Maqui berry (Aristotelia chilensis) extract improves memory and decreases oxidative stress in male rat brain exposed to ozone.

Introduction: Prolonged ozone exposure can produce a state of oxidative stress, which in turn causes alterations in the dynamics of the brain and affects memory and learning. Moreover, different investigations have shown that high flavonoid content berries show a great antioxidant activity. The relationship between the protective effect of the maqui berry extract and its antioxidant properties in the brain has not been studied in depth. Objectives: The present study evaluated whether the protection exerted by the aqueous extract of maqui berry in brain regions associated with cognitive performance is due to its antioxidant capacity. Methods: Sprague Dawley rats were exposed to 0.25 ppm ozone and administered with maqui berry extracts. At the end of the treatments, spatial learning and short- and long-term memory were evaluated, as well as oxidative stress markers. Results: The administration of 50 and 100 mg/kg of the aqueous extract of maqui berry was effective in preventing the cognitive deficit caused by chronic exposure to ozone. The antioxidant effect of the administration of maqui berry was analyzed in the prefrontal cortex, hippocampus, and amygdala. Oxidative stress markers levels decreased and the enzymatic activity of superoxide dismutase diminished in animals exposed to ozone treated with the 50 mg/kg dose of maqui berry. Discussion: These results show a relationship between protection at the cognitive level and a decrease in oxidative stress markers, which suggests that the prevention of cognitive damage is due to the antioxidant activity of the maqui berry.

Tibolone regulates systemic metabolism and the expression of sex hormone receptors in the central nervous system of ovariectomised rats fed with high-fat and high-fructose diet.

Estrogen replacement therapy decreases some risk factors of the metabolic syndrome but increases the risk of some types of cancer. Tibolone (TIB) has shown similar neuroprotective effects as estrogens. This study aimed to evaluate the effects of TIB on metabolic parameters and the expression of sex hormone receptors in the CNS in ovariectomised rats fed with a hypercaloric diet. Sprague-Dawley female rats were ovariectomised and fed for 30 days with a standard diet (SD) or high-fat high-fructose diet (HFFD) and treated with TIB (1 mg/kg) or vehicle. At the end of the treatments, HFFD increased body weight, glucose tolerance, triglycerides and cholesterol levels, while TIB treatment decreased these parameters. Subsequently, the hippocampus, the hypothalamus and the frontal cortex were dissected. RT-PCR was performed for progesterone receptor (PR), androgen receptor (AR), estrogen receptors alpha and beta (ERα, ERß), insulin receptor (IR) and insulin-like growth factor 1 (IGF-1). HFFD altered the expression of sex hormone receptors in specific brain structures involved in the regulation of homeostasis and cognition, which highlights the importance of a healthy diet. In turn, TIB modulated the expression of these receptors, particularly in the hypothalamus.

Electroacupuncture Reduces Seizure Activity and Enhances GAD 67 and Glutamate Transporter Expression in Kainic Acid Induced Status Epilepticus in Infant Rats.

Status epilepticus (SE) is one of the most significant complications in pediatric neurology. Clinical studies have shown positive effects of electroacupuncture (EA) as a therapeutic alternative in the control of partial seizures and secondary generalized clonic seizures. EA promotes the release of neurotransmitters such as GABA and some opioids. The present study aimed to evaluate the anticonvulsive and neuromodulatory effects of Shui Gou DM26 (SG_DM26) acupuncture point electrostimulation on the expression of the glutamate decarboxylase 67 (GAD67) enzyme and the glutamate transporter EAAC1 in an early SE model. At ten postnatal days (10-PD), male rats weighing 22-26 g were divided into 16 groups, including control and treatment groups: Simple stimulation, electrostimulation, anticonvulsant drug treatment, and combined treatment-electrostimulation and pentobarbital (PB). SE was induced with kainic acid (KA), and the following parameters were measured: Motor behavior, and expression of GAD67 and EAAC1. The results suggest an antiepileptic effect derived from SG DM26 point EA. The possible mechanism is most likely the increased production of the inhibitory neurotransmitter GABA, which is observed as an increase in the expression of both GAD67 and EAAC1, as well as the potential synergy between the neuromodulator effects of EA and PB.

The Importance of Natural Antioxidants in the Treatment of Spinal Cord Injury in Animal Models: An Overview.

Patients with spinal cord injury (SCI) face devastating health, social, and financial consequences, as well as their families and caregivers. Reducing the levels of reactive oxygen species (ROS) and oxidative stress are essential strategies for SCI treatment. Some compounds from traditional medicine could be useful to decrease ROS generated after SCI. This review is aimed at highlighting the importance of some natural compounds with antioxidant capacity used in traditional medicine to treat traumatic SCI. An electronic search of published articles describing animal models of SCI treated with natural compounds from traditional medicine was conducted using the following terms: Spinal Cord Injuries (MeSH terms) AND Models, Animal (MeSH terms) AND [Reactive Oxygen Species (MeSH terms) AND/OR Oxidative Stress (MeSH term)] AND Medicine, Traditional (MeSH terms). Articles reported from 2010 to 2018 were included. The results were further screened by title and abstract for studies performed in rats, mice, and nonhuman primates. The effects of these natural compounds are discussed, including their antioxidant, anti-inflammatory, and antiapoptotic properties. Moreover, the antioxidant properties of natural compounds were emphasized since oxidative stress has a fundamental role in the generation and progression of several pathologies of the nervous system. The use of these compounds diminishes toxic effects due to their high antioxidant capacity. These compounds have been tested in animal models with promising results; however, no clinical studies have been conducted in humans. Further research of these natural compounds is crucial to a better understanding of their effects in patients with SCI.

Neuroprotective effects of tibolone against oxidative stress induced by ozone exposure.

INTRODUCTION: Oxidative stress increases brain lipid peroxidation, memory and motor deficits and progressive neurodegeneration. Tibolone, a treatment for menopausal symptoms, decreases lipid peroxidation levels and improves memory and learning. AIM: To study the effect of chronic administration of tibolone on lipid peroxidation, memory and motor deficits in ozone induced oxidative stress. MATERIALS AND METHODS: 100 male Wistar adult rats were randomly divided into 10 experimental groups: control (C) was exposed to an airstream for 60 days; C + tibolone, airstream exposure plus 1 mg/kg of tibolone for 60 days; groups 3-6 were exposed to ozone for 7, 15, 30, and 60 days, and groups 7-10 received 1 mg/kg of tibolone treatment by oral gavage for 7, 15, 30 and 60 days and were then exposed to ozone. We determined the effect of tibolone on memory and motor activity. Hippocampus was processed to determine the content of 4-hydroxynonenal and nitrotyrosine by Western blot. Four animals were perfused and processed for analysis of neuronal death. RESULTS: In the hippocampus, administration of 1 mg/kg of tibolone for 30 days prevented increased levels of lipid peroxidation and protein oxidation, whereas after 60 days prevented neuronal death in the CA3 region caused by exposure to ozone. Therefore, tibolone prevents cognitive deficits in short- and long-term memory on the passive avoidance task and prevents a decrease in exploratory behavior and an increase in freezing behavior. CONCLUSION: Our results indicate a possible neuroprotective role of tibolone as a useful treatment to prevent oxidative stress neurodegeneration.

TITLE: Efecto neuroprotector de la tibolona contra el estres oxidativo inducido por la exposicion a ozono.Introduccion. El estres oxidativo aumenta la lipoperoxidacion, produce deficits de memoria y de actividad motora asi como una neurodegeneracion progresiva en el sistema nervioso central. La tibolona es un tratamiento para los sintomas de la menopausia que disminuye los niveles de peroxidacion de lipidos y mejora la memoria y el aprendizaje. Objetivo. Estudiar el efecto de la tibolona sobre la peroxidacion de lipidos, los deficits de memoria y motor en el modelo de estres oxidativo inducido por la exposicion cronica al ozono. Materiales y metodos. Se dividieron aleatoriamente 100 ratas adultas Wistar en 10 grupos: control (C), que recibio aire durante 60 dias; (C + tibolona), aire mas 1 mg/kg de tibolona durante 60 dias; los grupos 3-6, ozono durante 7, 15, 30, y 60 dias; y los grupos 7-10, 1 mg/kg de tibolona durante 7, 15, 30 y 60 dias previo a la exposicion al ozono. Se realizaron pruebas de memoria y motoras y se determino el contenido del 4-hidroxinonenal y de la nitrotirosina por Western blot, asi como la muerte neuronal en el hipocampo. Resultados. La administracion de tibolona disminuyo el contenido de lipidos peroxidados, la oxidacion de proteinas y la muerte neuronal en el hipocampo; mejoro la memoria y previno las alteraciones motoras en los animales expuestos a ozono. Conclusion. Nuestros resultados indican un posible papel neuroprotector de la tibolona como un tratamiento util para prevenir la neurodegeneracion inducida por el estres oxidativo.

Progesterone receptor isoforms differentially regulate the expression of tryptophan and tyrosine hydroxylase and glutamic acid decarboxylase in the rat hypothalamus.

Progesterone exerts a variety of actions in the brain through the interaction with its receptors (PR) which have two isoforms with different function and regulation: PR-A and PR-B. Progesterone may modulate neurotransmission by regulating the expression of neurotransmitters synthesizing enzymes or their receptors in several brain regions. The role of PR isoforms in this modulation is unknown. We explored the role of PR isoforms in the regulation of tryptophan (TPH) and tyrosine (TH) hydroxylase, and glutamic acid decarboxylase (GAD) expression in the hypothalamus of ovariectomized rats. Two weeks after ovariectomy, animals were subcutaneously injected with 5 µg of estradiol benzoate (EB), and 40 h later, progesterone (P) was intracerebroventricularly (ICV) injected. Each animal received two ICV injections of 1 µg/µl (4 nmol) of PR-B and total PR (PR-A+PR-B) sense or antisense (As) oligonucleotides (ODNs). First injection was made immediately before sc EB injection, and 24h later animals received the second one. Twenty-four hours after P administration, rats were euthanized and brains removed to measure the expression of PR-A and PR-B, TPH, TH and GAD by Western blot. We observed that sense ODNs modified neither PR isoforms nor enzymes expression in the hypothalamus, whereas PR A+B antisense (PR A+B As) clearly decreased the expression of both PR isoforms in this region. ICV administration of PR-B As only decreased PR-B isoform expression with no significant effects on PR-A expression. A differential protein expression of TPH, TH and GAD was observed after PR isoforms antisense administration. PR-B As administration decreased the expression of TPH (65% with respect to control). In contrast, PR A+B As and PR-B As administration increased (51.6% and 34.4%, respectively) TH expression. The administration of PR A+B As and PR-B As diminished GAD expression (33.4% and 41.6%, respectively). Our findings indicate that PR isoforms play a differential role in the regulation of the content of TPH, TH and GAD in the rat hypothalamus.

Role of progesterone receptor isoforms in female sexual behavior induced by progestins in rats.

Progesterone and its ring A reduced metabolites regulate female sexual behavior through the direct or indirect activation of progesterone receptor (PR) which has two isoforms with different function and regulation: PR-A and PR-B. The contribution of each PR isoform to the regulation of lordosis in rats is unknown. We explored the role of PR isoforms in lordosis display induced by progesterone and two of its ring A reduced metabolites: 5alpha-pregnan-3,20-dione (5alpha-DHP), and 5beta,3beta-pregnan-20-one (5beta,3beta-Pgl) in adult ovariectomized rats. Two weeks after ovariectomy, the animals were injected subcutaneously with 5 microg of estradiol benzoate (EB), and 40 h later, progestins were injected intracerebroventricularly. PR-B and total PR (PR-A + PR-B) sense or antisense oligonucleotides were administered intracerebroventricularly immediately before EB injection and 24 h later. Lordosis was evaluated 30, 120 and 240 min after progestin administration. Western blot analysis of both PR isoforms was performed in the hypothalamus and preoptic area 24 h after lordosis tests. All progestins induced maximal lordosis 120 min after administration, and antisense oligonucleotides against both PR isoforms inhibited lordosis in all animals. PR-B antisense oligonucleotides also inhibited lordosis induced by progesterone and 5alpha-DHP although with less efficacy than total PR antisense oligonucleotides, but the former inhibited lordosis induced by 5beta,3beta-Pgl in a similar manner as total PR antisense oligonucleotides. In the hypothalamus and preoptic area, the content of both PR isoforms or PR-B alone was diminished by the administration of total or PR-B antisense oligonucleotides, respectively. These results suggest that the PR-B isoform is essential for the display of the lordosis behavior in rats.

Biotin deficiency and biotin excess: effects on the female reproductive system.

Biotin deficiency and biotin excess have both been found to affect reproduction and cause teratogenic effects. In the reproductive tract, however, the effects of biotin have not been well established yet. We investigated the effects of varying biotin content diets on the oestrus cycle, ovarian morphology, estradiol and progesterone serum levels, and the uterine mRNA abundance of their nuclear receptors, as well as on the activity of the estradiol-degrading group of enzymes cytochrome P450 (CYP) in the liver. Three-week-old female BALB/cAnN Hsd mice were fed a biotin-deficient, a biotin-control, or a biotin-supplemented diet (0, 7.2 or 400 micromol of free biotin/kg diet, respectively) over a period of nine weeks. Striking effects were observed in the biotin-deficient group: mice showed arrested estrous cycle on the day of diestrus and changes in ovary morphology. Estradiol serum concentration increased 49.2% in biotin-deficient mice compared to the control group, while the enzymatic activities of CYP1A2 and CYP2B2 increased (P<0.05). The mRNA abundance of nuclear estrogen and progesterone receptors decreased in the biotin-deficient mice. In the biotin-supplemented group we found that, in spite of a significant (P<0.05) decrease in the number of primary and Graafian follicles and in CYP1A2 activities, mice exhibited 105.4% higher serum estradiol concentration than the control group. No changes in the expression of the nuclear receptors were observed. No significant differences were observed in serum progesterone among the groups. Our results indicate that both the deficiency and the excess of biotin have significant effects on the female mouse reproductive system.

Effects of progesterone and its reduced metabolites, dihydroprogesterone and tetrahydroprogesterone, on the expression and phosphorylation of glycogen synthase kinase-3 and the microtubule-associated protein tau in the rat cerebellum.

Progesterone exerts a variety of actions in the brain, where it is rapidly metabolized to 5alpha-dihydroprogesterone (DHP) and 3alpha,5alpha-tetrahydroprogesterone (THP). The effect of progesterone and its metabolites on the expression and phosphorylation of the microtubule-associated protein Tau and glycogen synthase kinase 3beta (GSK3beta), a kinase involved in Tau phosphorylation, were assessed in two progesterone-sensitive brain areas: the hypothalamus and the cerebellum. Administration of progesterone, DHP, and THP to ovariectomized rats did not affect Tau and GSK3beta assessed in whole hypothalamic homogenates. In contrast, progesterone and its metabolites resulted in a significant decrease in the expression of Tau and GSK3beta in the cerebellum. Furthermore, progesterone administration resulted in an increase in the phosphorylation of two epitopes of Tau (Tau-1 and PHF-1) phosphorylated by GSK3beta, but did not affect the phosphorylation of an epitope of Tau (Ser262) that is GSK3beta insensitive. These effects were accompanied by a decrease in the phosphorylation of GSK3beta in serine, which is associated to an increase in its activity, suggesting that the effect of progesterone on Tau-1 and PHF-1 phosphorylation in the cerebellum is mediated by GSK3beta. The regulation of Tau expression and phosphorylation by progesterone may contribute to the hormonal regulation of cerebellar function by the modification of neuronal cytoskeleton.

Changes in the content of steroid receptor coactivator-1 and silencing mediator for retinoid and thyroid hormone receptors in the rat brain during the estrous cycle.

In this work, we determined the variations in the content of the steroid receptor coactivator (SRC-1) and the silencing mediator for retinoic acid and thyroid hormone receptors corepressor (SMRT) in the hypothalamus, the preoptic area, and the hippocampus of adult intact rats during the estrous cycle by Western blot. SRC-1 content changed only in the hypothalamus where its lowest content was found on diestrus day with a significant increase at proestrus. This increase was maintained on estrus day. In contrast, SMRT content changed only in the preoptic area where it diminished at metestrus in comparison with the other days of the cycle. SRC-1 content was higher than that of SMRT in the hypothalamus throughout the estrous cycle, whereas SMRT content was higher in the preoptic area. In the hippocampus, there were no significant differences in the content of any cofactor. These results demonstrate that SRC-1 and SMRT content change in a tissue-specific manner in the rat brain during the estrous cycle, and suggest that the transcriptional activity of steroid hormone receptors in the rat brain in physiological conditions is regulated by changes in SRC-1 and SMRT content.

The 26S proteasome participates in the sequential inhibition of estrous behavior induced by progesterone in rats.

Estrous behavior induced by progesterone (P) treatment of estradiol-primed rats is followed by a period in which females do not respond behaviorally to a second administration of P [sequential inhibition (SI)]. SI is thought to involve P-dependent down-regulation of hypothalamic P receptor (PR) content. This study tested the hypothesis that the 26S proteasome participates in the regulation of SI and brain PR content in female rats. Ovariectomized, estrogen-primed (estradiol benzoate, 2 microg s.c.) adult rats were injected with P (1 mg s.c.) alone or P with the proteasome inhibitors Z-Ile-Glu (OBu(1))-Ala-Leu-H (PSI, 300 microg/100 g s.c.) or N alpha-tosyl-lysyl chloromethyl ketone (TLCK, 200 microg i.p.) administered 48 h after estradiol priming. Sexual behavior was assessed in all animals 4 h later. These two agents inhibit 26S proteasome-mediated protein degradation by different mechanisms. To explore SI, the animals received a second P injection 24 h after the first, and a second sexual behavior test was performed 4 h later. After this test, brains were excised, and proteins were extracted from the preoptic area and the hypothalamus and processed for semiquantitative immunoblotting. In the first sexual behavior test (facilitation test), all animals treated with estradiol + P exhibited intense lordosis behavior. In the second sexual behavior test (inhibition test), both lordosis and proceptivity were significantly reduced in response to the second administration of P (SI). The magnitude of SI was significantly attenuated by the administration of either PSI or TLCK concurrently with the first P injection. The first P injection reduced PR content in the hypothalamus but not in the preoptic area. In contrast, PSI and TLCK significantly increased PR content in both structures. Our results suggest that PR degradation by the 26S proteasome participates in the expression of P-induced SI in female rats.