2,4 Dinitrophenol Attenuates Mitochondrial Dysfunction and Improves Neurobehavioral Outcomes Postanoxia in Neonatal Rats

Melatonin attenuates developmental deficits and prevents hippocampal injuries in male and female rats subjected to neonatal anoxia

Hypoxia in preterm infants is a clinical condition that has been associated with cognitive and behavioral disturbances for which treatment strategies are strongly required. Melatonin administration following brain insults has been considered a promising therapeutic strategy due to its antioxidant and anti-inflammatory effects. Not surprisingly, it has been extensively studied for preventing disturbances following brain injury. This study evaluated the effects of melatonin on developmental disturbances, memory disruption, and hippocampal cell loss induced by neonatal anoxia in rats. Neonatal Wistar rats were subjected to anoxia and subsequently treated with melatonin. Later, maturation of physical characteristics, ontogeny of reflexes, learning and memory in the Morris water maze (MWM), and estimates of the number of hippocampal neurons, were evaluated. Melatonin treatment attenuated (1) female anoxia-induced delay in superior incisor eruption, (2) female anoxia-induced vibrissae placement reflexes, and (3) male and female anoxia-induced hippocampal neuronal loss. Melatonin also promoted an increase (5) in swimming speeds in the MWM. In addition, PCA analysis showed positive associations between the acoustic startle, auditory canal open, and free fall righting parameters and negative associations between the male vehicle anoxia group and the male melatonin anoxia group. Therefore, melatonin treatment attenuates both anoxia-induced developmental deficits and hippocampal neuronal loss.

Indole-3-carbinol ameliorated the neurodevelopmental deficits in neonatal anoxic injury in rats

Neonatal anoxia is linked to long-lasting neurodevelopmental deficits. Due to the lack of pharmacological intervention to treat neonatal anoxia, there is interest in finding new molecules for its treatment. Indole-3-carbinol (I3C) has shown neuroprotective effects in some disease conditions. However, the neuroprotective role of I3C in neonatal anoxia has not been explored. Consequently, we have investigated the effect of I3C on neonatal anoxia-induced brain injury and neurodevelopmental deficits. Rat pups after 30 h of birth were subjected to two episodes of anoxia (10 min in each) at a time interval of 24 h by flowing 100% nitrogen. I3C was administered within 30 min of the second episode of anoxia on a postnatal day (PND) 3 and continued for PND 9. Neurodevelopmental deficits, cortical mitochondrial membrane potential (MMP), opening of mitochondrial permeability transition pore (MPTP), electron transport chain (ETC) enzyme activities, oxidative stress, hypoxia-inducible factor-1α (HIF-1α) levels, histopathological changes, and apoptosis were measured. I3C treatment dose-dependently ameliorated the neurodevelopmental deficits and somatic growth in anoxic pups. I3C improved mitochondrial function by enhancing the MMP, mitochondrial ETC enzymes, and antioxidants. It blocked the MPTP opening and release of cytochrome C in anoxic pups. Further, I3C reduced the elevated cortical HIF-1α in neonatal anoxic pups. Furthermore, I3C ameliorated histopathological abnormalities and mitochondrial-mediated apoptotic indicators Cyt C, caspase-9, and caspase-3. Our study concludes that I3C improved neuronal development in anoxic pups by enhancing mitochondrial function, reducing HIF-1α, and mitigating apoptosis.

The relationship between experimental 2,4-Dinitrophenol administration and neurological oxidative stress: in terms of dose, time and gender differences

Although 2,4-DNP is claimed to promote fast weight reduction, it is also related with an intolerable high risk of serious side effects to various tissues. On the other hand, it is known to have neuroprotective effects. These different effects of 2,4-DNP may be due to the administration conditions. For this reason, in this study, it was aimed for the first time to clarify the oxidative changes that occur in the brain during the use of 2,4-DNP, depending on the dose, time and gender. For this purpose, 60 Wistar rats (30 male, 30 female) were divided into ten groups: control groups, short-term/long-term groups and low dose/high dose groups. Except for the control groups, 2,4-DNP was administered to the other groups by oral gavage. End of the experiment, thiobarbituric acid-reactive substances (TBARs), glutathione (GSH), nitric oxide (NOx) and ascorbic acid (AA) levels were measured in the brain tissues of sacrificed animals. 2,4-DNP administration showed attenuation impact on oxidative stress depending on both dose, time and gender. It can be said that it is more beneficial in terms of neuroprotection, especially in the short-term and male groups. In conclusion, our findings suggest that, depending on the dose, time, and gender, 2,4-DNP may be beneficial in the treatment of neurodegenerative disorders.

Pharmacological testing of therapeutics using normothermic machine perfusion: A pilot study of 2,4-dinitrophenol delivery to steatotic human livers

INTRODUCTION

Normothermic machine perfusion (NMP) provides a platform for drug-delivery. However, pharmacological considerations for therapeutics delivered during NMP are scarcely reported. We aimed to demonstrate the ability of NMP as a platform for pharmacological testing, using a drug which increases metabolism (2,4-dinitrophenol; DNP) as an example therapeutic.

METHODS

We performed 25 h of NMP on human livers which had been declined for transplant due to steatosis (n = 7). Three livers received a DNP bolus, three were controls, and one received a DNP infusion.

RESULTS

Toxicity studies revealed DNP delivery was safe, without hepatotoxic effects. The liver surface temperature was increased in the DNP group (p = 0.046), but no livers suffered hyperthermia-the mechanism of DNP toxicity in vivo. Pharmacokinetic studies revealed DNP elimination with first-order kinetics and 7.7 h half-life (95% CI = 5.1-15.9 hrs). The clearance of DNP in bile was negligible. As expected, DNP significantly increased oxygen consumption (p = 0.023); this increase was closely correlated with perfusate DNP concentration (r2  = 0.975; p = 0.002) and the effect was lost as DNP was eliminated by the liver. A DNP infusion rate, calculated using our pharmacokinetic data, successfully maintained perfusate DNP concentration.

DISCUSSION

Detailed pharmacological testing can be performed during NMP. Our therapeutic (DNP) is rapidly eliminated by the ex vivo liver, meaning the drug effect of increased metabolism is only transient. This demonstrates the importance of assessing pharmacokinetics when delivering therapeutics during NMP, especially for prolonged perfusion of organs with established roles in drug elimination. Rigorous pharmacological testing is needed to unlock the potential of NMP as a clinical drug-delivery platform.

Mitochondrial dysfunction in perinatal asphyxia: role in pathogenesis and potential therapeutic interventions

Perinatal asphyxia (PA)-induced brain injury may present as hypoxic-ischemic encephalopathy in the neonatal period, and long-term sequelae such as spastic motor deficits, intellectual disability, seizure disorders and learning disabilities. The brain injury is secondary to both the hypoxic-ischemic event and oxygenation-reperfusion following resuscitation. Following PA, a time-dependent progression of neuronal insult takes place in terms of transition of cell death from necrosis to apoptosis. This transition is the result of time-dependent progression of pathomechanisms which involve excitotoxicity, oxidative stress, and ultimately mitochondrial dysfunction in developing brain. More precisely mitochondrial respiration is suppressed and calcium signalling is dysregulated. Consequently, Bax-dependent mitochondrial permeabilization occurs leading to release of cytochrome c and activation of caspases leading to transition of cell death in developing brain. The therapeutic window lies within this transition process. At present, therapeutic hypothermia (TH) is the only clinical treatment available for treating moderate as well as severe asphyxia in new-born as it attenuates secondary loss of high-energy phosphates (ATP) (Solevåg et al. in Free Radic Biol Med 142:113-122, 2019; Gunn et al. in Pediatr Res 81:202-209, 2017), improving both short- and long-term outcomes. Mitoprotective therapies can offer a new avenue of intervention alone or in combination with therapeutic hypothermia for babies with birth asphyxia. This review will explore these mitochondrial pathways, and finally will summarize past and current efforts in targeting these pathways after PA, as a means of identifying new avenues of therapeutic intervention.

Mitochondrial Uncoupling: A Key Controller of Biological Processes in Physiology and Diseases

Mitochondrial uncoupling can be defined as a dissociation between mitochondrial membrane potential generation and its use for mitochondria-dependent ATP synthesis. Although this process was originally considered a mitochondrial dysfunction, the identification of UCP-1 as an endogenous physiological uncoupling protein suggests that the process could be involved in many other biological processes. In this review, we first compare the mitochondrial uncoupling agents available in term of mechanistic and non-specific effects. Proteins regulating mitochondrial uncoupling, as well as chemical compounds with uncoupling properties are discussed. Second, we summarize the most recent findings linking mitochondrial uncoupling and other cellular or biological processes, such as bulk and specific autophagy, reactive oxygen species production, protein secretion, cell death, physical exercise, metabolic adaptations in adipose tissue, and cell signaling. Finally, we show how mitochondrial uncoupling could be used to treat several human diseases, such as obesity, cardiovascular diseases, or neurological disorders.