Influence of sexual hormones on Chagas disease / Influencia de las hormonas sexuales en la enfermedad de Chagas

Abstract Objective: Analyze sex hormone's influence during Chagas disease. Methods: Male and female BALB/c mice were divided into six groups, four experimental (sham, orchiectomized, orchiectomized and supplemented with estradiol, orchiectomized supplemented with testosterone, oophorectomized, oophorectomized and supplemented with estradiol, and oophorectomized and supplemented with testosterone), and two control (healthy and intraperitoneally with T. cruzi strain NINOA infected). Clinical data were recorded daily, parasitemia was evaluated using a Neubauer chamber during the infection, and heart histopathological analysis was performed using the paraffin embedding technique. To analyze parasitemia curves and the area under the parametric curves, two-way ANOVA test was performed to correlate groups' data. P-values < 0.05 were considered statistically significant. Results: Higher mortality rates, cardiomegaly, hepatomegaly, ascites, edema, higher parasitemia levels, more amastigote nests, and more severe inflammatory infiltrate were found in higher testosterone concentration mice, whereas in higher estradiol concentration groups, paresia, prostration, edema, and necrosis were found. Conclusions: Our results showed that testosterone increased infection severity, whereas estradiol had the opposite effect. This research improves the understanding of sex hormones´ infuence upon this infection to contribute with the handling of Chagas´ disease.

Resumen Objetivo: Analizar la influencia de las hormonas durante la enfermedad de Chagas. Métodos: Se separaron grupos de ratones macho y hembras BALB/c, todos infectados con T. cruzi (cepa NINOA), 4 grupos experimentales de machos (Sham, orquidectamizados, orquidectimezados y suplementados con estradiol, orquidectamizaos y suplementados con testosterona). 4 grupos experimentales de hembras (oforectomizadas, oforectomizadas y suplementadas con estradiol, oforectomizadas y suplementadas con testosterona y sham), and y dos grupos control para cada sexo (sin infección e infectados intraperitonealmente con T. cruzi (cepa NINOA). Los datos clínicos fueron registrados diariamente, la parasitemia fue evaluada durante toda la infección utilizando una cámara de Neubauer y el análisis histopatológico del corazón fue realizada con la técnica de inclusión en parafina. Para el análisis de las curvas de parasitemia y el área bajo la curva, se realizó una prueba de ANOVA de dos vías, p < 0.05 fueron considerados estadísticamente diferentes. Resultados: Las mayores tasas de mortalidad, cardiomegalia, hepatomegalia y mayor infiltrado inflamatorio, se encontró en los ratones con una mayor concentración de testosterona. En contraste los ratones con mayor concentración de estradiol presentaron paresia, postración edema y necrosis. Conclusiones: Nuestros resultados ponen en manifiesto que la testosterona incrementa la severidad del curso de la enfermedad de Chagas, mientras que el estradiol tuvo el efecto opuesto. Este trabajo mejora el entendimiento del rol que juegan las hormonas sexuales en esta infección para contribuir en un mejor manejo de la enfermedad de Chagas.

Influence of sexual hormones on Chagas disease.

OBJECTIVE: Analyze sex hormone's influence during Chagas´ Disease. METHODS: Male and female BALB/c mice were divided into six groups, four experimental (sham, orchiectomized, orchiectomized and supplemented with estradiol, orchiectomized supplemented with testosterone, oophorectomized, oophorectomized and supplemented with estradiol, and oophorectomized and supplemented with testosterone), and two control (healthy and intraperitoneally with T. cruzi strain NINOA infected). Clinical data were recorded daily, parasitemia was evaluated using a Neubauer chamber during the infection, and heart histopathological analysis was performed using the paraffin embedding technique. To analyze parasitemia curves and the area under the parametric curves, two-way ANOVA test was performed to correlate groups´ data. P-values <0.05 were considered statistically significant. RESULTS: Higher mortality rates, cardiomegaly, hepatomegaly, ascites, edema, higher parasitemia levels, more amastigote nests, and more severe inflammatory infiltrate were found in higher testosterone concentration mice, whereas in higher estradiol concentration groups, paresia, prostration, edema, and necrosis were found. CONCLUSIONS: Our results showed that testosterone increased infection severity, whereas estradiol had the opposite effect. This research improves the understanding of sex hormones´infuence upon this infection to contribute with the handling of Chagas´disease.

Effect of Systemic Inflammation in the CNS: A Silent History of Neuronal Damage.

Central nervous system (CNS) infections including meningitis and encephalitis, resulting from the blood-borne spread of specific microorganisms, provoke nervous tissue damage due to the inflammatory process. Moreover, different pathologies such as sepsis can generate systemic inflammation. Bacterial lipopolysaccharide (LPS) induces the release of inflammatory mediators and damage molecules, which are then released into the bloodstream and can interact with structures such as the CNS, thus modifying the blood-brain barrier's (BBB´s) and blood-cerebrospinal fluid barrier´s (BCSFB´s) function and inducing aseptic neuroinflammation. During neuroinflammation, the participation of glial cells (astrocytes, microglia, and oligodendrocytes) plays an important role. They release cytokines, chemokines, reactive oxygen species, nitrogen species, peptides, and even excitatory amino acids that lead to neuronal damage. The neurons undergo morphological and functional changes that could initiate functional alterations to neurodegenerative processes. The present work aims to explain these processes and the pathophysiological interactions involved in CNS damage in the absence of microbes or inflammatory cells.

Influencia de la inoculación oral en la enfermedad de Chagas en modelo murino / Oral inoculation influence on Chagas disease in a murine model

Resumen: Objetivo: Determinar el comportamiento de la enfermedad de Chagas, comparando la vía de inoculación intraperitoneal (i.p.) y la vía oral (v.o.), mediante la ingestión alimentos infectados con Trypanosoma cruzi (T. cruzi). Materiales y métodos: En modelo murino, se comparó la parasitemia en la infección adquirida vía i.p. y vía oral Se formaron dos grupos que fueron inoculados con la cepa NINOA de T. cruzi (3x103); uno se administró v.o. y otro, se administró vía i.p. Además, se realizó un estudio histopatológico del tejido cardiaco de los individuos. Finalmente, se determinó y comparó la respuesta inmune montada como resultado de la inoculación por ambas vías, evaluando la concentración de IgG séricas contra T. cruzi mediante la realización de una ELISA casera. Resultados: El comportamiento de la infección fue diferente en ambas vías de inoculación. A través de los métodos parasitoscópicos e histopatológicos empleados, no fue detectable la infección en aquellos individuos infectados vía oral, interesantemente, la infección sí fue detectable mediante métodos inmunológicos. Aquellos individuos infectados vía oral empleando açaí, tuvieron un comportamiento inmune similar al presentado por aquellos inoculados vía i.p. Conclusiones: El presente estudio demuestra que la vía de infección del hospedero es determinante para la evolución de la enfermedad. Este trabajo proporciona evidencia para que en la práctica clínica, se realice a los individuos más de una prueba diagnóstica, hecho que, ayudará a un mejor manejo de la enfermedad de Chagas.

Abstract: Objective: Determine the behavior of Chagas's disease, comparing the intraperitoneal (i.p.), and the oral (v.o.) administration routes, by the ingestion of T. cruzi-contaminated food. Materials and methods: In mice, parasitemia oral and intraperitoneal acquiring routes were compared. Two groups were inoculated with T. cruzi (3x103) NINOA strain: one orally, and another intraperitoneally. Additionally, a hearth tissue histopathologic analysis was performed. Finally, the immune response triggered by both inoculation routes was determined by a homemade ELISA and compared. Results: The infection behavior was different in each inoculation route. In the orally infected group, infection was undetectable by parasitological, and histopathologic methods; interestingly, infection was detected by immune methods. Orally infected individuals using acai behaved similarly to intraperitoneally inoculated ones. Discussion: The vector and hosts close coexistence promote several infection routes. To improve the diagnosis, disease's course variants knowledge is needed. Conclusion: This study shows that the infection route strongly influences Chagas's disease course. Moreover, this work provides evidence that support the fact of doing more than one diagnostic test, improving the disease management.

Arthrospira maxima Paradoxical Effect on Trypanosoma cruzi Infection.

BACKGROUND: There are only two anti-trypanocidal drugs available, both have a lot of side effects. This is the pioneer study designed to evaluate the Arthrospira maxima effect in Trypanosoma cruzi -infected mice and macrophages. METHODS: A. maxima was administered in vivo, and in vitro (120µL/mL; 200 µL/mL; 500 µL/mL; 852 µL/mL) as prophylaxis, and treatment. In vitro, phagocytosis and viability were measured in macrophages cultures supplemented with A. maxima, and T. cruzi-infected. In vivo A. maxima was supplemented to T. cruzi-infected mice in order to obtain the parasitemia curves, parasite amount, and histopathologic changes. This assay was performed in Biological Sciences National School of National Polytechnic Institute, Mexico City, in 2019. RESULTS: In vivo, A. maxima administration exacerbates the immune innate host's response, followed by mice early death. In vitro, A. maxima supplementation promote T. cruzi- macrophage phagocytosis, but also a sooner T. cruzi- infected macrophage death. CONCLUSION: A. maxima administration overactive the immune system, decreasing the parasitemia, but causing a severe tissue damage. Then, this nutraceutical has a paradoxical effect on intracellular parasitic infections such as Chagas disease.

Hypothyroid offspring replacement with euthyroid wet nurses during lactation improves thyroid programming without modifying metabolic programming

ABSTRACT Objective Determine the milk quality effect during lactation on the metabolic and thyroid programming of hypothyroid offspring. Materials and methods Ten-week-old female Wistar rats were divided into two groups: euthyroid and thyroidectomy-caused hypothyroidism. The rats were matted and, one day after birth, the pups were divided into three groups: euthyroid offspring (EO), hypothyroid offspring (HO) and hypothyroid with a euthyroid replacement wet nurse (HRO). During lactation, the milk quality and offspring body length were evaluated. The body weight and energy intake were determined on a weekly basis, as well as the metabolic profile at the prepubertal (P35-36) and postpubertal (P55-56) ages. At P56, the animals were sacrificed, the adipose tissues were weighed and the thyroid glands were dissected for histological processing. Results The milk of the hypothyroid wet nurse decreases proteins (16-26%), lipids (22-29%) and lactate (22-37%) with respect to euthyroid. The HO has a lower body weight gain (23-33%), length (11-13%) and energy intake (15-21%). In addition, HO presents impaired fasting glucose and dyslipidemia, as well as a reduction in seric thyroid hormone (18-34%), adipose reserves (26-68%) and thyroid gland weight (25-34%). The HO present thyroid gland cytoarchitecture alteration. The HRO develop the same metabolic alterations as the HO. However, the thyroid gland dysfunction was partially prevented because the HRO improved under about 10% of the serum thyroid hormone concentration, the thyroid gland weight although histological glandular changes presented. Conclusions The replacement of hypothyroid offspring with a euthyroid wet nurse during lactation can improve the thyroid programming without modifying metabolic programming.

Hypothyroid offspring replacement with euthyroid wet nurses during lactation improves thyroid programming without modifying metabolic programming.

OBJECTIVE: Determine the milk quality effect during lactation on the metabolic and thyroid programming of hypothyroid offspring. MATERIALS AND METHODS: Ten-week-old female Wistar rats were divided into two groups: euthyroid and thyroidectomy-caused hypothyroidism. The rats were matted and, one day after birth, the pups were divided into three groups: euthyroid offspring (EO), hypothyroid offspring (HO) and hypothyroid with a euthyroid replacement wet nurse (HRO). During lactation, the milk quality and offspring body length were evaluated. The body weight and energy intake were determined on a weekly basis, as well as the metabolic profile at the prepubertal (P35-36) and postpubertal (P55-56) ages. At P56, the animals were sacrificed, the adipose tissues were weighed and the thyroid glands were dissected for histological processing. RESULTS: The milk of the hypothyroid wet nurse decreases proteins (16-26%), lipids (22-29%) and lactate (22-37%) with respect to euthyroid. The HO has a lower body weight gain (23-33%), length (11-13%) and energy intake (15-21%). In addition, HO presents impaired fasting glucose and dyslipidemia, as well as a reduction in seric thyroid hormone (18-34%), adipose reserves (26-68%) and thyroid gland weight (25-34%). The HO present thyroid gland cytoarchitecture alteration. The HRO develop the same metabolic alterations as the HO. However, the thyroid gland dysfunction was partially prevented because the HRO improved under about 10% of the serum thyroid hormone concentration, the thyroid gland weight although histological glandular changes presented. CONCLUSIONS: The replacement of hypothyroid offspring with a euthyroid wet nurse during lactation can improve the thyroid programming without modifying metabolic programming.

Cell proliferation and inhibition of apoptosis are related to c-Kit activation in leukaemic lymphoblasts.

Receptor tyrosine kinase (RTK) activity may contribute to carcinogenesis. The c-Kit receptor, a member of the RTK family, is expressed in immature haematopoietic system cells. Acute lymphoblastic leukaemia (ALL) presents incompletely differentiated lymphoblasts, and consequently, c-Kit expression can be detected in these cells. The BCR-ABL kinase, which is usually present in both ALL and chronic myeloid leukaemia, can trigger signalling pathways with neoplastic effects. However, a certain number of ALL patients and chronic myeloid leukaemia patients do not express this kinase, raising the question of which other proteins that intervene in signalling pathways may be involved in the development of these diseases. OBJECTIVES: To test whether c-Kit has proliferative effects and affects the inhibition of apoptosis of leukaemic lymphoblasts that do not express BCR-ABL. METHODS: We cultured RS4:11 lymphoblasts and analysed the expression and activation of c-Kit by immunofluorescence, and flow cytometry, evaluation of cell proliferation, apoptosis, cyclin D1 and Bak expression were carried out by flow cytometry; activation of AKT and survivin expression were tested by immunoblot. RESULTS: The c-Kit receptor was found to induce proliferation and to increase the expression of cyclin D1 via the PI3K/AKT/NF-kB signalling pathway. Additionally, the c-Kit/PI3K/AKT pathway increased the inhibition of apoptosis and survivin expression. Similarly, c-Kit was observed to reduce the expression of the pro-apoptotic Bak protein. CONCLUSION: These results suggest that, in leukaemic lymphoblasts, c-Kit triggers a signalling pathway with proliferative and anti-apoptotic effects; information to this effect has not yet been reported in the literature.

Hypothyroidism minimizes the effects of acute hepatic failure caused by endoplasmic reticulum stress and redox environment alterations in rats.

The aim of this study was to investigate if a protective effect from hypothyroidism in acute liver failure resulted from reduced endoplasmic reticulum stress and changes to the redox environment. Twenty male Sprague-Dawley rats were divided in four groups: (1) euthyroid (sham surgery), (2) hypothyroid, (3) euthyroid (sham surgery)+thioacetamide and (4) hypothyroid+thioacetamide. Hypothyroidism was confirmed two weeks after thyroidectomy, and thioacetamide (TAA) (400mg/kg, ip) was administrated to the appropriate groups for three days with supportive therapy. Grades of encephalopathy in all animals were determined using behavioral tests. Animals were decapitated and their blood was obtained to assess liver function. The liver was dissected: the left lobe was used for histology and the right lobe was frozen for biochemical assays. Body weight, rectal temperature and T4 concentration were lower in hypothyroid groups. When measurements of oxidative stress markers, redox environment, γ-glutamylcysteine synthetase and glutathione-S-transferase were determined, we observed that hypothyroid animals with TAA compensated better with oxidative damage than euthyroid animals treated with TAA. Furthermore, we measured reduced expressions of GADD34, caspase-12 and GRP78 and subsequently less hypothyroidism-induced cellular damage in hypothyroid animals. We conclude that hypothyroidism protects against hepatic damage caused by TAA because it reduces endoplasmic reticulum stress and changes to the redox environment.

Linking sub-individual and population level toxicity effects in Daphnia schoedleri (Cladocera: Anomopoda) exposed to sublethal concentrations of the pesticide α-cypermethrin.

Synthetic pyrethroids are classified as moderately toxic to mammals and birds; nevertheless, they are highly toxic to non-target aquatic organisms such as fish and zooplankters. Chemical pollutants produce different effects in exposed organisms, ranging from biochemical to population responses. Cladocerans can modify the energy content of their offspring according to the surrounding medium as a way to improve their odds in case they have to cope with stressful conditions at birth. In this study, the effect of a synthetic pesticide on two levels of response in a Daphnia species different from those traditionally used as test organisms was evaluated. With this aim, Daphnia schoedleri neonates (<24 h) were exposed for 21 days to three sublethal concentrations of α-cypermethrin, 0.54, 5.4, and 54 ng L(-1), which correspond to 48-h EC1/100, EC1/10, and EC1, respectively. Effects were measured through a life table analysis for fecundity and survivorship. For effects on progeny, protein, carbohydrates, and lipids were determined and then transformed to caloric content. Biomarkers (BM) were expected to be the most sensitive evaluated response; nevertheless, population parameters such as survivorship and net reproductive rate (R0) were more sensitive since they presented significant differences with respect to controls at the lowest tested concentration. Neonates' caloric content varied during the reproductive period assessed and was negatively correlated to fecundity: as more neonates were born, less energy was provided by the adult females. Macromolecules concentration and caloric content values in cypermethrin-exposed adults were not different from those recorded in the control at the end of exposure time. The results herein presented suggest that stressed daphnids allocate more energy reserves to their offspring, although this strategy can vary depending on the number of reproductive events during the lifecycle, and on the toxicant's concentration. Sub-individual approaches to assess toxicant effects should be accompanied by demographic studies, which support population effect predictions inferred from BMs assessment.

Hypothyroidism maintained reactive oxygen species-steady state in the kidney of rats intoxicated with ethylene glycol: effect related to an increase in the glutathione that maintains the redox environment.

Our objective was to determine whether hypothyroidism protects against ethylene glycol (EG)-induced renal damage and whether the redox environment participates in the protection process. We used 36 male Wistar rats divided into four groups: (1) euthyroid, (2) euthyroid + 0.75% EG, (3) hypothyroid, and (4) hypothyroid + 0.75% EG. Hypothyroidism occurred 2 weeks after thyroidectomy. The parathyroid gland was reimplanted. EG was administrated for 21 days in drinking water. On day 21, the renal function was assessed and then the rats were decapitated. The left kidney was processed for histology, and the right kidney was used to determine the redox environment, oxidative stress, and the testing of the antioxidant enzymatic system. EG in euthyroid rats reduced the hydric and electrolytic balance and it also caused oxidative stress and renal damage. Hypothyroidism per se modifies the renal function causing a low osmolal and potassium clearance and the filtered load of potassium and sodium. In addition, there was an enhanced redox state because hypothyroidism increases the reduced glutathione concentration caused by a high activity of γ-glutamylcysteine synthase. Hypothyroidism is a protective state against EG because the changes in the renal function were smaller than in the euthyroid state. The oxidative stress and cellular damage were ameliorated by the hypothyroid condition. Also, the hypothyroidism-enhanced redox environment protects against EG-induced oxidative stress, renal damage, and renal dysfunction.

Methimazole-induced hypothyroidism causes cellular damage in the spleen, heart, liver, lung and kidney.

It is known that a hypothyroidism-induced hypometabolic state protects against oxidative damage caused by toxins. However, some workers demonstrated that antithyroid drug-induced hypothyroidism can cause cellular damage. Our objective was to determine if methimazole (an antithyroid drug) or hypothyroidism causes cellular damage in the liver, kidney, lung, spleen and heart. Twenty-five male Wistar rats were divided into 5 groups: euthyroid, false thyroidectomy, thyroidectomy-induced hypothyroidism, methimazole-induced hypothyroidism (60 mg/kg), and treatment with methimazole (60 mg/kg) and a T4 injection (20 µg/kg/d sc). At the end of the treatments (4 weeks for the pharmacological groups and 8 weeks for the surgical groups), the animals were anesthetized with sodium pentobarbital and they were transcardially perfused with 10% formaldehyde. The spleen, heart, liver, lung and kidney were removed and were processed for embedding in paraffin wax. Coronal sections were stained with hematoxylin-eosin. At the end of treatment, animals with both the methimazole- and thyroidectomy-induced hypothyroidism had a significant reduction of serum concentration of thyroid hormones. Only methimazole-induced hypothyroidism causes cellular damage in the kidney, lung, liver, heart, kidney and spleen. In addition, animals treated with methimazole and T4 showed cellular damage in the lung, spleen and renal medulla with lesser damage in the liver, renal cortex and heart. The thyroidectomy only altered the lung structure. The alterations were prevented by T4 completely in the heart and partially in the kidney cortex. These results indicate that tissue damage found in hypothyroidism is caused by methimazole.

Methimazole-induced hypothyroidism causes alteration of the REDOX environment, oxidative stress, and hepatic damage; events not caused by hypothyroidism itself.

UNLABELLED: Our objective was to compare, over a time-course, markers of oxidative stress, the REDOX environment, and the antioxidant enzymatic system in the liver of rats with methimazole- or thyroidectomy-caused hypothyroidism. METHODS: We used 60 male Wistar rats divided into four groups: 1) the euthyroid, which received only tap water, 2) false thyroidectomy, which received the surgery and postoperative treatment, 3) thyroidectomy-caused hypothyroidism, which had the thyroid gland removed and a parathyroid reimplant, and 4) methimazole-caused hypothyroidism in rats that received 60 mg/kg/d of the antithyroid drug in drinking water. Five rats of the euthyroid and methimazole-caused hypothyroidism groups were killed at the end of the first, second, third, and fourth week after treatment, and five rats of false thyroidectomy and thyroidectomy-caused hypothyroidism groups were killed at the end of the second and eighth week after the surgical procedure. Each liver was removed and stored at -70 degrees C until oxidative stress, REDOX environment, and antioxidant enzymatic system markers were tested. We also made a histological study at the end of the treatment. RESULTS: The histological study revealed that only the methimazole-caused hypothyroidism caused cell damage. This damage is associated with an increase of oxidative stress markers that were not compensated for by the antioxidant system. The catalase activity is reduced and this allows H2O2-caused damage. In conclusion methimazole causes cell damage in the liver, whereas hypothyroidism per se does not cause hepatic-cell damage.

Ketamine prevents lidocaine-caused neurotoxicity in the CA3 hippocampal and basolateral amygdala regions of the brain in adult rats.

Our objective was to prove whether blocking the action of glutamate on N-methyl-D: -aspartate (NMDA) receptors could prevent the neuronal damage caused by the acute administration of lidocaine. Twenty male 2-month-old Wistar rats were randomly assigned to the following groups (n = 5 in each group): groups I and II received 0.9% saline i.p., and groups III and IV received 100 mg x kg(-1) of ketamine i.p. Thirty minutes later, groups I and III were again dosed with 0.9% saline i.p., and groups II and IV received 60 mg x kg(-1) of lidocaine i.p. During treatment, the rectal temperature of the animals was monitored and maintained at 37.5 +/- 0.5 degrees C. Ten days after administration of the agents, all rats were transcardially perfused, under pentobarbital anesthesia, with 10% formaldehyde. Their brains were removed and were embedded in paraffin. Coronal cuts of 7 microm were obtained from -2.3 to -3.8 mm from the bregma. Each brain section was stained with cresyl violet-eosin. The number of normal and abnormal pyramidal neurons in the CA3 hippocampal region and the number of large and medium neurons in the basolateral amygdala within an area of 10 000 microm2 were evaluated. We found that lidocaine significantly reduced the number of normal neurons in both the CA3 hippocampal region (F (3,16) = 225.8; P < 0.001) and the basolateral amygdala (F (3,16) = 253.3; P < 0.001). The ketamine pretreatment attenuated the lidocaine-induced damage in the CA3 hippocampal region and the basolateral amygdala. These results demonstrate the participation of NMDA-receptor activation by lidocaine in the CA3 hippocampal and basolateral amygdala regions as a neurotoxic mechanism.

Lidocaine affects the redox environment and the antioxidant enzymatic system causing oxidative stress in the hippocampus and amygdala of adult rats.

AIMS: Our objective was to investigate if oxidative stress is involved in the neural damage caused by lidocaine. MAIN METHODS: Male Wistar rats were used. The control group received 0.9% saline ip and the treated group received a single 60 mg/kg lidocaine dose ip. On days 1, 2, 5, and 10 after dosing, ten rats were sacrificed and their brains were quickly removed. The amygdala and hippocampus were dissected. Five samples were used to determine lipid peroxidation, reactive oxygen species (ROS), reduced glutathione (GSH), and oxidized glutathione (GSSG). Another five were used to measure antioxidant activities of glutathione peroxidase (GPX), catalase, Cu-Zn SOD (superoxide dismutase), Mn SOD, and total SOD. KEY FINDINGS: Ten days after injection of lidocaine, lipid peroxidation increases in the hippocampus because the ROS are enhanced from day 5, whereas in the amygdala lipid peroxidation and the ROS were enhanced only on the first day postinjection. Lidocaine causes an increased concentration of GSH and GSSG in the hippocampus from the first day. In the amygdala the GSH and GSSG content were increased at day 10. In the hippocampus the catalase activity was enhanced, whereas the total SOD and Cu-Zn SOD activities were decreased. In the amygdala the lidocaine enhances the activities of catalase and GPX, but no SOD isoenzymes were modified. SIGNIFICANCE: In this research we demonstrated that lidocaine affects the redox environment and promotes increases of the oxidative markers both in the hippocampus and amygdala but in a different pattern.

Hypothyroidism induces selective oxidative stress in amygdala and hippocampus of rat.

The effects of hypothyroidism on lipid peroxidation (LP), reactive oxygen species (ROS), and nitric oxide synthase (NOS), levels and expression, in rat brain were examined. Hypothyroidism was induced by administering methimazole in drinking water (60 mg/kg/day). In striatum, motor cortex and cerebellum of hypothyroid rats LP was not modified, whereas LP and ROS increased in amygdala and hippocampus of hypothyroid rats at the third week of treatment with methimazole as compared to euthyroid group values. Regarding NOS participation, only hippocampal constitutive-NOS activity was increased, accompanied by an augmentation in nNOS expression. Results show that hypothyroidism induces selective oxidative stress in both the hippocampus and amygdala, where the nitrergic system is involved.

Hippocampus and amygdala neurotoxicity produced by systemic lidocaine in adult rats.

There is evidence that using lidocaine-treated cellular culture produces cell damage. However, there are no studies in vivo demonstrating the potential injurious effect of lidocaine on the central nervous system. Therefore, the aim of our study was to investigate if lidocaine is involved in neuronal damage in the CA3 hippocampus and amygdala regions when using a single subconvulsive or a convulsive lidocaine dose. Two-month-old male Wistar rats (57) were used. The animals were randomly assigned to one of three groups. Group I received 0.9% saline ip (n=9), group II received a single lidocaine dose of 60 mg/kg (n=18), and group III received 90 mg/kg ip (n=12). At day 2, 7, and 10 after the dosing, three to six rats per group were sacrificed. The brains of the rats were removed and were embedded in paraffin. Coronal cuts of 7 microm were made. Each brain section was stained with cresyl-eosin. We evaluated the number of normal and abnormal neurons in the hippocampal CA3 (pyramidal) and basolateral amygdala (large and medium neurons) regions in a 10,000 microm2 section. To explore an association between lidocaine-induced seizure and neuronal damage, diazepam was used (10 mg/kg ig) as an anticonvulsant two hours before a 90 mg/kg dose of lidocaine. Lidocaine causes a morphological neuronal alteration in the CA3 hippocampal region and the basolateral amygdala and possibly an inhibition-excitation imbalance. Diazepam prevents lidocaine-induced seizures, but not neuronal damage in brain structures. Interaction of lidocaine with the membrane components produces disrupted Ca+2 homeostasis and causes neuronal damage. Moreover, it is possible that lidocaine or its metabolites could actively participate in the neuronal damage observed.

Perinatal hypothyroidism increases the susceptibility to lidocaine-kindling in adult rats.

The present study was developed to ascertain whether or not susceptibility to lidocaine-kindling persists into adulthood in perinatal hypothyroid rats. Pregnant Wistar rats were randomly divided into two groups: the first one, a control group, that drank tap water; and a second one, a hypothyroid group, were treated with 0.02% propylthiouracil in their drinking water from the 14th gestational day to the 10th postpartum day. The pups of both groups were maintained with food and tap water ad libitum until the experiment was over. The pups of each group were divided to test the susceptibility to lidocaine-kindling at 30 and 100 days old, for this, lidocaine (50 mg/kg, i.p.) was administered daily. The seizures were usually present in the form of tonic attacks of fore and hind limbs, followed by intermittent clonic movements. An animal was considered kindled when it showed clonic movements for two consecutive days. We observed that the number of stimuli necessary to produce lidocaine-kindling seizures in hypothyroid rats was significantly lower than in the control group for both ages. Also, the percentage of kindled rats aged 30 days (73% and 89%) was greater than aged of 100 days (26% and 59%) in both control and hypothyroid groups, respectively. In conclusion, the perinatal hypothyroidism increases the susceptibility to lidocaine-kindling in adult rats.

Kainic acid does not affect CA3 hippocampal region pyramidal cells in hypothyroid rats.

Thyroid hormones exert a crucial role on trophic events of the central nervous system during development, adulthood, and ageing. The deficiency of thyroid hormones could also produce a deficiency in neurotransmission in the hippocampal region. Kainic acid (KA) has become an important tool for studying functions related to excitatory amino acid transmission in mammals. Its neurotoxic effects on the pyramidal neurons of the CA3 hippocampal region are well known. We have examined the neurotoxicity of KA on these cells in hypothyroid rats. The hypothyroid state was induced by administration of methimazole. After 4 weeks of treatment, KA was administered once intraperitoneally at doses of 0, 1, 2.5, and 5mg/kg to the hypothyroid group, and 0 and 5mg/kg to the euthyroid group. In the euthyroid group, KA reduced the neuronal density in the CA3 hippocampal region, and in the hypothyroid rats with no administration of KA, the neuronal density of the CA3 hippocampal region is reduced also. Administering KA in hypothyroid rats did not reduce the number of CA3 pyramidal cells.

An improved histochemical technique for differentiating adrenaline-and noradrenaline-containing cells

Background. Sevki's histochemical technique allows specific staining of catechomamine-containing cells, yet discrimiantion between adrenaline-(ADR-) cells and noradrenaline-(NOR-) cells is unrealiable, being based on hue differences. Methods. In this work, histochemical differentiation of ADR- and NOR-cells in rat adrenal medulla was carried out by introducing two modifications to Sevki's technique: 1) employment of aged Giemsa solution, and 2) addition of an alkaline differentiating step. Results. With these changes, ADR-cell stained brown, whereas NOR-cells were deep-green, resulting in a clear-cut differentiation. Conclusions. The modified technique permits to differentiate ADR- from NOR-cells in the adrenal medulla using only a bright field microscope without any sophisticated equipment. The present procedure is inexpensive and easy to carry out