Mitochondrial Aging and Senolytic Natural Products with Protective Potential.

Living organisms do not disregard the laws of thermodynamics and must therefore consume energy for their survival. In this way, cellular energy exchanges, which aim above all at the production of ATP, a fundamental molecule used by the cell for its metabolisms, favor the formation of waste products that, if not properly disposed of, can contribute to cellular aging and damage. Numerous genes have been linked to aging, with some favoring it (gerontogenes) and others blocking it (longevity pathways). Animal model studies have shown that calorie restriction (CR) may promote longevity pathways, but given the difficult application of CR in humans, research is investigating the use of CR-mimetic substances capable of producing the same effect. These include some phytonutrients such as oleuropein, hydroxytyrosol, epigallo-catechin-gallate, fisetin, quercetin, and curcumin and minerals such as magnesium and selenium. Some of them also have senolytic effects, which promote the apoptosis of defective cells that accumulate over the years (senescent cells) and disrupt normal metabolism. In this article, we review the properties of these natural elements that can promote a longer and healthier life.

The dopamine beta-hydroxylase inhibitor nepicastat increases dopamine release and potentiates psychostimulant-induced dopamine release in the prefrontal cortex.

The dopamine-beta-hydroxylase inhibitor nepicastat has been shown to reproduce disulfiram ability to suppress the reinstatement of cocaine seeking after extinction in rats. To clarify its mechanism of action, we examined the effect of nepicastat, given alone or in association with cocaine or amphetamine, on catecholamine release in the medial prefrontal cortex and the nucleus accumbens, two key regions involved in the reinforcing and motivational effects of cocaine and in the reinstatement of cocaine seeking. Nepicastat effect on catecholamines was evaluated by microdialysis in freely moving rats. Nepicastat reduced noradrenaline release both in the medial prefrontal cortex and in the nucleus accumbens, and increased dopamine release in the medial prefrontal cortex but not in the nucleus accumbens. Moreover, nepicastat markedly potentiated cocaine- and amphetamine-induced extracellular dopamine accumulation in the medial prefrontal cortex but not in the nucleus accumbens. Extracellular dopamine accumulation produced by nepicastat alone or by its combination with cocaine or amphetamine was suppressed by the α2 -adrenoceptor agonist clonidine. It is suggested that nepicastat, by suppressing noradrenaline synthesis and release, eliminated the α2 -adrenoceptor mediated inhibitory mechanism that constrains dopamine release and cocaine- and amphetamine-induced dopamine release from noradrenaline or dopamine terminals in the medial prefrontal cortex.

NMDARs mediate the role of monoamine oxidase A in pathological aggression.

Converging evidence shows that monoamine oxidase A (MAO A), the key enzyme catalyzing serotonin (5-hydroxytryptamine; 5-HT) and norepinephrine (NE) degradation, is a primary factor in the pathophysiology of antisocial and aggressive behavior. Accordingly, male MAO A-deficient humans and mice exhibit an extreme predisposition to aggressive outbursts in response to stress. As NMDARs regulate the emotional reactivity to social and environmental stimuli, we hypothesized their involvement in the modulation of aggression mediated by MAO A. In comparison with WT male mice, MAO A KO counterparts exhibited increases in 5-HT and NE levels across all brain regions, but no difference in glutamate concentrations and NMDAR binding. Notably, the prefrontal cortex (PFC) of MAO A KO mice exhibited higher expression of NR2A and NR2B, as well as lower levels of glycosylated NR1 subunits. In line with these changes, the current amplitude and decay time of NMDARs in PFC was significantly reduced. Furthermore, the currents of these receptors were hypersensitive to the action of the antagonists of the NMDAR complex (dizocilpine), as well as NR2A (PEAQX) and NR2B (Ro 25-6981) subunits. Notably, systemic administration of these agents selectively countered the enhanced aggression in MAO A KO mice, at doses that did not inherently affect motor activity. Our findings suggest that the role of MAO A in pathological aggression may be mediated by changes in NMDAR subunit composition in the PFC, and point to a critical function of this receptor in the molecular bases of antisocial personality.

Effects of Functional and Nutraceutical Foods in the Context of the Mediterranean Diet in Patients Diagnosed with Breast Cancer.

Several studies report that breast cancer survivors (BCS) tend to have a poor diet, as fruit, vegetable, and legume consumption is often reduced, resulting in a decreased intake of nutraceuticals. Moreover, weight gain has been commonly described among BCS during treatment, increasing recurrence rate and mortality. Improving lifestyle and nutrition after the diagnosis of BC may have important benefits on patients' general health and on specific clinical outcomes. The Mediterranean diet (MD), known for its multiple beneficial effects on health, can be considered a nutritional pool comprising several nutraceuticals: bioactive compounds and foods with anti-inflammatory and antioxidant effects. Recent scientific advances have led to the identification of nutraceuticals that could amplify the benefits of the MD and favorably influence gene expression in these patients. Nutraceuticals could have beneficial effects in the postdiagnostic phase of BC, including helping to mitigate the adverse effects of chemotherapy and radiotherapy. Moreover, the MD could be a valid and easy-to-follow option for managing excess weight. The aim of this narrative review is to evaluate the recent scientific literature on the possible beneficial effects of consuming functional and nutraceutical foods in the framework of MD in BCS.

Perioperative Nutritional Management in Enhanced Recovery after Bariatric Surgery.

Obesity is a crucial health problem because it leads to several chronic diseases with an increased risk of mortality and it is very hard to reverse with conventional treatment including changes in lifestyle and pharmacotherapy. Bariatric surgery (BS), comprising a range of various surgical procedures that modify the digestive tract favouring weight loss, is considered the most effective medical intervention to counteract severe obesity, especially in the presence of metabolic comorbidities. The Enhanced Recovery After Bariatric Surgery (ERABS) protocols include a set of recommendations that can be applied before and after BS. The primary aim of ERABS protocols is to facilitate and expedite the recovery process while enhancing the overall effectiveness of bariatric procedures. ERABS protocols include indications about preoperative fasting as well as on how to feed the patient on the day of the intervention, and how to nourish and hydrate in the days after BS. This narrative review examines the application, the feasibility and the efficacy of ERABS protocols applied to the field of nutrition. We found that ERABS protocols, in particular not fasting the patient before the surgery, are often not correctly applied for reasons that are not evidence-based. Furthermore, we identified some gaps in the research about some practises that could be implemented in the presence of additional evidence.

Weight Maintenance after Dietary Weight Loss: Systematic Review and Meta-Analysis on the Effectiveness of Behavioural Intensive Intervention.

After a low-calorie diet, only 25% of patients succeed in maintaining the result of weight loss for a long time. This systematic review and meta-analysis aims to explore whether patients undergoing intensive intervention during the maintenance phase have a greater preservation of the weight achieved during the previous slimming phase than controls. A bibliographic search was conducted using PubMed, Scopus, and Cochrane databases for clinical trials and randomised, controlled trials investigating the role of choice in weight-loss-maintenance strategies. Only studies with a follow-up of at least 12 months were considered. A total of eight studies, for a total of 1454 patients, was identified, each comparing a group that followed a more intensive protocol to a control group. Our metanalysis highlighted that an intensive approach even in the maintenance phase could be important to ensure greater success in the phase following the weight-loss period. However, it should be pointed out that the improvement was not so different from the trend of the respective controls, with a non-statistically significant mean difference of the effect size (0.087; 95% CI -0.016 to 0.190 p = 0.098). This finding, along with the observation of a weight regain in half of the selected studies, suggests this is a long work that has to be started within the weight-loss phase and reinforced during the maintenance phase. The problem of weight control in patients with obesity should be understood as a process of education to a healthy lifestyle and a balanced diet to be integrated in the context of a multidisciplinary approach.

Repeated exposure to JWH-018 induces adaptive changes in the mesolimbic and mesocortical dopaminergic pathways, glial cells alterations, and behavioural correlates.

BACKGROUND AND PURPOSE: Spice/K2 herbal mixtures, containing synthetic cannabinoids such as JWH-018, have been marketed as marijuana surrogates since 2004. JWH-018 has cannabinoid CB1 receptor-dependent reinforcing properties and acutely increases dopaminergic transmission selectively in the NAc shell. Here, we tested the hypothesis that repeated administration of JWH-018 (i) modulates behaviour, (ii) affects dopaminergic transmission and its responsiveness to motivational stimuli, and (iii) is associated with a neuroinflammatory phenotype. EXPERIMENTAL APPROACH: Rats were administered with JWH-018 once a day for 14 consecutive days. We then performed behavioural, electrophysiological, and neurochemical evaluation at multiple time points after drug discontinuation. KEY RESULTS: Repeated JWH-018 exposure (i) induced anxious and aversive behaviours, transitory attentional deficits, and withdrawal signs; (ii) decreased spontaneous activity and number of dopamine neurons in the VTA; and (iii) reduced stimulation of dopaminergic transmission in the NAc shell while potentiating that in the NAc core, in response to acute JWH-018 challenge. Moreover, (iv) we observed a decreased dopamine sensitivity in the NAc shell and core, but not in the mPFC, to a first chocolate exposure; conversely, after a second exposure, dialysate dopamine fully increased in the NAc shell and core but not in the mPFC. Finally, selected dopamine brain areas showed (v) astrogliosis (mPFC, NAc shell and core, VTA), microgliosis (NAc shell and core), and downregulation of CB1 receptors (mPFC, NAc shell and core). CONCLUSION AND IMPLICATIONS: Repeated exposure to JWH-018 may provide a useful model to clarify the detrimental effects of recurring use of Spice/K2 drugs.

Noradrenergic Source of Dopamine Assessed by Microdialysis in the Medial Prefrontal Cortex.

Previous results indicate that dopamine (DA) release in the medial prefrontal cortex (mPFC) is modified by α2 adrenoceptor- but not D2 DA receptor- agonists and antagonists, suggesting that DA measured by microdialysis in the mPFC originates from noradrenergic terminals. Accordingly, noradrenergic denervation was found to prevent α2-receptor-mediated rise and fall of extracellular DA induced by atipamezole and clonidine, respectively, in the mPFC. The present study was aimed to determine whether DA released by dopaminergic terminals in the mPFC is not detected by in vivo microdialysis because is readily taken up by norepinephrine transporter (NET). Accordingly, the D2-antagonist raclopride increased the electrical activity of DA neurons in the ventral tegmental area (VTA) and enhanced extracellular DOPAC but failed to modify DA in the mPFC. However, in rats whose NET was either inactivated by nisoxetine or eliminated by noradrenergic denervation, raclopride still elevated extracellular DOPAC and activated dopaminergic activity, but also increased DA. Conversely, the D2-receptor agonist quinpirole reduced DOPAC but failed to modify DA in the mPFC in control rats. However, in rats whose NET was eliminated by noradrenergic denervation or inhibited by locally perfused nisoxetine, quinpirole maintained its ability to reduce DOPAC but acquired that of reducing DA. Moreover, raclopride and quinpirole, when locally perfused into the mPFC of rats subjected to noradrenergic denervation, were able to increase and decrease, respectively, extracellular DA levels, while being ineffective in control rats. Transient inactivation of noradrenergic neurons by clonidine infusion into the locus coeruleus, a condition where NET is preserved, was found to reduce extracellular NE and DA in the mPFC, whereas noradrenergic denervation, a condition where NET is eliminated, almost totally depleted extracellular NE but increased DA. Both transient inactivation and denervation of noradrenergic neurons were found to reduce the number of spontaneously active DA neurons and their bursting activity in the VTA. The results indicate that DA released in the mPFC by dopaminergic terminals is not detected by microdialysis unless DA clearance from extracellular space is inactivated. They support the hypothesis that noradrenergic terminals are the main source of DA measured by microdialysis in the mPFC during physiologically relevant activities.

Gating deficits in isolation-reared rats are correlated with alterations in protein expression in nucleus accumbens.

The isolation-rearing (IR) paradigm, consisting of the social deprivation for 6-9 weeks after weaning, induces a spectrum of aberrant behaviors in adult rats. Some of these alterations such as sensorimotor gating deficits are reminiscent of the dysfunctions observed in schizophrenia patients. Although gating impairments in IR rats have been linked to impairments in the cortico-mesolimbic system, the specific molecular mechanisms underlying this relation are unclear. To elucidate the neurochemical modifications underlying the gating disturbances exhibited by IR rats, we compared their pre-pulse inhibition (PPI) of the acoustic startle reflex with that of socially reared (SR) controls, and correlated this index to the results of proteomic analyses in prefrontal cortex and nucleus accumbens from both groups. As expected, IR rats exhibited significantly lower startle amplitude and PPI than their SR counterparts. Following behavioral testing, IR and SR rats were killed and protein expression profiles of their brain regions were examined using two-dimensional electrophoresis based proteomics. Image analysis in the Coomassie blue-stained gel revealed that three protein spots were differentially expressed in the nucleus accumbens of IR and SR rats. Mass spectrometry (matrix-assisted laser desorption ionization-time of flight and MS/MS) identified these spots as heat shock protein 60 (HSP60), alpha-synuclein (alpha-syn), and 14-3-3 protein zeta/delta. While accumbal levels of HSP60 was decreased in IR rats, alpha-syn and 14-3-3 proteins were significantly increased in IR in comparison with SR controls. Notably, these two last alterations were significantly correlated with different loudness intensity-specific PPI deficits in IR rats. In view of the role of these proteins in synaptic trafficking and dopaminergic regulation, these findings might provide a neurochemical foundation for the gating alterations and psychotic-like behaviors in IR rats.

Noradrenergic terminals are the primary source of α2-adrenoceptor mediated dopamine release in the medial prefrontal cortex.

In various psychiatric disorders, deficits in dopaminergic activity in the prefrontal cortex (PFC) are implicated. Treatments involving selective augmentation of dopaminergic activity in the PFC primarily depend on the inhibition of α2-adrenoreceptors singly or in combination with the inhibition of the norepinephrine transporter (NET). We aimed to clarify the relative contribution of dopamine (DA) release from noradrenergic and dopaminergic terminals to DA output induced by blockade of α2-adrenoreceptors and NET. To this end, we assessed whether central noradrenergic denervation modified catecholamine output in the medial PFC (mPFC) of rats elicited by atipamezole (an α2-adrenoreceptor antagonist), nisoxetine (an NET inhibitor), or their combination. Intraventricular administration of anti-dopamine-beta-hydroxylase-saporin (aDBH) caused a loss of DBH-positive fibers in the mPFC and almost total depletion of tissue and extracellular NE level; however, it did not reduce tissue DA level but increased extracellular DA level by 70% in the mPFC. Because noradrenergic denervation should have caused a loss of NET and reduced NE level at α2-adrenoceptors, the actual effect of an aDBH-induced lesion on DA output elicited by blockade of α2-adrenoceptors and NET was evaluated by comparing denervated and control rats following blockade of α2-adrenoceptors and NET with atipamezole and nisoxetine, respectively. In the control rats, extracellular NE and DA levels increased by approximately 150% each with 3 mg/kg atipamezole; 450% and 230%, respectively, with 3 mg/kg nisoxetine; and 2100% and 600%, respectively, with combined atipamezole and nisoxetine. In the denervated rats, consistent with the loss of NET, nisoxetine failed to modify extracellular DA level, whereas atipamezole, despite the lack of NE-induced stimulation of α2-adrenoceptors, increased extracellular DA level by approximately 30%. Overall, these results suggest that atipamezole-induced DA release mainly originated from noradrenergic terminals, possibly through the inhibition of α2-autoreceptors. Furthermore, while systemic and local administration of the α2-adrenoceptor agonist clonidine into the mPFC of the controls rats reduced extracellular NE level by 80% and 60%, respectively, and extracellular DA level by 50% and 60%, respectively, it failed to reduce DA output in the denervated rats, consistent with the loss of α2-autoreceptors. To eliminate the possibility that denervation reduced DA release potential via the effects at dopaminergic terminals in the mPFC, the effect of systemic administration of the D2-DA antagonist raclopride (0.5 mg/kg IP) on DA output was analyzed. In the control rats, raclopride was found to be ineffective when administered alone, but it increased extracellular DA level by 380% following NET inhibition with nisoxetine. In the denervated rats, as expected due to the loss of NET, raclopride-alone or with nisoxetine-increased DA release to approximately the same level as that observed in the control rats after NET inhibition. Overall, these results suggest that noradrenergic terminals in the mPFC are the primary source of DA released by blockade of α2-adrenoreceptors and NET and that α2-autoreceptors, and not α2-heteroreceptors, mediate DA output induced by α2-adrenoceptor blockade.

6-Hydroxydopamine lesion in the ventral tegmental area fails to reduce extracellular dopamine in the cerebral cortex.

Dopamine and noradrenaline are both involved in modulation of superior cognitive functions that are mainly dependent on frontal cortex activity. Experimental evidence points to parallel variations in extracellular concentrations of catecholamines in the cerebral cortex, which leads us to hypothesize their corelease from noradrenergic neurons. This study aimed to verify this hypothesis, by means of cerebral microdialysis following destruction of dopaminergic innervation in rats. The unilateral injury of dopaminergic neurons, by 6-hydroxydopamine injection in the ventral tegmental area, dramatically reduced the immunoreactivity for dopamine transporter in the cerebral hemisphere ipsilateral to the lesion. Tissue dopamine content in the ipsilateral nucleus accumbens and medial prefrontal and parietal cortex was also profoundly decreased, whereas noradrenaline was only slightly affected. Despite the lower tissue content in the denervated side, the extracellular dopamine level was not changed in the cortex, although it was markedly decreased in the nucleus accumbens ipsilateral to the lesion. The effect of drugs selective for D(2)-dopaminergic (haloperidol) or alpha(2)-noradrenergic (RS 79948) receptors was verified. Haloperidol failed to modify extracellular dopamine in either cortex but increased it in the nucleus accumbens, such an increase being greatly reduced in the denervated side. On the other hand, RS 79948 increased extracellular dopamine and DOPAC in all areas tested, the increases being of the same degree in both intact and lesioned sides. The results strongly support the hypothesis that the majority of extracellular dopamine in the cortex, unlike that in the nucleus accumbens, originates from noradrenergic terminals.

On the origin of cortical dopamine: is it a co-transmitter in noradrenergic neurons?

Dopamine (DA) and noradrenaline (NA) in the prefrontal cortex (PFC) modulate superior cognitive functions, and are involved in the aetiology of depressive and psychotic symptoms. Moreover, microdialysis studies in rats have shown how pharmacological treatments that induce modifications of extracellular NA in the medial PFC (mPFC), also produce parallel changes in extracellular DA.To explain the coupling of NA and DA changes, this article reviews the evidence supporting the hypothesis that extracellular DA in the cerebral cortex originates not only from dopaminergic terminals but also from noradrenergic ones, where it acts both as precursor for NA and as a co-transmitter.Accordingly, extracellular DA concentration in the occipital, parietal and cerebellar cortex was found to be much higher than expected in view of the scarce dopaminergic innervation in these areas.Systemic administration or intra-cortical perfusion of alpha(2)-adrenoceptor agonists and antagonists, consistent with their action on noradrenergic neuronal activity, produced concomitant changes not only in extracellular NA but also in DA in the mPFC, occipital and parietal cortex.Chemical modulation of the locus coeruleus by locally applied carbachol, kainate, NMDA or clonidine modified both NA and DA in the mPFC.Electrical stimulation of the locus coeruleus led to an increased efflux of both NA and DA in mPFC, parietal and occipital cortex, while in the striatum, NA efflux alone was enhanced.Atypical antipsychotics, such as clozapine and olanzapine, or antidepressants, including mirtazapine and mianserine, have been found to increase both NA and DA throughout the cerebral cortex, likely through blockade of alpha(2)-adrenoceptors. On the other hand, drugs selectively acting on dopaminergic transmission produced modest changes in extracellular DA in mPFC, and had no effect on the occipital or parietal cortex.Acute administration of morphine did not increase DA levels in the PFC (where NA is diminished), in contrast with augmented dopaminergic neuronal activity; moreover, during morphine withdrawal both DA and NA levels increased, in spite of a diminished dopaminergic activity, both increases being antagonised by clonidine but not quinpirole administration.Extensive 6-hydroxy dopamine lesion of the ventral tegmental area (VTA) decreases below 95% of control both intra- and extracellular DA and DOPAC in the nucleus accumbens, but only partially or not significantly in the mPFC and parietal cortex.The above evidence points to a common origin for NA and DA in the cerebral cortex and suggests the possible utility of noradrenergic system modulation as a target for drugs with potential clinical efficacy on cognitive functions.

Co-release of noradrenaline and dopamine in the cerebral cortex elicited by single train and repeated train stimulation of the locus coeruleus.

BACKGROUND: Previous studies by our group suggest that extracellular dopamine (DA) and noradrenaline (NA) may be co-released from noradrenergic nerve terminals in the cerebral cortex. We recently demonstrated that the concomitant release of DA and NA could be elicited in the cerebral cortex by electrical stimulation of the locus coeruleus (LC). This study analyses the effect of both single train and repeated electrical stimulation of LC on NA and DA release in the medial prefrontal cortex (mPFC), occipital cortex (Occ), and caudate nucleus. To rule out possible stressful effects of electrical stimulation, experiments were performed on chloral hydrate anaesthetised rats. RESULTS: Twenty min electrical stimulation of the LC, with burst type pattern of pulses, increased NA and DA both in the mPFC and in the Occ. NA in both cortices and DA in the mPFC returned to baseline within 20 min after the end of the stimulation period, while DA in the Occ reached a maximum increase during 20 min post-stimulation and remained higher than baseline values at 220 min post-stimulation. Local perfusion with tetrodotoxin (TTX, 10 microM) markedly reduced baseline NA and DA in the mPFC and Occ and totally suppressed the effect of electrical stimulation in both areas. A sequence of five 20 min stimulations at 20 min intervals were delivered to the LC. Each stimulus increased NA to the same extent and duration as the first stimulus, whereas DA remained elevated at the time next stimulus was delivered, so that baseline DA progressively increased in the mPFC and Occ to reach about 130 and 200% the initial level, respectively. In the presence of the NA transport (NAT) blocker desipramine (DMI, 100 microM), multiple LC stimulation still increased extracellular NA and DA levels. Electrical stimulation of the LC increased NA levels in the homolateral caudate nucleus, but failed to modify DA level. CONCLUSION: The results confirm and extend that LC stimulation induces a concomitant release of DA and NA in the mPFC and Occ. The different time-course of LC-induced elevation of DA and NA suggests that their co-release may be differentially controlled.

Selective inhibition of dopamine-beta-hydroxylase enhances dopamine release from noradrenergic terminals in the medial prefrontal cortex.

INTRODUCTION: Disulfiram has been claimed to be useful in cocaine addiction therapy, its efficacy being attributed to dopamine-beta-hydroxylase (DBH) inhibition. Our previous results indicate that disulfiram and the selective DBH inhibitor nepicastat increase extracellular dopamine (DA) in the rat medial prefrontal cortex (mPFC), and markedly potentiated cocaine-induced increase. Concomitantly, in rats with cocaine self-administration history, cocaine-seeking behavior induced by drug priming was prevented, probably through overstimulation of D1 receptors due to the DA increase. The present research was aimed at studying the neurochemical mechanisms originating the enhanced DA release. METHODS: Noradrenergic system ablation was attained by intracerebroventricular (i.c.v.) administration of the neurotoxin anti-DBH-saporin (aDBH-sap). DA, noradrenaline (NA), and DOPAC were assessed by HPLC after ex vivo tissue extraction or in vivo microdialysis. Control and denervated rats were subjected to microdialysis in the mPFC and caudate nucleus to evaluate the effect of nepicastat-cocaine combination on extracellular DA levels and their regulation by α2-adrenoceptors. RESULTS: Fifteen days after neurotoxin or its vehicle administration, tissue and extracellular NA were reduced to less than 2% the control value, while extracellular DA was increased by approximately 100%. In control rats, nepicastat given alone and in combination with cocaine increased extracellular DA by about 250% and 1100%, respectively. In denervated rats, nepicastat slightly affected extracellular DA, while in combination with cocaine increased extracellular DA by 250%. No differences were found in the caudate nucleus. Clonidine almost totally reversed the extracellular DA elevation produced by nepicastat-cocaine combination, while it was ineffective in denervated rats. CONCLUSIONS: This research shows that the increase of extracellular DA produced by nepicastat alone or in combination with cocaine was prevented by noradrenergic denervation. The results indicate that nepicastat enhances DA release from noradrenergic terminals supposedly by removing NA from α2-autoreceptors. In addition to the inhibition of DA uptake, the latter mechanism may explain the synergistic effect of cocaine on nepicastat-induced DA release.

Nitrergic system and plasmatic methylarginines: Evidence of their role in the perinatal programming of cardiovascular diseases.

Atherosclerosis, in turn preceded by endothelial dysfunction, underlies a series of important cardiovascular diseases. Reduced bioavailability of endothelial nitric oxide, by increasing vascular tone and promoting platelet aggregation, leukocyte adhesion, and smooth muscle cell proliferation, plays a key role in the onset of the majority of cardiovascular diseases. In addition, high blood levels of asymmetric dimethylarginine, a potent inhibitor of nitric oxide synthesis, are associated with future development of adverse cardiovascular events and cardiac death. Recent reports have demonstrated that another methylarginine, i.e., symmetric dimethylarginine, is also involved in the onset of endothelial dysfunction and hypertension. Almost a decade ago, prematurity at birth and intrauterine growth retardation were first associated with a potential negative influence on the cardiovascular apparatus, thus constituting risk factors or leading to early onset of cardiovascular diseases. This condition is referred to as cardiovascular perinatal programming. Accordingly, cardiovascular morbidity and mortality are higher among former preterm adults than in those born at term. The aim of this paper was to undertake a comprehensive literature review focusing on cellular and biochemical mechanisms resulting in both reduced nitric oxide bioavailability and increased methylarginine levels in subjects born preterm. Evidence of the involvement of these compounds in the perinatal programming of cardiovascular risk are also discussed.

Endodontic infection and endothelial dysfunction are associated with different mechanisms in men and women.

INTRODUCTION: To investigate the potential link between apical periodontitis (AP) and cardiovascular (CV) function, inflammation markers, endothelial flow reserve (EFR), and levels of asymmetrical dimethylarginine (ADMA), the endogenous inhibitor of nitric oxide synthase (NOS), were measured in young adults with AP aged 20-40 years of both sexes. METHODS: Forty men and 41 women (31 ± 5.71 years) free from periodontal disease, CV disease, and traditional CV risk factors were enrolled in the study. Twenty men and 21 women had AP; 40 healthy individuals matched for age, sex, and physical characteristics were also recruited as controls. All subjects underwent dental and complete physical examination, electrocardiography, conventional and tissue Doppler imaging echocardiography, and measurement of EFR. Interleukin (IL)-2, tumor necrosis factor alpha, reactive oxygen species (ROS), and ADMA were also assessed. Data were analyzed using the 2-tailed Student t test, the Pearson t test (or the Spearman t test for nonparametric variables), and multivariate linear regression analysis. RESULTS: Echocardiography excluded any morphologic and functional cardiac alteration in all the subjects studied. Patients with AP of both sexes showed a significant reduction in EFR (P < .05) and a significant increase in IL-2 (men: P < .01, women: P < .05), whereas ROS were increased significantly only in women (P < .05). ADMA levels were unchanged in women with AP, but they were significantly increased in men (P < .05). A significant direct correlation between ADMA and IL-2 (r = 0.67, P < .001) and an inverse correlation between ADMA and EFR (r = -0.42, P < .05) in men and a significant inverse correlation between ROS and EFR (r = -0.71, P < .01) in female patients were observed. CONCLUSIONS: The presence of chronic inflammation in young adults with AP may cause early endothelial dysfunction documented by the reduced EFR. AP in men may influence the metabolism of NOS, whereas in women it appears to implicate a more direct detrimental mechanism. This difference is sex dependent and may be attributable to the protective action of estrogen in women.

Co-release of noradrenaline and dopamine in the prefrontal cortex after acute morphine and during morphine withdrawal.

RATIONALE: Acute morphine and abstinence from chronic morphine have been shown to increase and to decrease extracellular dopamine (DA) in the nucleus accumbens, respectively. In contrast, extracellular DA in the prefrontal cortex (PFC) is not modified by acute morphine and is markedly increased during abstinence syndrome. OBJECTIVES: We investigated whether the peculiar behaviour of PFC DA might depend on the fact that extracellular DA originates not only from DA but, mainly, noradrenaline (NA) terminals. Accordingly, we studied if the effect of acute morphine and morphine-abstinence was modified by the inhibition of DA or NA neurons. METHODS: Extracellular DA and noradrenaline (NA) concentrations were determined by microdialysis in the PFC (densely innervated by DA) and in the parietal cortex (lacking DA afferents) both after acute morphine and in morphine-dependent rats during naloxone-precipitated abstinence syndrome. Dialysate catecholamine levels were evaluated by high performance liquid chromatography (HPLC) with electrochemical detection. RESULTS: Acute morphine (5 mg/kg IP) reduced extracellular NA (by 30%) and failed to modify extracellular DA level in the PFC, but reduced both amines by 40% in the parietal cortex. The co-administration of morphine and the D(2) agonist quinpirole (0.5 mg/kg IP) decreased both extracellular DA and NA by 40% in the PFC. In morphine dependent rats the administration of naloxone (1.0 mg/kg, SC) precipitated a typical abstinence syndrome associated with a concomitant dramatic increase in extracellular DA and NA by about 200 and 100%, respectively, in the PFC. The alpha(2)-adrenoceptor agonist clonidine (0.15 mg/kg IP) suppressed naloxone precipitated abstinence symptoms and brought both NA and DA output in the PFC to <50% baseline values. In contrast, quinpirole was totally ineffective. CONCLUSIONS: The results suggest that: a) morphine-stimulated DA release from DA terminals is compensated by reduced DA release from NA terminals; b) morphine abstinence-induced inhibition of DA release from DA terminals is overshadowed by a marked increase in DA released from NA terminals. Thus, the paradoxical response of PFC DA to morphine and morphine abstinence may be explained by the fact that extracellular DA in the PFC mainly represents the amine co-released from NA terminals.

Co-release of noradrenaline and dopamine from noradrenergic neurons in the cerebral cortex induced by clozapine, the prototype atypical antipsychotic.

RATIONALE: Clozapine has been shown to increase extracellular dopamine (DA) and noradrenaline (NA) in the medial prefrontal cortex (mPFC). A recent study of ours suggested that extracellular DA in the PFC originates not only from dopaminergic but also from noradrenergic terminals, its release being controlled by alpha(2)-adrenoceptors. OBJECTIVES: Since clozapine binds to alpha(2)-adrenoceptors, the possibility that it might co-release DA and NA was studied. METHODS: By means of microdialysis coupled to HPLC with electrochemical detection, the effect of clozapine on extracellular DA and NA in the mPFC, densely innervated by DA and NA, was compared to that in the occipital cortex, equally innervated by NA but receiving few DA projections. RESULTS: Extracellular NA was found to be the same in the two cortices, consistent with homogeneous NA innervation. On the other hand, extracellular DA in the occipital cortex was only 29% lower than in the mPFC, in spite of the scarce dopaminergic innervation in the occipital cortex. Clozapine (10 mg/kg IP) increased extracellular DA and NA not only in the mPFC (by about 320% and 290%, respectively) but also in the occipital cortex (by 560% and 230%, respectively). Administration of the alpha(2)-agonist clonidine (0.15 mg/kg) reversed the effect of clozapine in both cortices, while the D(2)-agonist quinpirole (0.1 mg/kg IP) was ineffective. CONCLUSIONS: The results suggest that clozapine, by inhibiting alpha(2)-adrenoceptors, co-releases DA and NA from noradrenergic terminals in the occipital cortex and that the same mechanism might be responsible for the concomitant increase of the two monoamines in the mPFC.

Delta(9)-tetrahydrocannabinol decreases extracellular GABA and increases extracellular glutamate and dopamine levels in the rat prefrontal cortex: an in vivo microdialysis study.

Cannabinoid modulation of prefrontal cortex and hippocampus neuronal functioning has been correlated to the disruptive action of marijuana on memory tasks. This study investigates the effects of delta(9)-tetrahydrocannabinol (delta(9)-THC) on dopamine, glutamate and GABA levels in vivo by brain microdialysis in the prefrontal cortex. Delta(9)-THC (1 mg/kg, i.v.) significantly increased extracellular dopamine and glutamate levels and decreased GABA levels. These effects were prevented by the cannabinoid antagonist SR141716A (1 mg/kg, i.v.), which per se was ineffective. These results suggest that delta(9)-THC disrupt the normal interplay between neurotransmitters in this area and may bear relevance in understanding neuronal mechanisms underlying cannabinoid-induced cognitive deficits.

Mirtazapine-induced corelease of dopamine and noradrenaline from noradrenergic neurons in the medial prefrontal and occipital cortex.

The novel antidepressant mirtazapine has been shown to increase extracellular noradrenaline and dopamine in the medial prefrontal cortex. Our previous studies indicate that extracellular dopamine in the cerebral cortex originates largely from noradrenergic terminals, such release being controlled by alpha(2)-adrenoceptors. Because mirtazapine inhibits alpha(2)-adrenoceptors, the possibility that it might corelease dopamine and noradrenaline was investigated. By means of microdialysis, the effect of mirtazapine on extracellular dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and noradrenaline in the medial prefrontal cortex, densely innervated by dopaminergic and noradrenergic neurons, and in the occipital cortex, receiving equal noradrenergic but scarce dopaminergic projections, was compared. Basal extracellular concentration of noradrenaline was similar in both cortices, while dopamine in the occipital cortex was only about 50% lower than in the medial prefrontal cortex, reflecting noradrenergic rather than dopaminergic projections. The intraperitoneal (i.p.) administration of mirtazapine (5 and 10 mg/kg) increased extracellular dopamine, DOPAC and noradrenaline to approximately the same extent in both cortices, an effect totally suppressed by the alpha(2)-adrenoceptors agonist clonidine (0.15 mg/kg, i.p.). To exclude the possibility that mirtazapine-induced increase in dopamine might result from reduced dopamine removal from extracellular space, noradrenaline and dopamine uptake mechanisms were blocked by perfusing 100 microM desipramine into either cortex. The combined i.p. administration of mirtazapine (5 mg/kg) and the local perfusion of desipramine produced an additional increase in extracellular dopamine, DOPAC and noradrenaline in the medial prefrontal cortex and occipital cortex compared with the increase produced by either drug given alone. The results suggest that mirtazapine by inhibiting alpha(2)-adrenoceptors produces a corelease of noradrenaline and dopamine from noradrenergic terminals in the cerebral cortex.