Giovanni Brotzu

Inhibition by chlorpromazine of the effects of dopamine on the dog kidney

Dopamine‐induced vasodilatation in the renal artery of the dog is reversed by chlorpromazine while the vasodilatation produced by isoprenaline is not. Pronethalol has the entirely opposite actions on this preparation. The infusion of dopamine into the renal artery enhances the kidney output of water, sodium, potassium and urea. These effects are also reversed by chlorpromazine.

Opposite pattern of MDR1 and caveolin-1 gene expression in human atherosclerotic lesions and proliferating human smooth muscle cells.

Abstract: Cholesterol esterification and smooth muscle cell (SMC) proliferation are the crucial events in the development of atherosclerotic lesions. The objective of this study was to analyse cholesterol esterification and the expression of MDR1 (multidrug resistance), ACAT (acyl-CoA:cholesterol acyltransferase) and caveolin-1 genes in atherosclerotic and healthy vascular walls, in SMCs obtained from atherosclerotic lesions and saphenous veins. Results demonstrated higher levels of cholesterol esters, ACAT and MDR1 mRNAs and lower levels of caveolin-1 mRNA in atherosclerotic segments compared to adjacent serial sections of the same artery and the corresponding non-atherosclerotic arteries from cadaveric donors. SMCs isolated from atherosclerotic plaques manifested an increased capacity to esterify cholesterol and to grow at a faster rate than SMCs isolated from saphenous veins. In addition, when SMCs from atherosclerotic plaques were cultured in the presence of progesterone, a potent inhibitor of cholesterol esterification, significant growth suppression was observed. An increase in ACAT and MDR1 expression and a concomitant decrease in caveolin-1 expression were also observed in SMCs isolated from atherosclerotic arteries as early as 12 h after serum stimulation. An opposite pattern was found when SMCs were treated with progesterone. These findings support the idea that cholesterol esterification plays a role both in early atherogenesis and in clinical progression of advanced lesions and raise the possibility that the cholesterol ester pathway might directly modulate the proliferation of SMCs.

MDR1 gene expression in normal and atherosclerotic human arteries(1).

Recent studies have shown that a membrane p-glycoprotein, encoded by MDR1 gene, is involved in the transport of free cholesterol from the plasma membrane to endoplasmic reticulum, the site of cholesterol esterification by acyl-CoA:cholesterol acyltransferase (ACAT). Moreover, results deriving from our previous studies have shown that the rate of cell proliferation was positively correlated with cholesteryl ester levels as well as with ACAT and MDR1 gene expression. In this study, lipid content and the expression of the genes involved in cholesterol metabolism such as hydroxy-methylglutaryl coenzyme A reductase (HMGCoA-R), low-density lipoprotein receptor (LDL-R), ACAT and MDR1 have been investigated in control and atherosclerotic arteries. The results have shown that the levels of cholesteryl ester increase with the age of cadaveric donors in arteries prone to atherosclerosis (abdominal aorta, superficial femoral artery) and become predominant in advanced atherosclerotic lesions. The mRNA levels of ACAT and MDR1 showed the same age correlation, reaching the highest values in atherosclerotic specimens. These results suggest that MDR1 may be involved in the accumulation of intracellular cholesterol ester levels found in atherosclerotic lesions. Moreover, the levels of HMGCoA-R, LDL-R and ACAT gene expressions progressively increased with the age of cadaveric donors; conversely, in atherosclerotic specimens, the mRNA levels of HMGCoA-R and LDL-R drastically decreased while ACAT gene expression reached its maximum. These findings suggest a reactivation of normal homeostatic regulation of cholesterol in advanced and complicated lesions.

The importance of presynaptic beta receptors in Raynaud's disease

The purpose of the present study was to investigate the effect of atenolol, a beta 1-selective blocker, along with flunarizine, a calcium antagonist, in the management of Raynauds disease. Forty patients with Raynauds disease were randomized into a trial in which atenolol (50 mg daily) was given with flunarizine (10 mg daily). During the trial all patients were subjected to finger photoplethysmography and were given a diary to note daily the number and duration of the crises and presence or absence of pain and paresthesia. The association of atenolol with flunarizine caused an 80% reduction in the number of vasospastic crises, a significant increase (p less than 0.001) in the photoplethysmographic wave amplitude, and complete disappearance of pain and paresthesia. These results were not observed in patients treated with a placebo. Flunarizine reinforces the action of atenolol in causing a decrease in vasoconstriction in patients with Raynauds disease, as observed previously by us, in that it acts directly on the beta-presynaptic receptors or on the calcium slow channels connected to the beta-receptors. The present study confirms that the principal role in the physiopathologic progression of Raynauds disease seems to be played by a modification of the beta-presynaptic receptors in the nerve endings of the peripheral vessels.

Substance P-like immunoreactivity in human sympathetic ganglia

Substance P-like immunoreactive nerve fibres and terminals are found in the human sympathetic paravertebral ganglia in connection with postganglionic neurones. Substance P may act as neurotransmitter or neuromodulator in the autonomic transmission in man.

Evidence of Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) in Pancreatic Islet Cells by Confocal Microscopy

Several studies have shown that pituitary adenylate cyclase activating polypeptide (PACAP) stimulates at very low concentration insulin release from pancreatic beta cells. In addition, PACAP has been evidenced in pancreatic nervous fibers surrounding the islets, the core of the islet, and the capillaries. The aim of the present study was to demonstrate internalization of PACAP in pancreatic islet cells. Pancreatic islets were obtained from Wistar rat pancreata by modified Lacys isolation method. The isolated islets were incubated in the presence of Fluo-PACAP 27, a fluorescent ligand specific for PACAP receptors. At the end of incubation the islets were fixed in paraformaldehyde and then observed by confocal microscope. Fluo-PACAP 27 was internalized into pancreatic islet cells, and this process was time-and temperature-dependent (37°C). The fluorescent molecules converged toward the nucleus where an intense fluorescence was evidenced after 60 minutes. Incubation with phenyl arsine oxide as well as with PACAP 6–38, a receptor antagonist, prevented the internalization process. Further studies are required to explain the internalization process of PACAP 27 into the nucleus of pancreatic islet cells.

Use of Biocytin as neuroanatomic tracer in harvested human pancreas: A confocal laser scanning microscopy analysis

Introduction To identify central neuroanatomic structure, biocytin labeling has recently been used. To date, there are no bibliographic references about the use of this molecule in investigations of the peripheral nervous system. In the present study, fresh, harvested human pancreas was used to evidence pancreatic innervations by biocytin. Aim To investigate for the first time pancreatic innervation in harvested pancreas from human multiorgan cadaveric donors. Methodology Biocytin labeling was used as a neuroanatomic tracing method, and confocal laser scanning microscopy was used for analysis for description by means of high-resolution images. Results The application of biocytin–avidin staining in harvested human pancreas revealed numerous bundles of nervous fibers, intrapancreatic ganglia, few small solitary neurons, and a large number of positive supporting cells (glial-like cells). Biocytin appeared to pass through gap junctions between glial elements and neurons and among the neurons. In human pancreas, biocytin is rapidly transported in both anterograde and retrograde directions, with consequent visualization of fine details of pancreatic innervation morphology. Indeed, evidence of anterograde and retrograde transportation of biocytin has been demonstrated in the extensive labeling of pancreatic preganglionic and postganglionic fibers as well as a great number of chemical buds that wind through exocrine tissue or undetermined target cells. Conclusion To our knowledge, this is the first report of the successful use of biocytin in neuronal retrograde and anterograde labeling in the human peripheral nervous system.

Stereomorphological arrangement of capillaries in skeletal muscle in normal and stenosed young and adult rats

The stereomorphological arrangement of skeletal muscle capillaries depends on many factors. Genetic biochemical composition of muscle fibers, age, and training can interfere with the growth of the capillary network. This study is focused on the age effect of chronic reduction of blood flow, as in arterial stenosis, in skeletal muscle network of young rats when compared with adult rats. It has been observed that there is a statistically significant decrease of the length of short capillaries which cross the muscle fibers. In adult rats the opposite occurs.