Does a therapeutical dose of ivermectin impairs testicular homeostasis of rats via excessive apoptosis?

Ivermectin is a medication used to treat parasite infestations in humans and in veterinary medicine. Previously we showed that therapeutical doses of ivermectin impaired spermatogenesis and spermiogenesis in adult rats. The present study was proposed to understand the pathophysiological mechanism that triggered these impairments induced by ivermectin. It was a particular objective to study if ivermectin induced excessive apoptosis. Adult rats were treated with a therapeutical dose of ivermectin (subcutaneously). Their testis was evaluated for the expression of caspase-3 (a marker of apoptosis), using immunohistochemistry techniques. Results revealed that ivermectin treatment increased the expression of caspase-3 (labeled seminiferous tubules and strongly labeled tubules), as well as increased the number of tubules that presented labeled cells in the tubular lumen, compared to the data of the control group. In conclusion, a therapeutical dose of ivermectin induced expressive apoptosis in cells of the seminiferous tubules of rats, affecting the testicular natural homeostasis process, which resulted in the spermatogenesis and spermiogenesis impairments previously reported.

MicroRNA biogenesis machinery activation and lncRNA and REST overexpression as neuroprotective responses to fight inflammation in the hippocampus.

Brain Long non-coding RNA (lncRNA) and microRNAs (miRs) play essential roles in the regulation of several important biological processes, including neuronal activity, cognitive processes, neurogenesis, angiogenesis, and neuroinflammation. In this context, the transcriptional repressor, RE1 silencing transcription factor (Rest), acts regulating the expression of neuronal genes as well as of lncRNAs and multiple miRNAs in the central nervous system. Nevertheless, its role in neuroinflammation was less explored. Here, we demonstrate, using an in vivo model of neuroinflammation induced by i.p. injection of LPS (0.33 mg/kg), that neuroinflammation increases gene expression of pro-inflammatory cytokines concomitant with the native and truncated forms of Rest and of non-coding RNAs. Additionally, the increased expression of enzymes Drosha ribonuclease III) (Drosha), Exportin 5 (Xpo5) and Endoribonuclease dicer (Dicer), associated with high expression of neuroprotective miRs 22 and 132 are indicative that the activation of biogenesis of miRs in the hippocampal region is a Central Nervous System (CNS) protective mechanism for the deleterious effects of neuroinflammation. Our results indicate that positive regulation of Rest gene expression in the hippocampal region by neuroinflammation correlates directly with the expression of miRs 22 and 132 and inversely with miR 335. In parallel, the confirmation of the possible alignment between the lncRNAs with miR 335 by bioinformatics corroborates with the sponge effect of Hottip and Hotair hybridizing and inhibiting the pro-inflammatory action of miR 335. This suggests the existence of a possible correlation between the activation of miR biogenesis machinery with increased expression of the transcription factor Rest, contributing to neuroprotection.

Propentofylline Improves Thiol-Based Antioxidant Defenses and Limits Lipid Peroxidation following Gliotoxic Injury in the Rat Brainstem.

Propentofylline (PROP) is a methylated xanthine compound that diminishes the activation of microglial cells and astrocytes, which are neuronal cells strongly associated with many neurodegenerative diseases. Based on previously observed remyelination and neuroprotective effects, PROP has also been proposed to increment antioxidant defenses and to prevent oxidative damage in neural tissues. Since most neurodegenerative processes have free radicals as molecular pathological agents, the aim of this study was to evaluate the antioxidant effects of 12.5 mg·kg-1·day-1 PROP in plasma and the brainstem of Wistar rats exposed to the gliotoxic agent 0.1% ethidium bromide (EB) for 7-31 days. The bulk of the data here demonstrates that, after 7 days of EB treatment, TBARS levels were 2-fold higher in the rat CNS than in control, reaching a maximum of 2.4-fold within 15 days. After 31 days of EB treatment, lipoperoxidation in CNS was still 65% higher than that in the control. Clearly, PROP treatment limited the progression of lipoperoxidation in EB-oxidized CNS: it was, for example, 76% lower than in the EB-treated group after 15 days. Most of these effects were associated with PROP-induced activity of glutathione reductase in the brainstem: the EB + PROP group showed 59% higher GR activity than that of the EB or control groups within 7 days. In summary, aligning with previous studies from our group and with literature about MTXs, we observed that propentofylline (PROP) improved the thiol-based antioxidant defenses in the rat brainstem by the induction of the enzymatic activity of glutathione reductase (GR), which diminished lipid oxidation progression and rebalanced the redox status in the CNS.

Progressive tremor and motor impairment in seizure-prone mutant tremor mice are associated with neurotransmitter dysfunction.

BACKGROUND: The tremor mutant mice present motor impairments comprised of whole-body tremors, ataxia, decreased exploratory behavior, and audiogenic seizures. OBJECTIVES: This study aims to investigate the development of motor dysfunction in this mutant mouse and the relationships with cortical, striatal, and cerebellar levels of GABA, glutamate, glycine, dopamine (DA), serotonin (5-HT), noradrenaline (NOR), and its metabolites. The serum cytokines levels, myelin content, and the astrocytic expression of the glial fibrillary acidic protein (GFAP) investigated the possible influence of inflammation in motor dysfunction. RESULTS: Relative to wild-type (WT) mice, the tremor mice presented: increased tremors and bradykinesia associated with postural instability, decreased range of motion, and difficulty in initiating voluntary movements directly proportional to age; reduced step length for right and left hindlimbs; reduced cortical GABA, glutamate and, aspartate levels, the DOPAC/DA and ratio and increased the NOR levels; in the striatum, the levels of glycine and aspartate were reduced while the HVA levels, the HVA/DA and 5HIAA/5-HT ratios increased; in the cerebellum the glycine, NOR and 5-HIAA levels increased. CONCLUSIONS: We suggest that the motor disturbances resulted mainly from the activation of the indirect striatal inhibitory pathway to the frontal cortex mediated by GABA, glutamate, and aspartate, reducing the dopaminergic activity at the prefrontal cortex, which was associated with the progressive tremor. The reduced striatal and increased cerebellar glycine levels could be partially responsible for the mutant tremor motor disturbances.

Bate palmas mutant mice as a model of Kabuki syndrome: Higher susceptibility to infections and vocalization impairments?

The recessive mutant mouse bate palmas (bapa) arose from N-ethyl-N-nitrosourea mutagenesis. Previous studies of our group revealed some behavioral impairments and a mutation in the lysine (K)-specific methyltransferase 2D (Kmt2d) gene. Because mutations in the KMT2D gene in humans are mainly responsible for Kabuki syndrome, this study was proposed to validate bapa mice as a model of Kabuki syndrome. Besides other symptoms, Kabuki syndrome is characterized by increased susceptibility to infections and speech impairments, usually diagnosed in the early childhood. Thus, juvenile male and female bapa mice were studied in different developmental stages (prepubertal period and puberty). To induce sickness behavior and to study infection susceptibility responses, lipopolysaccharide (LPS) was used. To study oral communication, ultrasonic vocalizations were evaluated. Behavioral (open-field test) and central (astrocytic glial fibrillary acidic protein [GFAP] and tyrosine hydroxylase [TH]) evaluations were also performed. Control and bapa female mice emitted 31-kHz ultrasounds on prepubertal period when exploring a novel environment, a frequency not yet described for mice, being defined as 31-kHz exploratory vocalizations. Males, LPS, and puberty inhibited these vocalizations. Bapa mice presented increased motor/exploratory behaviors on prepubertal period due to increased striatal TH expression, revealing striatal dopaminergic system hyperactivity. Combining open-field behavior and GFAP expression, bapa mice did not develop LPS tolerance, that is, they remained expressing signs of sickness behavior after LPS challenge, being more susceptible to infectious/inflammatory processes. It was concluded that bapa mice is a robust experimental model of Kabuki syndrome.

Luffa operculata at a late period of gestation dysregulates melatonin and cytokines interfering with weight of dams and their male offspring.

ETHNOPHARMACOLOGICAL RELEVANCE: The tea made with the fruits of Luffa operculata (L.) Cogn. (Cucurbitaceae; EBN) is popularly used as abortive. AIM OF THE STUDY: The present work aimed at accessing how the exposition of female Wistar rats to 1.0 mg/kg of EBN (experimental group, EG), or distilled water (control group, CG), by gavage, at gestational days (GD) 17-21 interfered with the reproductive performance, and with dams' behavior after weaning. MATERIALS AND METHODS: At post-natal day 2 (PND2), the number of male and female pups was evaluated, as well as their weight. After weaning (PND21), dams were euthanized, and their liver and kidneys were removed for histological and biochemical analyses, while the blood was used in the evaluation of cytokines IL-1α, IL-1ß, IL-6 and TNF-α, corticosterone, adrenocorticotrophic hormone, melatonin, AST, ALT and creatinine levels. RESULTS AND DISCUSSION: Dams that were treated with EBN showed an anxiety-like behavior, weight loss at the end of gestation and weight gain at weaning, accompanied with a significant decrease in pro-inflammatory cytokines and in the melatonin level. No significant histological or biochemical alterations have occurred in the liver or kidneys. The number of female pups was significantly higher in the EG. The male pups showed weight gain at PND60. CONCLUSION: The presence of cucurbitacins is probably involved in the dysregulations that were found, due to their polycyclic steroid triterpene structure.

Vertical exposition to Luffa operculata extract deregulates behavior and hypothalamus neurotransmitters in juvenile rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Luffa operculata (L.) Cogn (Cucurbitaceae) is a traditional plant popularly used in the abortion induction, against sinusitis and is toxic. AIM OF THE STUDY: To verify the influence of the aqueous extract obtained from the dry fruit of L. operculata (BNE) on the male rats vertically exposed to a subabortive dose of BNE, by evaluating alterations in behavior and neurochemical features in hypothalamus, striatum and frontal cortex, at a juvenile age, after receiving a stress challenge given by the use of the "New York subway stress" technique (NYS). MATERIALS AND METHODS: Pregnant female rats (F0 generation) received 1.0 mg/kg BNE, or distilled water (100 mL/kg), by gavage, between gestation days GD17 and GD21. The pups were weaned at PND21 and were kept up to PND60 (juvenile age) in controlled environmental conditions. Four groups were obtained: control (CG), experimental (EG), stress control (SCG) and stress experimental (SEG) After being stressed, the animals were behavioral screened for in the open field (OF) and in light-dark box (LDB) apparatuses. They were euthanized, and the liver, kidneys and brain were removed for both macroscopic and microscopic analyses, and for quantification of vanillylmandelic acid (VMA), norepinephrine (NE), dopamine (DA) and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC) and the serotonin (5-HT) and its metabolite 5-hydroxyindolylacetic acid (5-HIAA) were accessed in the hypothalamus, frontal cortex and striatum. RESULTS AND DISCUSSION: although most of the behavior changes were due to the stress challenge, the rats spent more time in the dark side of the LDB and were less likely to explore the light side, indicating that the treatment with BNE induced to fear. Interferences of BNE over behavior were due to impairment of VMA, NE, 5-HT and DA and increasing of DOPAC in the hypothalamus, and an increase of 5-HIAA in the frontal cortex, indicating alterations in the hypothalamic-hypophysis-adrenal axis (HHAA). No macroscopic or histopathological changes were observed in the liver, kidneys, or brain, although GFAP was diminished in the SCG, as expected for stressed rats. CONCLUSION: the vertical exposition of juvenile rats to BNE led to the manifestation of fear and to a down regulation of the hypothalamic-hypophysis-adrenal axis.

Zinc, but not paracetamol, prevents depressive-like behavior and sickness behavior, and inhibits interferon-gamma and astrogliosis in rats.

Considering all mental and addictive disorders, depression is the most responsible for years of life lost due to premature mortality and disability. Antidepressant drugs have limited effectiveness. Depression can be triggered by immune/inflammatory factors. Zinc and paracetamol interfere with immune system and have demonstrated beneficial effects on depression treatment when administered concomitant with antidepressant drugs. The objective of this study was to test zinc and/or paracetamol as treatments of depressive-like behavior, sickness behavior, and anxiety in rats, as well as to understand the central and peripheral mechanisms involved. Sickness behavior and depressive-like behavior were induced in rats with repetitive lipopolysaccharide (LPS, 1 mg/kg for two consecutive days) administrations. Rats received zinc and/or paracetamol for three consecutive days. Sickness behavior (daily body weight and open field general activity); anxiety (light-dark test); depressive-like/antidepressant behavior (forced swim test); plasma corticosterone and interferon (IFN)-gamma levels; and glial fibrillary acidic protein (GFAP) and tyrosine hydroxylase (TH) brain expression were evaluated. LPS induced sickness behavior and depressive-like behavior, as well as elevated IFN-gamma levels and increased GFAP expression. Zinc prevented both behavioral and biochemical impairments. Paracetamol and zinc + paracetamol association induced only slight beneficial effects. Anxiety, corticosterone, and TH do not seem be related with depression and the other behavioral and neuroimmune changes. In conclusion, zinc treatment was beneficial for sickness behavior and depressive-like behavior without concomitant administration of antidepressants. IFN-gamma and GFAP were linked with the expression of sickness behavior and depressive-like behavior and were also involved with the antidepressant effects. Therefore, zinc, IFN-gamma, and GFAP pathways should be considered for depression treatment.

Billings reservoir water used for human consumption presents microbiological contaminants and induces both behavior impairments and astrogliosis in zebrafish.

The Billings reservoir is the largest water-storage facility in the São Paulo Metropolitan Region, with only a small part of the reservoir used for water supply. Recently, the São Paulo Metropolitan Region has experienced the greatest water collapse ever recorded. Thus, the intensification of use of the Billings reservoir should be considered. The objective of this study was to evaluate the quality of the water from different areas of the Billings reservoir related to human consumption (water supply and fishing): Rio Pequeno, Rio Grande, and Bororé rivers. We performed microbiological and physical studies on one water sample collected at each of these sites. Adult zebrafish were exposed to such water samples and their behaviors were evaluated. Finally, we studied central glial fibrillary acidic protein (GFAP) expression, which is related to neuroinflammatory processes. Water samples from Rio Pequeno, Rio Grande, and Bororé presented microbiological contamination for Escherichia coli and heterotrophic bacteria. Water from the Rio Pequeno river induced both motor/exploratory impairments and anxiogenic-like behavior in zebrafish. Water from the Bororé river induced behaviors in zebrafish related to respiratory impairments (hypoxia) as well as higher alarm reaction. Zebrafish exposed to water from the Bororé also presented astrogliosis, which seems to have happened in detrimental of the high heterotrophic bacterial contamination. Rio Grande and Bororé water increased the lethality rates. Considering the present results of microbiological contaminants and behavior impairments, lethality, as well as astrogliosis in zebrafish, the water from Rio Pequeno, Rio Grande, and Bororé rivers should be considered unacceptable for human use in their untreated state. The Basic Sanitation Company of the State of Sao Paulo should consider adopting rigorous processes of microbiological water treatment. Authorization for fishing at Bororé river should be reconsidered.

Induction of Type 2 Iodothyronine Deiodinase After Status Epilepticus Modifies Hippocampal Gene Expression in Male Mice.

Status epilepticus (SE) is an abnormally prolonged seizure that results from either a failure of mechanisms that terminate seizures or from initiating mechanisms that inherently lead to prolonged seizures. Here we report that mice experiencing a 3 hours of SE caused by pilocarpine exhibit a rapid increase in expression of type 2 iodothyronine deiodinase gene (Dio2) and a decrease in the expression of type 3 iodothyronine deiodinase gene in hippocampus, amygdala and prefrontal cortex. Type 3 iodothyronine deiodinase in hippocampal sections was seen concentrated in the neuronal nuclei, typical of ischemic injury of the brain. An unbiased analysis of the hippocampal transcriptome of mice undergoing 3 hours of SE revealed a number of genes, including those involved with response to oxidative stress, cellular homeostasis, cell signaling, and mitochondrial structure. In contrast, in mice with targeted disruption of Dio2 in astrocytes (Astro D2KO mouse), the highly induced genes in the hippocampus were related to inflammation, apoptosis, and cell death. We propose that Dio2 induction caused by SE accelerates production of T3 in different areas of the central nervous system and modifies the hippocampal gene expression profile, affecting the balance between adaptive and maladaptive mechanisms.

Propentofylline Prevents Sickness Behavior and Depressive-Like Behavior Induced by Lipopolysaccharide in Rats via Neuroinflammatory Pathway.

Recent studies have demonstrated the intimate relationship between depression and immune disturbances. Aware of the efficacy limits of existing antidepressant drugs and the potential anti-inflammatory properties of propentofylline, we sought to evaluate the use of propentofylline as a depression treatment. We used a rat model of depression induced by repetitive lipopolysaccharide (LPS) administrations. We have studied sickness behavior, by assessing daily body weight, open field behavior, and TNF-α plasmatic levels. Anxiety-like behavior (light-dark test), depressive-like behavior (forced swim test), plasmatic levels of the brain-derived neurotrophic factor (BDNF, depression biomarker), and central glial fibrillary acidic protein (GFAP) expression (an astrocyte biomarker) were also evaluated. LPS induced body weight loss, open field behavior impairments (decreased locomotion and rearing, and increased immobility), and increased TNF-α levels in rats, compared with control group. Thus, LPS induced sickness behavior. LPS also increased the immobility and reduced climbing in the forced swim test, when compared with the control group, i.e., LPS induced depressive-like behavior in rats. Propentofylline prevented sickness behavior after four days of consecutive treatment, as well as prevented the depressive-like behavior after five days of consecutive treatments. Propentofylline also prevented the increase in GFAP expression induced by LPS. Neither LPS nor propentofylline has influenced the anxiety and BDNF levels of rats. In conclusion, repetitive LPS administrations induced sickness behavior and depressive-like behavior in rats. Propentofylline prevented both sickness behavior and depressive-like behavior via neuroinflammatory pathway. The present findings may contribute to a better understanding and treatment of depression and associated diseases.

Redox Status and Neuro Inflammation Indexes in Cerebellum and Motor Cortex of Wistar Rats Supplemented with Natural Sources of Omega-3 Fatty Acids and Astaxanthin: Fish Oil, Krill Oil, and Algal Biomass.

Health authorities worldwide have consistently recommended the regular consumption of marine fishes and seafood to preserve memory, sustain cognitive functions, and prevent neurodegenerative processes in humans. Shrimp, crabs, lobster, and salmon are of particular interest in the human diet due to their substantial provision of omega-3 fatty acids (n-3/PUFAs) and the antioxidant carotenoid astaxanthin (ASTA). However, the optimal ratio between these nutraceuticals in natural sources is apparently the key factor for maximum protection against most neuro-motor disorders. Therefore, we aimed here to investigate the effects of a long-term supplementation with (n-3)/PUFAs-rich fish oil, ASTA-rich algal biomass, the combination of them, or krill oil (a natural combination of both nutrients) on baseline redox balance and neuro-inflammation indexes in cerebellum and motor cortex of Wistar rats. Significant changes in redox metabolism were only observed upon ASTA supplementation, which reinforce its antioxidant properties with a putative mitochondrial-centered action in rat brain. Krill oil imposed mild astrocyte activation in motor cortex of Wistar rats, although no redox or inflammatory index was concomitantly altered. In summary, there is no experimental evidence that krill oil, fish oil, oralgal biomass (minor variation), drastically change the baseline oxidative conditions or the neuro-inflammatory scenario in neuromotor-associated rat brain regions.

Glial cells of the central nervous system of Bothrops jararaca (Reptilia, Ofidae): an ultrastructural study / Células gliais do sistema nervoso central de Bothrops jararaca (Reptilia, Ofidae): um estudo ultraestrutural

Although ultrastructural characteristics of mature neuroglia in the central nervous system (CNS) are very well described in mammals, much less is known in reptiles, especially serpents. In this context, two specimens of Bothrops jararaca were euthanized for morphological analysis of CNS glial cells. Samples from telencephalon, mesencephalon and spinal cord were collected and processed for light and transmission electron microscopy investigation. Astrocytes, oligodendrocytes, microglial cells and ependymal cells, as well as myelin sheaths, presented similar ultrastructural features to those already observed in mammals and tended to maintain their general aspect all over the distinct CNS regions observed. Morphological similarities between reptilian and mammalian glia are probably linked to their evolutionary conservation throughout vertebrate phylogeny...

Muito embora as características ultraestruturais da neuróglia madura do sistema nervoso central (SNC) sejam bem descritas em mamíferos, muito pouco é conhecido em répteis, especialmente em serpentes. Neste contexto, dois espécimes de Bothrops jararaca foram eutanasiados para análise morfológica das células gliais presentes no SNC. Amostras de telencéfalo, mesencéfalo e medula espinhal foram coletadas e processadas para investigação por microscopia de luz e eletrônica de transmissão. Astrócitos, oligodendócitos, células microgliais e ependimárias, bem como bainhas de mielina, apresentaram características ultraestruturais similares àquelas já observadas em mamíferos e tenderam a manter seu aspecto geral pelas diferentes regiões observadas no SNC. Similaridades morfológicas entre as células gliais de mamíferos e de répteis estão provavelmente ligadas a sua conservação evolutiva ao longo da filogenia dos vertebrados...

Neuroprotective properties of the marine carotenoid astaxanthin and omega-3 fatty acids, and perspectives for the natural combination of both in krill oil.

The consumption of marine fishes and general seafood has long been recommended by several medical authorities as a long-term nutritional intervention to preserve mental health, hinder neurodegenerative processes, and sustain cognitive capacities in humans. Most of the neurological benefits provided by frequent seafood consumption comes from adequate uptake of omega-3 and omega-6 polyunsaturated fatty acids, n-3/n-6 PUFAs, and antioxidants. Optimal n-3/n-6 PUFAs ratios allow efficient inflammatory responses that prevent the initiation and progression of many neurological disorders. Moreover, interesting in vivo and clinical studies with the marine antioxidant carotenoid astaxanthin (present in salmon, shrimp, and lobster) have shown promising results against free radical-promoted neurodegenerative processes and cognition loss. This review presents the state-of-the-art applications of n-3/n-6 PUFAs and astaxanthin as nutraceuticals against neurodegenerative diseases associated with exacerbated oxidative stress in CNS. The fundamental "neurohormesis" principle is discussed throughout this paper. Finally, new perspectives for the application of a natural combination of the aforementioned anti-inflammatory and antioxidant agents (found in krill oil) are also presented herewith.

Single early prenatal lipopolysaccharide exposure impairs striatal monoamines and maternal care in female rats.

AIMS: Environmental information received by a mother can induce a phenotype change in her offspring, commonly known as a maternal effect (trans-generational effect). The present work verified the effects of lipopolysaccharide (LPS), which mimics bacterial infection, on maternal care and on the activity of related brain areas in F1 offspring, i.e., female rats that were prenatally exposed to LPS. MAIN METHODS: Pregnant rats received 100µg/kg of LPS intraperitoneally on gestational day (GD) 9.5. Female offspring of the F1 generation were mated to naïve males and were evaluated during their lactation period for open field, maternal and aggressive behaviors. Striatal and hypothalamic dopamine and serotonin levels and turnover were also evaluated. Furthermore, astrocyte protein expression in the nucleus accumbens (NA) was analyzed in F1 females to assess LPS-induced neuroinflammation. KEY FINDINGS: Prenatal LPS did not change open field behavior but impaired both maternal and maternal aggressive behaviors in the F1 generation. LPS exposure also reduced both striatal levels of dopamine and serotonin and its metabolites, but induced no changes in NA astrocyte expression. SIGNIFICANCE: We suggested that the observed impairments in the F1 females were a consequence of a motivational change induced by prenatal LPS, as (1) no changes in motor activity were observed, (2) prenatal LPS-exposure was reported by our group to induce motivational impairments in males, and (3) the existence of a strong connection between striatal dopaminergic activity and motivation-oriented activities. The present findings strongly indicate a maternal effect for prenatal LPS, at least for the F1 generation.

[Pharmacologically immunosuppressed mice as a model for study of opportunistic parasite infections]. / Camundongos imunossuprimidos farmacologiamente como modelo para estudo de infecções parasitárias oportunistas.

Immunodeficient animals are important research models for studies in parasitology, oncology and immunology. Immunosuppressive drugs have been experimentally used to obtain a state of immunodeficiency in mice. This investigation aimed to quantify the circulating T and B cells of mice treated with the immunosuppressive agents dexamethasone (Dx), cyclosporine (CsA) and cyclophosphamide (CY), as well as to observe the behaviour of lymphocytic populations in the spleen of these animals. Blood samples were collected for counting the total peripheral blood leukocytes and T and B lymphocytes using flow cytometry. Total leukocytes of mice treated with the three drugs during all study showed a significant decrease when compared to the results of the control group. The proportion of B and T lymphocytes from the treated animals also decreased significantly. Spleen sections revealed a moderate decrease in the cellularity of the white pulp and the development of lymphocyte apoptosis in mice from groups treated with CY and Dx. Results showed that the proposed experimental models demonstrated to be suitable for studies of murine immunodeficiency.