Effects of undernourishment, recurrent seizures and enriched environment during early life in hippocampal morphology

Does the enriched environment alter memory capacity in malnourished rats by modulating BDNF expression?

Environmental factors interfere in the neural plasticity processes. Among these, malnutrition in the early stages of life stands out as one of the main non-genetic factors that can interfere in the morphofunctional development of the nervous system. Furthermore, sensory stimulation from enriched environments (EE) also interferes with neural development. These two factors can modify areas related to memory and learning as the hippocampus, through mechanisms related to the gene expression of brain-derived neurotrophic factor (BDNF). The BDNF may interfere in synaptic plasticity processes, such as memory. In addition, these changes in early life may affect the functioning of the hippocampus during adulthood through mechanisms mediated by BDNF. Therefore, this study aims to conduct a literature review on the effects of early malnutrition on memory and the relationship between the underlying mechanisms of EE, BDNF gene expression, and memory. In addition, there are studies that demonstrate the effect of EE reversal on exposure to changes in the functioning of hippocampal malnutrition in adult rats that were prematurely malnourished. Thereby, evidence from the scientific literature suggests that the mechanisms of synaptic plasticity in the hippocampus of adult animals are influenced by malnutrition and EE, and these alterations may involve the participation of BDNF as a key regulator in memory processes in the adult animal hippocampus.

Memory deterioration based on the tobacco smoke exposure and methylazoxymethanol acetate administration vs. aripiprazole, olanzapine and enrichment environment conditions

Enrichment environment conditions, as well as tobacco smoke exposure, may affect cognitive function (e.g. spatial memory) in an animal model of schizophrenia and schizophrenic patients. The aim of this study was to find whether spatial memory function impairment is found in methylazoxymethanol acetate treated rats (an animal model of schizophrenia) and whether aripiprazole (1.5 mg/kg) and olanzapine (0.5 mg/kg) modify these functions. We also were able to determine whether tobacco smoke exposure and enrichment environment conditions have an impact on drug efficacy. The effect of methylazoxymethanol acetate, tobacco smoke exposure, enrichment environment and the use of drugs were studied in the Morris Water Maze test (spatial memory). The results of our study clearly show that enriched environment may have a procognitive effect while tobacco smoke and methylazoxymethanol acetate have a contradictory effect. This paper also confirmed that the use of neuroleptics, namely ARI and OLA, reduced the process of spatial memory deterioration tested in the Morris water maze both in terms of the number of escape latencies and crossed quadrants.

Association of Socioeconomic Status and Brain Injury With Neurodevelopmental Outcomes of Very Preterm Children

IMPORTANCE

Studies of socioeconomic status and neurodevelopmental outcome in very preterm neonates have not sensitively accounted for brain injury.

OBJECTIVE

To determine the association of brain injury and maternal education with motor and cognitive outcomes at age 4.5 years in very preterm neonates.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of preterm neonates (24-32 weeks' gestation) recruited August 16, 2006, to September 9, 2013, at British Columbia Women's Hospital in Vancouver, Canada. Analysis of 4.5-year outcome was performed in 2018.

MAIN OUTCOMES AND MEASURES

At age 4.5 years, full-scale IQ assessed using the Wechsler Primary and Preschool Scale of Intelligence, Fourth Edition, and motor outcome by the percentile score on the Movement Assessment Battery for Children, Second Edition.

RESULTS

Of 226 survivors, neurodevelopmental outcome was assessed in 170 (80 [47.1%] female). Based on the best model to assess full-scale IQ accounting for gestational age, standardized β coefficients demonstrated the effect size of maternal education (standardized β = 0.21) was similar to that of white matter injury volume (standardized β = 0.23) and intraventricular hemorrhage (standardized β = 0.23). The observed and predicted cognitive scores in preterm children born to mothers with postgraduate education did not differ in those with and without brain injury. The best-performing model to assess for motor outcome accounting for gestational age included being small for gestational age, severe intraventricular hemorrhage, white matter injury volume, and chronic lung disease.

CONCLUSIONS AND RELEVANCE

At preschool age, cognitive outcome was comparably associated with maternal education and neonatal brain injury. The association of brain injury with poorer cognition was attenuated in children born to mothers of higher education level, suggesting opportunities to promote optimal outcomes.

A Novel Protocol to Reduce Early Seizures After Cranioplasty: A Single-Center Experience

BACKGROUND

Cranioplasty is a relatively simple and straightforward intervention; however, it is associated with a high incidence of postoperative seizures. Postcranioplasty seizures, especially early seizures, are common and associated with poor outcomes and longer hospital stays. Protocols for preventing and managing early seizures have not been well established.

METHODS

The medical records of 595 patients who underwent cranioplasty were retrospectively reviewed. Of these patients, 259 had preexisting seizures and 336 had no seizures before cranioplasty. Prophylactic antiepileptic drugs (AEDs) were administered to patients who had no seizures before cranioplasty for 1 week, whereas an advanced AED regimen was administered to patients with preexisting seizures. Subsequently, clinical characteristics, occurrence of recurrent seizures, early seizures, and postoperative complications were analyzed.

RESULTS

Our previous study showed positive results for prophylaxis in new-onset early seizures. In the patients with preexisting seizures, 46.7% of the patients (121/259) experienced recurrent seizures after cranioplasty and 17.4% of the patients (45/259) experienced early recurrent seizures within 1 week of their operation. In the group who received the advanced AEDs, early recurrent seizures were significantly reduced to 8.7% compared with the regular group (20.5%; P = 0.027). Younger age and preoperative hydrocephalus engendered a higher risk of recurrent seizures. The number of previous craniotomies was observed to have a trend of increasing early recurrent seizures.

CONCLUSIONS

Cranioplasty is associated with a high incidence of postoperative seizures. Our management protocol for postcranioplasty seizures includes seizure prophylaxis and advanced use of AEDs, which can reduce the occurrence of early seizures.

Late-emerging effects of perinatal undernutrition in neuronal limbic structures underlying the maternal response in the rat

Maternal care in the rat is an ancient behavioral response to specific multisensory inputs widely integrated in a complex forebrain, limbic and brain stem network to meet the basic needs of the young. Early undernutrition interferes with the morphofunctional organization of the brain, including maternal circuitry. The late-emerging effects of pre- and neonatal undernutrition on nest building and pup retrieval by lactating Wistar rats were correlated with dendritic arbor and perikaryon measurements (Golgi-Cox) in layer II pyramidal neurons of the anterior cingulate cortex, layer III pyramidal neurons of the medial prefrontal cortex and multipolar basolateral amygdala neurons examined on lactation days 4 and 12. In the underfed group, pregnant F0 dams received different percentages of a balanced diet. After birth, prenatally underfed (F1) pups continued the undernutrition by remaining with a nipple-ligated mother for 12 h. Weaning occurred at 25 days of age, and pups were subsequently provided an ad libitum diet. At 90 days of age, F1 dams were maternally tested. Early underfed dams showed significant reductions in nest building and prolonged retrieval latencies for grasping pups by inappropriate body areas. The behavioral alterations were concurrent with highly significant reductions in the somatic cross-sectional area and perimeter, spine density and dendritic crossings of cingulate cells and medial prefrontal cortical pyramids, as well as smaller effects on amygdala neurons. The anatomical findings suggest different postsynaptic organizations that may affect the neuronal excitability stages for the integration and encoding of cues triggering the altered maternal response components of early underfed dams.

Anatomy Based Networks and Topology Alteration in Seizure-Related Cognitive Outcomes

Epilepsy is a paroxysmal neurological disorder characterized by recurrent and unprovoked seizures affecting approximately 50 million people worldwide. Cognitive dysfunction induced by seizures is a severe comorbidity of epilepsy and epilepsy syndromes and reduces patients’ quality of life. Seizures, along with accompanying histopathological and pathophysiological changes, are associated with cognitive comorbidities. Advances in imaging technology and computing allow anatomical and topological changes in neural networks to be visualized. Anatomical components including the hippocampus, amygdala, cortex, corpus callosum (CC), cerebellum and white matter (WM) are the fundamental components of seizure- and cognition-related topological networks. Damage to these structures and their substructures results in worsening of epilepsy symptoms and cognitive dysfunction. In this review article, we survey structural, network changes and topological alteration in different regions of the brain and in different epilepsy and epileptic syndromes, and discuss what these changes may mean for cognitive outcomes related to these disease states.

Hypoxia/ischemia a key player in early post stroke seizures: modulation by opioidergic and nitrergic systems

Stroke is a leading cause of death, disability, and socioeconomic loss worldwide. All attempts at pharmacological reduction of the complications of stroke (e.g. post-stroke seizure, and brain׳s vulnerability to hypoxic/ischemic injury) have failed. Endogenous opioids and nitric oxide (NO) overproduction has been documented in brain hypoxia/ischemia (H/I), which can exert pro-convulsive effects. In this study, we aimed to examine the possible involvement of opioidergic and nitrergic pathways in the pathogenesis of post-stroke seizure. H/I was induced by right common carotid ligation and sham-operated mice served as controls. We demonstrated that right common carotid ligation decreases the threshold for clonic seizures induced by pentylenetetrazole (PTZ), a GABA antagonist. Furthermore, pro-convulsive effect of H/I following right common carotid ligation was blocked by naltrexone (NTX) (3mg/kg), NG-Nitro-l-arginine methyl ester (l-NAME) (10mg/kg), and aminoguanidine (AG) (100mg/kg) administration (P<0.001). Interestingly, co-administration of non-effective doses of NTX and l-NAME (1 and 0.5mg/kg, respectively) reverses epileptogenesis of H/I (P<0.001). In the same way, co-administration of non-effective doses of NTX and AG (1 and 5mg/kg, respectively), reverses epileptogenesis of H/I (P<0.001). Indeed, the histological studies performed on mice exposed to H/I confirmed our previous data. These findings suggest hyper-susceptibility to PTZ induced seizure following H/I is mediated by interaction of opioidergic, and iNOS/NO pathways. Therefore, our results identify new pharmacological targets and provide the rationale for a novel strategy to promote recovery after stroke and possibly other brain injuries.