Knowledge and Attitudes on Food Hygiene among Food Services Staff on Board Ships

BACKGROUND

Ships have long been sites for outbreaks of infectious diseases, particularly gastrointestinal diseases. The ship environment has the potential to facilitate the spread of such diseases, infecting susceptible cohorts of embarked passengers and crew. Gastrointestinal disorders among seafarers are fairly common and usually represent the first or second cause of requests for medical assistance aboard ships in international waters.

STUDY DESIGN

The purpose of this study was to evaluate food safety and the level of knowledge among food service personnel on board merchant ships, where food handlers could be a cause of health problems for all crew members.

METHODS

An anonymous self-administered questionnaire containing specific questions about food hygiene and safety knowledge was administered.

RESULTS

The overall score of correct answers for the food safety aspects tested was 51.77 (SD 3.87) out of 76 points, corresponding to 68.12% of questions answered correctly. Food workers who followed a training course showed higher mean knowledge score (p < 0.05) compared to not-trained workers. The most relevant significant differences (p < 0.05) were noticeable in the personal hygiene, cross-contamination, safe storage, and knowledge of foodborne pathogens sections.

CONCLUSION

Food services staff on board cargo ships should be adequately trained and should understand basic and fundamental aspects of food hygiene, related pathologies and sanitation, as they are responsible for the health and wellbeing of many seafarers.

Evaluation of medical prescriptions and off-label use on board ships to improve healthcare quality

OBJECTIVE

This study analyzed the appropriateness of drug therapies prescribed for a particular category of patients: the seafarers. We investigated an important problem of this area: the off-label use of drugs, which resulted to be a consequence of major shortcomings in the on-board pharmacies of ships. The off-label use of drugs is allowed, but can lead to some not negligible ethical and health problems, compromising the quality of provided healthcare.

MATERIALS AND METHODS

The analysis was performed on electronic health records of patients onboard ships without physicians, and assisted by the CIRM from 2011 to 2015. This work is divided into two phases: in the first one, we classified the diagnoses registered onboard on the basis of the ICD-10 classification proposed by the WHO. In the second phase, we evaluated the congruence of the pharmacological therapies prescribed by CIRM physicians, according to the MICROMEDEX Database, which provides comprehensive information about drugs and their use.

RESULTS

From the analysis emerged that prescribed drugs were not always corresponded to their primary indication of use. In particular, in 2011 off-label drug use was widely spread (more than 30%) in some ICD-10 classes. In the following years (2012-2015) a decrease of off-label use of drugs was noticed.

CONCLUSIONS

The results suggest that a standardization of onboard pharmacies is crucial, in order to have a complete on-board pharmacy that will allow preventing and counteracting any situation of health danger, which may occur onboard, ensuring high quality healthcare to seafarers all over the world.

Effect of lipoic acid and α-glyceryl-phosphoryl-choline on astroglial cell proliferation and differentiation in primary culture

Lipoic acid plays a crucial role as antioxidant and metabolic component of enzymes involved in glucose metabolism of different cell types. Choline alphoscerate (α-glyceryl-phosphoryl-choline [αGPC]) is a semisynthetic derivative of phosphatidylcholines representing, among acetilcholine precursors, a cholinergic drug. In the present study, we evaluated the expression of some proliferation and differentiation markers in 15 or 21 DIV astrocyte cultures treated with 50 μM (+)lipoic acid or (+/-)lipoic acid and/or 10 mM αGPC for 24 hr. In addition, we evaluated the possible genoprotective effect by analysis of DNA status detected by alkaline comet assay. The addition of single drugs [(+)lipoic acid, (+/-)lipoic acid, or αGPC] induced an "upward modulation" of the expression of biomarkers used in our study. On the contrary, the cotreatment with either (+)lipoic acid + αGPC or (+/-)lipoic + αGPC surprisingly showed no significant modification or even a downregulation of the above-mentioned biomarkers. This latter finding demonstrated no additional effect after the cotreatment with both drugs with respect to the single treatments alone. Further studies are necessary to clarify the specific mechanism evoked by the processing of these neuroprotective agents in our in vitro models. Finally, these preliminary findings may represent a good tool with which to clarify the antioxidant and metabolic roles played by lipoic acid in proliferating and differentiating astroglial cell cultures, during an interactive cross-talk between glial and neuronal cells, after brain lesions or damage correlated with oxidative stress that may occur in some degenerative diseases.

Cholinergic precursors modulate the expression of heme oxigenase-1, p21 during astroglial cell proliferation and differentiation in culture

Heme oxygenase-1 (HO-1) plays a crucial role in oxidative stress processes, apoptosis and cell differentiation. Further, some proteins related to cell cycle including cyclins and p21 are important markers of astrocyte cultures. Aim of investigation was to study the effects of cholinergic precursors (choline, CDP-choline, Acetylcholine and α-Glyceril-Phosphorylcholine) on HO-1 and p21 expression during astroglial cell proliferation and differentiation in primary cultures at 14 and 35 days in vitro (DIV) treated for 24 h with choline metabolites. Our results showed a slight reduction of HO-1 expression (data not statistical significant) in astroglial cell cultures treated with CDP-choline at 14 DIV and 35 DIV. On the contrary, ACh and choline induced a significant increase of HO-1 expression in 14 DIV astrocyte cultures. Surprisingly, choline and ACh dramatically reduced HO-1 expression at 35 DIV. A slight decrease not statistical significant was detectable for α-GPC at 14 DIV and particularly significant at 35 DIV. Data concerning p21 expression, a well known protein inhibiting cell cycle, evidenced a significant increase at 14 and 35 DIV after α-GPC treatment. CDP-choline treatment caused a high increase of p21 expression in 14 DIV astrocyte cultures, but no modification at 35 DIV. Instead, ACh treatment induced a marked increment of p21 expression at 35 DIV. Our data suggest that cholinergic precursors modulate HO-1 and p21 expression during astroglial cell proliferation and differentiation in culture and could be considered a tool to study the induced effects of ischemia and hypoxia diseases in some in vitro models to prevent and reduce its effects after treatment with cholinergic drugs.

Aldosterone does not modify gene expression in human endothelial cells

The toxic effects of aldosterone on the vasculature, and in particular on the endothelial layer, have been proposed as having an important role in the cardiovascular pathology observed in mineralocorticoid-excess states. In order to characterize the genomic molecular mechanisms driving the aldosterone-induced endothelial dysfunction, we performed an expression microarray on transcripts obtained from both human umbilical vein endothelial cells and human coronary artery endothelial cells stimulated with 10 - 7 M aldosterone for 18 h. The results were then subjected to qRT-PCR confirmation, also including a group of genes known to be involved in the control of the endothelial function or previously described as regulated by aldosterone. The state of activation of the mineralocorticoid receptor was investigated by means of a luciferase-reporter assay using a plasmid encoding a mineralocorticoid and glucocorticoid-sensitive promoter. Aldosterone did not determine any significant change in gene expression in either cell type both in the microarray and in the qRT-PCR analysis. The luciferase-reporter assay showed no activation of the mineralocorticoid receptor following aldosterone stimulation. The status of nonfunctionality of the mineralocorticoid receptor expressed in cultured human umbilical and coronary artery endothelial cells does not allow aldosterone to modify gene expression and provides evidence against either a beneficial or harmful genomic effect of aldosterone on healthy endothelial cells.

Awareness of health risks at the workplace and of risks of contracting communicable diseases including those related to food hygiene, among seafarers

BACKGROUND

The awareness of health risks on board ships in terms of knowledge of dangers and discomfort at the workplace, and of risks of contracting communicable diseases including those related to food hygiene was assessed in a sample of workers of an Italian shipping company. Analysis was performed on crew members and on ashore personnel of the same firm to assess possible differences in risk perception.

MATERIALS AND METHODS

The study was conducted by proposing an anonymous questionnaire to the crew members of 9 tankers and to the office staff of the shipping company Finaval S.p.A., which has its headquarters in Rome.

RESULTS

People living ashore have a better knowledge of infectious risks than seafarers. Both ashore workers and seafarers have a reasonable awareness of blood-borne and sexually-transmitted diseases. Seafarers are more concerned about the risks of psychological problems due to isolation than are office personnel. The risk of not being adequately cared for in case of disease or injury on board is also perceived as a major problem by seafarers. Ashore personnel, eating raw fish more than their mates on board, are at a greater risk of communicable gastrointestinal diseases.

CONCLUSIONS

Seafarers should be the target of specific informative campaigns about health risks, possible consequences, and how to minimize exposure to them during travel/life at sea.

Survey on HIV risk perception and sexual behaviours among seafarers

Because the nature of their work seafarers spend long periods of time away from their families and therefore represent a group at risk for sexually transmitted diseases, including HIV infection. This paper reports the results of a survey to evaluate awareness and knowledge of the risk of HIV infection among seafarers. Risky behaviours for HIV transmission were also assessed. The survey was conducted using anonymous questionnaires on 197 workers of 9 vessels and 26 office employees of an Italian shipping company (FINAVAL S.p.A., Rome). The respondents considered HIV/AIDS as one of the diseases with a high risk of transmission. Most respondents had a good general knowledge of HIV/AIDS and on the ways of its transmission. However, there is still lack of knowledge on the basics of this disease. On the other hand, in spite of knowledge and awareness about the risks of the disease, only 56.35% of the interviewed crewmembers used protection in sexual intercourse with occasional partners. Compared to data available in literature, the percentage of self-protecting people is increasing, but the number of seafarers exposing themselves to risky behaviours is still high. As expected, condoms are used with regular partners with lower frequency compared to occasional intercourse. The results of this survey indicate that adequate prevention campaigns and major attention paid to seafarers health is useful for stimulating responsible conduct for the prevention of infectious diseases, including HIV infection. Nevertheless, it is still necessary to increase information about the risk of sexually transmitted diseases and how to reduce it.

Effect of growth factors and steroids on transglutaminase activity and expression in primary astroglial cell cultures

Type-2 transglutaminase (TG-2) is a multifunctional enzyme involved in the regulation of cell differentiation and survival that recently has been shown to play an emerging role in astrocytes, where it is involved in both proliferation and differentiation processes. Growth factors (GFs) such as EGF, basic fibroblast growth factor, insulin-like growth factor-I (IGF-I), and insulin (INS) are trophic and mitogenic peptides that participate in neuron-glia interactions and stimulate neuronal and astroglial proliferation and differentiation. Steroid hormones such as glucocorticoids and estrogens also play a pivotal role in neuronal and astroglial proliferation and differentiation and are key hormones in neurodegenerative and neuroprotective processes. We investigated the effects of the interaction of GFs with dexamethasone (DEX) or 17beta-estradiol (E(2)) on TG-2 activity and their expression in cultured astrocytes. We observed a significant increase in TG-2 activity and expression in astroglial cells treated for 24 hr with IGF-I, EGF, or INS. Priming of the cells with DEX or E(2), for 48 hr also led to an increase in TG-2 levels. When growth factors were present in the last 24 hr of the steroid treatment, a reduction in TG-2 expression and activity and a different subcellular TG-2 distribution were found. Our data indicate that steroid hormone-GF interaction may play an important role in astroglial function. The effect on TG-2 could be part of the regulation of intracellular pathways associated with the astrocyte response observed in physiological conditions and, possibly, also in neuropathological diseases.

Pathways of acetylcholine synthesis, transport and release as targets for treatment of adult-onset cognitive dysfunction

Acetylcholine (ACh) is a neurotransmitter widely diffused in central, peripheral, autonomic and enteric nervous system. This paper has reviewed the main mechanisms of ACh synthesis, storage, and release. Presynaptic choline transport supports ACh production and release, and cholinergic terminals express a unique transporter critical for neurotransmitter release. Neurons cannot synthesize choline, which is ultimately derived from the diet and is delivered through the blood stream. ACh released from cholinergic synapses is hydrolyzed by acetylcholinesterase into choline and acetyl coenzyme A and almost 50% of choline derived from ACh hydrolysis is recovered by a high-affinity choline transporter. Parallel with the development of cholinergic hypothesis of geriatric memory dysfunction, cholinergic precursor loading strategy was tried for treating cognitive impairment occurring in Alzheimer's disease. Controlled clinical studies denied clinical usefulness of choline and lecithin (phosphatidylcholine), whereas for other phospholipids involved in choline biosynthetic pathways such as cytidine 5'-diphosphocholine (CDP-choline) or alpha-glyceryl-phosphorylcholine (choline alphoscerate) a modest improvement of cognitive dysfunction in adult-onset dementia disorders is documented. These inconsistencies have probably a metabolic explanation. Free choline administration increases brain choline availability but it does not increase ACh synthesis/or release. Cholinergic precursors to serve for ACh biosynthesis should be incorporate and stored into phospholipids in brain. It is probable that appropriate ACh precursors and other correlated molecules (natural or synthesized) could represent a tool for developing therapeutic strategies by revisiting and updating treatments/supplementations coming out from this therapeutic stalemate.

Dopamine receptor subtypes in the human pulmonary arterial tree

Dopamine induces vasorelaxation of pulmonary artery primarily through an endothelium-dependent mechanism, but dopamine receptor subtypes involved in these mechanisms have not been identified yet. The expression and localization of dopamine D1-like (D1 and D5) and D2-like (D2, D3 and D4) receptors were investigated in hilar, lobar and intrapulmonary branches of human pulmonary artery by immunoblotting and immunohistochemistry. Pulmonary artery expresses dopamine D1, D2, D4 and D5 receptor subtypes, but not the D3 receptor subtype. Dopamine D1 and to a lesser extent D5 receptors were accumulated primarily in the endothelium of extrapulmonary branches of pulmonary artery. A faint dopamine D1 and D5 receptor immunoreactivity was found in the inner media of extrapulmonary and of large sized intrapulmonary branches of pulmonary artery, but not in medium- or small-sized intrapulmonary artery branches. Dopamine D2 and to a lesser extent D4 receptor immunoreactivity co-localized with the tyrosine hydroxylase-immunoreactive sympathetic plexus supplying pulmonary artery was found in the adventitia and in the adventitia-media of both extra- and different-sized intrapulmonary branches of pulmonary artery. These findings suggest the possible role of dopamine receptors in the pulmonary endothelium-dependent vasorelaxing activity. The D1 receptor subtype seems to be the most involved in this mechanism. Dopamine D2-like receptors are prejunctional and are located at the level of sympathetic neuroeffector plexus. The heterogeneous distribution and density of dopamine receptor subtypes along the human pulmonary arterial tree may be related to the different functional roles of dopamine at various levels of the pulmonary circulation.

Dopamine plasma membrane transporter (DAT) in rat thymus and spleen: an immunochemical and immunohistochemical study

The expression of the dopamine plasma membrane transporter (DAT) was investigated in rat thymus and spleen by immunochemical and immunohistochemical techniques. Antibodies raised against a peptide mapping near the amino terminus of DAT were bound to a single band of approximately 76 kDa in thymus and spleen membranes as well as in striatal and kidney membranes which were used as dopaminergic reference tissues. Reverse transcription-polymerase chain reaction analysis revealed that both thymus and spleen expressed DAT mRNA. Immunohistochemistry revealed in rat thymus a DAT immune reaction in the wall of arteries located in septa of connective tissue as well as in the medulla, with a reticular localization and an apparent negative reaction of thymocytes. In the spleen, DAT immunoreactivity was located primarily in the red-white pulp marginal zone, within small cells, likely corresponding to lymphocytes and in the wall of white pulp arteries. The presence of a dopamine transporter suggests that dopamine released in the lymphoid microenvironment may contribute to neuroimmune modulation. It cannot be excluded a different activity of dopamine in primary and secondary immune organs, such as maturation and selection of lymphocytes and activation of immune responses in the spleen.

Age-related changes in the visual cortex: a review

The main age related changes in visual cortex are reviewed. The visual cortex (occipital cortex, areas 17-19) undergoes a variety of anatomical, biochemical and functional changes with aging. From a morphological point of view the visual cortex loses nerve cells mainly in the last period of life. From a biochemical point of view cholinergic, serotonergic, and GABAergic neurotransmissions seem to be the most remarkably affected. In terms of functional correlates, a decline of several activities of the visual cortex has been documented in the elderly. Due to the importance of visual cortex in the realization of visual function, the influence of aging on this cerebrocortical area requires a more detailed analysis.

Effect of choline alfoscerate treatment on changes in rat hippocampus mossy fibres induced by monolateral lesioning of the nucleus basalis magnocellularis

We have recently demonstrated that monolateral lesions of the Nucleus Basalis Magnocellularis (NBM), which is a nucleus sending cholinergic projections to the fronto-parietal cortex, cause a loss in the intensity of Timm staining in the intrahippocampal pathway of mossy fibres (MF). Moreover, these lesions induce ultrastructural changes consistent with the occurrence of degeneration of presynaptic buttons of MF. The present study was designed to quantify the effects of NBM lesioning on the morphology of the presynaptic buttons of MF. Moreover the effects of 4-week choline alfoscerate (alphaGFC) treatment on the density of Timm staining and on the ultrastructure of presynaptic buttons of MF were assessed, alphaGFC, which was given at an oral daily dose of 100 mg/kg, is a precursor in the biosynthesis of several brain phospholipids which increases the availability of choline in the nervous tissue. Monolateral lesions of NBM cause, 4 weeks after lesioning, a significant decrease in the intensity of Timm staining in the MF area accompanied by a loss of about 23% of presynaptic buttons of MF. Moreover about 40% of presynaptic buttons of MF show an impaired morphology. alphaGFC administration restored the intensity of Timm staining in the MF area. In alphaGFC-treated rats, the loss of presynaptic buttons and the number of impaired buttons were reduced to about 12% and 27%, respectively in comparison with non-treated animals. These results confirm and extend our previous observations indicative of the occurrence of transneuronal degenerations in the MF of the hippocampus after monolateral NBM lesioning. Moreover these findings show that alphaGFC treatment is able to counter in part these degenerative changes.

Changes of dopamine-sensitive cyclic AMP-generating system in the rat hippocampus as a function of age

The dopamine (DA) D(1) and D(2) receptors coupled to the 3',5'-cyclic adenosine monophosphate (cAMP)-generating system were studied in membrane particles of the dorsal hippocampus in 3 (considered to be young), 12 (considered to be adult) and 24 (considered to be old) month male Sprague-Dawley rats. Activation of D(1) receptors with DA, apomorphine or SKF 82526 enhanced accumulation of cAMP in the hippocampus of rats of the three age groups examined. This stimulatory effect was significantly reduced in adult rats. No further changes were noticeable in old animals. D(2) receptors negatively coupled to cAMP generation were demonstrated by incubating hippocampus membrane particles with SCH 23390 plus DA or with D(2) receptor agonists quinpirole or bromocriptine. The D(2) inhibitory effect on cAMP generation was unchanged in the three age groups. No difference was detectable between young, adult and old rats in the activation of cAMP production by forskolin.

Autonomic innervation of immune organs and neuroimmune modulation

1. Increasing evidence indicates the occurrence of functional interconnections between immune and nervous systems, although data available on the mechanisms of this bi-directional cross-talking are frequently incomplete and not always focussed on their relevance for neuroimmune modulation. 2. Primary (bone marrow and thymus) and secondary (spleen and lymph nodes) lymphoid organs are supplied with an autonomic (mainly sympathetic) efferent innervation and with an afferent sensory innervation. Anatomical studies have revealed origin, pattern of distribution and targets of nerve fibre populations supplying lymphoid organs. 3. Classic (catecholamines and acetylcholine) and peptide transmitters of neural and non-neural origin are released in the lymphoid microenvironment and contribute to neuroimmune modulation. Neuropeptide Y, substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide represent the neuropeptides most involved in neuroimmune modulation. 4. Immune cells and immune organs express specific receptors for (neuro)transmitters. These receptors have been shown to respond in vivo and/or in vitro to the neural substances and their manipulation can alter immune responses. Changes in immune function can also influence the distribution of nerves and the expression of neural receptors in lymphoid organs. 5. Data on different populations of nerve fibres supplying immune organs and their role in providing a link between nervous and immune systems are reviewed. Anatomical connections between nervous and immune systems represent the structural support of the complex network of immune responses. A detailed knowledge of interactions between nervous and immune systems may represent an important basis for the development of strategies for treating pathologies in which altered neuroimmune cross-talking may be involved.

Localization of the m5 muscarinic cholinergic receptor in rat circle of Willis and pial arteries

The expression and microanatomical localization of the muscarinic cholinergic m5 receptor subtype was investigated in rat circle of Willis and pial arteries by in situ hybridization, immunoblotting and immunohistochemistry. In situ hybridization histochemistry revealed a strong signal in the endothelium of circle of Willis and pial arteries and a moderate signal in the tunica media of the same arteries, within smooth muscle. Exposure of membranes of arteries to anti-m5 receptor protein antibodies caused the development of a band of approximately 81 kDa. Immunohistochemistry revealed the accumulation of m5 receptor protein immunoreactivity primarily within endothelium of circle of Willis and cerebral arteries and to a lesser extent in the tunica media, within smooth muscle. Medium (external diameter 200-100 microm) and small-sized (external diameter smaller than 100 microm) pial arteries displayed a significantly higher immune staining than large-sized pial arteries or circle of Willis arteries. The above data that are consistent with recent functional studies reporting cholinergic dilation of cerebral blood vessels mediated via a m5 receptor, have shown that both endothelial and muscular components of cerebral arteries synthesize and express a muscarinic m5 receptor. In view of the peculiar localization in cerebral vessels, handling of the muscarinic m5 receptor may be considered as an approach in the treatment of cerebrovascular disease.

Activities of the International Radio Medical Centre (C.I.R.M.) in Rome during the last five years (1996-2000). Centro Internazionale Radio Medico

This paper reviews medical activity provided from 1996 to 2000 by the International Radio Medical Centre (Centro Internazionale Radio Medico, C.I.R.M.). C.I.R.M. is a non-profit organization headquartered in Rome and providing freely telemedical advice to ships flying of any flag navigating on all seas of the world, to civil airplanes and to small Italian islands. From 1996 to 2000 C.I.R.M. has assisted 4,982 patients, 4,686 of which (94%) on board ships, 85 on airplanes and 206 on small Italian islands. More than 65% of requests of telemedical advice received by C.I.R.M. were from non-Italian ships. This indicates the really international nature of C.I.R.M.'s activity. The largest number of medical requests come from the Atlantic Ocean, followed by the Mediterranean sea, Indian Ocean and Pacific Ocean. In terms of pathologies assisted, accidents took the first place, followed as main pathologies by gastrointestinal disorders, cardiovascular pathologies, respiratory disorders, infectious and parasitic diseases and nervous system complaints. Analysis of the outcome of C.I.R.M.'s medical activity showed that more than 50% of patients assisted were recovered or improved while assisted by the Centre.

The peripheral dopaminergic system: morphological analysis, functional and clinical applications

In vivo administration or in vitro application of dopamine or of dopamine receptor agonists induce vasodilatation in the cerebral, coronary, renal and mesenteric vascular beds and cause hypotension. Moreover, dopamine stimulates cardiac contractility and induces diuresis and natriuresis. Peripheral (cardiovascular and renal) dopamine receptors belong to the D1-like and D2-like receptor superfamilies, thought to be located post-junctionally and pre-junctionally respectively. Stimulation of vascular D1-like receptors causes direct vasodilatation and reduction of vascular resistance. Stimulation of vascular D2-like receptors causes indirect vasodilatation, resulting from inhibition of sympathetic vasoconstrictor tone. Combined radioligand binding assay and light microscope autoradiography have investigated the anatomical localization of cardiovascular and renal dopamine D1-like and D2-like receptors in different animal species including humans. The application of molecular biology techniques to dopamine receptor research has shown that the picture of dopamine receptor subtypes is more complicated than it was suggested in the past, with at least 5 subtypes belonging to the dopamine D1-like (D1 and D5 receptors) and D2-like (D2, D3 and D4 receptors) superfamilies. The development of antibodies raised against selected sequences of dopamine receptor subtypes has allowed a more detailed characterization of the density and pattern of peripheral dopamine receptors. Dopamine receptor protein immunohistochemistry confirmed the localization of dopamine D1 and D5 receptors in the tunica media of systemic arteries and of prejunctional dopamine D2-D4 receptors closely associated with sympathetic neuroeffector junctions. The distribution and the density of prejunctional dopamine D2-like receptors was different in various vascular beds investigated. The kidney expresses the 5 different subtypes of dopamine receptors, displaying a not homogeneous vascular and tubular localization. Dopamine acting as autocrine or paracrine substance is probably involved in the regulation of immune activity. Human peripheral blood lymphocytes contain dopamine and express plasma membrane and vesicular dopamine transporters as well as dopamine D3, D4 and D5 receptors. Another recently characterized peripheral dopaminergic system is located in the lung. Dopamine D1-like receptor immunoreactive structures were found in a small percentage of nerve fibres contained in pulmonary nerve trunks. D1-immunoreactive nerve fibres were approximately 2-3% of total fibres, whereas D5-immunoreactive fibres accounted approximately for 5-6% of total fibres. Also dopamine D2-like receptor immunoreactive fibres were found in pulmonary trunks. D2-immunoreactive fibres accounted for approximately 3-5% of total nerve fibres, D3 receptor-immnunoreactive fibres accounted for about 8-10% of total nerve fibres, whereas only rare profiles of D4 receptor protein-immunoreactive fibres were observed. Dopamine recepetor protein immunostaining was also found in neurons of nodose ganglion, that display immunoreactivity for different neuropeptides. Based on the correspondence between the number of dopamine receptor immunoreactive pulmonary nerve fibres and of vagal ganglionic neurons immunoreactive for dopamine receptors it is possible to hypothesize that these receptors are located on pulmonary afferents. In spite of the heterogeneity of peripheral systems expressing dopamine receptors, analysis of their localization with appropriate microanatomical techniques may contribute to investigate their role in health and disease.

Peripheral blood lymphocytes muscarinic cholinergic receptor subtypes in Alzheimer's disease: a marker of cholinergic dysfunction?

Muscarinic M2-M5 muscarinic cholinergic receptors were investigated in peripheral blood lymphocytes of patients with mild cognitive impairment of the Alzheimer's type (MCIAT), probable Alzheimer's disease (AD) and probable vascular dementia (VaD). [3H]-N-methyl scopolamine (NMS) in the presence of muscarinic antagonists and Mamba venom to occlude different receptor subtypes was used as radioligand. Analysis of [3H]-NMS binding curves without receptor subtype assessment resulted in a slight decrease of receptor density in AD patients. Evaluation of receptor subtypes in MCIAT and AD patients revealed a decrease of M3 receptor by more than 50%, an increase of M4 receptor expression by about 20% and no changes of M2 or M5 receptors. The expression of M2-M5 receptors was unaltered in VaD patients. Strong positive and negative correlations respectively were found between the density of lymphocyte M3 and M4 receptors and MMSE score in both MCIAT (0.78 for M3 receptor and 0.80 for M4 receptor) and AD (0.82 for M3 receptor and 0.83 for M4 receptor) patients. These findings suggest that changes in the expression of peripheral blood lymphocyte M3 and M4 receptors in AD are related to the degree of cognitive impairment. Assessment of lymphocyte muscarinic receptor subtypes may contribute to characterization of cholinergic impairment in AD.

Choline alphoscerate in cognitive decline and in acute cerebrovascular disease: an analysis of published clinical data

This paper has reviewed the documentation on the clinical efficacy of choline alphoscerate, a cholinergic precursor, considered as a centrally acting parasympathomimetic drug in dementia disorders and in acute cerebrovascular disease. Thirteen published clinical trials, examining in total 4054 patients, have evaluated the use of choline alphoscerate in various forms of dementia disorders of degenerative, vascular or combined origin, such as senile dementia of the Alzheimer's type (SDAT) or vascular dementia (VaD) and in acute cerebrovascular diseases, such as transitory ischemic attack (TIA) and stroke. Analysis has assessed the design of each study, in particular with respect to experimental design, number of cases, duration of treatment and tests used to evaluate drug clinical efficacy. Most of the ten studies performed in dementia disorders were controlled trials versus a reference drug or placebo. Overall, 1570 patients were assessed in these studies, 854 of which in controlled trials. As detected by validated and appropriate tests, such as Mini Mental State Evaluation (MMSE) in SDAT and Sandoz Clinical Assessment Geriatric (SCAG) in VaD, administration of choline alphoscerate significantly improved patient clinical condition. Clinical results obtained with choline alphoscerate were superior or equivalent to those observed in control groups under active treatment and superior to the results observed in placebo groups. Analysis stresses the clear internal consistency of clinical data gathered by different experimental situations on the drug effect, especially with regard to the cognitive symptoms (memory, attention) characterising the clinical picture of adult-onset dementia disorders. The therapeutic usefulness of choline alphoscerate in relieving cognitive symptoms of chronic cerebral deterioration differentiates this drug from cholinergic precursors used in the past, such as choline and lecithin. Three uncontrolled trials were performed with choline alphoscerate in acute cerebrovascular stroke and TIA, totalling 2484 patients. The results of these trials suggest that this drug might favour functional recovery of patients with cerebral stroke and should be confirmed in future investigations aimed at establish the efficacy of the drug in achieving functional recovery of patients with acute cerebrovascular disease.

Hypertensive brain damage: comparative evaluation of protective effect of treatment with dihydropyridine derivatives in spontaneously hypertensive rats

Hypertension is the main risk factor for cerebrovascular disease including vascular dementia and control of blood pressure might protect from lesions causing cognitive impairment. The influence of anti-hypertensive treatment on hypertensive brain damage was assessed in spontaneously hypertensive rats (SHR). SHR and age-matched normotensive Wistar Kyoto (WKY) rats were treated from the 14-26th week of age with the dihydropyridine-type Ca2+ channel blockers lercanidipine, manidipine and nimodipine and as a reference with the non-dihydropyridine-type vasodilator hydralazine. Volume of brain areas, number of nerve cells and glial fibrillary-acidic protein (GFAP)-immunoreactive astrocytes and neurofilament 200 kDa immunoreactivity were investigated in frontal and occipital cortex and in hippocampus. In control SHR, systolic blood pressure (SBP) was significantly higher in comparison with WKY rats. Compounds tested decreased to a similar extent SBP values in SHR, with the exception of nimodipine that caused a smaller reduction of SBP compared with other compounds. Decreased volume and number of nerve cells and loss of neurofilament protein immunoreactivity were observed in SHR. GFAP-immunoreactive astrocytes increased in number (hyperplasia) and in size (hypertrophy) in the frontal and occipital cortex of control SHR, and only in number in the hippocampus. Anti-hypertensive treatment countered in part microanatomical changes occurring in SHR. Drugs investigated with the exception of nimodipine exerted an equi-hypotensive effect. In spite of this the best protection was exerted by lercanidipine and, to a lesser extent, by nimodipine. Compared with nimodipine, lercanidipine induced a more effective decrease of SBP. This may represent an advantage in the treatment of hypertension with risk of brain damage.

Treatment of cognitive dysfunction associated with Alzheimer's disease with cholinergic precursors. Ineffective treatments or inappropriate approaches?

The observations of the loss of cholinergic function in neocortex and hippocampus in Alzheimer's disease (AD) developed the hypothesis that replacement of cholinergic function may be of therapeutic benefit to AD patients. The different approaches proposed or tested included intervention with acetylcholine (ACh) precursors, stimulation of ACh release, use of muscarinic or nicotinic receptor agonists and acetylcholinesterase (AChE) or cholinesterase (ChE) inhibition. Inhibition of endogenous ACh degradation through ChE inhibitors and precursor loading were treatments more largely investigated in clinical trials. Of the numerous compounds in development for the treatment of AD, AChE and ChE inhibitors are the most clinically advanced, although clinical trials conducted to date did not always confirm a significant benefit of these drugs on all symptom domains of AD. The first attempts in the treatment of AD with cholinergic precursors did not confirm a clinical utility of this class of compounds in well controlled clinical trials. However, cholinergic precursors most largely used such as choline and phosphatidylcholine (lecithin) were probably not suitable for enhancing brain levels of ACh. Other phospholipids involved in choline biosynthetic pathways such as CDP-choline, choline alphoscerate and phosphatidylserine clearly enhanced ACh availability or release and provided a modest improvement of cognitive dysfunction in AD, these effects being more pronounced with choline alphoscerate. Although some positive results cannot be generalized due to the small numbers of patients studied, they probably would justify reconsideration of the most promising molecules in larger carefully controlled trials.

Age-related changes of dopamine receptors in the rat hippocampus: a light microscope autoradiography study

Hippocampus is a brain region involved in learning and memory and is particularly sensitive to ageing. It is supplied with a dopaminergic innervation arising from the midbrain, which is part of the mesolimbic dopaminergic pathway. Dysfunction of the dopaminergic mesolimbic system is probably involved in the pathophysiology of psychosis and behavioural disturbances occurring in the elderly. The present study was designed to assess the density and localisation of dopamine D1- and D2-like receptor subtypes in the hippocampus of male Sprague-Dawley rats aged 3 months (young), 12 months (adult) and 24 months (old). Dopamine D1-like receptors, labelled by [3H]-SCH 23390, in young rats displayed a dentate gyrus-CA1 subfield gradient. The expression was increased in the cell body of dentate gyrus, CA4 and CA3 subfield of old rats compared to younger cohorts, as well as in the neuropil of dentate gyrus. A decreased density of dopamine D1-like receptors was found in the stratum oriens of CA1 and CA3 subfields. Dopamine D2-like receptors, labelled using [3H]-spiperone as radioligand, were expressed rather homogeneously throughout different subfields of the hippocampus. In old rats, the density of dopamine D2-like receptors was decreased in the dentate gyrus, unchanged in the CA4 and CA1 subfields and increased in the CA3 subfield. The above results indicate the occurrence of inhomogeneous changes in the density of dopamine D1- and D2-like receptors in specific portions of hippocampus of old rats. These findings support the hypothesis of an involvement of dopaminergic system in behavioural abnormalities or psychosis occurring in ageing.

Changes of retinal neurons and glial fibrillary acid protein immunoreactive astrocytes in spontaneously hypertensive rats

OBJECTIVE

The influence of arterial hypertension on retinal neurons and glial fibrillary acid protein (GFAP) immunoreactive astrocytes was investigated in spontaneously hypertensive rats (SHRs).

METHODS

The retinas of 4- and 6-month-old SHRs and age-matched Wistar-Kyoto rats (WKY) were investigated. A group of SHRs, treated from 4 to 6 months with the hypotensive drug hydralazine, was also examined. Microanatomical and immunohistochemical techniques associated with image analysis and the terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labelling (TUNEL) technique for apoptosis or necrosis were used, as well as astrocyte molecular biology (Western blot) techniques.

RESULTS

In 4-month-old SHR and WKY rats, retinal morphology and the number of retinal neurons and of GFAP-immunoreactive astrocytes were similar, with the exception of the occurrence of 1% of TUNEL-positive ganglionic neurons in SHRs. In 6-month-old SHRs a decrease of retinal volume and of the number of ganglionic neurons and photoreceptors was observed, compared with age-matched normotensive WKY rats or younger SHR and WKY rats. Two per cent of ganglionic neurons and 5% of photoreceptors were also TUNEL positive. In 6-month-old SHRs, hypertrophic perivascular GFAP-immunoreactive astrocytes were found, whereas their number was unchanged compared to younger cohorts or WKY rats. An increased expression of GFAP was also noticeable in SHRs by Western blot analysis. Hypotensive treatment with hydralazine partly countered retinal changes occurring in SHRs.

CONCLUSIONS

The occurrence of neuronal and astroglial changes when a stable hypertension was developed, and their sensitivity to antihypertensive treatment, suggest that they may represent a hypertension-related phenomenon.

Neurotrophins and neurotrophin receptors in human lung cancer

The expression of neurotrophins (NTs) and related high- and low-affinity receptors was studied in surgical samples of histologically diagnosed human tumors of the lower respiratory tract. The experiment was conducted with 30 non-small cell lung cancer specimens and in eight small cell lung cancer specimens by Western blot analysis and immunohistochemistry to assess expression and distribution of NT and NT receptor proteins in tissues examined. Immunoblots of homogenates from human tumors displayed binding of anti-nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and NT-3 antibodies as well as of anti-tyrosine-specific protein kinase (Trk) A, TrkB, and TrkC receptor antibodies, with similar migration characteristics than those displayed by human beta-NGF and proteins from rat brain. A specific immunoreactivity for NTs and NT receptors was demonstrated in vessel walls, stromal fibroblasts, immune cells, and sometimes within neoplastic cell bodies. Approximately 33% of bronchioloalveolar carcinomas exhibited a strong membrane NGF and TrkA immunoreactivity, whereas 46% adenocarcinomas expressed an intense TrkA immunoreactivity but a weak immunostaining for NGF within tumor cells. Moreover, squamous cell carcinomas developed an intense TrkA immunoreactivity only within stroma surrounding neoplastic cells. A faint BDNF and TrkB immunoreactivity was documented in adenocarcinomas, squamous cell carcinomas, and small cell lung cancers. NT-3 and its corresponding TrkC receptor were found in a small number of squamous cell carcinomas within large-size tumor cells. No expression of low-affinity p75 receptor protein was found in tumor cells. The detection of NTs and NT receptor proteins in tumors of the lower respiratory tract suggests that NTs may be involved in controlling growth and differentiation of human lung cancer and/or influencing tumor behavior.

Alpha1-adrenergic receptor subtypes in peripheral blood lymphocytes of essential hypertensives

OBJECTIVE

The expression of alpha1-adrenergic receptor subtypes in peripheral blood lymphocytes was investigated in 28 essential hypertensive patients as well as in the peripheral blood lymphocytes and aorta of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats.

METHODS

Alpha1-adrenergic receptors were quantified by radioligand binding assays, employing [3H]-prazosin as the radioligand in association with compounds displaying different degrees of selectivity for alpha1A-, alpha1B- and alpha1D-adrenergic receptor subtypes.

RESULTS

The affinity of [3H]-prazosin binding was similar in peripheral blood lymphocytes of different stage essential hypertensive and normotensive subjects or of SHR and age-matched normotensive WKY rats as well as in the aortas of SHR and WKY rats. The radioligand binding assay revealed no change in the expression of alpha1-adrenergic receptors in peripheral blood lymphocytes of essential hypertensives compared with normotensive subjects; a moderate decrease of alpha1B-adrenergic receptors and an increase of alpha1D-adrenergic receptors. The relative densities of the alpha1-adrenergic receptor subtypes were similar in the three groups of essential hypertensives. In peripheral blood lymphocytes and in aorta of SHR, [3H]-prazosin binding was significantly reduced compared with normotensive WKY rats. The expression of alpha1-adrenergic receptor subtypes in peripheral blood lymphocytes of SHR was similar to that found in peripheral blood lymphocytes of essential hypertensives.

CONCLUSIONS

Changes of lymphocyte alpha1-adrenergic receptor subtypes in essential hypertensives are similar to those observed in lymphocytes and vascular tissues of animal models of hypertension. This suggests that assays of lymphocyte alpha1-adrenergic receptors may represent an indirect marker of their involvement in essential hypertension.

Microanatomical changes of intracerebral arteries in spontaneously hypertensive rats: a model of cerebrovascular disease of the elderly

Changes occurring in intracerebral arteries of 24-week-old spontaneously hypertensive rats (SHR) compared with age-matched normotensive Wistar-Kyoto (WKY) rats were assessed using microanatomical techniques associated with image analysis. Morphometric parameters investigated included arterial diameter, lumen area, wall area, and wall-to-lumen ratio. Intracerebral arteries (lumen diameter>46 microm) and arterioles (lumen diameter 46-10 microm) of frontal cortex, striatum, and hippocampus were examined. In frontal cortex of SHR arterial wall hypertrophy and luminal narrowing were observed. In striatum, an increase of wall area not accompanied by luminal narrowing predominates resulting in arterial hypertrophy without vasoconstriction. In hippocampal arteries of SHR, luminal narrowing, without changes of wall area was found indicating the occurrence of remodeling. In brain areas investigated, hypertensive changes affected primarily arterioles. The demonstration of a sensitivity of intracerebral arteries to hypertension suggests that changes of these vessels may represent a cause of brain structural alterations occurring in hypertension. The specificity of alterations occurring in intracerebral arteries of brain areas investigated may account for the different localization of cerebral lesions in cerebrovascular disease. The possibility that microanatomical changes developed in intracerebral arteries of SHR may represent a model of cerebrovascular disease of the elderly is discussed.

Identification of dopamine plasma membrane and vesicular transporters in human peripheral blood lymphocytes

Plasma membrane dopamine transporter (DAT), vesicular monoamine transporters (VMAT) type-1 and -2 and the expression of the dopaminergic markers dopamine and tyrosine hydroxylase were assessed in membranes and/or in cytospin centrifuged human peripheral blood lymphocytes. The radiolabeled DAT ligand [3H]GBR12935 was bound to peripheral lymphocytes in a manner consistent with the specific binding to a dopamine uptake system, with a dissociation constant similar to that found in striatum, but with a lower density of binding sites. On the other hand, no specific binding occurred in cerebellum used as a test tissue not expressing DAT. Western blot analysis using antibodies raised against amino or carboxy terminus of DAT or against VMAT-1 or VMAT-2 revealed labeling of single bands of approximately 76, 55 or 68 KDa, respectively, displaying similar migration characteristics in lymphocytes and test tissues used for comparison. Immunofluorescence revealed that anti-dopamine, anti-tyrosine hydroxylase, anti-DAT, anti-VMAT-1 and anti-VMAT-2 antibodies labeled the total population of cytospin-centrifuged lymphocytes mounted on microscope slides. Confocal laser microscopy demonstrated that dopamine and VMAT-2 immunoreactivity was developed mainly in cytoplasmic punctiform areas likely corresponding to vesicles and to a lower extent was associated to plasma membrane. Tyrosine hydroxylase immunoreactivity was diffused to cytoplasm and to plasma membrane of lymphocytes, whereas DAT and VMAT-1 immunoreactivity were located almost exclusively in lymphocyte plasma membrane and cytoplasm, respectively. Lymphocyte DAT characterized in this study has probably functional relevance as [3H]dopamine was taken up by intact lymphocytes and uptake was inhibited specifically by compounds known to affect dopamine transport. These findings indicate that human peripheral blood lymphocytes possess DAT plasma membrane and VMAT-1 and VMAT-2 transporters. Increasing evidence indicates that dopamine transporter changes may be related to neuronal injury. In view of this assessment of lymphocyte DAT and VMAT transporters can be considered for identifying pathologies characterized by impaired dopaminergic neurotransmission.

Influence of treatment with Ca(2+) antagonists on cerebral vasculature of spontaneously hypertensive rats

Hypertension is the main cause of stroke that represents the second most common cause of death in the industrialized world and a leading cause of inability of the elderly. Lowering blood pressure reduces cerebrovascular morbidity and mortality, but it is still controversial if blood pressure should be lowered in elderly individuals with concomitant cerebrovascular disease. The present study has analyzed comparatively the effect of treatment with the dihydropyridine-type Ca(2+) channel blockers lercanidipine, manidipine and nimodipine and with the non dihydropyridine-type vasodilator hydralazine on hypertension-dependent cerebrovascular changes in spontaneously hypertensive rats (SHR). Analysis included medium and small sized pial arteries and intracerebral arteries of frontal cortex, hippocampus, striatum, and cerebellum. In control SHR, systolic pressure (SBP) values were significantly higher in comparison with WKY rats. Pharmacological treatment significantly decreased SBP values, with nimodipine reducing only moderately SBP. In control SHR, thickening of arterial wall accompanied by luminal narrowing with consequent increase of the wall-to-lumen ratio occurred both in pial and intracerebral arteries. Dihydropyridine-type Ca(2+) antagonists and to a lesser extent hydralazine countered these morphological alterations. Lercanidipine displayed a particular activity on small sized intraparenchymal brain arteries, where it was more effective than other compounds tested. This activity of lercanidipine on small-sized intracerebral arteries might represent an interesting property for the treatment of hypertensive brain damage with concomitant ischemia.

The International Radio Medical Centre (C.I.R.M.): an organization providing free medical assistance to seafarers of any nationality world wide

The International Radio Medical Centre (Centro Internazionale Radio Medico, C.I.R.M.) was founded in 1935 with the purpose of giving radio medical advice to ships on any nationality navigating on all seas of the world. The Centre has its headquarters in Rome, and its medical services are completely free of charge. They also include arrangements for the transfer, if necessary, of a patient to a ship with a doctor on board or if the distance allows it, to evacuate the patient for hospitalization. Requests for medical advice reaching C.I.R.M. are handled by doctors on continuos duty at the C.I.R.M. headquarters. These doctors advice on the appropriate treatment and keep in contact with every ship that has asked for assistance, following up the progress of the patient until his recovery or evacuation to the hospital on shore.

Dopamine receptors in human platelets

The expression of dopamine receptors by human platelets was investigated by Western blot analysis and immunocytochemical techniques using antibodies raised against dopamine D1-D5 receptor protein. The influence of dopamine D1-like and D2-like receptor agonists on adrenaline-induced platelet aggregation was also investigated. Western blot analysis revealed that platelet membranes bind anti-dopamine D3 or D5 receptor protein antibodies, but not anti-D1, D2 or D4 receptor protein antibodies. Cytospin centrifuged human platelets exposed to anti-dopamine D3 or D5 receptor protein antibodies developed a specific immune staining, whereas no positive staining was noticeable in platelets exposed to other antibodies tested. Both the D1-like receptor agonist 1-phenyl2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrochloride (SKF 38393) and the D2-like receptor agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) dose-dependently inhibited adrenaline-induced platelet aggregation. These effects were decreased respectively by the D-like and D2-like receptor antagonists R(+)-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol hydrochloride (SCH 23390) and (-)sulpiride. The above findings indicate that human platelets express dopamine D3 and D5 receptors probably involved in the regulation of platelet function.

The hippocampus in spontaneously hypertensive rats: a quantitative microanatomical study

The influence of hypertension on the morphology of hippocampus was assessed in spontaneously hypertensive rats of two, four and six months and in age-matched normotensive Wistar-Kyoto rats. Values of systolic pressure were slightly increased in two-month-old spontaneously hypertensive rats in comparison with age-matched Wistar-Kyoto rats and augmented progressively with age in spontaneously hypertensive rats. No microanatomical changes were observed in the hippocampus of spontaneously hypertensive rats of two months in comparison with age-matched Wistar-Kyoto rats, whereas a decrease of white matter volume was observed in the CA(1) subfield and in the dentate gyrus of four-month-old spontaneously hypertensive rats. In the hippocampus of six-month-old spontaneously hypertensive rats a reduction of grey matter volume both in the CA(1) subfield and in the dentate gyrus, a loss of neurons affecting to a greater extent the CA(1) subfield and an increase of glial fibrillary acid protein-immunoreactive astrocytes was found. The occurrence of apoptosis and/or necrosis identified using the terminal deoxyribonucleotidyl transferase-mediated biotin-16-dUTP nick end labelling technique was also observed in the CA(1) subfield and to a lesser extent in the dentate gyrus. The only change noticeable in the CA(3) subfield of six-month-old spontaneously hypertensive rats was a slight increase in the number of glial fibrillary acid protein-immunoreactive astrocytes. These findings indicate the occurrence of neuronal loss and of astrocyte changes in the hippocampus of spontaneously hypertensive rats of six months, being the CA(1) subfield the area most affected. The relevance of these neurodegenerative changes in hypertension and the possible occurrence of apoptosis and/or necrosis as expression of hypertensive brain damage is discussed.

Muscarinic cholinergic receptors subtypes in rat cerebellar cortex: light microscope autoradiography of age-related changes

Muscarinic cholinergic M1-M5 receptor subtypes were investigated in the cerebellar cortex of Fischer 344 rats aged 6 (young), 15 (adult) and 22 months (senescent) by combined kinetic and equilibrium binding and light microscope autoradiography. In young rats the rank order of receptor density was M5<M4<M3 and M3<M5<M4 in the molecular and granular layers, respectively. M1, M2, M4 and M5 receptors were also observed within Purkinje neurons. M1 receptor did not show age-related changes as well as the M2 receptor in the molecular layer. In this layer, M3-M5 receptors were increased in senescent compared to younger rats. In the granular layer the expression of M2 and M5 muscarinic receptors was similar in young and senescent rats and higher in adult rats. M3 and M4 receptors were more in adult and senescent rats compared to young animals. In Purkinje neurons, a slight-to-moderate age-related increase of M1 and M5 receptor expression was observed.

The dopaminergic system in hypertension

Dopamine exerts cardiovascular and renal actions mediated through interaction with specific dopamine receptors. Dopamine receptors are cell surface receptors coupled to G-proteins and classified into two main super families based on biochemical, pharmacological and molecular characteristics. The dopamine D1-like receptor super family includes D1 and D5 receptors, known also in rodents as D1A and D1B sites. These receptors are linked to stimulation of adenylate cyclase. The dopamine D2-like receptor super family includes D2, D3 and D4 receptors. These receptors are linked to inhibition of adenylate cylase or not related with this enzyme activity. They also interfere with opening of Ca+2 channels and are linked to stimulation of K+ receptors. Dopamine receptor subtypes are expressed in brain as well as in extracerebral structures such as the heart, blood vessels, carotid body, kidney, adrenal gland, parathyroid gland and gastrointestinal tract. In the kidney, which represents the peripheral organ where dopamine receptors were more extensively investigated, dopamine receptors are involved in regulation of hemodynamic, electrolyte and water transport, as well as renin secretion. Hypertension-related dopamine receptor changes were also investigated primarily in the kidney. Defective renal dopamine production and/or dopamine receptor function have been reported in human primary hypertension as well as in genetic models of animal hypertension. There may be a primary defect in D1-like receptors and an altered signalling system in the proximal tubules that lead to reduced dopamine-mediated effects on renal sodium excretion in hypertension. Studies on the influence of hypertension on dopamine D2-like receptors are sparse Disruption of either D1A or D3 receptors at the gene level causes hypertension in mice. Using peripheral blood lymphocytes as possible markers of the status of dopamine receptors in essential hypertension, no changes of dopamine D1-like receptors were noticeable, whereas an increase of dopamine D2-like receptors likely representing an up-regulation mechanism was reported. Available information collectively indicates an involvement of peripheral dopaminergic system in hypertension consisting either in impaired receptor transduction mechanisms and/or in receptor loss. A better knowledge of molecular bases of these changes may contribute to the development of specific therapeutic approaches in the future.

Occupancy by oral administration of nicardipine of L-type calcium channels in rat brain

The occupancy of L-type Ca2+ channels by treatment with an oral dose of the dihydropyridine-type Ca2+ antagonist nicardipine (sustained-release formulation) was evaluated in membrane preparations of rat frontal cortex and hippocampus using a radioligand binding assay technique, with [3H]-nicardipine as a ligand. Three hours after nicardipine administration, specific binding was decreased by about 15-20%, both in the frontal cortex and hippocampus. This indicates that oral nicardipine occupied approximately 15-20% of L-type Ca2+ channels. A progressive occupancy of Ca2+ channels was observed between six and 12 h after nicardipine administration. Twelve hours after drug administration, approximately 65-70% of Ca2+ channels were occupied. These findings indicate that oral treatment with 3 mg/kg of nicardipine (sustained-release formulation) occupies L-type Ca2+ channels in rat brain by more than 40% from the 6th to the 24th h after drug administration. This suggests that an oral dose of nicardipine (sustained-release formulation) in duces a significant occupancy of L-type Ca2+ channels in rat frontal cortex and hippocampus for about one day. The possible clinico-therapeutic relevance of this observation is discussed.

Protective effect of treatment with nicardipine on cerebrovascular tree of spontaneously hypertensive rats

The effect of an eight-week treatment with the Ca2+ channel blocker nicardipine on different-sized pial arteries and intracerebral arteries was assessed in spontaneously hypertensive rats (SHR) by microanatomical techniques. Normotensive Wistar-Kyoto (WKY) rats were used as normotensive reference animals. In SHR a significant increase of systolic blood pressure (SBP) in comparison with WKY rats was noticeable. An increased thickness of tunica media and luminal narrowing were also seen in medium- and small-sized pial arteries, and in intracerebral arteries of SHR in comparison with WKY rats. The media-to-lumen ratio was also increased in medium (diameter between 150 and 50 microm) and small-sized (diameter < than 50 microm) pial and intracerebral arteries. Treatment with nicardipine significantly reduced SBP, the thickness of tunica media, media-to-lumen ratio and increased luminal area of medium- and small-sized pial arteries and of intracerebral arteries. These findings demonstrate that treatment of SHR with nicardipine induces a moderate vasodilatation of both pial and intracerebral arteries regulating cerebrovascular resistance. This property may be useful in avoiding generalized or exaggerated cerebrovascular dilatation in hypertension which could be accompanied by impaired brain perfusion.

Effect of nicardipine treatment on the expression of neurofilament 200 KDa immunoreactivity in the brain of spontaneously hypertensive rats

Neurofilaments (NFP) are components of neuronal cytoskeleton involved primarily in axonal transport and in the regulation of dynamic activities of nerve cells. NFP consist of three subunits denominated high- (200 kDa, NFP-H), intermediate- (160 kDa, NFP-I), and low-molecular weight (68 kDa, NFP-L) neurofilament proteins. Their function and polymerization depends on phosphorylation status, and is regulated by Ca2+ influx. Ca2+ overload enhances degradation of NFP and may compromise axonal transport. An increased susceptibility to ischemia occurs in hypertension, which is also a cause of brain damage. In this study, the expression of phosphorylated NFP (P-NFP) was investigated in the brain of spontaneously hypertensive rats (SHR) using immunohistochemical techniques with antibodies against the phosphorylated epitope of NFP RT-97. Microanatomical analysis included frontal cortex, occipital cortex, hippocampus and cerebellar cortex. The effect of long-term treatment with the dihydropyridine-type Ca2+ antagonist nicardipine on the expression of P-NFP was investigated as well. In hypertension a decreased P-NFP immunoreactivity was observed in frontal and occipital cortex, in the CA1 subfield of hippocampus and in the dentate gyrus, but not in the CA3 subfield of hippocampus or in the cerebellar cortex. Treatment with a daily dose of 3 mg/kg of nicardipine and 10 mg/kg of hydralazine significantly reduced systolic pressure in SHR. The above dose of nicardipine and to a lesser extent a non-hypotensive dose of the compound (0.1 mg/kg/day), but not hydralazine, increased P-NFP immunoreactivity in the cerebral cortex and hippocampus, except the CA3 subfield. The possibility that rescued P-NFP immunoreactivity by treatment with nicardipine depends on improved brain perfusion caused by the compound and/or by countering neuronal Ca2+ overload is discussed.

Effect of antihypertensive treatment on peripheral nerve vasculature in spontaneously hypertensive rats

The influence of hypertension and of treatment with the dihydropyridine-type Ca+2 antagonist nicardipine on peripheral nerve vasculature were investigated in spontaneously hypertensive rats (SHR). Male SHR were treated from the 16th to the 26th week of age with vehicle (control group), with nicardipine, at the hypotensive dose of 3 mg/kg/day, or at the nonhypotensive dose of 0.1 mg/kg/day or with an equihypotensive dose (10 mg/kg/day) of the nondihydropyridine-type vasodilator hydralazine. Age-matched normotensive Wistar-Kyoto (WKY) rats were left untreated and used as normotensive reference animals. In SHR a significant increase of systolic pressure values accompanied by sciatic nerve microvascular changes, involving primarily interfascicular arteries and to a lesser extent intrafascicular arteries, was observed. Treatment with the hypotensive dose of nicardipine countered hypertension-dependent microvascular changes occurring in both interfascicular and intrafascicular arteries. The nonhypotensive dose of nicardipine and hydralazine displayed a modest activity on interfascicular arteries, but significantly countered hypertension-related changes involving intrafascicular arteries. The above findings indicate the occurrence of hypertension-related changes of peripheral nerve microvasculature and of positive effects induced by appropriate pharmacological treatment. Further work is in progress to identify the functional relevance of microanatomical observations of the present study.