New insights into sodium phenylbutyrate as a pharmacotherapeutic option for neurological disorders

Neurological disorders (NDs) are diseases of the central and peripheral nervous systems that affect more than one billion people worldwide. The risk of developing an ND increases with age due to the vulnerability of the different organs and systems to genetic, environmental, and social changes that consequently cause motor and cognitive deficits that disable the person from their daily activities and individual and social productivity. Intrinsic factors (genetic factors, age, gender) and extrinsic factors (addictions, infections, or lifestyle) favor the persistence of systemic inflammatory processes that contribute to the evolution of NDs. Neuroinflammation is recognized as a common etiopathogenic factor of ND. The study of new pharmacological options for the treatment of ND should focus on improving the characteristic symptoms and attacking specific molecular targets that allow the delay of damage processes such as neuroinflammation, oxidative stress, cellular metabolic dysfunction, and deregulation of transcriptional processes. In this review, we describe the possible role of sodium phenylbutyrate (NaPB) in the pathogenesis of Alzheimer's disease, hepatic encephalopathy, aging, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis; in addition, we describe the mechanism of action of NaPB and its beneficial effects that have been shown in various in vivo and in vitro studies to delay the evolution of any ND.

The administration of Cerebrolysin elicits neuroprotective and neurorepair effects in an animal model of type 1 diabetes mellitus

Diabetes mellitus (DM) is a metabolic disorder impacting cerebral function. The administration of Streptozotocin (STZ) is a well-known animal model of insulinopenic type 1 DM in rats. STZ-induced DM results in a myriad of alteration in the periphery and central nervous system (CNS). Cerebrolysin (CBL) is a neuropeptide preparation that promotes synaptic and neuronal plasticity in various animal models. In all cases, CBL was administered when the model was established. This research aims to investigate the neuroprotective and neurorepair effect of CBL on the cytoarchitecture of neurons and spine density in pyramidal neurons of the prefrontal (PFC) and the CA1 region of the dorsal hippocampus, as well as spheroidal neurons of the dentate gyrus (DG), in STZ-induced DM. In the first experimental condition, STZ and CBL are administered at the same time to evaluate the potential preventive effect of CBL. In the second experimental condition, CBL was administered two months after establishing the DM model to measure the potential neurorepair effect of CBL. STZ-induced hyperglycemia remained unaltered by the administration of CBL in both experimental conditions. In the first experimental condition, CBL treatment preserved the neuronal morphology in PFC layer 3, PFC layer 5 and the DG of the hippocampus, while also maintaining spine density in the PFC-3, DG and CA1 hippocampus. Furthermore, CBL induced neurorepair in neurons within the PFC-3, PFC-5 and CA1 regions of the hippocampus, along with an increase in spine density in the PFC-3, DG and CA1 hippocampus. These findings suggest that CBL´s effects on neuroplasticity could be observed before or after the damage was evident.

Differential Effects of Neonatal Ventral Hippocampus Lesion on Behavior and Corticolimbic Plasticity in Wistar-Kyoto and Spontaneously Hypertensive Rats

Dysfunction of the corticolimbic system, particularly at the dendritic spine level, is a recognized core mechanism in neurodevelopmental disorders such as schizophrenia. Neonatal ventral hippocampus lesion (NVHL) in Sprague-Dawley rats induces both a schizophrenia-related behavioral phenotype and dendritic spine pathology (reduced total number and mature spines) in corticolimbic areas, which is mitigated by antipsychotics. However, there is limited information on the impact of rat strain on NVHL outcomes and antipsychotic effects. We compared the behavioral performance in the open field, novel object recognition (NORT), and social interaction tests, as well as structural neuroplasticity with the Golgi-Cox stain in Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) male rats with and without NVHL. Additionally, we explored the effect of the atypical antipsychotic risperidone (RISP). WKY rats with NVHL displayed motor hyperactivity without impairments in memory and social behavior, accompanied by dendritic spine pathology in the neurons of the prefrontal cortex (PFC) layer 3 and basolateral amygdala. RISP treatment reduced motor activity and had subtle and selective effects on the neuroplasticity alterations. In SH rats, NVHL increased the time spent in the border area during the open field test, impaired the short-term performance in NORT, and reduced social interaction time, deficits that were corrected after RISP administration. The NVHL caused dendritic spine pathology in the PFC layers 3 and 5 of SH rats, which RISP treatment ameliorated. Our results support the utility of the NVHL model for exploring neuroplasticity mechanisms in schizophrenia and understanding pharmacotherapy.

Polyoxidovanadates a new therapeutic alternative for neurodegenerative and aging diseases

Aging is a natural phenomenon characterized by a progressive decline in physiological integrity, leading to a deterioration of cognitive function and increasing the risk of suffering from chronic-degenerative diseases, including cardiovascular diseases, osteoporosis, cancer, diabetes, and neurodegeneration. Aging is considered the major risk factor for Parkinson's and Alzheimer's disease develops. Likewise, diabetes and insulin resistance constitute additional risk factors for developing neurodegenerative disorders. Currently, no treatment can effectively reverse these neurodegenerative pathologies. However, some antidiabetic drugs have opened the possibility of being used against neurodegenerative processes. In the previous framework, Vanadium species have demonstrated a notable antidiabetic effect. Our research group evaluated polyoxidovanadates such as decavanadate and metforminium-decavanadate with preventive and corrective activity on neurodegeneration in brain-specific areas from rats with metabolic syndrome. The results suggest that these polyoxidovanadates induce neuronal and cognitive restoration mechanisms. This review aims to describe the therapeutic potential of polyoxidovanadates as insulin-enhancer agents in the brain, constituting a therapeutic alternative for aging and neurodegenerative diseases.

Structural and biochemical alterations in dendritic spines as key mechanisms for severe mental illnesses

Severe mental illnesses (SMI) collectively affect approximately 20% of the global population, as estimated by the World Health Organization (WHO). Despite having diverse etiologies, clinical symptoms, and pharmacotherapies, these diseases share a common pathophysiological characteristic: the misconnection of brain areas involved in reality perception, executive control, and cognition, including the corticolimbic system. Dendritic spines play a crucial role in excitatory neurotransmission within the central nervous system. These small structures exhibit remarkable plasticity, regulated by factors such as neurotransmitter tone, neurotrophic factors, and innate immunity-related molecules, and other mechanisms - all of which are associated with the pathophysiology of SMI. However, studying dendritic spine mechanisms in both healthy and pathological conditions in patients is fraught with technical limitations. This is where animal models related to these diseases become indispensable. They have played a pivotal role in elucidating the significance of dendritic spines in SMI. In this review, the information regarding the potential role of dendritic spines in SMI was summarized, drawing from clinical and animal model reports. Also, the implications of targeting dendritic spine-related molecules for SMI treatment were explored. Specifically, our focus is on major depressive disorder and the neurodevelopmental disorders schizophrenia and autism spectrum disorder. Abundant clinical and basic research has studied the functional and structural plasticity of dendritic spines in these diseases, along with potential pharmacological targets that modulate the dynamics of these structures. These targets may be associated with the clinical efficacy of the pharmacotherapy.

Preventing Teen Pregnancy: A Qualitative Study of the Perspectives of Parenting and Expecting Latino Adolescents

STUDY OBJECTIVE

Latino youths in the United States experience disproportionately high rates of teen pregnancy. The aim of this study was to obtain expecting and parenting Latino adolescents' perspectives regarding factors contributing to teen pregnancy and pregnancy prevention.

METHODS

Expecting/parenting Latino adolescents were recruited from high schools with high proportions of Latino youths and teen pregnancy. Participants completed a questionnaire on sociodemographic and background characteristics. Focus groups were stratified by age and gender and audio recorded. Grounded theory was used to identify themes from the transcribed audio recordings.

RESULTS

Thirty-two expecting/parenting Latino adolescents (20 females, 12 males) 14-19 years old participated in four focus groups. Quantitative results revealed that two-thirds of participants at birth had adolescent mothers. Over three-quarters of participants reported that their pregnancies had occurred too soon. Qualitative themes for factors contributing to teen pregnancy included lack of contraceptive knowledge/access, belief of invincibility, influence within relationships, male decisions on contraceptive use, desire to belong among peers, lack of parental support for contraceptive use, lack of parental attention, rebellion, normalization of adolescent parenthood in Latino culture, and media. Themes for pregnancy prevention included time alone with physicians, parenting teens as mentors, reproductive health education, and community pregnancy-prevention programs.

CONCLUSION

Multiple factors contribute to teen pregnancy in Latino youth, including influences from Latino culture, family, peers, partners, and social determinants of health. Pregnancy prevention should incorporate interventions to address these aspects, including disseminating culturally sensitive education materials, providing parenting teens as peer mentors, encouraging time alone with health care providers, and addressing various social determinants of health.

The antipsychotic olanzapine reduces memory deficits and neuronal abnormalities in a male rat model of Autism

The prevalence of autism spectrum disorder (ASD), a neurodevelopmental condition that impacts social interaction and sensory processing, is rising. Valproic acid (VPA) exposure during pregnancy causes autistic-like traits in offspring. Olanzapine (OLZ), an atypical antipsychotic, is used to treat ASD. We assessed the impact of OLZ on behavior, neuromorphology, and nitric oxide (NO) levels in the hippocampus using prenatal VPA treatment in rats. It is commonly known that ASD patients exhibit sensory abnormalities. As such, we utilized the tail flick test to validate the ASD model. In the novel object recognition test (NORT), VPA exposure reduces the discrimination index (DI) in the first introduction to the novel object. Moreover, OLZ and vehicle-treated rats perform differently in the second exposition to the DI of the novel object, suggesting that OLZ reverses VPA-induced deficits in recognition memory. The latency to find the hidden platform in the Morris water maze test of memory and learning improves in VPA-exposed rats after OLZ administration, indicating that OLZ improves spatial memory in these rats. Administration of prenatal VPA induces neuronal hypotrophy and reduces spine density in pyramidal neurons of the CA1 region of the hippocampus. Treatment with OLZ corrects the neuromorphological changes brought on by VPA. In the CA1 region of the hippocampus, VPA treatment increases the number of neurons, which normalizes with OLZ treatment. OLZ increases the NO levels in the dorsal hippocampus in control rats. In rats exposed to VPA, the second-generation antipsychotic OLZ reduces memory-related and neuroplastic alterations. The current findings support the use of OLZ in this illness and further validate the use of prenatal VPA as a model of ASD.

Aripiprazole attenuates the medial prefrontal cortex morphological and biochemical alterations in rats with neonatal ventral hippocampus lesion

Schizophrenia is a neurodevelopmental disorder characterized by a loss of dendritic spines in the medial prefrontal cortex (mPFC). Multiple subclinical and clinical studies have evidenced the ability of antipsychotics to improve neuroplasticity. In this study, it was evaluated the effect of the atypical antipsychotic aripiprazole (ARI) on the behavioral and mPFC neuronal disturbances of rats with neonatal ventral hippocampus lesion (nVHL), which is a heuristic developmental model relevant to the study of schizophrenia. ARI attenuated open field hyperlocomotion in the rats with nVHL. Also, ARI ameliorated structural neuroplasticity disturbances of the mPFC layer 3 pyramidal cells, but not in the layer 5 neurons. These effects can be associated with the ARI capability of increasing brain-derived neurotrophic factor (BDNF) levels. Moreover, in the animals with nVHL, ARI attenuated the immunoreactivity for some oxidative stress-related molecules such as the nitric oxide synthase 2 (NOS-2), 3-nitrotyrosine (3-NT), and cyclooxygenase 2 (COX-2), as well as the reactive astrogliosis in the mPFC. These results contribute to current knowledge about the neurotrophic, anti-inflammatory, and antioxidant properties of antipsychotics which may be contributing to their clinical effects and envision promising therapeutic targets for the treatment of schizophrenia.

Increased suicide rates in Mexico City during the COVID-19 pandemic outbreak: An analysis spanning from 2016 to 2021

Objective

Coronavirus disease 2019 (COVID-19) has impacted mental health worldwide, and suicide can be a serious outcome of this. Thus, suicide characteristics were examined before and during the COVID-19 pandemic in Mexico City.

Methods

This is a retrospective study including all Mexico City residents who had a coroner's record with a cause of death of intentional self-harm (ICD-10) from January 2016 to December 2021.

Results

From 2016 to 2021, 3636 people committed suicide, of which 2869 were males (78.9%) and 767 females (21.1%). From 2016 to 2019 the suicide rate remained constant (∼6 per 100000) and dramatically increased in 2020 (10.45 per 100,000), to return to the levels of the previous year in 2021 (6.95 per 100000). The suicide rate in 2020 specifically increased from January to June (COVID-19 outbreak) in all age groups. Moreover, every year young people (15-24 years) have the maximum suicide rate and depression was the main suicide etiology.

Conclusion

The COVID-19 pandemic outbreak increased the suicide rate, regardless of age, but suicide prevalence was higher in males and young people, regardless of the COVID-19 pandemic. These findings confirm that suicide is a complex and multifactorial problem and will allow the establishment of new guidelines for prevention and care strategies.

Olfactory bulbectomy induces nociceptive alterations associated with gliosis in male rats

Major depressive disorder (MDD) is a major health concern worldwide with a wide array of symptoms. Emerging evidence suggests a high comorbidity between MDD and chronic pain, however, the relationship between these two diseases is not completely understood. Growing evidence suggests that glial cells play a key role in both disorders. Hence, we examined the effect of olfactory bulbectomy (OBX), a well-known model of depression-related behavior, on nociceptive behaviors and the number and morphology of astrocytes and glial cells in brain regions involved in the control of nociceptive processes in male rats. The brain regions analyzed included the basolateral amygdala (BLA), central amygdala (CeA), prefrontal cortex (PFC), and CA1 subregion of the hippocampus. A battery of behavioral tests, mechanical allodynia, thermal cold allodynia and mechanical hyperalgesia, was evaluated before and four weeks after OBX. Quantitative morphological analysis, as well as assessment of the number of glial fibrillary acidic protein (GFAP) and ionizing calcium-binding adaptor molecule 1 (Iba1) positive astrocytes and microglia were carried out to characterize glial remodeling and density, respectively. OBX caused mechanical and cold allodynia in an asynchronous pattern. The cold allodynia was noticeable one week following surgery, while mechanical allodynia became apparent two weeks after surgery. In the BLA, CeA and CA1, OBX caused significant changes in glial cells, such as hypertrophy and hypotrophy in GFAP-positive astrocytes and Iba1-positive microglia, respectively. Iba1-positive microglia in the PFC underwent selective hypotrophy due to OBX and OBX enhanced both GFAP-positive astrocytes and Iba1-positive microglia in the BLA. In addition, OBX increased the number of GFAP-positive astrocytes in the CeA and CA1. The amount of Iba1-positive microglia in the PFC also increased as a result of OBX. Furthermore, we found that there was a strong link between the observed behaviors and glial activation in OBX rats. Overall, our work supports the neuroinflammatory hypothesis of MDD and the comorbidity between pain and depression by demonstrating nociceptive impairment and significant microglial and astrocytic activation in the brain.

Chronic resveratrol administration reduces oxidative stress and brain cell loss and improves memory of recognition in old rats

The cognitive functions of people over 60 years of age have been diminished, due to the structural and functional changes that the brain has during aging. The most evident changes are at the behavioral and cognitive level, with decreased learning capacity, recognition memory, and motor incoordination. The use of exogenous antioxidants has been implemented as a potential pharmacological option to delay the onset of brain aging by attenuating oxidative stress and neurodegeneration. Resveratrol (RSVL) is a polyphenol present in various foods, such as red fruits, and drinks, such as red wine. This compound has shown great antioxidant capacity due to its chemical structure. In this study, we evaluated the effect of chronic RSVL treatment on oxidative stress and cell loss in the prefrontal cortex, hippocampus, and cerebellum of 20-month-old rats, as well as its impact on recognition memory and motor behavior. Rats treated with RSVL showed an improvement in locomotor activity and in short- and long-term recognition memory. Likewise, the concentration of reactive oxygen species and lipid peroxidation decreased significantly in the group with RSVL, coupled with an improvement in the activity of the antioxidant system. Finally, with the help of hematoxylin and eosin staining, it was shown that chronic treatment with RSVL prevented cell loss in the brain regions studied. Our results demonstrate the antioxidant and neuroprotective capacity of RSVL when administered chronically. This strengthens the proposal that RSVL could be an important pharmacological option to reduce the incidence of neurodegenerative diseases that affect older adults.

Neonatal olfactory bulbectomy induces anxiety-related behavior and modifies dopaminergic receptor expression in post-pubertal rats

Olfaction is a complex physiological process producing effects in the central nervous system (CNS) and implicated in emotional processes. Indeed, the olfactory bulbs (OB) send projections to various CNS regions including the nucleus accumbens (NAcc) and caudate-putamen (CPu). Both the NAcc and CPu receive important dopaminergic input. Emerging evidence suggests that dopamine (DA) is related to anxiety-related behaviors. Therefore, we aimed to investigate the consequences of neonatal olfactory bulbectomy (nOBX) to anxiety-related behavior as assayed in the elevated plus maze (EPM) as well as the expression of dopaminergic receptors (D1-like, D2-like, and D3) in the NAcc and CPu at pre- and post-pubertal ages in the rat. The results show that nOBX increased the number of entries in the open arm of the EPM post-pubertally, suggesting an anxiolytic-related effect. nOBX increased the D2-like binding in the NAcc shell and D3 binding in the NAcc core pre-pubertally. At post-pubertal ages, the D3 binding was reduced at the olfactory tubercle and islands of Calleja in nOBX rats. Alterations in the DA receptor expression may be one mechanism responsible for the observed behavioral modifications in nOBX rats.

Cellular mechanisms in brain aging: Focus on physiological and pathological aging

Aging is a natural phenomenon characterized by accumulation of cellular damage and debris. Oxidative stress, cellular senescence, sustained inflammation, and DNA damage are the main cellular processes characteristic of aging associated with morphological and functional decline. These effects tend to be more pronounced in tissues with high metabolic rates such as the brain, mainly in regions such as the prefrontal cortex, hippocampus, and amygdala. These regions are highly related to cognitive behavior, and therefore their atrophy usually leads to decline in processes such as memory and learning. These cognitive declines can occur in physiological aging and are exacerbated in pathological aging. In this article, we review the cellular processes that underlie the triggers of aging and how they relate to one another, causing the atrophy of nerve tissue that is typical of aging. The main topic of this review to determine the central factor that triggers all the cellular processes that lead to cellular aging and discriminate between normal and pathological aging. Finally, we review how the use of supplements with antioxidant and anti-inflammatory properties reduces the cognitive decline typical of aging, which reinforces the hypothesis of oxidative stress and cellular damage as contributors of physiological atrophy of aging. Moreover, cumulative evidence suggests their possible use as therapies, which improve the aging population's quality of life.

High-carbohydrate and fat diet consumption causes metabolic deterioration, neuronal damage, and loss of recognition memory in rats

The number of people diagnosed with metabolic syndrome (MetS) has increased dramatically to reach alarming proportions worldwide. The origin of MetS derives from bad eating habits and sedentary lifestyle. Most people consume foods high in carbohydrates and saturated fat. In recent years, it has been reported that alterations in insulin at the brain level could have an impact on the appearance of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, dementia, depression, and other types of disorders that compromise brain function. These alterations have been associated with damage to the structure and function of neurons located in the reptilian and limbic systems, a decrease in dendritic arborization and an exacerbated inflammatory state that impaired learning and memory and increased in the state of stress and anxiety. Although the molecular mechanisms induced by MetS to cause neurodegeneration are not fully understood. The aim of this study is to know the effect of the intake of hypercaloric diets on the structure and function of neurons located in the frontal cortex, hypothalamus and hippocampus and its impact on behavior in rats with metabolic syndrome. In conclusion, the present study illustrated that chronic exposure to hypercaloric diets, with a high content of sugars and saturated fatty acids, induces a proinflammatory state and exacerbates oxidative stress in brain regions such as the hypothalamus, hippocampus, and frontal cortex, leading to dysfunction. metabolism, neuronal damage, and recognition memory loss.

Mirror neurons and empathy-related regions in psychopathy: systematic review, meta-analysis, and a working model

Mirror neurons have been associated with empathy. People with psychopathic traits present low levels of empathy. To analyze this, a systematic review of fMRI studies of people with psychopathic traits during an emotional facial expression processing task was performed. The regions of interest were structures associated with the mirror neuron system: ventromedial prefrontal cortex (vmPFC), inferior parietal lobe (IPL), inferior frontal gyrus and superior temporal sulcus. The analysis was also extended to structures related to affective empathy (insula, amygdala and anterior cingulate cortex) and to two more emotional processing areas (orbitofrontal cortex and fusiform gyrus). Hypoactivation was more frequently observed in regions of the mirror neuron system from people with high psychopathic traits, as well as in the emotional processing structures, and those associated with affective empathy, except for the insula, where it presented higher activity. Differences were observed for all types of emotions. The results suggest that the mirror neuron system is altered in psychopathy and their relationship with affective empathy deficits is discussed.

Second-generation antipsychotic olanzapine attenuates behavioral and prefrontal cortex synaptic plasticity deficits in a neurodevelopmental schizophrenia-related rat model

Second-generation antipsychotics are the drugs of choice for the treatment of neurodevelopmental-related mental diseases such as schizophrenia. Despite the effectiveness of these drugs to ameliorate some of the symptoms of schizophrenia, specifically the positive ones, the mechanisms beyond their antipsychotic effect are still poorly understood. Specifically, second-generation antipsychotics are reported to have anti-inflammatory, antioxidant and neuroplastic properties. Using the neonatal ventral hippocampus lesion (nVHL) in the rat, an accepted schizophrenia-related model, we evaluated the effect of the second-generation antipsychotic olanzapine (OLZ) in the behavioral, neuroplastic, and neuroinflammatory alterations exhibited in the nVHL animals. OLZ corrected the hyperlocomotion and impaired working memory of the nVHL animals but failed to enhance social disturbances of these animals. In the prefrontal cortex (PFC), OLZ restored the pyramidal cell structural plasticity in the nVHL rats, enhancing the dendritic arbor length, the spinogenesis and the proportion of mature spines. Moreover, OLZ attenuated astrogliosis as well as some pro-inflammatory, oxidative stress, and apoptosis-related molecules in the PFC. These findings reinforce the evidence of anti-inflammatory, antioxidant, and neurotrophic mechanisms of second-generation antipsychotics in the nVHL schizophrenia-related model, which allows for the possibility of developing more specific drugs for this disorder and thus avoiding the side effects of current schizophrenia treatments.

Adenosine and Astrocytes Determine the Developmental Dynamics of Spike Timing-Dependent Plasticity in the Somatosensory Cortex

During development, critical periods of synaptic plasticity facilitate the reordering and refinement of neural connections, allowing the definitive synaptic circuits responsible for correct adult physiology to be established. The L4-L2/3 synapses in the somatosensory cortex (S1) exhibit a presynaptic form of spike timing-dependent long-term depression (t-LTD) that probably fulfills a role in synaptic refinement. This t-LTD persists until the fourth postnatal week in mice, disappearing thereafter. When we investigated the mechanisms underlying this maturation-related loss of t-LTD in either sex mouse slices, we found that it could be completely recovered by antagonizing adenosine type 1 receptors. By contrast, an agonist of A1R impeded the induction of t-LTD at P13-27. Furthermore, we found that the adenosine that mediated the loss of t-LTD at the end of the fourth week of development is most probably supplied by astrocytes. At more mature stages (P38-60), we found that the protocol used to induce t-LTD provokes t-LTP. We characterized the mechanisms underlying the induction of this form of LTP, and we found it to be expressed presynaptically, as witnessed by paired-pulse and coefficient of variation analysis. In addition, this form of presynaptic t-LTP requires the activation of NMDARs and mGlu1Rs, and the entry of Ca2+ into the postsynaptic neuron through L-type voltage-dependent Ca2+ channels. Nitric oxide is also required for t-LTP as a messenger in the postsynaptic neuron as are the adenosine and glutamate that are released in association with astrocyte signaling. These results provide direct evidence of the mechanisms that close the window of plasticity associated with t-LTD and that drive the switch in synaptic transmission from t-LTD to t-LTP at L4-L2/3 synapses, in which astrocytes play a central role.SIGNIFICANCE STATEMENT During development, critical periods of plasticity facilitate the reordering and refining of neural connections, allowing correct adult physiology to be established. The L4-L2/3 synapses in the somatosensory cortex exhibit a presynaptic form plasticity (LTD) that probably fulfills a role in synaptic refinement. It is present until the fourth postnatal week in mice, disappearing thereafter. The mechanisms that are responsible for this loss of plasticity are not clear. We describe here these mechanisms and those involved in the switch from LTD to LTP observed as the brain matures. Defining these events responsible for closing (and opening) plasticity windows may be important for brain repair, sensorial recovery, the treatment of neurodevelopmental disorders, and for educational policy.

Effect of cadmium administration on the antioxidant system and neuronal death in the hippocampus of rats

Cadmium (Cd) is a heavy metal classified as a carcinogen whose exposure could affect the function of the central nervous system. Studies suggest that Cd modifies neuronal morphology in the hippocampus and affects cognitive tasks. The oxidative stress pathway is proposed as a mechanism of toxicity. However, this mechanism is not precise yet. This study aimed to evaluate the effect of Cd administration on oxidative stress markers in the male rat's hippocampus. Male Wistar rats were divided into (1) control (drinking water) and (2) treatment with Cd (32.5 ppm of cadmium chloride (CdCl₂ ) in water). The Cd was administered for 2, 3, and 4 months. The results show that the oral administration of CdCl₂ increased the concentration of Cd in plasma and hippocampus, and this response is time-dependent on its administration. Likewise, it caused an increase in lipid peroxidation and nitrosative stress markers. Moreover, it increased reactive astrogliosis and antioxidant enzyme activity. Consequently, the progression of the oxidative response exacerbated neurodegeneration in hippocampal cells. Our results suggest that Cd exposure induces a severe oxidative response that contributes critically to hippocampal neurodegeneration. It is suggested that exposure to Cd increases the risk of developing neurological diseases, which contributes to a decrease in the quality of life of the human and the environment in which it lives.

Effect of selective dopamine D3 and D4 receptor agonists on trunk pulmonary artery vascular reactivity from control and monocrotaline-treated rats

Dopamine D1-like and D2-like receptors are expressed in the pulmonary arteries, however there is a little information about their effect on vascular tone in pulmonary circulation, even the vascular effect of activation of the dopamine D₃ and D₄ subtypes in physiological and pathological conditions such as pulmonary hypertension is unknown. The objective of this study was to evaluate the vascular response of trunk pulmonary artery rings from saline and monocrotaline-treated rats in the presence of selective dopamine receptor agonists. In trunk pulmonary artery rings with intact and denuded endothelium, cumulative concentration-response curves were performed for phenylephrine, acetylcholine, and dopamine receptor agonists (apomorphine-D2-like, SKF38393-D₁, quinpirole-D₂/D₃, 7-OH-DPATD₃, and PD168077-D₄) alone and in the presence of corresponding selective dopamine receptor antagonists (SCH23390-D₁, raclopride-D₂/D₃, U99194 maleate-D₃, and L-745,870-D₄). Contractile and relaxant effects generated during the activation with phenylephrine and acetylcholine, respectively, were significantly reduced in intact and denuded endothelium trunk pulmonary artery rings from monocrotaline rats in comparison with control rats. All dopamine receptor agonists, except the 7-OH-DPAT, produced significant vascular relaxation in intact trunk pulmonary artery rings precontracted with phenylephrine in both experimental groups. Also, the vascular relaxation of SKF38393, and particularly apomorphine and PD168077 was significant in denuded endothelium trunk pulmonary artery rings from control and monocrotaline groups. Furthermore, the vasorelaxation induced by these dopamine agonists was significantly reduced in pulmonary preparations from monocrotaline-treated rats in comparison to that recorded in preparations from control rats. The effect of dopamine receptor agonists decreased significantly in the presence of the corresponding antagonist in both experimental groups. The results support that dopamine D₄ receptor agonist induces significant vascular relaxation, whereas dopamine D₃ receptor agonist induces vasoconstriction in intact and denuded endothelium trunk pulmonary artery rings in control and monocrotaline-induced pulmonary arterial hypertension rats.

Curcumin induces cortico-hippocampal neuronal reshaping and memory improvements in aged mice

Aging induces cognitive decline, reduces of synaptic plasticity and increases oxidative reactive species (ROS) in the central nervous system. Traditional medicine has long benefitted from naturally occurring molecules such as curcumin (diferuloymethane). Curcumin is extracted from the plant Curcuma longa and is known for its synaptic and antioxidant-related benefits. In this study, we tested the hypothesis that chronic curcumin treatment reduces cognitive and cellular effects of aging. Curcumin-treated mice showed improved learning and memory using the Morris Water Maze and novel object recognition task. In addition, using the Golgi-Cox stain, curcumin treatment increased spine density in all evaluated regions and increased dendritic arborization in the prefrontal cortex (PFC) layer 3 and CA3 subregion of the hippocampus. Moreover, chronic curcumin exposure increased synaptophysin and actin expression and reduced glial fibrillary acidic protein expression, a marker of astrocytes, in the hippocampus (CA1 and CA3 subregions), while simultaneously reducing the ROS-related molecule, metallothionein 3 expression in the PFC and hippocampus. Collectively, these novel findings suggest that curcumin reduces cognitive, neuronal and astrocytic signs of aging in mice.

Losartan enhances cognitive and structural neuroplasticity impairments in spontaneously hypertensive rats

Hypertension is a risk factor for vascular dementia, which is the second most prevalent type of dementia, just behind Alzheimer's disease. This highlights the brain vulnerability due to hypertension, which may increase with aging. Thus, studying how hypertension affects neural cells and behavior, as well as the effects of antihypertensives on these alterations, it's important to understand the hypertension consequences in the brain. The spontaneously hypertensive rat (SHR) has been useful for the study of hypertension alterations in diverse organs, including the brain. Thus, we studied the losartan effects on cognitive and structural neuroplasticity impairments in SHR of 10 months of age. In the first instance, we evaluated the losartan effects on exploratory behavior and novel object recognition test (NORT) in the SHR. Then, we assessed the density and morphology of dendritic spines of pyramidal neurons from the prefrontal cortex (PFC) layers 3 and 5, and CA1 of the dorsal Hp (dHp). Our results indicate that in SHR, losartan treatment (2 months, 15 mg/Kg/day) reduces high blood pressure to age-matched vehicle-treated Wistar-Kyoto (WKY) rat levels. Moreover, losartan improved long-term memory in SHR compared with age-matched vehicle-treated WKY rats, without affecting the locomotor and anxiety behaviors. The behavioral improvement of the SHR can be associated with the increase in the number of dendritic spines and the mushroom spine population in the PFC and the dHp. In conclusion, losartan enhances cognitive impairments by controlling the high blood pressure and improving neuroplasticity in animals with chronic hypertension.

Dendritic and behavioral changes in rats neonatally treated with homocysteine; A proposal as an animal model to study the attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHAD) is a neurobehavioral disorder that affects children and adolescents with a high prevalence. Despite its prevalence and an unclear etiology, previous reports suggest that it is closely related to homocysteine metabolism. Male Sprague Dawley rats were administered with homocysteine from postnatal day (PD) 2 to PD 16. Locomotor activity was evaluated at 35 PD (prepuberal age) and 60 PD (adult age) before and after amphetamine administration. In rats evaluated at both ages, homocysteine induced hyperactivity, and the amphetamine administration reduced hyperactivity significantly at 35 PD, but not at 60 PD. In the social interaction test, homocysteine reduced the number of contacts and increased the latency to the first contact only in rats at 35 PD. Homocysteine also had an effect on short term memory at 35D and 60 PD and long-term memory at 60 PD. Morphological changes were found mainly in the shape of dendritic spines in the prefrontal cortex (PFC-3), dorsal hippocampus (CA1), dentate gyrus (DG) and nucleus accumbens (NAcc), in rats administered neonatally with homocysteine at both ages studied. In prepuberal and adult rats, there was an increase in dendritic length in DG and NAcc, respectively. The dendritic spine morphology also was altered at both ages, mainly decreasing the number of mushroom spines in NAcc and CA1 at 30 PD and in all the areas studied at 60 PD rats. Those areas are associated with the processes of attention, learning and memory that were studied, and those alterations are possibly related to changes observed in the behavioral tests. These behavioral and morphological changes in rats at 35 PD administered with homocysteine could be similar to changes found in children diagnosed with ADHD. Moreover, half to two thirds of children diagnosed with ADHD reach adulthood with this disorder. In this study we found similarities with ADHD, finding alterations in both rats at 35 PD and 60 PD. So, this may be proposed as an animal model to study this disorder present in children, adolescents and adults.