Short-term effects of cannabidiol after global hypoxia-ischemia in newborn piglets

Gene expression in the intestine of newborn piglets after hypoxia-reoxygenation

BACKGROUND

In preterm infants, intestinal hypoxia may partly contribute to the pathophysiology of necrotizing enterocolitis through changes in gene expression. Splanchnic hypoxia can be detected with monitoring of regional splanchnic oxygen saturation (rsSO2). Using a piglet model of asphyxia, we aimed to correlate changes in rsSO2 to gene expression.

METHODS

Forty-two newborn piglets were randomized to control or intervention groups. Intervention groups were subjected to hypoxia until they were acidotic and hypotensive. Next, they were reoxygenated for 30 min according to randomization, i.e., 21% O2, 100% O2, or 100% O2 for 3 min followed by 21% O2, and observed for 9 h. We continuously measured rsSO2 and calculated mean rsSO2 and variability of rsSO2 (rsCoVar = SD/mean). Samples of terminal ileum were analyzed for mRNA expression of selected genes related to inflammation, erythropoiesis, fatty acid metabolism, and apoptosis.

RESULTS

The expression of selected genes was not significantly different between control and intervention groups. No associations between mean rsSO2 and gene expression were observed. However, lower rsCoVar was associated with the upregulation of apoptotic genes and the downregulation of inflammatory genes (P < 0.05).

CONCLUSION

Our study suggests that hypoxia and reoxygenation cause reduced vascular adaptability, which seems to be associated with the upregulation of apoptosis and downregulation of inflammation.

IMPACT

Our results provide important insight into the (patho)physiological significance of changes in the variability of rsSO2. Our findings may advance future research and clinical practice regarding resuscitation strategies of preterm infants.

Neuroprotective therapies in the NICU in term infants: present and future

Outcomes of neonatal encephalopathy (NE) have improved since the widespread implementation of therapeutic hypothermia (TH) in high-resource settings. While TH for NE in term and near-term infants has proven beneficial, 30-50% of infants with moderate-to-severe NE treated with TH still suffer death or significant impairments. There is therefore a critical need to find additional pharmacological and non-pharmacological interventions that improve the outcomes for these children. There are many potential candidates; however, it is unclear whether these interventions have additional benefits when used with TH. Although primary and delayed (secondary) brain injury starting in the latent phase after HI are major contributors to neurodisability, the very late evolving effects of tertiary brain injury likely require different interventions targeting neurorestoration. Clinical trials of seizure management and neuroprotection bundles are needed, in addition to current trials combining erythropoietin, stem cells, and melatonin with TH. IMPACT: The widespread use of therapeutic hypothermia (TH) in the treatment of neonatal encephalopathy (NE) has reduced the associated morbidity and mortality. However, 30-50% of infants with moderate-to-severe NE treated with TH still suffer death or significant impairments. This review details the pathophysiology of NE along with the evidence for the use of TH and other beneficial neuroprotective strategies used in term infants. We also discuss treatment strategies undergoing evaluation at present as potential adjuvant treatments to TH in NE.

Splanchnic oxygen saturation during reoxygenation with 21% or 100% O2 in newborn piglets

BACKGROUND

Increasing evidence recognizes the harm of excess oxygen to lungs, eyes, and brain of preterm infants, but not yet to the intestine. We assessed changes in splanchnic oxygenation during reoxygenation with 21% compared to 100% O₂ in a newborn piglet model of perinatal asphyxia.

METHODS

We randomized 25 piglets to control or intervention. Intervention groups underwent global hypoxia until acidosis and hypotension occurred. Piglets were reoxygenated for 30 min with 21% or 100% O₂ and observed for 9 h. We continuously measured regional splanchnic oxygen saturation (r_sSO₂) using near-infrared spectroscopy (NIRS). We calculated mean r_sSO₂ and r_sCoVar (as SD/mean). We measured PaO₂ and SaO₂, sampled from the right carotid artery.

RESULTS

Reoxygenation after global hypoxia restored r_sSO₂. Reoxygenation with 100% O₂ increased r_sSO₂ to values significantly higher than baseline. In intervention groups, r_sCoVar decreased during observation compared to baseline. We found a correlation between r_sSO₂ and PaO₂ (r = 0.420, P < 0.001) and between r_sSO₂ and SaO₂ (r = 0.648, P < 0.001) in pooled data from the entire experiment.

CONCLUSION

Reoxygenation after global hypoxia improves splanchnic oxygenation, but is associated with reduced variability of r_sSO₂. Reoxygenation with 100% O₂ exposes the intestine to hyperoxia. Splanchnic NIRS is able to detect intestinal hypoxia and hyperoxia.

IMPACT

Splanchnic oxygenation improves during reoxygenation after global hypoxia, though reoxygenation with 100% O₂ exposes the intestine to hyperoxia. Decreased variability of splanchnic oxygenation several hours after hypoxia and reoxygenation seems to be independent of the resuscitation strategy, and may indicate intestinal injury. Splanchnic NIRS monitoring was able to detect intestinal hypoxia and exposure to hyperoxia, as evidenced by a strong correlation between splanchnic oxygenation and arterial oxygen content.

Herbs as an Active Ingredient in Sport: Availability and Information on the Internet

The use of supplements containing herbal active ingredients in sport has increased in recent years. Their consumption is explained by the benefits they may provide and because their natural origin do not involve health complications, from the point of view of the consumers. The aim of this study is to analyze the availability of four supplements (caffeine, turmeric, ginseng, cannabidiol) on the internet and understand the nature of these websites. A descriptive, observational, and cross-sectional study design was used. A detailed search was carried out with specifically developed software. The searches and data evaluation took 10 days. The websites consulted correspond to those that sell supplements, or some sport websites in the case of the Spanish ones, whereas those in English belong to pharmacies, parapharmacies, or herbalists. It is concluded that the websites do not provide adequate information to ensure proper consumption and lack advice on the choices of supplements and their administration guidelines.

Cannabinoids as Glial Cell Modulators in Ischemic Stroke: Implications for Neuroprotection

Stroke is the second leading cause of death worldwide following coronary heart disease. Despite significant efforts to find effective treatments to reduce neurological damage, many patients suffer from sequelae that impair their quality of life. For this reason, the search for new therapeutic options for the treatment of these patients is a priority. Glial cells, including microglia, astrocytes and oligodendrocytes, participate in crucial processes that allow the correct functioning of the neural tissue, being actively involved in the pathophysiological mechanisms of ischemic stroke. Although the exact mechanisms by which glial cells contribute in the pathophysiological context of stroke are not yet completely understood, they have emerged as potentially therapeutic targets to improve brain recovery. The endocannabinoid system has interesting immunomodulatory and protective effects in glial cells, and the pharmacological modulation of this signaling pathway has revealed potential neuroprotective effects in different neurological diseases. Therefore, here we recapitulate current findings on the potential promising contribution of the endocannabinoid system pharmacological manipulation in glial cells for the treatment of ischemic stroke.

Cannabinoid Analogue WIN 55212-2 Protects Paraquat-Induced Lung Injury and Enhances Macrophage M2 Polarization

WIN 55212-2 is an endocannabinoids analogue that has been reported to have anti-inflammatory and anti-fibrosis effects on different models. In this study, we investigated the protective effects of WIN 55212-2 on paraquat (PQ)-induced poison on mice especially on lung injury. Mice were administrated with different dose of PQ and thereafter treated with 0.2 mg/kg or 1 mg/kg WIN 55212-2. The survival of mice was recorded during 4 weeks of observation. Twenty-eight days after PQ treatment, the cell population and inflammatory factors IL-6, IL-10, and TNF-α were measured in bronchoalveolar lavage fluid (BALF). Pulmonary fibrosis was evaluated by Masson staining. Our results showed that WIN 55212-2 treatment reduced PQ-induced mortality of mice in a dose dependent manner. It decreased the number of inflammation-associated cells, as well as the level of pro-inflammatory factors in BALF (P < 0.05). WIN 55212-2 increased M2 cells in BALF (P < 0.05), improved the lung histology, reduced fibrosis formation, and decreased TGF-β, α-SMA and PDGFRa expression. The protective effects of WIN 55212-2 on PQ-induced lung injury and fibrosis were associated with an increase inM2 cells and increased expressions of IL-10, CD163, and CD206, suggesting that polarization of M2 macrophages may be involved in WIN 55212-2 protective effects on PQ-induced lung injury.

New possibilities for neuroprotection in neonatal hypoxic-ischemic encephalopathy

Around 0.75 million babies worldwide suffer from moderate or severe hypoxic-ischemic encephalopathy (HIE) each year resulting in around 400,000 babies with neurodevelopmental impairment. In 2010, neonatal HIE was associated with 2.4% of the total Global Burden of Disease. Therapeutic hypothermia (TH), a treatment that is now standard of care in high-income countries, provides proof of concept that strategies that aim to improve neurodevelopment are not only possible but can also be implemented to clinical practice. While TH is beneficial, neonates with moderate or severe HIE treated with TH still experience devastating complications: 48% (range: 44-53) combined death or moderate/severe disability. There is a concern that TH may not be effective in low- and middle-income countries. Therapies that further improve outcomes are desperately needed, and in high-income countries, they must be tested in conjunction with TH. We have in this review focussed on pharmacological treatment options (e.g. erythropoietin, allopurinol, melatonin, cannabidiol, exendin-4/exenatide). Erythropoietin and allopurinol show promise and are progressing towards the clinic with ongoing definitive phase 3 randomised placebo-controlled trials. However, there remain global challenges for the next decade. Conclusion: There is a need for more optimal animal models, greater industry support/sponsorship, increased use of juvenile toxicology, dose-ranging studies with pharmacokinetic-pharmacodynamic modelling, and well-designed clinical trials to avoid exposure to harmful medications or abandoning putative treatments. What is Known: • Therapeutic hypothermia is beneficial in neonatal hypoxic-ischemic encephalopathy. • Neonates with moderate or severe hypoxic-ischemic encephalopathy treated with therapeutic hypothermia still experience severe sequelae. What is New: • Erythropoietin, allopurinol, melatonin, cannabidiol, and exendin-4/exenatide show promise in conjunction with therapeutic hypothermia. • There is a need for more optimal animal models, greater industry support/sponsorship, increased use of juvenile toxicology, dose-ranging studies with pharmacokinetic-pharmacodynamic modelling, and well-designed clinical trials.

Identification of the Ghrelin and Cannabinoid CB2 Receptor Heteromer Functionality and Marked Upregulation in Striatal Neurons from Offspring of Mice under a High-Fat Diet

Cannabinoids have been reported as orexigenic, i.e., as promoting food intake that, among others, is controlled by the so-called “hunger” hormone, ghrelin. The aim of this paper was to look for functional and/or molecular interactions between ghrelin GHSR1a and cannabinoid CB₂ receptors at the central nervous system (CNS) level. In a heterologous system we identified CB₂-GHSR1a receptor complexes with a particular heteromer print consisting of impairment of CB₂ receptor/G_i-mediated signaling. The blockade was due to allosteric interactions within the heteromeric complex as it was reverted by antagonists of the GHSR1a receptor. Cannabinoids acting on the CB₂ receptor did not affect cytosolic increases of calcium ions induced by ghrelin acting on the GHSR1a receptor. In situ proximity ligation imaging assays confirmed the expression of CB₂-GHSR1a receptor complexes in both heterologous cells and primary striatal neurons. We tested heteromer expression in neurons from offspring of high-fat-diet mouse mothers as they have more risk to be obese. Interestingly, there was a marked upregulation of those complexes in striatal neurons from siblings of pregnant female mice under a high-fat diet.

Cannabidiol for the Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Each year, more than two million babies die or evolve to permanent invalidating sequelae worldwide because of Hypoxic-Ischemic Brain Injury (HIBI). There is no current treatment for that condition except for therapeutic hypothermia, which benefits only a select group of newborns. Preclinical studies offer solid evidence of the neuroprotective effects of Cannabidiol (CBD) when administered after diffuse or focal HI insults to newborn pigs and rodents. Such effects are observable in the short and long term as demonstrated by functional, neuroimaging, histologic and biochemical studies, and are related to the modulation of excitotoxicity, inflammation and oxidative stress—the major components of HIBI pathophysiology. CBD protects neuronal and glial cells, with a remarkable effect on preserving normal myelinogenesis. From a translational point of view CBD is a valuable tool for HIBI management since it is safe and effective. It is administered by the parenteral route a posteriori with a broad therapeutic time window. Those findings consolidate CBD as a promising treatment for neonatal HIBI, which is to be demonstrated in clinical trials currently in progress.

The Effects of Cannabidiol, a Non-Intoxicating Compound of Cannabis, on the Cardiovascular System in Health and Disease

Cannabidiol (CBD) is a non-intoxicating and generally well-tolerated constituent of cannabis which exhibits potential beneficial properties in a wide range of diseases, including cardiovascular disorders. Due to its complex mechanism of action, CBD may affect the cardiovascular system in different ways. Thus, we reviewed the influence of CBD on this system in health and disease to determine the potential risk of cardiovascular side effects during CBD use for medical and wellness purposes and to elucidate its therapeutic potential in cardiovascular diseases. Administration of CBD to healthy volunteers or animals usually does not markedly affect hemodynamic parameters. Although CBD has been found to exhibit vasodilatory and antioxidant properties in hypertension, it has not affected blood pressure in hypertensive animals. Hypotensive action of CBD has been mainly revealed under stress conditions. Many positive effects of CBD have been observed in experimental models of heart diseases (myocardial infarction, cardiomyopathy, myocarditis), stroke, neonatal hypoxic ischemic encephalopathy, sepsis-related encephalitis, cardiovascular complications of diabetes, and ischemia/reperfusion injures of liver and kidneys. In these pathological conditions CBD decreased organ damage and dysfunction, oxidative and nitrative stress, inflammatory processes and apoptosis, among others. Nevertheless, further clinical research is needed to recommend the use of CBD in the treatment of cardiovascular diseases.

Cannabidiol and Sports Performance: a Narrative Review of Relevant Evidence and Recommendations for Future Research

Cannabidiol (CBD) is a non-intoxicating cannabinoid derived from Cannabis sativa. CBD initially drew scientific interest due to its anticonvulsant properties but increasing evidence of other therapeutic effects has attracted the attention of additional clinical and non-clinical populations, including athletes. Unlike the intoxicating cannabinoid, Δ9-tetrahydrocannabinol (Δ9-THC), CBD is no longer prohibited by the World Anti-Doping Agency and appears to be safe and well-tolerated in humans. It has also become readily available in many countries with the introduction of over-the-counter "nutraceutical" products. The aim of this narrative review was to explore various physiological and psychological effects of CBD that may be relevant to the sport and/or exercise context and to identify key areas for future research. As direct studies of CBD and sports performance are is currently lacking, evidence for this narrative review was sourced from preclinical studies and a limited number of clinical trials in non-athlete populations. Preclinical studies have observed robust anti-inflammatory, neuroprotective and analgesic effects of CBD in animal models. Preliminary preclinical evidence also suggests that CBD may protect against gastrointestinal damage associated with inflammation and promote healing of traumatic skeletal injuries. However, further research is required to confirm these observations. Early stage clinical studies suggest that CBD may be anxiolytic in "stress-inducing" situations and in individuals with anxiety disorders. While some case reports indicate that CBD improves sleep, robust evidence is currently lacking. Cognitive function and thermoregulation appear to be unaffected by CBD while effects on food intake, metabolic function, cardiovascular function, and infection require further study. CBD may exert a number of physiological, biochemical, and psychological effects with the potential to benefit athletes. However, well controlled, studies in athlete populations are required before definitive conclusions can be reached regarding the utility of CBD in supporting athletic performance.

Cannabinoid-mediated Modulation of Oxidative Stress and Early Inflammatory Response after Hypoxia-Ischemia

In the process of neonatal encephalopathy, oxidative stress and neuroinflammation have a prominent role after perinatal asphyxia. With the exception of therapeutic hypothermia, no therapeutic interventions are available in the clinical setting to target either the oxidative stress or inflammation, despite the high prevalence of neurological sequelae of this devastating condition. The endocannabinoid system (ECS), recently recognized as a widespread neuromodulatory system, plays an important role in the development of the central nervous system (CNS). This study aims to evaluate the potential effect of the cannabinoid (CB) agonist WIN 55,212-2 (WIN) on reactive oxygen species (ROS) and early inflammatory cytokine production after hypoxia–ischemia (HI) in fetal lambs. Hypoxic–ischemic animals were subjected to 60 min of HI by partial occlusion of the umbilical cord. A group of lambs received a single dose of 0.01 μg/kg WIN, whereas non-asphyctic animals served as controls. WIN reduced the widespread and notorious increase in inflammatory markers tumor necrosis factor (TNF)-α and interleukin (IL)-1β and IL-6 induced by HI, a modulatory effect not observed for oxidative stress. Our study suggests that treatment with a low dose of WIN can alter the profile of pro-inflammatory cytokines 3 h after HI.

Harmful Effects of Smoking Cannabis: A Cerebrovascular and Neurological Perspective

Apart from being used as a medicine, cannabis or marijuana is the most widely abused recreational drug all over the world. The legalization and decriminalization of cannabis in Canada and various states of USA may be the underlying reason of the widespread popularity of it among young population. Various studies have reported about the relationship between cannabis use and different detrimental effects like cardiovascular, cerebrovascular, and neurological complications among different age groups. Specifically, the young population is getting adversely affected by this, harmful yet, readily accessible recreational drug. Although the mechanism behind cannabis mediated neurological and cerebrovascular complications has not been elucidated yet, the results of these studies have confirmed the association of these diseases with cannabis. Given the lack of comprehensive study relating these harmful complications with cannabis use, the aim of this narrative literature review article is to evaluate and summarize current studies on cannabis consumption and cerebrovascular/neurological diseases along with the leading toxicological mechanisms.

The endocannabinoid system and stroke: A focused review

Stroke is an important cause of morbidity and mortality worldwide. Development of novel neuroprotectants is of paramount importance. This review seeks to summarize the recent evidence for the role of the endocannabinoid signaling system in stroke pathophysiology, as well as the evidence from preclinical studies regarding the efficacy of cannabinoids as neuroprotective therapies in the treatment of stroke. Recent evidence from rodent models implicating cannabinoid 1 receptor (CB1R), cannabinoid 2 receptor (CB2R), and CB1R and CB2R co-antagonism as neuroprotective strategies in stroke are reviewed. Rodent evidence for the therapeutic role of the endocannabinoid system in treating poststroke depression is reviewed. Finally, evidence for the role of cannabidiol, a publicly available cannabinoid that does not bind directly to known endocannabinoid receptors, as a stroke neuroprotectant is also reviewed. The review closes with a consideration of the role of human cannabinoid abuse in stroke and considers future directions for research on endocannabinoid-based stroke therapeutics.

Increased expression of cannabinoid CB2 and serotonin 5-HT1A heteroreceptor complexes in a model of newborn hypoxic-ischemic brain damage

Preclinical work shows cannabidiol as a promising drug to manage neonatal hypoxic-ischemic brain damage (NHIBD). The molecular mechanism is not well defined but the beneficial effects of this phytocannabinoid are blocked by antagonists of both cannabinoid CB₂ (CB₂R) and serotonin 5-HT_1A (5-HT1AR) receptors that, in addition, may form heteromers in a heterologous expression system. Using bioluminescence energy transfer, we have shown a direct interaction of the two receptors that leads to a particular signaling in a heterologous system. A property attributed to the heteromer, namely cross-antagonism, was found in primary cultures of neurons thus indicating the occurrence of the receptor heteromer in the CNS. Oxygen-glucose deprivation to neurons led to an increase of CB₂R-mediated signaling and an upregulation of CB₂-5-HT_1A heteroreceptor complex expression. In situ proximity ligation assays in brain cortical sections were performed to compare the expression of CB₂-5-HT_1A complexes in rat E20 fetuses and at different postnatal days. The expression, which is elevated in fetus and shortly after birth, was sharply reduced at later ages (even at P7). The expression of heteromer receptors was more marked in a model of NHIBD and, remarkably, the drop in expression was significantly delayed with respect to controls. These results indicate that CB₂-5-HT_1A heteroreceptor complex may be considered as a target in the therapy of the NHIBD. This article is part of the Special Issue entitled 'Receptor heteromers and their allosteric receptor-receptor interactions'.

Regional differences of hypothermia on oxidative stress following hypoxia-ischemia: a study of DHA and hypothermia on brain lipid peroxidation in newborn piglets

Background Oxidative stress plays an important part in the pathophysiology of hypoxic-ischemic encephalopathy (HIE) and is reliably measured through prostanoids following lipid peroxidation of polyunsaturated fatty acids (PUFAs). The aim of the study is to measure oxidative stress in the prefrontal cortex, white matter and hippocampus in the brains of hypoxic-ischemic piglets treated with docosahexaenoic acid (DHA) and therapeutic hypothermia (TH) and investigate the additive effects of DHA on hypothermia by factorial design. Methods Fifty-five piglets were randomized as having severe global hypoxia (n=48) or not (sham, n=7). Hypoxic piglets were further randomized: vehicle (VEH), DHA, VEH+hypothermia (HT) or HT+DHA. A total of 5 mg/kg DHA was given intravenously 210 min after the end of hypoxia. Brain tissues were analyzed using liquid chromatography triple quadrupole mass spectrometry technique (LC-MS). A two-way analysis of variance (ANOVA) was performed with DHA and HT as main effects. Results In the white matter, we found main effects of DHA on DH-isoprostanes (P=0.030) and a main effect of HT on F4-neuroprostanes (F4-NeuroPs) (P=0.007), F2-isoprostanes (F2-IsoPs) (P=0.043) and DH-isoprostanes (P=0.023). In the cortex, the ANOVA analysis showed the interactions of main effects between DHA and HT for neurofuranes (NeuroFs) (P=0.092) and DH-isoprostanes (P=0.015) as DHA significantly reduced lipid peroxidation in the absence of HT. DHA compared to VEH significantly reduced NeuroFs (P=0.019) and DH-isoprostanes (P=0.010). No differences were found in the hippocampus. Conclusion After severe hypoxia, HT reduced lipid peroxidation in the white matter but not in the cortical gray matter. HT attenuated the reducing effect of DHA on lipid peroxidation in the cortex. Further studies are needed to determine whether DHA can be an effective add-on therapy for TH.

Temporal patterns of circulating cell-free DNA (cfDNA) in a newborn piglet model of perinatal asphyxia

Perinatal asphyxia is a severe medical condition resulting from oxygen deficiency (hypoxia) at the time of birth, causing worldwide approximately 680,000 newborn deaths every year. Better prediction of severity of damages including early biomarkers is highly demanded. Elevated levels of circulating cell-free DNA (cfDNA) in blood have been reported for a range of different diseases and conditions, including cancer and prematurity. The objective of this study was to validate methods for assessing cfDNA in blood and cerebrospinal fluid (CSF) and to explore temporal variations in a piglet model of neonatal hypoxia-reoxygenation. Different cfDNA extraction methods in combination with cfDNA detection systems were tested, including a fluorescent assay using SYBR Gold and a qRT-PCR-based technique. Newborn piglets (n = 55) were exposed to hypoxia-reoxygenation, hypoxia-reoxygenation and hypothermia, or were part of the sham-operated control group. Blood was sampled at baseline and at post-intervention, further at 30, 270, and 570 minutes after the end of hypoxia. Applying the fluorescent method, cfDNA concentration in piglets exposed to hypoxia (n = 32) increased from 36.8±27.6 ng/ml prior to hypoxia to a peak level of 61.5±54.9 ng/ml after the intervention and deceased to 32.3±19.1 ng/ml at 570 minutes of reoxygenation, whereas the group of sham-operated control animals (n = 11) revealed a balanced cfDNA profile. Animals exposed to hypoxia and additionally treated with hypothermia (n = 12) expressed a cfDNA concentration of 54.4±16.9 ng/ml at baseline, 39.2±26.9 ng/ml at the end of hypoxia, and of 41.1±34.2 ng/ml at 570 minutes post-intervention. Concentrations of cfDNA in the CSF of piglets exposed to hypoxia revealed at post-intervention higher levels in comparison to the controls. However, these observations were only tendencies and not significant. In a first methodological proof-of-principle study exploring cfDNA using a piglet model of hypoxia-reoxygenation variations in the temporal patterns suggest that cfDNA might be an early indicator for damages caused by perinatal asphyxia.

Neuroprotection by cannabidiol and hypothermia in a piglet model of newborn hypoxic-ischemic brain damage

OBJECTIVE

Hypothermia, the gold standard after a hypoxic-ischemic insult, is not beneficial in all treated newborns. Cannabidiol is neuroprotective in animal models of newborn hypoxic-ischemic encephalopathy. This study compared the relative efficacies of cannabidiol and hypothermia in newborn hypoxic-ischemic piglets and assessed whether addition of cannabidiol augments hypothermic neuroprotection.

METHODS

One day-old HI (carotid clamp and FiO₂ 10% for 20 min) piglets were randomized to vehicle or cannabidiol 1 mg/kg i.v. u.i.d. for three doses after being submitted to normothermia or 48 h-long hypothermia with a subsequent rewarming period of 6 h. Non-manipulated piglets (naïve) served as controls. Hemodynamic or respiratory parameters as well as brain activity (aEEG amplitude) were monitored throughout the experiment. Following termination, brains were obtained for histological (TUNEL staining, apoptosis; immunohistochemistry for Iba-1, microglia), biochemical (protein carbonylation, oxidative stress; and TNFα concentration, neuroinflammation) or proton magnetic resonance spectroscopy (Lac/NAA: metabolic derangement; Glu/NAA: excitotoxicity).

RESULTS

HI led to sustained depressed brain activity and increased microglial activation, which was significantly improved by cannabidiol alone or with hypothermia but not by hypothermia alone. Hypoxic-ischemic-induced increases in Lac/NAA, Glu/NAA, TNFα or apoptosis were not reversed by either hypothermia or cannabidiol alone, but combination of the therapies did. No treatment modified the effects of HI on oxidative stress or astroglial activation. Cannabidiol treatment was well tolerated.

CONCLUSIONS

cannabidiol administration after hypoxia-ischemia in piglets offers some neuroprotective effects but the combination of cannabidiol and hypothermia shows some additive effect leading to more complete neuroprotection than cannabidiol or hypothermia alone.

DHA and therapeutic hypothermia in a short-term follow-up piglet model of hypoxia-ischemia: Effects on H+MRS biomarkers

Background

Therapeutic hypothermia has become the standard of care for newborns with hypoxic-ischemic encephalopathy in high and middle income countries. Docosahexaenoic acid (DHA) has neuroprotective properties of reducing excitotoxicity, neuroinflammation and apoptosis in rodent models. We aim to study whether post hypoxic administration of i.v. DHA will reduce H⁺MRS biomarkers and gene expression of inflammation and apoptosis both with and without hypothermia in a large animal model.

Methods

Fifty-five piglets were randomized to severe global hypoxia (N = 48) or not (Sham, N = 7). Hypoxic piglets were further randomized by factorial design: Vehicle (VEH), DHA, VEH + Hypothermia (HT), or DHA + HT. 5 mg/kg DHA was given intravenously 210 min after end of hypoxia. Two-way ANOVA analyses were performed with DHA and hypothermia as main effects.

Results

Cortical lactate/N-acetylaspartate (Lac/NAA) was significantly reduced in DHA + HT compared to HT. DHA had significant main effects on increasing N-acetylaspartate and glutathione in hippocampus. Therapeutic hypothermia significantly reduced the Lac/NAA ratio and protein expression of IL-1β and TNFα in hippocampus and reduced Troponin T in serum. Neuropathology showed significant differences between sham and hypoxia, but no differences between intervention groups.

Conclusion

DHA and therapeutic hypothermia significantly improve specific H⁺MRS biomarkers in this short-term follow up model of hypoxia-ischemia. Longer recovery periods are needed to evaluate whether DHA can offer translational neuroprotection.

DHA reduces oxidative stress following hypoxia-ischemia in newborn piglets: a study of lipid peroxidation products in urine and plasma

BACKGROUND

Lipid peroxidation mediated by reactive oxygen species is a major contributor to oxidative stress. Docosahexaenoic acid (DHA) has anti-oxidant and neuroprotective properties. Our objective was to assess how oxidative stress measured by lipid peroxidation was modified by DHA in a newborn piglet model of hypoxia-ischemia (HI).

METHODS

Fifty-five piglets were randomized to (i) hypoxia, (ii) DHA, (iii) hypothermia, (iv) hypothermia+DHA or (v) sham. All groups but sham were subjected to hypoxia by breathing 8% O2. DHA was administered 210 min after end of hypoxia and the piglets were euthanized 9.5 h after end of hypoxia. Urine and blood were harvested at these two time points and analyzed for F4-neuroprostanes, F2-isoprostanes, neurofuranes and isofuranes using UPLC-MS/MS.

RESULTS

F4-neuroprostanes in urine were significantly reduced (P=0.006) in groups receiving DHA. Hypoxia (median, IQR 1652 nM, 610-4557) vs. DHA (440 nM, 367-738, P=0.016) and hypothermia (median, IQR 1338 nM, 744-3085) vs. hypothermia+DHA (356 nM, 264-1180, P=0.006). The isoprostane compound 8-iso-PGF2α was significantly lower (P=0.011) in the DHA group compared to the hypoxia group. No significant differences were found between the groups in blood.

CONCLUSION

DHA significantly reduces oxidative stress by measures of lipid peroxidation following HI in both normothermic and hypothermic piglets.

Neuroprotection with hypothermia and allopurinol in an animal model of hypoxic-ischemic injury: Is it a gender question?

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is one of the most important causes of neonatal brain injury. Therapeutic hypothermia (TH) is the standard treatment for term newborns after perinatal hypoxic ischemic injury (HI). Despite this, TH does not provide complete neuroprotection. Allopurinol seems to be a good neuroprotector in several animal studies, but it has never been tested in combination with hypothermia. Clinical findings show that male infants with (HI) fare more poorly than matched females in cognitive outcomes. However, there are few studies about neuroprotection taking gender into account in the results. The aim of the present study was to evaluate the potential additive neuroprotective effect of allopurinol when administrated in association with TH in a rodent model of moderate HI. Gender differences in neuroprotection were also evaluated.

METHODS

P10 male and female rat pups were subjected to HI (Vannucci model) and randomized into five groups: sham intervention (Control), no treatment (HI), hypothermia (HIH), allopurinol (HIA), and dual therapy (hypothermia and allopurinol) (HIHA). To evaluate a treatment's neuroprotective efficiency, 24 hours after the HI event caspase3 activation was measured. Damaged area and hippocampal volume were also measured 72 hours after the HI event. Negative geotaxis test was performed to evaluate early neurobehavioral reflexes. Learning and spatial memory were assessed via Morris Water Maze (MWM) test at 25 days of life.

RESULTS

Damaged area and hippocampal volume were different among treatment groups (p = 0.001). The largest tissue lesion was observed in the HI group, followed by HIA. There were no differences between control, HIH, and HIHA. When learning process was analyzed, no differences were found. Females from the HIA group had similar results to the HIH and HIHA groups. Cleaved caspase 3 expression was increased in both HI and HIA. Despite this, in females cleaved caspase-3 was only differently increased in the HI group. All treated animals present an improvement in short-term (Negative geotaxis) and long-term (WMT) functional tests. Despite this, treated females present better long-term outcome. In short-term outcome no sex differences were observed.

CONCLUSIONS

Our results suggest that dual therapy confers great neuroprotection after an HI event. There were functional, histological, and molecular improvements in all treated groups. These differences were more important in females than in males. No statistically significant differences were found between HIHA and HIH; both of them present a great improvement. Our results support the idea of different regulation mechanisms and pathways of cell death, depending on gender.

A Systematic Review and Meta-Analysis of the Haemodynamic Effects of Cannabidiol

Despite cannabidiol (CBD) having numerous cardiovascular effects in vitro, its haemodynamic effects in vivo are unclear. Nonetheless, the clinical use of CBD (Epidiolex) is becoming more widespread. The aim of this systematic review was to establish whether CBD is associated with changes in haemodynamics in vivo. Twenty-five studies that assessed the haemodynamic effects of CBD (from PubMed, Medline and EMBASE) were systematically reviewed and meta-analyzed. Data on blood pressure (BP), heart rate (HR), and blood flow (BF) were extracted and analyzed using random effects models. Twenty-two publications assessed BP and HR among 6 species (BP n = 344 and HR n = 395), and 5 publications assessed BF in 3 species (n = 56) after acute dosing of CBD. Chronic dosing was assessed in 4 publications in 3 species (total subjects BP, n = 6; HR, n = 27; BF, n = 3). Acute CBD dosing had no effect on BP or HR under control conditions. Similarly, chronic dosing with CBD had no effect on HR. In models of stress, acute CBD administration significantly reduced the increase in BP and HR induced by stress (BP, mean difference (MD) −3.54, 95% CI −5.19, −1.9, p < 0.0001; HR, MD −16.23, 95% CI −26.44, −6.02, p = 0.002). In mouse models of stroke, CBD significantly increased cerebral blood flow (CBF, standardized mean difference (SMD) 1.62, 95% CI 0.41, 2.83, p = 0.009). Heterogeneity among the studies was present, there was no publication bias except in HR of control and stressful conditions after acute CBD dosing, and median study quality was 5 out of 9 (ranging from 1 to 8). From the limited data available, we conclude that acute and chronic administration of CBD had no effect on BP or HR under control conditions, but reduces BP and HR in stressful conditions, and increases cerebral blood flow (CBF) in mouse models of stroke. Further studies are required to fully understand the potential haemodynamic effects of CBD in humans under normal and pathological conditions.

High-Dose Cannabidiol Induced Hypotension after Global Hypoxia-Ischemia in Piglets

BACKGROUND

Cannabidiol (CBD) is considered a promising neuroprotectant after perinatal hypoxia-ischemia (HI). We have previously studied the effects of CBD 1 mg/kg in the early phase after global HI in piglets. In contrast to prior studies, we found no evidence of neuroprotection and hypothesized that higher doses might be required to demonstrate efficacy in this animal model.

OBJECTIVE

To assess the safety and potential neuroprotective effects of high-dose CBD.

METHODS

Anesthetized newborn piglets underwent global HI by ventilation with 8% O2 until the point of severe metabolic acidosis (base excess -20 mmol/L) and/or hypotension (mean arterial blood pressure ≤20 mm Hg). Piglets were randomized to intravenous treatment with vehicle (n = 9) or CBD (n = 13). The starting dose, CBD 50 mg/kg, was reduced if adverse effects occurred. The piglets were euthanized 9.5 h after HI and tissue was collected for analysis.

RESULTS

CBD 50 mg/kg (n = 4) induced significant hypotension in 2 out of 4 piglets, and 1 out of 4 piglets suffered a fatal cardiac arrest. CBD 25 mg/kg (n = 4) induced significant hypotension in 1 out of 4 piglets, while 10 mg/kg (n = 5) was well tolerated. A significant negative correlation between the plasma concentration of CBD and hypotension during drug infusion was observed (p < 0.005). Neuroprotective effects were evaluated in piglets that did not display significant hypotension (n = 9) and CBD did not alter the degree of neuronal damage as measured by a neuropathology score, levels of the astrocytic marker S100B in CSF, magnetic resonance spectroscopy markers (Lac/NAA and Glu/NAA ratios), or plasma troponin T.

CONCLUSIONS

High-dose CBD can induce severe hypotension and did not offer neuroprotection in the early phase after global HI in piglets.

Temporal Profile of Circulating microRNAs after Global Hypoxia-Ischemia in Newborn Piglets

BACKGROUND

There is a lack of reliable biomarkers that can identify and grade acute hypoxic-ischemic encephalopathy in newborns. MicroRNAs (miRNA) are short, non-coding strands of RNA that are released into the circulation in response to tissue stress and injury. Some miRNAs are highly tissue specific and thus may potentially be non-invasive biomarkers of neonatal hypoxic-ischemic brain injury.

OBJECTIVE

The aim of this study was to characterize the temporal expression of selected circulating miRNAs in a clinically relevant piglet model of neonatal hypoxia-ischemia (HI).

METHODS

A total of 13 anesthetized newborn piglets were randomized to either a control group (n = 5) or transient global HI group (n = 8). HI was achieved by ventilation with 8% oxygen until the point of severe acidosis (arterial base excess ≤-20 mmol/l) and/or hypotension (mean arterial blood pressure ≤20 mm Hg) was reached. Plasma was sampled at baseline, at the end of HI and 0.5, 3.5 and 9.5 h after HI. MiRNA expression was measured by qRT-PCR.

RESULTS

Compared to baseline, miR-374a increased during HI (p = 0.01), remained elevated at 0.5 h after HI (p = 0.02) and was downregulated at 9.5 h after HI (p = 0.02). MiR-210 increased during HI (p = 0.02) and rapidly normalized by 0.5 h after HI. MiR-124 and miR-125b did not exhibit significant alterations. Correlations were observed between miR-374a, arterial pH, base excess and lactate levels, and between miR-210 and pO2 (p < 0.05).

CONCLUSIONS

Our data suggest that miR-374a and miR-210 are important regulators in neonatal HI and might have a place as biomarkers in this setting.