by the endothelial cells. Angiotensin-converting enzyme inhibition by enalapril or quinapril was equally effective in improving endothelial vasodilator function, prostacyclin endothelial production and restoring aortic eNOS mRNA.

Coronary Flow Reserve and Asymmetric Dimethylarginine Levels: New Measurements for Identifying Subclinical Atherosclerosis in Patients with Psoriatic Arthritis

Objective. To identify the presence of subclinical atherosclerosis in patients with psoriatic arthritis (PsA) and healthy controls using intima-media thickness (IMT), coronary flow reserve (CFR), and the plasma concentration of asymmetric dimethylarginine (ADMA), to evaluate the correlations among ADMA, IMT, and CFR. Methods. The study involved 22 patients who fulfilled the ClASsification of Psoriatic ARthritis study group criteria for PsA and a cohort of 35 healthy controls with no history or current signs of coronary artery disease (CAD). Common carotid IMT was measured using high-resolution B-mode ultrasonography. Dipyridamole transthoracic stress echocardiography was used to evaluate CFR. Blood samples were obtained to assess ADMA levels. The clinical manifestations were recorded. All patients were treated with disease-modifying antirheumatic drug, but none had received any biological or steroid therapy. Results. Plasma ADMA levels were significantly higher in the patients with PsA (0.71 ± 0.07 μmol/l vs 0.48 ± 0.07 μmol/l; p = 0.00) and CFR was significantly reduced in that group (2.86 ± 0.70 vs 3.3 ± 0.43; p < 0.01) compared to controls. Common carotid IMT was greater in the patients with PsA, but the difference was not significant (0.64 ± 0.26 mm vs 0.62 ± 0.5 mm; p = 0.65). There was a significant correlation between CFR and plasma ADMA levels in the PsA group (R = 0.28; p < 0.01), but no correlation between plasma ADMA levels and IMT (R = 0.02; p = 0.32), Disease Activity Score 28 (p = 0.52), or Psoriasis Area and Severity Index (p = 0.98). Conclusion. Our patients with PsA showed a profile of subclinical atherosclerosis. ADMA may be a useful marker of endothelial dysfunction in PsA.

Central mechanisms subserving the impaired growth hormone secretion induced by persistent blockade of NMDA receptors in immature male rats

Recently, we have reported in immature female rats that short-term blockade of glutamate receptors of the N-methyl-D-aspartic acid (NMDA) subtype by the noncompetitive antagonist MK-801 induced a reduction of growth rate, basal and stimulated growth hormone (GH) release and plasma somatomedin C levels. In the present study, we investigated in immature male rats the mechanism(s) through which agonists and antagonists of glutamate receptors affect GH secretion. In 21-day-old male rats, administration of MK-801 (0.2 mg/kg i.p.b.i.d.) for 10 days induced a significant impairment of growth rate, which was unrelated to a significant reduction of food intake. GH secretion from anterior pituitary fragments of MK-801-treated rats was not significantly reduced under basal conditions but was significantly less under stimulation by 40 mM K+. Incubation of dispersed pituitary cells of 31-day-old rats with N-methyl-aspartic acid (1 and 100 microM), alone or associated with MK-801 (1 microM) did not change GH secretion. Semi quantitative densitometric analysis of hypothalami of MK-801-treated rats evidenced a clearcut decrease in the intensity of GHRH-like immuno-reactivity (LI) staining in the median eminence (ME), whereas no difference was observed in the ME-somatostatin (SS)-LI. Finally, GHRH mRNA but not SS-mRNA, evaluated by slot-blot hybridization, was reduced in the hypothalamus of MK-801-treated rats. These and our previous data would demonstrate that NMDA glutamate receptors play an important role in the neuroendocrine control of GH secretion in the rat, and suggest an action mediated by GHRH-secreting neurons.

Silent cardiovascular involvement in patients with diffuse systemic sclerosis: a controlled cross-sectional study.

An association between systemic autoimmune diseases and atherosclerosis has been described in many connective tissue diseases, and this association is known to lead to increased cardiovascular morbidity and mortality. Systemic sclerosis (SSc) is characterized by multisystem organ inflammation, endothelial wall damage, and vasculopathy. There are many markers of endothelial dysfunction and/or atherosclerotic risk, such as asymmetric dimethylarginine (ADMA), arterial stiffness parameters, carotid intima‐media thickness (CIMT), and coronary flow reserve (CFR) assessed by transthoracic echocardiography. The aim of this pilot study was to use various endothelial and atherosclerosis markers to identify early cardiovascular involvement in a group of SSc patients.

Feedback effects of growth hormone on growth hormone-releasing hormone and somatostatin are not evident in aged rats

In 8- and 20-month-old male rats, treated or not with growth hormone (GH) for 4 days, simultaneous evaluation of hypothalamic GH-releasing hormone (GHRH) and somatostatin (SS) gene expression, GH secretion from anterior pituitaries (APs) in vitro (basal and GHRH-stimulated) and plasma IGF-I levels was performed. Twenty-month-old rats showed decreased GHRH mRNA levels, decreased GH secretion from APs in vitro (not responsive to GHRH stimulation) and reduced plasma IGF-I levels as compared to younger counterparts. SS mRNA levels were only slightly reduced in the hypothalamus of aged rats. Short-term administration of biosynthetic human GH (125 microgram/rat, twice daily, IP) to 8-month-old rats abolished the in vitro GHRH-stimulated GH release from APs and altered GH regulatory neuropeptides gene expression, i.e., reducing GHRH mRNA levels and increasing SS mRNA levels. In 20-month-old rats, hGH administration increased plasma IGF-I levels but did not change significantly GHRH and SS gene expression. These data indicate that the feedback effects exerted by circulating GH on GHRH and SS neurons, while evident in adult rats, are not detectable in aged rats.

Robotic treadmill training improves cardiovascular function in spinal cord injury patients.

BACKGROUND Body weight supported treadmill training (BWSTT) assisted with a robotic driven gait orthosis (DGO) is an emerging tool in rehabilitating patients with lost sensorimotor function. Few information about the effects of BWSTT on cardiovascular system are available. The purpose of this study was to determine the effects of BWSTT on: 1) left ventricular (LV) systo-diastolic function; 2) coronary flow reserve (CFR); 3) endothelial function in patients with lost sensorimotor function due to neurologic lesions. METHODS Fourteen adults (males 10, age 50.6±17.1years) with motor incomplete spinal cord injuries (SCI) due to trauma or spondylotic diseases underwent standard echocardiographic examination, non invasive assessment of CFR by dipyridamole stress echo and determination of plasma asymmetric dimethylarginine (ADMA) levels at baseline and after 6weeks of BWSTT. RESULTS At post training evaluation we observed lower LV end-diastolic (P=0.0164) and end-systolic volumes (P=0.0029) with increased ejection fraction (EF) (P=0.0266). We also observed a LV interventricular septum (IVS) (P=0.00469) increase. At the same time, we detected an improvement of LV diastolic function as witnessed by the reduction of isovolumic relaxation time (IVRT) (P=0.0404) and deceleration time (DT) (P=0.0405) with an increased E/A ratio (P=0.0040). Improved CFR (P=0.020) and reduced plasma ADMA levels (P=0.0005) have been observed too, in association with a reduction of the inflammatory status (C-reactive protein (CRP) (P=0.0022) and erythrocyte sedimentation rate (ESR) (P=0.0005)). CONCLUSION For the first time, this study demonstrated that 6weeks of BWSTT improved not only the sensorimotor function but also systo-diastolic LV function, CFR and endothelial dysfunction associated with a reduction of the inflammatory status in patients with incomplete SCI.

The heart in rheumatoid arthritis.

Morbidity and mortality rates are higher in rheumatoid arthritis (RA) patients than in the general population. Many studies have shown that coronary artery disease is one of the most common causes of death in RA and seems to occur at a younger age than in the general population. RA per se is as much a cardiovascular (CV) risk factor as diabetes, arterial hypertension and dyslipidemia etc., and so it is necessary to plan a follow-up using the same diagnostic and therapeutic approaches as those commonly used for primary and secondary prevention in non-RA patients at high CV risk. All of the cardiac structures can be affected during the course of RA (valves, the conduction system, the myocardium, endocardium and pericardium, and the coronary arteries), and cardiac complications include a variety of clinical manifestations. As these are all associated with an unfavourable prognosis, it is essential to detect subclinical cardiac involvement in still asymptomatic RA patients in order to assure adequate long-term treatment.