Ángel L. López de Pablo

LESION OF THE DORSAL RAPHE NUCLEUS INDUCES SUPERSENSITIVITY TO SEROTONIN IN ISOLATED CAT MIDDLE CEREBRAL ARTERY

Simultaneous lesions of dorsal and median raphe nuclei were induced after 15 days postjunctional supersensitivity to serotonin in isolated segments of cat middle cerebral artery. The same result was obtained when only the dorsal raphe nucleus was destroyed. The lesion of the median raphe nucleus brought about an increased contractile response to serotonin only at the three first doses used. The contractile response to noradrenaline was unaffected by these treatments. These results suggest the existence of a serotonergic innervation of the cat middle cerebral artery whose main origin might be the dorsal raphe nucleus.

Estimation of scavenging capacity of melatonin and other antioxidants: Contribution and evaluation in germinated seeds

Seven edible seeds for the levels of melatonin, phenolic compounds and their antioxidant capacity were evaluated during germination process. Radical scavenging parameters were also studied in standard antioxidants to understand their antiradical actions. Germination brought about significant increases of total phenol compounds in all edible seeds, showing red cabbage, radish and broccoli the highest contents (21.6, 20.4 and 16.4 mg GAE/g DW, respectively). The concentration of melatonin is greatly variable in edible seeds, exhibiting significant increases during germination. The highest levels were found in red cabbage (857 pg/g DW) radish (536 pg/g DW) and broccoli (439 pg/g DW). The germinated seeds which had the highest levels of polyphenols and melatonin were those that showed the most relevant antiradical activities (>97%). This information is valuable for the incorporation of red cabbage, radish and broccoli germinated seeds into the diet to promote potential health benefits.

Fetal undernutrition is associated with perinatal sex-dependent alterations in oxidative status.

Intrauterine growth retardation predisposes to hypertension development, known as fetal programming. Females are less susceptible, which has been mainly attributed to estrogen influence. We hypothesize that perinatal differences in oxidative status might also contribute. We studied 21-day-old (prepuberal) and 6-month-old male and female offspring from rats fed ad libitum during gestation (Control) or with 50% of Control daily intake from day 10 to delivery (maternal undernutrition, MUN). We assessed in vivo blood pressure and the following plasma biomarkers of oxidative status: protein carbonyls, thiols, reduced glutathione (GSH), total antioxidant capacity, superoxide anion scavenging activity (SOSA) and catalase activities; we calculated a global score (oxy-score) from them. Estradiol and melatonin concentration was measured in young rats. Prepuberal MUN males were normotensive but already exhibited increased carbonyls and lower thiols, GSH, SOSA and melatonin; oxy-score was significantly lower compared to Control males. Prepuberal MUN females only exhibited reduced SOSA compared to Control females. Adult rats from all experimental groups showed a significant increase in carbonyls and a decrease in antioxidants compared to prepuberal rats; oxy-score was negative in adult rats suggesting the development of a prooxidative status as rat age. Adult MUN males were hypertensive and exhibited the highest increase in carbonyls despite similar or even higher antioxidant levels compared to Controls. Adult MUN females remained normotensive and did not exhibit differences in any of the biomarkers compared to Controls. The better global antioxidant status developed by MUN females during perinatal life could contribute to their protection against hypertension programming.

Nitric Oxide and Superoxide Anion Balance in Rats Exposed to Chronic and Long Term Intermittent Hypoxia

Work at high altitude in shifts exposes humans to a new form of chronic intermittent hypoxia, with still unknown health consequences. We have established a rat model resembling this situation, which develops a milder form of right ventricular hypertrophy and pulmonary artery remodelling compared to continuous chronic exposure. We aimed to compare the alterations in pulmonary artery nitric oxide (NO) availability induced by these forms of hypoxia and the mechanisms implicated. Rats were exposed for 46 days to normoxia or hypobaric hypoxia, either continuous (CH) or intermittent (2 day shifts, CIH2x2), and assessed: NO and superoxide anion availability (fluorescent indicators and confocal microscopy); expression of phosphorylated endothelial NO synthase (eNOS), NADPH-oxidase (p22phox), and 3-nitrotyrosine (western blotting); and NADPH-oxidase location (immunohistochemistry). Compared to normoxia, (1) NO availability was reduced and superoxide anion was increased in both hypoxic groups, with a larger effect in CH, (2) eNOS expression was only reduced in CH, (3) NADPH-oxidase was similarly increased in both hypoxic groups, and (4) 3-nitrotyrosine was increased to a larger extent in CH. In conclusion, intermittent hypoxia reduces NO availability through superoxide anion destruction, without reducing its synthesis, while continuous hypoxia affects both, producing larger nitrosative damage which could be related to the more severe cardiovascular alterations.

Different Influence of Endothelium in the Mechanical Responses of Human and Cat Isolated Cerebral Arteries to Several Agents

Abstract— The present work was undertaken to elucidate the role of the vascular endothelium in the changes of isometric tension elicited by different compounds in isolated cylinders of human and cat cerebral arteries and cat pulmonary arteries. Endothelium removal by rubbing significantly reduced the relaxing response to acetylcholine (ACh) of isolated segments of all the arteries. The same treatment did not modify the contraction elicited by 5‐hydroxytryptamine (5‐HT) in the human and cat cerebral segments but increased the contractile effect of the amine in cat pulmonary arteries. The mechanical responses to vasopressin, ATP and adenosine in isolated segments of cat cerebral arteries were unaffected after removing the endothelial layer. L‐Arginine, but not D‐arginine (10−5 M), enhanced significantly the relaxation induced by increasing doses of ACh in unrubbed cat cerebral arteries whereas it did not modify the response to ACh in rubbed ones. However, L‐arginine had no effect on the dose‐response curve to 5‐HT in both kinds of preparation and did not change the tone in precontracted unrubbed cat cerebral segments. These results suggest that the endothelium of the cerebrovascular bed plays a minor role in regulating the mechanical response induced by several vasoactive agents, although it retains its ability to produce an endothelium‐derived relaxing factor.

A simple dot-blot-Sirius red-based assay for collagen quantification.

AbstractThe assessment of collagen content in tissues is important in biomedical research, since this protein is altered in numerous diseases. Hydroxyproline and Sirius red based assays are the most common methods for collagen quantification. However, these procedures have some pitfalls, such as the requirement of oxygen-free medium or expensive equipment and large sample size or being unsuitable for hydrolyzed collagen, respectively. Our objective was to develop a specific, versatile, and user-friendly quantitative method applicable to small tissue samples and extracts obtained from elastin purification, therefore, suitable for simultaneous quantification of elastin. This method is based on the binding of Sirius red to collagen present in a sample immobilized on a PVDF membrane, as in the dot-blot technique, and quantified by a scanner and image analysis software. Sample loading, Sirius red concentration, temperature and incubation time, type of standard substance, albumin interference, and quantification time are optimized. The method enabled the quantification of (1) intact collagen in several rat tissue homogenates, including small resistance-sized arteries, (2) partially hydrolyzed collagen obtained from NaOH extracts, compatible with elastin purification, and (3) for the detection of differences in collagen content between hypertensive and normotensive rats. We conclude that the developed technique can be widely used since it is versatile (quantifies intact and hydrolyzed collagen), requires small sample volumes, is user-friendly (low-cost, easy to use, minimum toxic materials, and reduced time of test), and is specific (minimal interference with serum albumin). FigureDot-blot–Sirius red-based assay for collagen quantification

Local Treatments of Dorsal Raphe Nucleus Induce Changes in Serotonergic Activity in Rat Major Cerebral Arteries

BACKGROUND AND PURPOSE Rat major cerebral arteries seem to receive serotonergic fibers originating from the dorsal raphe nucleus (DRN), but little is known about their function. The aim of our present work was to establish a functional relationship between this brain stem nucleus and the cerebral blood vessels by studying the effects of several treatments in the DRN on cerebrovascular serotonergic activity. METHODS Serotonin, clomipramine, 8-OH-DPAT, and WAY-100635 were administered in DRN. A stereotaxically localized electrode allowed the electrical stimulation of this brain stem nucleus. Serotonergic activity was appraised in major cerebral arteries, striatum, and hippocampus from 5-hydroxytryptophan accumulation after aromatic L-amino acid decarboxylase inhibition with NSD-1015. RESULTS Serotonin significantly decreased serotonergic activity in major cerebral arteries and striatum without affecting it in hippocampus. This reduction was blocked by previous injection of WAY-100635 in DRN. Local administration of 8-OH-DPAT or clomipramine elicited an effect similar to that of serotonin, whereas that of WAY-100635 did not modify serotonergic activity in either of the tissues. Electrical stimulation of DRN significantly increased serotonergic activity in major cerebral arteries and striatum but not in hippocampus. CONCLUSIONS These results confirm the presence of a serotonergic innervation in rat major cerebral arteries functionally related to DRN. 5-HT(1A) receptor activation partly mediates the action of serotonin in DRN. A serotonergic tone acting on these somatodendritic receptors was not clearly found.

Cat Cerebral Arteries Are Functionally Innervated by Serotoninergic Fibers From Central and Peripheral Origins

BACKGROUND AND PURPOSE Tryptophan hydroxylase activity and responses to tyramine were analyzed in cat cerebral arteries to investigate serotoninergic innervation. METHODS Enzymatic activity and responses to tyramine were measured in vessels from animals subjected to cervical gangliectomy and dorsal and median raphe nuclei lesions. RESULTS Tryptophan hydroxylase activity in cat cerebral arteries was reduced after ganglia removal and raphe nuclei destruction. Contractile responses of the middle cerebral artery after gangliectomy were decreased by ketanserine. Dorsal raphe nucleus destruction had a significant effect on the contractile response, whereas median raphe nucleus destruction had only a slight effect. CONCLUSIONS Cat cerebral arteries receive serotoninergic innervation from central and peripheral origins.

Long term effects of fetal undernutrition on rat heart. Role of hypertension and oxidative stress.

Background and aims Fetal undernutrition is a risk factor for heart disease in both genders, despite the protection of women against hypertension development. Using a rat model of maternal undernutrition (MUN) we aimed to assess possible sex differences in the development of cardiac alterations and the implication of hypertension and cardiac oxidative stress. Methods Male and female offspring from rats fed ad libitum (control) or with 50% of the normal daily intake during the second half of gestation (MUN) were used. Heart weight/body weight ratio (HW/BW), hemodynamic parameters (anaesthetized rats) and plasma brain natriuretic peptide (BNP, ELISA) were assessed in 21-day, 6-month and 22-month old rats. Plasma testosterone (ELISA) and cardiac protein expression of enzymes related to reactive oxygen species synthesis (p22phox, xanthine-oxidase) and degradation (catalase, Cu/Zn-SOD, Mn-SOD, Ec-SOD) were evaluated in 21-day and 6-month old rats (Western Blot). Heart structure and function was studied at the age of 22 months (echocardiography). Results At the age of 21 days MUN males exhibited significantly larger HW/BW and cardiac p22phox expression while females had reduced p22phox expression, compared to their respective sex-matched controls. At the age of 6-months, MUN males showed significantly larger blood pressure and cardiac xanthine-oxidase expression; MUN females were normotensive and had a lower cardiac expression of antioxidant enzymes, compared to their respective sex-matched controls. At the age of 22 months, both MUN males and females showed larger HW/BW and left ventricular mass and lower ejection fraction compared to sex-matched controls; only MUN males exhibited hypertension and a larger plasma BNP compared to aged male controls. Conclusions 1) During perinatal life females exposed to fetal undernutrition are protected from cardiac alterations, but in ageing they exhibit ventricular hypertrophy and functional loss, like MUN males; 2) cardiac oxidative stress might be implicated in the observed heart alterations in both sexes and 3) the severity of cardiac damage might be greater in males due to hypertension.

Adventitial Alterations Are the Main Features in Pulmonary Artery Remodeling due to Long-Term Chronic Intermittent Hypobaric Hypoxia in Rats

Long-term chronic intermittent exposure to altitude hypoxia is a labor phenomenon requiring further research. Using a rat model, we examined whether this type of exposure differed from chronic exposure in terms of pulmonary artery remodeling and other features. Rats were subjected to chronic hypoxia (CH, n = 9) and long-term intermittent hypoxia (CIH2x2; 2 days of hypoxia/2 days of normoxia, n = 10) in a chamber (428 Torr, 4,600 m of altitude) for 46 days and compared to rats under normoxia (NX, n = 10). Body weight, hematocrit, and right ventricle ratio were measured. Pulmonary artery remodeling was assessed using confocal microscopy of tissues stained with a nuclear dye (DAPI) and CD11b antibody. Both hypoxic conditions exhibited increased hematocrit and hypertrophy of the right ventricle, tunica adventitia, and tunica media, with no changes in lumen size. The medial hypertrophy area (larger in CH) depicted a significant increase in smooth muscle cell number. Additionally, CIH2x2 increased the adventitial hypertrophy area, with an increased cellularity and a larger prevalence of clustered inflammatory cells. In conclusion, CIH2x2 elicits milder effects on pulmonary artery medial layer muscularization and subsequent right ventricular hypertrophy than CH. However, CIH2x2 induces greater and characteristic alterations of the adventitial layer.