Effects of Progesterone on Preclinical Animal Models of Traumatic Brain Injury: Systematic Review and Meta-analysis

Since the publication of two phase III clinical trials not supporting the use of progesterone in patients with traumatic brain injury (TBI), several possible explanations have been postulated, including limitations in the analysis of results from preclinical evidence. Therefore, to address this question, a systematic review and meta-analysis was performed to evaluate the effects of progesterone as a neuroprotective agent in preclinical animal models of TBI. A total of 48 studies were included for review: 29 evaluated brain edema, 21 evaluated lesion size, and 0 studies reported the survival rate. In the meta-analysis, it was found that progesterone reduced brain edema (effect size - 1.73 [- 2.02, - 1.44], p < 0.0001) and lesion volume (effect size - 0.40 [- 0.65, - 0.14], p = 0.002). Lack of details in the studies hindered the assessment of risk of bias (through the SYRCLE tool). A funnel plot asymmetry was detected, suggesting a possible publication bias. In conclusion, preclinical studies show that progesterone has an anti-edema effect in animal models of TBI, decreasing lesion volume or increasing remaining tissue. However, more studies are needed using assessing methods with lower risk of histological artifacts.

FREQUÊNCIA DE TESTES RÁPIDOS POSITIVOS PARA SARS-COV-2 ENTRE DOADORES DE SANGUE

Introdução

A COVID-19 é síndrome respiratória aguda grave causada pelo Coronavírus SARS-CoV-2. Visando a segurança transfusional, novos critérios de triagem clínica foram estabelecidos considerando o risco de COVID-19 entre doadores.

Objetivo

Este estudo teve como objetivo avaliar a frequência de testes positivos para SARS-Cov-2 entre doadores de sangue considerados aptos para doar.

Métodos

Foi realizado um estudo transversal retrospectivo com amostras de soro de doadores de sangue, que doaram entre janeiro e março de 2021 no Banco de Sangue do Hospital de Clínicas de Porto Alegre. Essas amostras foram triadas para pesquisa de anticorpos IgG e IgM contra o epítopo RBD da proteína Spike do SARS-CoV-2 no Teste Rápido (TR) qualitativo Kit One Step COVID-2019 (CELER). Os dados foram compilados e analisados no sistema SPSS v. 18.

Resultados

Foram realizados TR para COVID-19 em 1837 amostras de soro, sendo que 245 apresentaram positividade, representando uma frequência de 13,3%. Dentre essas amostras positivas, 102 (41,63%) referiram não ter tido contato prévio com o Coronavírus nem serem vacinados. Por outro lado, 67 doadores (27,34%) com resultados positivos, informaram durante a triagem clínica estarem vacinados com a 1ª ou a 2ª dose contra o COVID-19, sendo que cerca de 37% dessas pessoas vacinadas já haviam apresentado diagnóstico prévio de COVID-19. Ainda entre os positivos, 18 doadores (7,3%) referiram ter tido COVID-19 há mais de 6 meses do ato da doação, enquanto que 68 (27,75%) apresentaram diagnóstico positivo há menos de 6 meses.

Conclusão

Os resultados encontrados demonstraram uma elevada taxa de positividade nos TR contra COVID-19 entre doadores de sangue. Fato que preocupa, é que uma parcela importante de doadores poderia estar assintomática no momento da doação, visto que a maior parte dos positivos afirmaram não ser vacinados e não ter tido contato prévio com o Coronavírus. Apesar da regulamentação acerca dos critérios para a triagem clínica dos doadores de sangue, a triagem laboratorial para COVID-19 não é obrigatória. Não há até o momento consenso na literatura quanto à transmissão transfusional do coronavírus. Desta forma, é necessário o acompanhamento dos pacientes que receberam hemocomponentes provenientes de doadores com testes positivos para SARS-CoV-2 a fim de comprovar ou descartar a transmissão de COVID-19 por transfusão sanguínea.

Behind teaching-learning strategies in physiology: perceptions of students and teachers of Brazilian medical courses

The teaching-learning process must constantly overcome the barriers imposed by rapid scientific and technological advances, as well as changes in the profiles of students and access to information. This study intended to analyze the perceptions of students and professors of medical courses of the teaching-learning strategies used in physiology at different Brazilian universities as well as the factors that influence or hinder the learning of this discipline. Questionnaires were analyzed from 174 students and 16 professors of physiology from medical courses of 20 higher education institutions (public and private) in a southern Brazilian state. The teaching strategies most used by physiology teachers coincided with the classroom activities that students consider to have the greatest contribution to their learning (expository classes/lectures, tests and questionnaires, problem-based learning/clinical case studies, and demonstrative/practical classes). It was also evidenced that teachers' didactic is considered as a very influencing factor for the students during their learning process, whereas the teachers pointed out daily pedagogical practice as the most relevant factor in the development of their skills within the classroom. In addition, some factors hindering the teaching-learning process of physiology were identified by the respondents, such as large amounts of information, little time for study outside the classroom, previous knowledge, and intrinsic difficulty of the discipline. Finally, students tended to study alone and generally used teachers' slides and their own notes as study materials. The continuous assessment of the perceptions, needs, and difficulties of students and teachers plays an essential role in improving the teaching-learning process.

Plants with Anti-Addictive Potential

Drug addiction is prevalent among individuals of modern society, being a major cause of disability and premature loss of life. Although the drug addiction have profound social, economical and health impact in the world population, its management remains a challenge as available pharmacological treatments remains ineffective for most people. The limited efficacy and adverse effects have led to a search for alternative therapies to treat drug addiction. In this context, natural products are an important source for new chemical substances with a potential therapeutic applicability. Therefore, this chapter will present data obtained after an extensive literature search regarding the use of medicinal plants as a pharmacological alternative for drug addiction treatment.

Resveratrol Derivatives as Potential Treatments for Alzheimer's and Parkinson's Disease

Neurodegenerative diseases are characterized by the progressive loss of neurons in different regions of the nervous system. Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the two most prevalent neurodegenerative diseases, and the symptoms associated with these pathologies are closely related to the regions that are most affected by the process of neurodegeneration. Despite their high prevalence, currently, there is no cure or disease-modifying drugs for the treatment of these conditions. In the last decades, due to the need for the development of new treatments for neurodegenerative diseases, several authors have investigated the neuroprotective actions of naturally occurring molecules, such as resveratrol. Resveratrol is a stilbene found in several plants, including grapes, blueberries, raspberries, and peanuts. Studies have shown that resveratrol presents neuroprotective actions in experimental models of AD and PD, however, its clinical application is limited due to its rapid metabolism and low bioavailability. In this context, studies have proposed that structural changes in the resveratrol molecule, including glycosylation, alkylation, halogenation, hydroxylation, methylation, and prenylation could lead to the development of derivatives with enhanced bioavailability and pharmacological activity. Therefore, this review article aims to discuss how resveratrol derivatives could represent viable molecules in the search for new drugs for the treatment of AD and PD.

Female rats are more susceptible to metabolic effects of dehydroepiandrosterone treatment

Dehydroepiandrosterone (DHEA) is a steroid hormone that presents several effects on metabolism; however, most of the studies have been performed on male animals, while few authors have investigated possible sex differences regarding the metabolic effects of DHEA. Therefore, the aim of this study was to evaluate the effect of different doses of DHEA on metabolic parameters of male and ovariectomized female Wistar rats. Sex differences were found in the metabolism of distinct substrates and in relation to the effect of DHEA. In respect to the glucose metabolism in the liver, the conversion of glucose to CO₂ and the synthesis of lipids from glucose were 53% and 33% higher, respectively, in males. Also, DHEA decreased hepatic lipogenesis only in females. Regarding the hepatic glycogen synthesis pathway, females presented 73% higher synthesis than males, and the effect of DHEA was observed only in females, where it decreased this parameter. In the adipose tissue, glucose uptake was 208% higher in females and DHEA decreased this parameter. In the muscle, glucose uptake was 168% higher in females and no DHEA effect was observed. In summary, males and females present a different metabolic profile, with females being more susceptible to the metabolic effects of DHEA.

Acute intraperitoneal administration of taurine decreases the glycemia and reduces food intake in type 1 diabetic rats

Taurine, an amino acid with antioxidant and osmoregulatory properties, has been studied for its possible antidiabetic properties in type 1 and type 2 diabetic animals. In type 2 diabetic mice, taurine decreases blood glucose through increased insulin secretion and insulin receptor sensitization. However, insulin is absent in type 1 diabetic individuals. The aim of this study was to evaluate the effects of taurine on parameters related to the energy balance that could explain the metabolic action of this amino acid in type 1 diabetic rats. Control and streptozotocin-induced diabetic rats received saline or taurine (100 mg/kg/day), intraperitoneally, for 30 days. Parameters such as palatable food intake, gastrointestinal transit rate, serum glucose, insulin, leptin, and glucagon levels were measured 60 min after the last taurine administration. Liver, kidneys, heart, and retroperitoneal fat were dissected and weighted. Glycogen levels were measured in the liver and soleus muscle. Our results showed that acute taurine administration decreased glycemia. It also decreased food intake in diabetic rats, without affecting other metabolic parameters. Altogether, our results suggest that in type 1 diabetic rats, taurine decreases blood glucose by a non-insulin-dependent mechanism. Due to the safety profile of taurine, and its effect on glycemia, this amino acid may help to design new drugs to add benefit to insulin therapy in type 1 diabetic individuals.

Diet-induced obesity alters memory consolidation in female rats

Obesity is a multifactorial disease characterized by the abnormal or excessive fat accumulation, which is caused by an energy imbalance between consumed and expended calories. Obesity leads to an inflammatory response that may result in peripheral and central metabolic changes, including insulin and leptin resistance. Insulin and leptin resistance have been associated with metabolic and cognitive dysfunctions. Obesity and some neurodegenerative diseases that lead to dementia affect mainly women. However, the effects of diet-induced obesity on memory consolidation in female rats are poorly understood. Therefore, the aim of this study was to evaluate the effect of a hypercaloric diet on the object recognition memory of female rats and on possible related metabolic changes. The animals submitted to the hypercaloric diet presented a higher food intake in grams and in calories, resulting in increased weight gain and liposomatic index in comparison with the animals exposed to the control diet. These animals presented a memory deficit in the object recognition test and increased serum levels of glucose and leptin. However, no significant differences were found in the serum levels of insulin, TNF-α and IL-1β, in the index of insulin resistance (HOMA), in the hippocampal levels of insulin, TNF-α and IL-1β, as well as on Akt expression or activation in the hippocampus. Our findings indicate that adult female rats submitted to a hypercaloric diet present memory consolidation impairment, which could be associated with diet-induced weight gain and leptin resistance, even without the development of insulin resistance.

Sex-specific effects of dehydroepiandrosterone (DHEA) on glucose metabolism in the CNS

DHEA is a neuroactive steroid, due to its modulatory actions on the central nervous system (CNS). DHEA is able to regulate neurogenesis, neurotransmitter receptors and neuronal excitability, function, survival and metabolism. The levels of DHEA decrease gradually with advancing age, and this decline has been associated with age related neuronal dysfunction and degeneration, suggesting a neuroprotective effect of endogenous DHEA. There are significant sex differences in the pathophysiology, epidemiology and clinical manifestations of many neurological diseases. The aim of this study was to determine whether DHEA can alter glucose metabolism in different structures of the CNS from male and female rats, and if this effect is sex-specific. The results showed that DHEA decreased glucose uptake in some structures (cerebral cortex and olfactory bulb) in males, but did not affect glucose uptake in females. When compared, glucose uptake in males was higher than females. DHEA enhanced the glucose oxidation in both males (cerebral cortex, olfactory bulb, hippocampus and hypothalamus) and females (cerebral cortex and olfactory bulb), in a sex-dependent manner. In males, DHEA did not affect synthesis of glycogen, however, glycogen content was increased in the cerebral cortex and olfactory bulb. DHEA modulates glucose metabolism in a tissue-, dose- and sex-dependent manner to increase glucose oxidation, which could explain the previously described neuroprotective role of this hormone in some neurodegenerative diseases.

4'-Chlorodiazepam is neuroprotective against amyloid-beta in organotypic hippocampal cultures

The translocator protein (TSPO) is an outer mitochondrial membrane protein involved in the transport of cholesterol into the mitochondria, which is the first step for the synthesis of steroid hormones, as well as in the regulation of mitochondrial permeability transition pore opening and apoptosis. Studies have shown that the activation of TSPO may promote neuroprotective actions in experimental models of neurodegeneration and brain injury. In a previous study, our group showed that 4'-chlorodiazepam (4'-CD), a TSPO ligand, was neuroprotective against amyloid-beta (Aβ) in SHSY-5Y neuroblastoma cells. The aim of this study was to evaluate if 4'-CD was also neuroprotective against Aβ in organotypic hippocampal cultures and to identify its mechanisms of action. Aβ decreased the cell viability of organotypic hippocampal cultures, while 4'-CD had a neuroprotective effect when administered at 100nM and 1000nM. The neuroprotective effects of 4'-CD against Aβ were associated with an increased expression of superoxide dismutase (SOD). No differences were found in the expression of catalase, glial fibrillary acidic protein, Akt and procaspase-3. In summary, our results show that 4'-CD is neuroprotective against Aβ by a mechanism involving the modulation of SOD protein expression.

4'-Chlorodiazepam modulates the development of primary hippocampal neurons in a sex-dependent manner

The translocator protein 18kDa (TSPO) is located in the outer mitochondrial membrane and is involved in the cholesterol transport into the mitochondria and in the regulation of steroidogenesis and other mitochondrial functions. It is known that steroid hormones, such as estradiol, testosterone and dihydrotestosterone are neuroprotective and regulate neuritogenesis in the CNS by different mechanisms. However, the developmental effects of TSPO ligands in the CNS are not known. Therefore, the aim of this study was to identify the developmental effects of 4'-chlorodiazepam (4'-CD), a TSPO ligand, in primary cultures of male and female mouse hippocampal neurons. We observed that female neurons showed an advanced neuritogenesis compared to male neurons after 2days in vitro. Moreover, it was shown that 4'-CD administration accelerated the maturation of male hippocampal neurons, without changing the development of female neurons. These findings, showing that 4'-CD modulates the development of hippocampal neurons in a sex-dependent manner, suggest that TSPO may be involved in the regulation of neuritogenesis.

Dehydroepiandrosterone protects male and female hippocampal neurons and neuroblastoma cells from glucose deprivation

Dehydroepiandrosterone (DHEA) modulates neurogenesis, neuronal function, neuronal survival and metabolism, enhancing mitochondrial oxidative capacity. Glucose deprivation and hypometabolism have been implicated in the mechanisms that mediate neuronal damage in neurological disorders, and some studies have shown that these mechanisms are sexually dimorphic. It was also demonstrated that DHEA is able to attenuate the hypometabolism that is related to some neurodegenerative diseases, eliciting neuroprotective effects in different experimental models of neurodegeneration. The aim of this study was to evaluate the effect of DHEA on the viability of male and female hippocampal neurons and SH-SY5Y neuroblastoma cells exposed to glucose deprivation. It was observed that after 12h of pre-treatment, DHEA was able to protect SH-SY5Y cells from glucose deprivation for 6h (DHEA 10(-12), 10(-8) and 10(-6)M) and 8h (DHEA 10(-8)M). In contrast, DHEA was not neuroprotective against glucose deprivation for 12 or 24h. DHEA (10(-8)M) also protected SH-SY5Y cells when added together or even 1h after the beginning of glucose deprivation (6h). Furthermore, DHEA (10(-8)M) also protected primary neurons from both sexes against glucose deprivation. In summary, our findings indicate that DHEA is neuroprotective against glucose deprivation in human neuroblastoma cells and in male and female mouse hippocampal neurons. These results suggest that DHEA could be a promising candidate to be used in clinical studies aiming to reduce neuronal damage in people from both sexes.

4'-Chlorodiazepam is neuroprotective against amyloid-beta through the modulation of survivin and bax protein expression in vitro

The translocator protein of 18kDa (TSPO) is located in the outer mitochondrial membrane and is involved in the cholesterol transport into the mitochondria and in the regulation of steroidogenesis, mitochondrial permeability transition pore opening and apoptosis. TSPO ligands have been investigated as therapeutic agents that promote neuroprotective effects in experimental models of brain injury and neurodegenerative diseases. The aim of this study was to identify the neuroprotective effects of 4'-chlorodiazepam (4'-CD), a ligand of TSPO, against amyloid-beta (Aβ) in SHSY-5Y neuroblastoma cells and its mechanisms of action. Aβ decreased the viability of SHSY-5Y neuroblastoma cells, while 4'-CD had a neuroprotective effect at the doses of 1nM and 10nM. The neuroprotective effects of 4'-CD against Aβ were associated with the inhibition of Aβ-induced upregulation of Bax and downregulation of survivin. In summary, our findings indicate that 4'-CD is neuroprotective against Aβ-induced neurotoxicity by a mechanism that may involve the regulation of Bax and survivin expression.

Therapeutic actions of translocator protein (18 kDa) ligands in experimental models of psychiatric disorders and neurodegenerative diseases

Translocator protein (TSPO) is an 18kDa protein located at contact sites between the outer and the inner mitochondrial membrane. Numerous studies have associated TSPO with the translocation of cholesterol across the aqueous mitochondrial intermembrane space and the regulation of steroidogenesis, as well as with the control of some other mitochondrial functions, such as mitochondrial respiration, mitochondrial permeability transition pore opening, apoptosis and cell proliferation. In the brain, changes in TSPO expression occur in several neuropathological conditions including neurodegenerative diseases and psychiatric disorders. Furthermore, TSPO ligands have been shown to promote neuroprotection in animal models of brain pathology. At least in some cases, the mechanisms of neuroprotection are associated with modifications in brain steroidogenesis. In addition, regulation of neuroinflammation seems to be a common mechanism in the neuroprotective actions of TSPO ligands in different animal models of brain pathology.

Sex-related differences in the effects of high-fat diets on DHEA-treated rats

Several studies have investigated the beneficial effects of dehydroepiandrosterone (DHEA) on lipid and glucose metabolism. However, many of these studies are inconclusive about the effects of DHEA administration on metabolic disorders, and there appear to be sex-related differences in the effects of DHEA treatment. Few animal studies have addressed the effects of DHEA on diet-induced metabolic disorders. The present study sought to ascertain whether sex differences exist in the effects of a high-fat diet (HFD) on weight gain, adiposity, and biochemical and hormonal parameters in DHEA-treated rats. Rats were fed a HFD for 4 weeks and simultaneously received treatment with DHEA (10 mg/kg by subcutaneous injection) once weekly. Body weight, retroperitoneal fat depot weight, serum glucose, insulin, and leptin levels, and hepatic lipids were measured. HFD exposure increased the adiposity index in both sexes, the hepatic triglyceride content in both sexes, and the hepatic total cholesterol level in males. Moreover, the HFD induced an increase in blood glucose levels in both sexes, and hyperinsulinemia in males. In this experimental model, DHEA treatment reduced hepatic triglyceride levels only in females, regardless of HFD exposure. Exposure to a HFD, even if it does not cause obesity, may enhance risk factors for metabolic disorders, and males are more sensitive to this effect. DHEA treatment can help prevent metabolic derangements, but its effect varies with sex.