What is the best treatment for hypotension in healthy dogs during anaesthesia maintained with isoflurane?

Hypotension is a common and potentially life-threatening complication of general anaesthesia in dogs. Due to the combination of cardiovascular side effects of many anaesthetic, sedative and analgesic drugs used peri-operatively hypotension is frequently reported even in healthy dogs undergoing elective procedures. Several treatment options for hypotension have been advocated. Potential treatments include rapid administration of either crystalloid or colloid fluids; pharmacological treatments to increase cardiac output and/or systemic vascular resistance; or reduction in the delivery of the volatile anaesthetic agents. This critical appraisal considers the current evidence for which treatment is the best option for treating hypotension in healthy euvolemic dogs undergoing general anaesthesia maintained with isoflurane. Fourteen relevant studies were appraised, including 12 laboratory studies and two small clinical trials. One study demonstrated that reduction in the delivery of isoflurane may correct hypotension, but this treatment may not always be feasible. In general, rapid administration of fluids did not increase blood pressure and failed to correct hypotension. Synthetic colloids demonstrated some efficacy, but results were inconsistent between studies and large volumes may be required. Infusion of dopamine appears to be the most reliable pharmacological option consistently increasing blood pressure, cardiac output and correcting hypotension.

Effects of bee venom and dopamine-loaded nanoparticles on reserpine-induced Parkinson's disease rat model

Parkinson's disease (PD) is a progressive chronic neurodegenerative condition characterized by the loss of dopaminergic neurons within the substantia nigra. Current PD therapeutic strategies are mainly symptomatic and can lead to motor complications overtime. As a result, alternative medicine may provide an effective adjuvant treatment for PD as an addition to or as a replacement of the conventional therapies. The aim of this work was to evaluate the effects of Bee Venom (BV) and dopamine (DA)-loaded nanoparticles in a reserpine-induced animal model of PD. After inducing PD with reserpine injection, different groups of male rats were treated with L-Dopa, BV, DA-nanoparticles. Our findings showed that BV and DA-nanoparticles administration restored monoamines, balanced glutamate/GABA levels, halted DNA fragmentation, decreased pro-inflammatory mediators (IL-1β and TNF-α), and elevated anti-inflammatory mediators (PON1) and neurotropic factor (BDNF) levels in comparison with conventional therapy of PD. Furthermore, in a reserpine-induced PD rat model, the ameliorative effects of BV were significantly superior to that of DA-nanoparticles. These findings imply that BV and DA-nanoparticles could be useful as adjuvant treatments for PD.

Dopamine-loaded nanoparticle systems circumvent the blood-brain barrier restoring motor function in mouse model for Parkinson's Disease

Parkinson's disease (PD) is a progressive and chronic neurodegenerative disease of the central nervous system. Early treatment for PD is efficient; however, long-term systemic medication commonly leads to deleterious side-effects. Strategies that enable more selective drug delivery to the brain using smaller dosages, while crossing the complex brain-blood barrier (BBB), are highly desirable to ensure treatment efficacy and decrease/avoid unwanted outcomes. Our goal was to design and test the neurotherapeutic potential of a forefront nanoparticle-based technology composed of albumin/PLGA nanosystems loaded with dopamine (ALNP-DA) in 6-OHDA PD mice model. ALNP-DA effectively crossed the BBB, replenishing dopamine at the nigrostriatal pathway, resulting in significant motor symptom improvement when compared to Lesioned and L-DOPA groups. Notably, ALNP-DA (20 mg/animal dose) additionally up-regulated and restored motor coordination, balance, and sensorimotor performance to non-lesioned (Sham) animal level. Overall, ALNPs represent an innovative, non-invasive nano-therapeutical strategy for PD, considering its efficacy to circumvent the BBB and ultimately deliver the drug of interest to the brain.

On-Demand Reversible UV-Triggered Interpenetrating Polymer Network-Based Drug Delivery System Using the Spiropyran-Merocyanine Hydrophobicity Switch

A reversible switchable on-demand UV-triggered drug delivery system (DDS) based on interpenetrating polymer networks (IPNs) with silicone as the host polymer and spiropyran (SP)-functionalized guest polymer is designed and demonstrated. The photo-responsive IPNs provide a new triggered drug delivery concept as they exploit the change in intermolecular interactions (work of adhesion) among the drug, matrix, and solvent when the incorporated hydrophobic SP moieties transform into the hydrophilic merocyanine form upon light irradiation without degradation and disruption of the DDS. The change in how the copolymer composition (hydrophilicity and content) and the lipophilicity of the drug (log P) affect the release profile was investigated. A thermodynamic model, based on Hansen solubility parameters, was developed to design and optimize the polymer composition of the IPNs to obtain the most efficient light-triggered drug release and suppression of the premature release. The developed IPNs showed excellent result for dopamine, l-dopa, and prednisone with around 90-95% light-triggered release. The model was applied to study the release behavior of drugs with different log P and to estimate if the light-induced hydrophobic-to-hydrophilic switch can overcome the work of adhesion between polymers and drugs and hence the desorption and release of the drugs. To the best of our knowledge, this is the first time that work of adhesion is used for this aim. Comparing the result obtained from the model and experiment shows that the model is useful for evaluating and estimating the release behavior of specific drugs merocyanine, IPN, DDS, and spiropyran.

Noradrenaline enhances the excitatory effects of dopamine on medial prefrontal cortex pyramidal neurons in rats

Aim

Our previous studies showed that exposure to acute restraint stress enhanced cocaine‐induced conditioned place preference (cocaine‐CPP) and suggested the possibility that co‐activation of adrenergic transmission boosts the increase in medial prefrontal cortex (mPFC) neuronal activity by the activation of dopaminergic transmission. To examine this possibility, the effects of the co‐treatment with dopamine (DA) and noradrenaline (NA) on mPFC neurons were compared with those of treatment with DA alone using whole‐cell patch‐clamp recordings.

Methods

The effects of DA alone and a mixture of DA and NA on the membrane potentials and spontaneous excitatory postsynaptic currents (sEPSCs) were examined by electrophysiological recordings of mPFC pyramidal neurons in brain slices of male Sprague Dawley rats. Extracellular DA and NA levels in the mPFC during and after restraint stress exposure were also examined by in vivo microdialysis.

Results

Dopamine significantly produced depolarizing effects on mPFC neurons and tended to increase sEPSC frequency. Co‐administration of NA with DA produced stronger depolarizing effects and significantly increased sEPSC frequency. The findings suggest that the additional depolarizing effect of NA on DA‐responsive neurons, rather than the excitation of DA‐nonresponsive neurons by NA, contributes to the stronger effect of co‐treatment of NA with DA.

Conclusion

The present study suggests that NA released by restraint stress exposure cooperates with DA to stimulate DA‐responsive neurons in the mPFC, thereby causing the stress‐induced enhancement of cocaine‐CPP.

Our previous studies showed that exposure to acute restraint stress enhanced cocaine‐induced conditioned place preference (cocaine‐CPP). The present study revealed that noradrenaline enhanced the excitatory effects of dopamine on medial prefrontal cortex (mPFC) pyramidal neurons in rats. Noradrenaline released by restraint stress exposure may cooperate with dopamine to stimulate dopamine‐responsive neurons in the mPFC, thereby causing the stress‐induced enhancement of cocaine‐CPP.

Altered dopaminergic pathways and therapeutic effects of intranasal dopamine in two distinct mouse models of autism

The dopamine (DA) system has a profound impact on reward-motivated behavior and is critically involved in neurodevelopmental disorders, such as autism spectrum disorder (ASD). Although DA defects are found in autistic patients, it is not well defined how the DA pathways are altered in ASD and whether DA can be utilized as a potential therapeutic agent for ASD. To this end, we employed a phenotypic and a genetic ASD model, i.e., Black and Tan BRachyury T+Itpr3tf/J (BTBR) mice and Fragile X Mental Retardation 1 knockout (Fmr1-KO) mice, respectively. Immunostaining of tyrosine hydroxylase (TH) to mark dopaminergic neurons revealed an overall reduction in the TH expression in the substantia nigra, ventral tegmental area and dorsal striatum of BTBR mice, as compared to C57BL/6 J wild-type ones. In contrast, Fmr1-KO animals did not show such an alteration but displayed abnormal morphology of TH-positive axons in the striatum with higher "complexity" and lower "texture". Both strains exhibited decreased expression of striatal dopamine transporter (DAT) and increased spatial coupling between vesicular glutamate transporter 1 (VGLUT1, a label for glutamatergic terminals) and TH signals, while GABAergic neurons quantified by glutamic acid decarboxylase 67 (GAD67) remained intact. Intranasal administration of DA rescued the deficits in non-selective attention, object-based attention and social approaching of BTBR mice, likely by enhancing the level of TH in the striatum. Application of intranasal DA to Fmr1-KO animals alleviated their impairment of social novelty, in association with reduced striatal TH protein. These results suggest that although the DA system is modified differently in the two ASD models, intranasal treatment with DA effectively rectifies their behavioral phenotypes, which may present a promising therapy for diverse types of ASD.

BTBD9 and dopaminergic dysfunction in the pathogenesis of restless legs syndrome

Restless legs syndrome (RLS) is characterized by an urge to move legs, usually accompanied by uncomfortable sensations. RLS symptoms generally happen at night and can be relieved by movements. Genetic studies have linked polymorphisms in BTBD9 to a higher risk of RLS. Knockout of BTBD9 homolog in mice (Btbd9) and fly results in RLS-like phenotypes. A dysfunctional dopaminergic system is associated with RLS. However, the function of BTBD9 in the dopaminergic system and RLS is not clear. Here, we made use of the simple Caenorhabditis elegans nervous system. Loss of hpo-9, the worm homolog of BTBD9, resulted in hyperactive egg-laying behavior. Analysis of genetic interactions between hpo-9 and genes for dopamine receptors (dop-1, dop-3) indicated that hpo-9 and dop-1 worked similarly. Reporter assays of dop-1 and dop-3 revealed that hpo-9 knockout led to a significant increase of DOP-3 expression. This appears to be evolutionarily conserved in mice with an increased D₂ receptor (D₂R) mRNA in the striatum of the Btbd9 knockout mice. Furthermore, the striatal D₂R protein was significantly decreased and Dynamin I was increased. Overall, activities of DA neurons in the substantia nigra were not altered, but the peripheral D₁R pathway was potentiated in the Btbd9 knockout mice. Finally, we generated and characterized the dopamine neuron-specific Btbd9 knockout mice and detected an active-phase sleepiness, suggesting that dopamine neuron-specific loss of Btbd9 is sufficient to disturb the sleep. Our results suggest that increased activities in the D₁R pathway, decreased activities in the D₂R pathway, or both may contribute to RLS.

In vitro investigations on dopamine loaded Solid Lipid Nanoparticles

The progressive degeneration of nigrostriatal neurons leads to depletion of the neurotransmitter dopamine (DA) in Parkinson's disease (PD). The hydrophilicity of DA, hindering its cross of the Blood Brain Barrier, makes impossible its therapeutic administration. This work aims at investigating some physicochemical features of novel Solid Lipid Nanoparticles (SLN) intended to enhance DA brain delivery for PD patients by intranasal administration. For this aim, novel SLN were formulated in the presence of Glycol Chitosan (GCS), and it was found that SLN containing GCS and DA were smaller than DA-loaded SLN, endowed with a slightly positive zeta potential value and, remarkably, incorporated 81 % of the initial DA content. The formulated SLN were accurately characterized by Infrared Spectroscopy in Attenuated Total Reflectance mode (FT-IT/ATR) and Thermogravimetric Analysis (TGA) to highlight SLN solid-state properties as a preliminary step forward biological assay. Overall, in vitro characterization shows that SLN are promising for DA incorporation and stable from a thermal viewpoint. Further studies are in due course to test their potential for PD treatment.

The effect of carotid chemoreceptor inhibition on exercise tolerance in chronic obstructive pulmonary disease: A randomized-controlled crossover trial

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory response to exercise, contributing to exertional dyspnea and exercise intolerance. We recently demonstrated enhanced activity and sensitivity of the carotid chemoreceptor (CC) in COPD which may alter ventilatory and cardiovascular regulation and negatively affect exercise tolerance. We sought to determine whether CC inhibition improves ventilatory and cardiovascular regulation, dyspnea and exercise tolerance in COPD.

METHODS

Twelve mild-moderate COPD patients (FEV₁ 83 ± 15 %predicted) and twelve age- and sex-matched healthy controls completed two time-to-symptom limitation (T_LIM) constant load exercise tests at 75% peak power output with either intravenous saline or low-dose dopamine (2 μg·kg^-1·min^-1, order randomized) to inhibit the CC. Ventilatory responses were evaluated using expired gas data and dyspnea was evaluated using a modified Borg scale. Inspiratory capacity maneuvers were performed to determine operating lung volumes. Cardiac output was estimated using impedance cardiography and vascular conductance was calculated as cardiac output/mean arterial pressure (MAP).

RESULTS

At a standardized exercise time of 4-min and at T_LIM; ventilation, operating volumes and dyspnea were unaffected by dopamine in COPD patients and controls. In COPD, dopamine decreased MAP and increased vascular conductance at all time points. In controls, dopamine increased vascular conductance at T_LIM, while MAP was unaffected.

CONCLUSION

There was no change in time to exhaustion in either group with dopamine. These data suggest that the CC plays a role in cardiovascular regulation during exercise in COPD; however, ventilation, dyspnea and exercise tolerance were unaffected by CC inhibition in COPD patients.

Transcriptome analysis of hemocytes from the white shrimp Litopenaeus vannamei with the injection of dopamine

As a crucial neuroendocrine-immune factor, dopamine (DA) could regulate the immune system of Litopenaeus vannamei. To understand the immune mechanisms and regulatory pathways of DA in L. vannamei, the transcriptome analysis of hemocytes of L. vannamei with injection of DA (10^-6 mol/shrimp) at 3 and 12 h were performed in this study. Moreover, quantitative real-time PCR (qPCR) method was applied to validate the accuracy of transcriptome sequencing and analyze the expression pattern of candidate differentially expressed genes (DEGs) at different time points (0, 3, 6, 12, and 24 h) after DA injection. The results showed that a total of 51382 unigenes with a N50 length of 2341 bp were generated. And 1397 and 457 DEGs were obtained by comparative transcriptome at 3 and 12h respectively. Moreover, the results of functional annotation and enriched pathway showed that the DEGs were involved in phagosome (ko04145), lysosome (ko04142), Endocytosis (ko04144), and NOD-like receptor signaling pathway (ko04621). Besides, the Pearson's correlation coefficient (R) between transcriptome sequencing and qPCR was 0.845, which confirmed the reliability of the transcriptome sequencing results and the accuracy of assembly. Furthermore, the expression pattern of 15 candidate DEGs, containing 9 up-regulated and 6 down-regulated DEGs at 3 h, indicated the regulation of DA in physiological functions especially in the immune system. Therefore, these results revealed that DA induced the expressions of membrane receptors or proteins, activated intracellular signaling pathways, regulated cellular and humoral immune systems, controlled antioxidation and apoptosis, and was involved in the regulation of neuroendocrine system. These findings are helpful to promote the understanding on the effects of biogenic amines on physiological functions and regulatory networks of crustacean, and offer a substantial material and foundation for researching the immune response of crustacean.

Dopamine enhancement of dextrorphan-induced skin antinociception in response to needle pinpricks in rats

BACKGROUND

Dextrorphan with long-acting local anesthetic effects did not cause system toxicity as fast as bupivacaine, while catecholamines (i.e., epinephrine) with the vasoconstrictive characteristics enhanced the effects of local anesthetic drugs. The objective of the experiment was to examine the synergistic effect of local dopamine (a catecholamine) injection on cutaneous antinociception of dextrorphan.

METHODS

The panniculus reflex in response to skin stimulation with a needle was used as the primary endpoint when dextrorphan (1.50, 2.61, 5.46, 10.20 and 20.40 μmol) alone, dopamine (16.20, 32.40, 51.60, 60.00 and 81.60 μmol) alone, or dopamine + dextrorphan (a ratio of ED₅₀vs. ED₅₀) was injected subcutaneously on the rat's back. We used an isobolographic modelling approach to determine whether a synergistic effect would be observed.

RESULTS

We showed that dextrorphan, dopamine, or the mixture of dopamine and dextrorphan produced dose-related skin antinociception. The potency (ED₅₀, 50% effective dose) for cutaneous antinociception was dextrorphan [6.02 (5.93-6.14) μmol] greater than dopamine [48.91 (48.80-49.06) μmol] (p < 0.01). The duration of nociceptive inhibition induced by dopamine was longer than that induced by dextrorphan (p <  0.01) based on their equipotent doses (ED₂₅, ED₅₀, and ED₇₅). Enhancement and prolongation of skin antinociception occurred after co-administration of dopamine with dextrorphan.

CONCLUSIONS

When compared to dopamine, dextrorphan was more potent and had a shorter duration of skin nociceptive block. Dopamine produced a synergistic effect on dextrorphan-mediated antinociception, and prolonged dextrorphan's antinociceptive duration.

Anti-inflammatory Effects of Dopamine in Lipopolysaccharide (LPS)-stimulated RAW264.7 Cells via Inhibiting NLRP3 Inflammasome Activation

OBJECTIVE

Dopamine (DA) is a neurotransmitter and chemical mediator, and DA receptors (particularly DRD1) are present on the majority of immune cells. The aim of this study was to investigate the effects of DA on lipopolysaccharide (LPS)-stimulated inflammatory responses in RAW264.7 cells.

METHODS

Cells were exposed to DA (10*^-3, 10*^-4 and 10*^-5M) for 2 hr prior, with or without LPS (1μg/ml) for 6hr. Additionally, DA and NLRP3 inhibitor, MCC950 had treated LPS-stimulated RAW264.7 cells. CCK8 assays were used for the assessment of cell viability and Quantitative real-time PCR (qRT-PCR) and western blot analysis were used to examine mRNA and protein expression levels, respectively.

RESULTS

Our results reveal that DA reduces the mRNA and protein expression of tumor necrosis factor-a (TNF-α), interleukin-6 (IL-6) and interleukin (1L), (IL-1β) in RAW 264.7 cells stimulated with LPS. DA also inhibited the mRNA and protein expression levels of nitric oxide synthase (iNOS) and downregulated NLRP3 and caspase-1 expression. The administration of DA and NLRP3 inhibitor, MCC950 played a synergistic role in suppressing NLRP3 activity.

CONCLUSION

Taken together, these findings demonstrate that DA displays potent anti-inflammatory effects that are mediated by the suppression of pro-inflammatory mediators (IL-1β, IL-6, TNF-α), cytokines (iNOS) and the NLRP3 inflammasome activation. Improvement of DA correlated with its effect on NLRP3 activation. Thus, DA and agonists of DRD1, as a functional molecule that bridges the neuronal and immune systems, may represent effective strategies for limiting pathological inflammation.

A Novel Somatostatin-Dopamine Chimera (BIM23B065) Reduced GH Secretion in a First-in-Human Clinical Trial

CONTEXT

A somatostatin-dopamine chimera (BIM23B065) was under investigation to reduce GH secretion for the treatment of pituitary adenomas.

OBJECTIVE

To determine pharmacokinetics, safety, and tolerability and to monitor hormonal changes after single and multiple subcutaneous BIM23B065 administrations.

DESIGN

Randomized, double-blind, placebo-controlled, parallel-group design with five single and three 13-day multiple ascending-dose cohorts.

PATIENTS

A total of 63 healthy male white volunteers were enrolled (47 active, 16 placebo).

MAIN OUTCOME MEASURES

Pharmacokinetics, GH, prolactin (PRL), IGF-1, GH after GHRH administration, and general clinical safety criteria.

RESULTS

The maximum dosage of BIM23B065 administered in this study was 1.5 mg. BIM23B065 reduced the mean GH concentrations after 8 and 13 days of treatment. A decrease in GH release after GHRH administration indicated inhibition of the hypothalamic-pituitary-somatotropic axis. IGF-1 was not altered after single doses but showed a significant change from baseline after multiple dosing. PRL secretion was reduced in all subjects who were treated. Orthostatic hypotension and injection site reactions were commonly observed at high dosages. A 6-day uptitration period was included to successfully lower the cardiovascular effects in the multiple ascending dose part of the study.

CONCLUSIONS

Proof of pharmacology of BIM23B065 was shown by a reduction in GH, IGF-1, and PRL concentrations in healthy male volunteers, supporting activity of the somatostatin analog and dopamine agonist moieties. The safety and tolerability of the higher dosing regions was limited mainly by orthostatic hypotension.

Fréquence et profil clinique de la maladie de Parkinson et des autres syndromes Parkinsoniens vus au service de neurologie de l'hôpital Befelatanana Antananarivo

Introduction

Méthodes

Résultats

Conclusion

Dopamine-dependent prefrontal reactivations explain long-term benefit of fear extinction

Fear extinction does not prevent post-traumatic stress or have long-term therapeutic benefits in fear-related disorders unless extinction memories are easily retrieved at later encounters with the once-threatening stimulus. Previous research in rodents has pointed towards a role for spontaneous prefrontal activity occurring after extinction learning in stabilizing and consolidating extinction memories. In other memory domains spontaneous post-learning activity has been linked to dopamine. Here, we show that a neural activation pattern - evoked in the ventromedial prefrontal cortex (vmPFC) by the unexpected omission of the feared outcome during extinction learning - spontaneously reappears during postextinction rest. The number of spontaneous vmPFC pattern reactivations predicts extinction memory retrieval and vmPFC activation at test 24 h later. Critically, pharmacologically enhancing dopaminergic activity during extinction consolidation amplifies spontaneous vmPFC reactivations and correspondingly improves extinction memory retrieval at test. Hence, a spontaneous dopamine-dependent memory consolidation-based mechanism may underlie the long-term behavioral effects of fear extinction.

The effect of dopamine on conditioned placebo analgesia in healthy individuals: a double-blind randomized trial

RATIONALE

Better means to control placebo effects are key to optimizing treatment outcomes. Dopamine-based reward and learning mechanisms have been hypothesized to drive placebo effects. Here, we tested whether dopamine augmentation can modulate learned placebo effects.

METHODS

We performed a randomized, double-blind parallel group study with 70 healthy adult participants to test whether a single oral dose of the dopamine precursor levodopa/carbidopa (100/25 mg) administered before the acquisition of conditioned placebo analgesia enhances the placebo response in an established experimental placebo model using heat pain.

RESULTS

Overall, the observed levels of placebo analgesia in our sample were low and not statistically significant. Levodopa, compared to placebo, only led to a marginal increase in placebo analgesia. Female participants tended to show larger placebo responses than male participants. Within the female subgroup, levodopa showed small-to-moderate effects on placebo analgesia; however, this effect was not statistically significant.

CONCLUSIONS

In summary, the present study could not provide evidence for a placebo augmenting effect of levodopa-enhanced dopamine levels in healthy subjects. Further studies are needed to elucidate whether placebo enhancement can be achieved through dopamine augmentation.

Level of uric acid and uric acid/creatinine ratios in correlation with stage of Parkinson disease

This study aims to investigate relationship between the level of uric acid (UA) and UA/creatinine ratios (UA/Cr) to the stage of Parkinson disease (PD).A total of 120 cases of PD patients who were admitted in our hospital between 2013 and 2015 were enrolled into this study; these 120 cases of PD patients were divided into 3 groups, according to Hoehn-Yahr (H-Y) classification: early stage (1-2 classification), medium stage (2.5-3 classification), and advanced stage (4-5 classification); UA and UA/Cr level in each group was compared. Then, factors including age, gender, dopamine dosage, UA, and UA/Cr levels were analyzed to find the independent predictive factors of PD by logistic regression.UA and UA/Cr levels in the early and medium stage PD patients were significantly higher than in the advanced stage ones. UA and UA/Cr levels in patients with good prognosis were significantly higher than in the poor ones.UA and UA/Cr levels are negatively correlated with the stages of PD and are independent negatively predicting biological indexes of PD incidence and progression.

Dietary Neurotransmitters: A Narrative Review on Current Knowledge

Foods are natural sources of substances that may exert crucial effects on the nervous system in humans. Some of these substances are the neurotransmitters (NTs) acetylcholine (ACh), the modified amino acids glutamate and γ-aminobutyric acid (GABA), and the biogenic amines dopamine, serotonin (5-HT), and histamine. In neuropsychiatry, progressive integration of dietary approaches in clinical routine made it necessary to discern the more about some of these dietary NTs. Relevant books and literature from PubMed and Scopus databases were searched for data on food sources of Ach, glutamate, GABA, dopamine, 5-HT, and histamine. Different animal foods, fruits, edible plants, roots, and botanicals were reported to contain NTs. These substances can either be naturally present, as part of essential metabolic processes and ecological interactions, or derive from controlled/uncontrolled food technology processes. Ripening time, methods of preservation and cooking, and microbial activity further contributes to NTs. Moreover, gut microbiota are considerable sources of NTs. However, the significance of dietary NTs intake needs to be further investigated as there are no significant data on their bioavailability, neuronal/non neuronal effects, or clinical implications. Evidence-based interventions studies should be encouraged.

Adding Dopamine to Proxymetacaine or Oxybuprocaine Solutions Potentiates and Prolongs the Cutaneous Antinociception in Rats

BACKGROUND

We evaluated the interaction of dopamine-proxymetacaine and dopamine- oxybuprocaine antinociception using isobolograms.

METHODS

This experiment uses subcutaneous drug (proxymetacaine, oxybuprocaine, and dopamine) injections under the skin of the rat's back, thus simulating infiltration blocks. The dose-related antinociceptive curves of proxymetacaine and oxybuprocaine alone and in combination with dopamine were constructed, and then the antinociceptive interactions between the local anesthetic and dopamine were analyzed using isobolograms.

RESULTS

Subcutaneous proxymetacaine, oxybuprocaine, and dopamine produced a sensory block to local skin pinpricks in a dose-dependent fashion. The rank order of potency was proxymetacaine (0.57 [0.52-0.63] μmol/kg) > oxybuprocaine (1.05 [0.96-1.15] μmol/kg) > dopamine (165 [154-177] μmol/kg; P < .01 for each comparison) based on the 50% effective dose values. On the equianesthetic basis (25% effective dose, 50% effective dose, and 75% effective dose), the nociceptive block duration of proxymetacaine or oxybuprocaine was shorter than that of dopamine (P < .01). Oxybuprocaine or proxymetacaine coinjected with dopamine elicited a synergistic antinociceptive effect and extended the duration of action.

CONCLUSIONS

Oxybuprocaine and proxymetacaine had a higher potency and provoked a shorter duration of sensory block compared with dopamine. The use of dopamine increased the quality and duration of skin antinociception caused by oxybuprocaine and proxymetacaine.

Inhibition of basal and amphetamine-stimulated extracellular signal-regulated kinase (ERK) phosphorylation in the rat forebrain by muscarinic acetylcholine M4 receptors

The mitogen-activated protein kinase (MAPK), especially its extracellular signal-regulated kinase (ERK) subfamily, is a group of kinases enriched in the mammalian brain. While ERK is central to cell signaling and neural activities, the regulation of ERK by transmitters is poorly understood. In this study, the role of acetylcholine in the regulation of ERK was investigated in adult rat striatum in vivo. We focused on muscarinic M1 and M4 receptors, two principal muscarinic acetylcholine (mACh) receptor subtypes in the striatum. A systemic injection of the M1-preferring antagonist telenzepine did not alter ERK phosphorylation in the two subdivisions of the striatum, the caudate putamen and nucleus accumbens. Similarly, telenzepine did not affect ERK phosphorylation in the medial prefrontal cortex (mPFC), hippocampus, and cerebellum. Moreover, telenzepine had no effect on the ERK phosphorylation induced by dopamine stimulation with the psychostimulant amphetamine. In contrast to telenzepine, the M4-preferring antagonist tropicamide consistently increased ERK phosphorylation in the striatum and mPFC. This increase was rapid and transient. Tropicamide and amphetamine when coadministered at subthreshold doses induced a significant increase in ERK phosphorylation. These results demonstrate that mACh receptors exert a subtype-specific modulation of ERK in striatal and mPFC neurons. While the M1 receptor antagonist has no effect on ERK phosphorylation, M4 receptors inhibit constitutive and dopamine-stimulated ERK phosphorylation in these dopamine-innervated brain regions.

Effects of intra-accumbal administration of dopamine and ionotropic glutamate receptor drugs on delay discounting performance in rats

Nucleus accumbens core (NAcc) has been implicated in impulsive choice, as measured in delay discounting. The role of dopamine (DA) in impulsive choice has received considerable attention, whereas glutamate (Glu) has recently been shown to be an important mediator of discounting. However, research has not examined how DA or Glu receptors in NAcc mediate different aspects of delay discounting performance, that is, (a) sensitivity to reinforcer magnitude and (b) sensitivity to delayed reinforcement. Adult male Sprague-Dawley rats were first trained in a delay discounting task, in which the delay to a large magnitude food reinforcer increased across blocks of trials. Following behavioral training, rats received bilateral implantation of guide cannulas into NAcc. Half of the rats (n = 12) received infusions of the DA-selective ligands SKF 38393 (D1-like agonist: 0.03 or 0.1 μg), SCH 23390 (D1-like antagonist: 0.3 or 1.0 μg), quinpirole (D2-like agonist: 0.3 or 1.0 μg), and eticlopride (D2-like antagonist: 0.3 or 1.0 μg). The other half received infusions of the ionotropic Glu ligands MK-801 (NMDA uncompetitive antagonist: 0.3 or 1.0 μg), AP-5 (NMDA competitive antagonist: 0.3 or 1.0 μg), ifenprodil (noncompetitive antagonist at NR2B-containing NMDA receptors: 0.3 or 1.0 μg), and CNQX (AMPA competitive antagonist: 0.2 or 0.5 μg). Results showed that SCH 23390 (0.3 μg) decreased sensitivity to reinforcer magnitude without altering impulsive choice, whereas ifenprodil (1.0 μg) decreased sensitivity to delayed reinforcement (i.e., impulsive choice). The current results show that DA and NMDA receptors in NAcc mediate distinct aspects of discounting performance. (PsycINFO Database Record

Functional single-walled carbon nanotubes 'CAR' for targeting dopamine delivery into the brain of parkinsonian mice

Current treatments for Parkinson's disease (PD) are limited, partly due to the difficulties posed by the blood brain barrier (BBB) when delivering drugs to the brain. Herein, we explore the feasibility and efficacy of functional single-walled carbon nanotubes 'CAR' (SWCNT-PEGs-Lf) which carry and target-deliver dopamine (DA) to the brain in PD mice for treatment. SWCNTs can penetrate the cell-membrane remarkably, with the characteristics including high drug-loading and pH-dependent therapeutic unloading capacities. It has been reported that polyethylene glycol (PEG)-coated SWCNTs could increase the circulation time and thus prolong the concentration gradient of SWCNTs to the brain. Besides, an obvious lactoferrin-nanoparticle (Lf-NP) accumulation in the striatum, wherein the pharmacological target site of PD has been reported, a dual modification of PEG and Lf onto SWCNTs was applied and thus a specific 'CAR' to carry DA. The results from in vitro studies demonstrate that with 20 mol L^-1 DA loaded onto SWCNT-polyethylene glycol (PEGs) in addition to 100 μmol L^-1 6-hydroxydopamine (6-OHDA), the activity of PC12 cells increases significantly (p < 0.05), and that the lactate dehydrogenase (LDH) levels and reactive oxygen species (ROS) content also significantly decrease (p < 0.01). Furthermore, the levels of oxidative stress, tumor necrosis factor (TNF)-α and interleukin (IL)-1β are all reduced significantly in PD mice and the CAR-25 mg kg^-1 DA group in comparison with that in 6-OHDA-lesioned mice with saline and 6-OHDA-lesioned mice, as well as the Tyrosine hydroxylase-immunoreactive (TH-ir) density increased (p < 0.01). The toxicity of CAR was in vitro and in vivo investigated, showing that the safe dose of SWCNT-PEG exposure to PC12 cells was 6.25 μg μl^-1 or lower with a higher metabolic activity in comparison with that in the control group and the safe dose of CAR in the mice experiments was 3.25 mg kg^-1 or less, given by intraperitoneal injection with a lower level of oxidative stress and inflammatory responses in comparison with that in the control group. This study suggests that 25 mg kg^-1 DA loaded onto 3.25 mg kg^-1 CAR can alleviate the oxidative stress and inflammatory responses in parkinsonian mice and increase the TH-ir density in the striatum.

Review of surgical and anesthetic management for esophageal atresia with tracheoesophageal fistula, unilateral pulmonary agenesis and dextrocardia

Association of unilateral severe pulmonary atresia or agenesis and esophageal atresia (EA) with or without tracheoesophageal fistula (TEF) and dextrocardia is a rare and highly lethal combination. We report a case of a full-term female infant who had EA with TEF, right lung agenesis, and dextrocardia. Repair of the fistula took place on day of life 3. We describe anesthetic and surgical concerns of this patient's case which are keys to a good operative outcome as well as follow-up for the patient.

Continuous cerebroventricular administration of dopamine: A new treatment for severe dyskinesia in Parkinson's disease?

In Parkinson's disease (PD) depletion of dopamine in the nigro-striatal pathway is a main pathological hallmark that requires continuous and focal restoration. Current predominant treatment with intermittent oral administration of its precursor, Levodopa (l-dopa), remains the gold standard but pharmacological drawbacks trigger motor fluctuations and dyskinesia. Continuous intracerebroventricular (i.c.v.) administration of dopamine previously failed as a therapy because of an inability to resolve the accelerated dopamine oxidation and tachyphylaxia. We aim to overcome prior challenges by demonstrating treatment feasibility and efficacy of continuous i.c.v. of dopamine close to the striatum. Dopamine prepared either anaerobically (A-dopamine) or aerobically (O-dopamine) in the presence or absence of a conservator (sodium metabisulfite, SMBS) was assessed upon acute MPTP and chronic 6-OHDA lesioning and compared to peripheral l-dopa treatment. A-dopamine restored motor function and induced a dose dependent increase of nigro-striatal tyrosine hydroxylase positive neurons in mice after 7days of MPTP insult that was not evident with either O-dopamine or l-dopa. In the 6-OHDA rat model, continuous circadian i.c.v. injection of A-dopamine over 30days also improved motor activity without occurrence of tachyphylaxia. This safety profile was highly favorable as A-dopamine did not induce dyskinesia or behavioral sensitization as observed with peripheral l-dopa treatment. Indicative of a new therapeutic strategy for patients suffering from l-dopa related complications with dyskinesia, continuous i.c.v. of A-dopamine has greater efficacy in mediating motor impairment over a large therapeutic index without inducing dyskinesia and tachyphylaxia.

Effects of Dopamine Donor Pretreatment on Graft Survival after Kidney Transplantation: A Randomized Trial

BACKGROUND AND OBJECTIVES

Donor dopamine improves initial graft function after kidney transplantation due to antioxidant properties. We investigated if a 4 µg/kg per minute continuous dopamine infusion administered after brain-death confirmation affects long-term graft survival and examined the exposure-response relationship with treatment duration.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Five-year follow-up of 487 renal transplant patients from 60 European centers who had participated in the randomized, multicenter trial of dopamine donor pretreatment between 2004 and 2007 (ClinicalTrials.gov identifier: NCT00115115).

RESULTS

Follow-up was complete in 99.2%. Graft survival was 72.6% versus 68.7% (P=0.34), and 83.3% versus 80.4% (P=0.42) after death-censoring in treatment and control arms according to trial assignment. Although infusion times varied substantially in the treatment arm (range 0-32.2 hours), duration of the dopamine infusion and all-cause graft failure exhibited an exposure-response relationship (hazard ratio, 0.96; 95% confidence interval [95% CI], 0.92 to 1.00, per hour). Cumulative frequency curves of graft survival and exposure time of the dopamine infusion indicated a maximum response rate at 7.10 hours (95% CI, 6.99 to 7.21), which almost coincided with the optimum infusion time for improvement of early graft function (7.05 hours; 95% CI, 6.92 to 7.18). Taking infusion time of 7.1 hours as threshold in subsequent graft survival analyses indicated a relevant benefit: Overall, 81.5% versus 68.5%; P=0.03; and 90.3% versus 80.2%; P=0.04 after death-censoring.

CONCLUSIONS

We failed to show a significant graft survival advantage on intention-to-treat. Dopamine infusion time was very short in a considerable number of donors assigned to treatment. Our finding of a significant, nonlinear exposure-response relationship disclosed a threshold value of the dopamine infusion time that may improve long-term kidney graft survival.

Synergistic Effects of Serotonin or Dopamine Combined With Lidocaine at Producing Nociceptive Block in Rats

BACKGROUND

The purpose of this experiment was to investigate the interactions of the local anesthetic lidocaine combined with an agent (serotonin or dopamine) as infiltrative anesthetics.

METHODS

Cutaneous analgesia was characterized by the blockade of the cutaneous trunci muscle reflex following 6 skin pinpricks on the rat back. Serotonin or dopamine at producing cutaneous analgesia in a dosage-dependent fashion was compared with lidocaine. Drug-drug interactions were calculated using the isobolographic analysis.

RESULTS

We revealed that serotonin, dopamine, and lidocaine provoked dose-related cutaneous analgesic effects. On the 50% effective dose basis, the rank of drugs' potency was found to be serotonin (1.70 [1.56-1.85] μmol) > lidocaine (5.18 [4.67-5.75] μmol) > dopamine (43.0 [40.9-45.2] μmol) (P < 0.01). At doses equivalent to their 25%, 50%, and 75% effective doses, serotonin or dopamine elicited a longer duration of action than lidocaine (P < 0.01) on producing cutaneous analgesia. Coadministration of serotonin or dopamine with lidocaine produced a synergistic effect.

CONCLUSIONS

The preclinical data showed that serotonin and dopamine produce dose-related cutaneous analgesic effects as an infiltrative anesthetic. Serotonin has a better potency with a much longer duration of action compared with lidocaine at provoking cutaneous analgesia. Serotonin or dopamine as an adjuvant increases the quality of lidocaine in cutaneous analgesia.

Risk factors and outcomes associated with a higher use of inotropes in kidney transplant recipients

Preservation of adequate perfusion pressures to the graft is a main focus of intraoperative management during kidney transplantation. We undertook this study to investigate the incidence of the higher use of inotropes in kidney transplant recipients and identify the patient outcomes and preoperative and intraoperative variables related to this.We retrospectively analyzed 1053 patients who underwent kidney transplantation at Asan Medical Center between January 2006 and February 2012, stratified by their inotropic score ([dopamine] + [dobutamine] + [epinephrine × 100] + [norepinephrine × 100]) <7 versus ≥7, wherein all doses are expressed as μg/kg/min. We evaluated preoperative characteristics, hemodynamic parameters, and intraoperative variables as well as postoperative outcomes, such as length of hospital stay and 1-year rejection and mortality rate.Receiver-operating characteristic analysis was performed to determine inotropic score to predict 1-year mortality. An inotropic score of 7 had the best combined sensitivity and specificity. An inotropic score ≥7 (137 patients, 13.0%) was significantly more prevalent in older patients, those with polycystic kidney disease, and at a 2nd transplant. Anesthesia time, the amounts of crystalloid and 5% albumin infused, and the need for red blood cell transfusion were significantly higher in the inotropic score ≥7 group. The patients with a higher use of inotropes required longer postoperative hospital stay and experienced a >2-fold higher rejection within the 1st year and a 4-fold higher 1-year mortality rate.A higher use of inotropes in kidney transplant recipients is more prevalent in older patients, those with a 2nd transplant and in patients with polycystic kidney disease as their primary renal disease. The postoperative hospital stay, rejection within the 1st year, and 1-year mortality rate are increased in patients with an inotropic score ≥7.

Severe Coronary Artery Spasm with Anaphylactoid Shock Caused by Contrast Medium

This study reports 2 cases of severe coronary artery spasm with anaphylactoid shock caused by contrast medium. The first patient had anaphylactoid shock in response to contrast medium and severe coronary spasms of both the left anterior descending coronary artery and the left circumflex coronary artery. The patient developed ventricular arrhythmia and complete atrioventricular block following the severe coronary spasm. The second patient had a totally occluded right coronary artery, owing to a spasm after anaphylactoid shock. Anaphylactoid shock should always be considered when persistent shock is noted after the coronary artery spasm has been relieved.

Functional Characterisation of Eel Dopamine D2 Receptors and Involvement in the Direct Inhibition of Pituitary Gonadotrophins

In various vertebrate species, dopamine (DA) exerts an inhibitory action on reproduction. In the European eel, DA plays a pivotal role in the inhibitory control of gonadotroph function and the blockade of puberty. In vivo studies have suggested that this effect is mediated by receptors pharmacologically related to the D2 family. In the European eel, two distinct D2 receptor (D2-R) paralogous genes have been identified (D2A-R and D2B-R) and both were shown to be expressed in the pituitary. We investigated the potential role of each paralogue in the control of gonadotroph function in this species. Eel recombinant D2A-R or D2B-R were expressed in HEK 293 cells, with a universal Gα subunit, and receptor activation was followed by inositol phosphate production. Recombinant D2-Rs exhibited a comparable affinity for DA, although they had differential affinities for mammalian D2-R agonists and antagonists, supporting subtle structure/activity differences. Furthermore, using eel pituitary cell primary cultures, the expression by gonadotroph cells of both native eel D2-R paralogues was examined by in situ hybridisation of D2A-R or D2B-R transcripts, coupled with immunofluorescence of luteinising hormone (LH)β or follicle-stimulating (FSH)β. LH and to a lesser extent, FSH cells expressed both D2-R transcripts but with a clear predominance of D2B-R. Notably, D2B-R transcripts were detected for the majority of LH cells. Accordingly, using these cultures, we showed that DA potently inhibited basal and testosterone-stimulated LHβ expression and less potently basal and activin-stimulated FSHβ expression. We also tested some D2-R antagonists, aiming to select the most adequate one to be used in innovative protocols for induction of eel sexual maturation. We identified eticlopride as the most potent inhibitor of DA action on basal and stimulated LH expression in vitro. Our data suggest a differential functionalisation of the duplicated receptor genes and demonstrate that mainly D2B-R is involved in the dopaminergic inhibitory control of eel gonadotroph function.

Renal-Dose Dopamine: From Hypothesis to Paradigm to Dogma to Myth and, Finally, Superstition?

Acute renal failure (ARF) is common in the critically ill and is associated with a high mortality rate. Its pathogenesis is not understood. Because animal models use ischemia to induce experimental ARF, there is the widespread belief that lack of blood flow is responsible for ARF. Low-dose dopamine (LDD) has been shown to increase renal blood flow in animal and in human volunteers. Thus, it has been administered to humans for almost 3 decades in the belief that it would lead to renal arterial vasodilation and increase renal blood flow (RBF). However, the etiology of ARF in critical illness is likely multifactorial, and the contribution of hypovolemia and reduced renal perfusion is unknown. Furthermore, interindividual variation in the pharmacokinetics of dopamine typically results in poor correlation between blood levels and administered dose, making accurate and reliable delivery of LDD difficult. Finally, dopamine is a proximal tubular diuretic that increases Na+ delivery to tubular cells, thus increasing their oxygen demands. Accordingly, even if LDD were able to preferentially increase RBF, there is no guarantee that it would restore renal parenchymal oxygen homeostasis. More important, 2 meta-analyses and a large double-blind, prospective, multiple-center, randomized controlled trial have failed to demonstrate that dopamine protects the kidney in critically ill patients with ARF. Currently, there is insufficient evidence to support the use of renal-dose dopamine in the intensive care unit.

Dopamine treatment does not need speed recovery of newborns from transient tachypnea

OBJECTIVE

Transient tachypnea of the newborn (TTN) results from inadequate neonatal lung fluid clearance. Low-dose dopamine induces natriuresis in the kidneys and it has been assumed that, at this low dosage, dopamine increases renal perfusion in critically ill patients. Medium doses have positive inotropic and chronotropic effects via increased β-receptor activation. Recent studies have demonstrated that dopamine stimulates the clearance of pulmonary edema. Furthermore, β-adrenergic agonists regulate Na+ channels and Na-K-ATPase activity in the pulmonary epithelium. This study investigated the effect of dopamine at different dosages on TTN treatment.

METHODS

A prospective controlled study examined 60 infants with TTN older than 34 weeks of gestation who required at least 24 h of O2 and nasal continuous positive airway pressure (nCPAP) treatment. The infants were randomized into three groups of 20: controls, infants treated with low-dose dopamine (3 μg/kg/min), and infants treated with a medium dose (5 μg/kg/min). The control and study groups were compared in terms of the requirement for mechanical ventilation, and the durations of nCPAP, oxygen requirement, and hospitalization.

RESULTS

The requirement for mechanical ventilation, and durations of nCPAP, oxygen requirement, and hospitalization did not differ significantly among the three groups (P=0.54, 0.16 and 0.11, respectively).

CONCLUSION

Dopamine treatment in low-moderate doses does not improve the outcome in TTN. Thus, further studies in this area are needed.

Dopamine increases NMDA-stimulated calcium flux in striatopallidal neurons through a matrix metalloproteinase-dependent mechanism

Dopamine (DA) is a potent neuromodulator known to influence glutamatergic transmission in striatal medium spiny neurons (MSNs). It acts on D1- and D2-like DA receptors that are expressed on two distinct subpopulations. MSNs projecting to the substantia nigra express D1 receptors (D1Rs), while those projecting to the lateral globus pallidus express D2 receptors (D2Rs). D1R signalling in particular can increase excitatory transmission through varied protein kinase A-dependent, cell-autonomous pathways. Mechanisms by which D1R signalling could increase excitatory transmission in D2R-bearing MSNs have been relatively less explored. Herein, the possibility is considered that D1R agonists increase levels of soluble factors that subsequently influence N-methyl-D-aspartate (NMDA)-stimulated calcium flux in D2R neurons. This study focuses on matrix metalloproteinases (MMPs) and MMP-generated integrin binding ligands, important soluble effectors of glutamatergic transmission that may be elevated in the setting of excess DA. It was observed that DA and a D1R agonist, SKF81297, increase MMP activity in extracts from striatal slices, as determined by cleavage of the substrate β-dystroglycan. Using mice engineered to express the calcium indicator GCaMP3 in striatopallidal D2R-bearing neurons, it was also observed that SKF81297 pretreatment of slices (60 min) potentiates NMDA-stimulated calcium increases in this subpopulation. Effects are diminished by pretreatment with an antagonist of MMP activity or an inhibitor of integrin-dependent signalling. Together, results suggest that DA signalling can increase excitatory transmission in D2R neurons through an MMP-dependent mechanism. Future studies may be warranted to determine whether D1R-stimulated MMP-dependent processes contribute to behaviours in which increased activity in striatopallidal MSNs plays a role.

Comparison Between Phenylephrine and Dopamine in Maintaining Cerebral Oxygen Saturation in Thoracic Surgery: A Randomized Controlled Trial

Fluid is usually restricted during thoracic surgery, and vasoactive agents are often administered to maintain blood pressure. One-lung ventilation (OLV) decreases arterial oxygenation; thus oxygen delivery to the brain can be decreased. In this study, we compared phenylephrine and dopamine with respect to maintaining cerebral oxygenation during OLV in major thoracic surgery.Sixty-three patients undergoing lobectomies were randomly assigned to the dopamine (D) or phenylephrine (P) group. The patients' mean arterial pressure was maintained within 20% of baseline by a continuous infusion of dopamine or phenylephrine. Maintenance fluid was kept at 5 mL/kg/h. The depth of anesthesia was maintained with desflurane 1MAC and remifentanil infusion under bispectral index guidance. Regional cerebral oxygen saturation (rScO2) and hemodynamic variables were recorded using near-infrared spectroscopy and esophageal cardiac Doppler.The rScO2 was higher in the D group than the P group during OLV (OLV 60 min: 71 ± 6% vs 63 ± 12%; P = 0.03). The number of patients whose rScO2 dropped more than 20% from baseline was 0 and 6 in the D and P groups, respectively (P = 0.02). The D group showed higher cardiac output, but lower mean arterial pressure than the P group (4.7 ± 1.0 vs 3.9 ± 1.2 L/min; 76.7 ± 8.1 vs 84.5 ± 7.5 mm Hg; P = 0.02, P = 0.02). Among the variables, age, hemoglobin concentration, and cardiac output were associated with rScO2 by correlation analysis.Dopamine was superior to phenylephrine in maintaining cerebral oxygenation during OLV in thoracic surgery.

Association between acute motor axonal neuropathy and septic shock due to Acinetobacter baumannii

In this report, we describe a case of acute motoral axonal neuropathy (AMAN) following septic shock due to Acinetobacter baumannii. The aetiology of AMAN is still not fully clarified. An association with a potential infection by Campylobacter jejuni, resulting in stimulation of autoimmune response against gangliosides mediated by a phenomenon of molecular mimicry, is believed to play a major role. Since the lipopolysaccharide of A. baumannii has a structure that is similar to that of C. jejuni, we hypothesise that the infection by A. baumannii in our patient may have had a pathogenic role in the development of the neurological picture via a mechanism of molecular mimicry.

Propranolol combined with dopamine has a synergistic action in intensifying and prolonging cutaneous analgesia in rats

BACKGROUND

The purpose of the experiment was to assess interactions of dopamine with propranolol as an infiltrative anesthetic.

METHODS

After injecting the rats with four doses of drugs subcutaneously, the cutaneous analgesic effect of propranolol was compared with dopamine through the blockade of cutaneous trunci muscle reflex (CTMR) in response to local skin pinprick. Drug-drug interactions were examined via an isobolographic analysis.

RESULTS

We demonstrated that the action of propranolol and dopamine was dose dependent to skin infiltrative analgesia. On the ED(50) (50% effective dose) basis, the rank of drug potency was propranolol (11.3 [10.6-12.2]μmol) > dopamine (195 [188-205]μmol) (p < 0.001). At the equi-anesthetic doses (ED(25), ED(50), ED(75)), the block duration caused by dopamine was equal to that caused by propranolol. Coadministration of dopamine and propranolol exhibited a synergistic effect on infiltrative cutaneous analgesia.

CONCLUSIONS

The preclinical data showed that dopamine produced a lesser potency but a comparable duration of cutaneous analgesia compared to propranolol. Adding dopamine to propranolol potentiated and prolonged propranolol's cutaneous analgesic effect.

Brain aging and Parkinson's disease: New therapeutic approaches using drug delivery systems

The etiology and pathogenesis of Parkinson's disease (PD) is unknown, aging being the strongest risk factor for brain degeneration. Understanding PD pathogenesis and how aging increases the risk of disease would aid the development of therapies able to slow or prevent the progression of this neurodegenerative disorder. In this review we provide an overview of the most promising therapeutic targets and strategies to delay the loss of dopaminergic neurons observed both in PD and aging. Among them, handling alpha-synuclein toxicity, enhancing proteasome and lysosome clearance, ameliorating mitochondrial disruptions and modifying the glial environment are so far the most promising candidates. These new and conventional drugs may present problems related to their labile nature and to the difficulties in reaching the brain. Thus, we highlight the latest types of drug delivery system (DDS)-based strategies for PD treatment, including DDS for local and systemic drug delivery. Finally, the ongoing challenges for the discovery of new targets and the opportunities for DDS-based therapies to improve and efficacious PD therapy will be discussed.

Safety of peripheral intravenous administration of vasoactive medication

BACKGROUND

Central venous access is commonly performed to administer vasoactive medication. The administration of vasoactive medication via peripheral intravenous access is a potential method of reducing the need for central venous access. The aim of this study was to evaluate the safety of vasoactive medication administered through peripheral intravenous access.

METHODS

Over a 20-month period starting in September 2012, we monitored the use of vasoactive medication via peripheral intravenous access in an 18-bed medical intensive care unit. Norepinephrine, dopamine, and phenylephrine were all approved for use through peripheral intravenous access.

RESULTS

A total of 734 patients (age 72 ± 15 years, male/female 398/336, SAPS II score 75 ± 15) received vasoactive medication via peripheral intravenous access 783 times. Vasoactive medication used was norepinephrine (n = 506), dopamine (n = 101), and phenylephrine (n = 176). The duration of vasoactive medication via peripheral intravenous access was 49 ± 22 hours. Extravasation of the peripheral intravenous access during administration of vasoactive medication occurred in 19 patients (2%) without any tissue injury following treatment, with local phentolamine injection and application of local nitroglycerin paste. There were 95 patients (13%) receiving vasoactive medication through peripheral intravenous access who eventually required central intravenous access.

CONCLUSIONS

Administration of norepinephrine, dopamine, or phenylephrine by peripheral intravenous access was feasible and safe in this single-center medical intensive care unit. Extravasation from the peripheral intravenous line was uncommon, and phentolamine with nitroglycerin paste were effective in preventing local ischemic injury. Clinicians should not regard the use of vasoactive medication is an automatic indication for central venous access.

Effects of acute exposure to WIFI signals (2.45GHz) on heart variability and blood pressure in Albinos rabbit

Electrocardiogram and arterial pressure measurements were studied under acute exposures to WIFI (2.45GHz) during one hour in adult male rabbits. Antennas of WIFI were placed at 25cm at the right side near the heart. Acute exposure of rabbits to WIFI increased heart frequency (+22%) and arterial blood pressure (+14%). Moreover, analysis of ECG revealed that WIFI induced a combined increase of PR and QT intervals. By contrast, the same exposure failed to alter maximum amplitude and P waves. After intravenously injection of dopamine (0.50ml/kg) and epinephrine (0.50ml/kg) under acute exposure to RF we found that, WIFI alter catecholamines (dopamine, epinephrine) action on heart variability and blood pressure compared to control. These results suggest for the first time, as far as we know, that exposure to WIFI affect heart rhythm, blood pressure, and catecholamines efficacy on cardiovascular system; indicating that radiofrequency can act directly and/or indirectly on cardiovascular system.

Dopaminergic control of the globus pallidus through activation of D2 receptors and its impact on the electrical activity of subthalamic nucleus and substantia nigra reticulata neurons

The globus pallidus (GP) receives dopaminergic afferents from the pars compacta of substantia nigra and several studies suggested that dopamine exerts its action in the GP through presynaptic D2 receptors (D2Rs). However, the impact of dopamine in GP on the pallido-subthalamic and pallido-nigral neurotransmission is not known. Here, we investigated the role of dopamine, through activation of D2Rs, in the modulation of GP neuronal activity and its impact on the electrical activity of subthalamic nucleus (STN) and substantia nigra reticulata (SNr) neurons. Extracellular recordings combined with local intracerebral microinjection of drugs were done in male Sprague-Dawley rats under urethane anesthesia. We showed that dopamine, when injected locally, increased the firing rate of the majority of neurons in the GP. This increase of the firing rate was mimicked by quinpirole, a D2R agonist, and prevented by sulpiride, a D2R antagonist. In parallel, the injection of dopamine, as well as quinpirole, in the GP reduced the firing rate of majority of STN and SNr neurons. However, neither dopamine nor quinpirole changed the tonic discharge pattern of GP, STN and SNr neurons. Our results are the first to demonstrate that dopamine through activation of D2Rs located in the GP plays an important role in the modulation of GP-STN and GP-SNr neurotransmission and consequently controls STN and SNr neuronal firing. Moreover, we provide evidence that dopamine modulate the firing rate but not the pattern of GP neurons, which in turn control the firing rate, but not the pattern of STN and SNr neurons.

Performance of the Baxter Infusor LV10 under hyperbaric conditions

INTRODUCTION

Elastomeric drug delivery devices are a simple way to provide long-term IV therapy to patients in the outpatient setting. Patients receiving hyperbaric oxygen therapy occasionally need these devices. This study compared the performance of the Baxter infusor LV10 elastomeric device in repetitive conditions at pressures of 101.3 kPa and 243 kPa.

METHODS

Ten Baxter infusor LV10 elastomeric devices were pressurised in a hyperbaric chamber to 243 kPa over a two-hour period consistent with a standard medical treatment run. This process was repeated 10 times for each device giving a total of 20 hours under pressure. The fluid delivered by each device was measured and the device weighed at the end of each pressurisation. Ten control devices containing identical drugs were tested in the same manner at 101.3 kPa over the same time period.

RESULTS

No significant differences in output of the devices were observed between hyperbaric and control conditions. The flow rates measured in both study groups were 35% lower than the manufacturer's stated flow rate, possibly due to lower test environment temperature and outdated devices used in the tests.

CONCLUSION

Despite lower than expected flow rates, this study demonstrated no significant difference in the delivery rate of the Baxter infusor LV10 under 243 kPa hyperbaric conditions compared with room pressure.

Epidemiology and clinical features of ciguatera fish poisoning in Hong Kong

In the present review, the main objective was to describe the epidemiology and clinical features of ciguatera fish poisoning in Hong Kong. From 1989 to 2008, the annual incidence of ciguatera varied between 3.3 and 64.9 (median 10.2) per million people. The groupers have replaced the snappers as the most important cause of ciguatera. Pacific-ciguatoxins (CTX) are most commonly present in reef fish samples implicated in ciguatera outbreaks. In affected subjects, the gastrointestinal symptoms often subside within days, whereas the neurological symptoms can persist for weeks or even months. Bradycardia and hypotension, which can be life-threatening, are common. Treatment of ciguatera is primarily supportive and symptomatic. Intravenous mannitol (1 g/kg) has also been suggested. To prevent ciguatera outbreaks, the public should be educated to avoid eating large coral reef fishes, especially the CTX-rich parts. A Code of Practice on Import and Sale of Live Marine Fish for Human Consumption for Prevention and Control of Ciguatera Fish Poisoning was introduced from 2004 to 2013. The Food Safety Ordinance with a tracing mechanism came into full effect in February 2012. The Government would be able to trace the sources of the fishes more effectively and take prompt action when dealing with ciguatera incidents.

Dopamine receptor activation reorganizes neuronal ensembles during hippocampal sharp waves in vitro

Hippocampal sharp wave (SW)/ripple complexes are thought to contribute to memory consolidation. Previous studies suggest that behavioral rewards facilitate SW occurrence in vivo. However, little is known about the precise mechanism underlying this enhancement. Here, we examined the effect of dopaminergic neuromodulation on spontaneously occurring SWs in acute hippocampal slices. Local field potentials were recorded from the CA1 region. A brief (1 min) treatment with dopamine led to a persistent increase in the event frequency and the magnitude of SWs. This effect lasted at least for our recording period of 45 min and did not occur in the presence of a dopamine D1/D5 receptor antagonist. Functional multineuron calcium imaging revealed that dopamine-induced SW augmentation was associated with an enriched repertoire of the firing patterns in SW events, whereas the overall tendency of individual neurons to participate in SWs and the mean number of cells participating in a single SW were maintained. Therefore, dopaminergic activation is likely to reorganize cell assemblies during SWs.

[Stereological study of the placenta in patients receiving different vasopressors for hypotension during cesarean section]

OBJECTIVE

To study the effects of dopamine and phenylephrine for treatment of hypotension during cesarean section under combined spinal epidural anesthesia (CSEA) on the stereology of the placenta.

METHODS

Forty puerperants undergoing cesarean section under CSEA were randomly divided into dopamine group and phenylephrine group. Ropivacaine (16 mg) was administered immediately after spinal anethesia. Blood pressure was maintained near the baseline by adjusting the drug infusion rate. Fetal blood gas, Apgar score, and placental villus microvascular stereological changes were observed during the operation.

RESULTS

The microvascular density was significantly lower in dopamine group than in phenylephrine group (P<0.05). Phenylephrine group showed significantly lower umbilical artery blood pH than dopamine group (P<0.05). The Apgar score and blood pressure were comparable between the two groups (P>0.05). Compared to the baseline, both of the two groups showed significantly lowered heart rate during the operation (P<0.01).

CONCLUSION

Dopamine is associated with the risk of fetal acidosis. Phenylephrine is helpful for preventing hypotension by increasing placental blood flow and improving oxygen supply to ensure maternal and fetal safety during cesarean section.

Sticky "delivering-from" strategies using viral vectors for efficient human neural stem cell infection by bioinspired catecholamines

Controlled release of biosuprastructures, such as viruses, from surfaces has been a challenging task in providing efficient ex vivo gene delivery. Conventional controlled viral release approaches have demonstrated low viral immobilization and burst release, inhibiting delivery efficiency. Here, a highly powerful substrate-mediated viral delivery system was designed by combining two key components that have demonstrated great potential in the fields of gene therapy and surface chemistry, respectively: adeno-associated viral (AAV) vectors and adhesive catecholamine surfaces. The introduction of a nanoscale thin coating of catecholamines, poly(norepinephrine) (pNE) or poly(dopamine) (pDA) to provide AAV adhesion followed by human neural stem cell (hNSC) culture on sticky solid surfaces exhibited unprecedented results: approximately 90% loading vs 25% (AAV_bare surface), no burst release, sustained release at constant rates, approximately 70% infection vs 20% (AAV_bare surface), and rapid internalization. Importantly, the sticky catecholamine-mediated AAV delivery system successfully induced a physiological response from hNSCs, cellular proliferation by a single-shot of AAV encoding fibroblast growth factor-2 (FGF-2), which is typically achieved by multiple treatments with expensive FGF-2 proteins. By combining the adhesive material-independent surface functionalization characters of pNE and pDA, this new sticky "delivering-from" gene delivery platform will make a significant contribution to numerous fields, including tissue engineering, gene therapy, and stem cell therapy.

Dopamine infusion and fluid administration improve renal function during laparoscopic surgery

BACKGROUND

Previous studies have documented the negative influence of pneumoperitoneum on cardiac and renal function during laparoscopy. In this respect, regard there is a lack of data regarding the use of an appropriate management of fluid therapy to decrease these side effects. The aim of this study was to investigate the cardiac and renal responses to the administration of different amounts of crystalloid solution, alone or in association with dopamine during laparoscopy.

METHODS

Sixty ASA I patients undergoing laparoscopic surgery for endometriosis were randomly assigned to three groups. Group A was given saline solution at 5 mL/kg/h; group B received saline solution at 5 mL/kg/h and dopamine 3 mg/kg/min, and group C received saline solution at 10 mL/kg/h. Patients received A, B or C perioperatively. Renal function was evaluated by assessing total intraoperative diuresis and estimated glomerular filtration rate. Vasopressin plasmatic levels before and after surgery were measured. Transthoracic echocardiography was performed to estimate left ventricular filling pressure by using Tissue Doppler Imaging and registering the E/Ea ratio every hour after pneumoperitoneum.

RESULTS

Total intraoperative diuresis was impaired in group A and significantly increased in group C (P<0.001). In group A estimated glomerular filtration rate significantly decreased after the end of surgery (P<0.003) and vasopressin significantly increased (P<0.001). The E/Ea ratio was significantly increased in group C (P<0.001). The infusion of saline solutions with the addition of dopamine slightly affected this parameter.

CONCLUSION

A low rate of saline infusion could lead to an impaired renal function during laparoscopic surgery. This could be prevented by increasing the amount of saline solutions infused per hour or by adding a dopamine infusion.

[Intraoperative asystole in a patient with concealed sick sinus syndrome: a case report]

We report a patient with concealed sick sinus syndrome who developed intraoperative bradycardia and asystole. An 81-year-old man was scheduled to undergo total gastrectomy under general and epidural anesthesia. There was no history of syncope, and preoperative 12-lead ECG showed normal sinus rhythm. Anesthesia was induced with propofol and remifentanil, maintained with sevoflurane, remifentanil and thoracic epidural infusion of lidocaine, fentanyl and levobupivacaine. Bradycardia was detected on ECG 110 minutes after the start of surgery. Intravenous atropine (0.5 mg, repeated up to a total dose of 1.5 mg) was ineffective in restoring a normal heart rhythm. Ten minutes later, the ECG changed to asystole lasting for about 15 seconds. Regular chest compression and intravenous administration of dopamine (5 microg x kg(-1) x min(-1)) resulted in successful recovery of sinus rhythm. Postoperative ECG showed sinus rhythm. The final diagnosis by a cardiologist was concealed sick sinus syndrome. Many anesthetic agents have some effects on the cardiac conduction system. Remifentanil may have played a role in the development of asystole in this patient. The existence of concealed sick sinus syndrome should be kept in mind even in patients who show no clinical abnormalities on preoperative assessment.

Basal ganglia local field potentials: applications in the development of new deep brain stimulation devices for movement disorders

The analysis of neural rhythms measured in local field potentials (LFPs) through deep brain stimulation (DBS) electrodes have provided a new insight into brain mechanisms of information processing. The application of novel methodological approaches for LFP analysis is of key importance to uncover the complexity of such mechanisms, thereby clarifying the relationship between the LFP code and patient's clinical state. Thanks to a new device for recording artifact-free LFPs during high-frequency stimulation, DBS-induced neural rhythms modulations and their nonlinear features can be analyzed and used in the development of a new, adaptive DBS approach: the frequency, strength and site of DBS could be controlled, in a closed-loop system, through LFP-based variables obtained through the application of different methodological approaches.