Anabolic steroids and their effects of on neuronal density in cortical areas and hippocampus of mice / Esteroides anabolizantes e seus efeitos na densidade neuronal em áreas corticais e no hipocampo de camundongos

Anabolic substances have been increasingly used by bodybuilders and athletes with the goal of improving performance and aesthetics. However, this practice has caused some concern to physicians and researchers because of unknowledge of consequences that the indiscriminate and illicit use of these substances can cause. Thus, this study analyzed the effects of two commercially available anabolic steroids (AS), Winstrol Depot® (Stanozolol) and Deposteron® (Testosterone Cypionate), in the neuronal density of limbic, motor and sensory regions on the cerebral cortex and in CA1, CA2, CA3 regions of the hippocampus. A total of 60 Swiss mice were used (30 males and 30 females), separated into three groups: control and two experimental groups, which received the AAS. From each brain, homotypic and semi-serial samples were taken in frontal sections from areas established for the study. The results showed that females treated with testosterone cypionate presented a reduction in all regions tested and the ones treated with Stanozolol showed a decrease in some hippocampal areas. Regarding male animals, stanozolol led to a decrease in neuron number in one hippocampal region. These data allow us to conclude that supra-physiological doses of steroids used in this study, can cause considerable damage to nervous tissue with ultrastructural and consequently behavioral impairment. These changes could interfere with the loss of physical yield and performance of athletes and non-athletes and may cause irreparable damage to individuals making irresponsible use of anabolic steroids.(AU)

As substancias anabólicas tem sido cada vez mais utilizadas por fisiculturistas e atletas com o objetivo de melhorar o desempenho e a estética. No entanto, essa prática tem causado algumas preocupações aos médicos e pesquisadores, devido ao desconhecimento das consequencias que o uso indiscriminado e ilícito dessas substâncias podem causar. Diante disso, este estudo analisou os efeitos de dois esteroides anabolizantes (EA) comercialmente disponíveis, Winstrol Depot® (Stanozolol) e Deposteron® (cipionato de testosterona), na densidade neuronal das regiões corticais límbica, motora e sensitive bem como das áreas CA1, CA2, CA3 do hipocampo. Foram utilizados 60 camundongos Swiss (30 machos e 30 fêmeas), separados em três grupos: controle e dois grupos experimentais, que receberam o EA. De cada cérebro, foram coletadas amostras homotípicas e semi-seriadas em cortes frontais das áreas estabelecidas para o estudo. Os resultados mostraram que as fêmeas tratadas com cipionato de testosterona apresentaram uma redução em todas as regiões analisadas já as fêmeas tratadas com Stanozolol mostraram uma diminuição em algumas áreas do hipocampo. Em relação aos animais machos, o stanozolol levou a uma diminuição na densidade neuronal em uma região do hipocampo. Estes dados nos permitem concluir que doses supra fisiológicas de esteroides utilizadas neste estudo podem causar danos consideráveis ao tecido nervoso com comprometimento ultraestrutural e consequentemente comportamental. Essas alterações podem interferir na perda de rendimento físico e no desempenho de atletas e não atletas e podem causar danos irreparáveis a indivíduos que fazem uso irresponsável destes EA.(AU)

The antibiotic doxycycline mimics the NGF signaling in PC12 cells: A relevant mechanism for neuroprotection.

Doxycycline has been used as antibiotic since the 1960s. Recently, studies have shown that doxycycline is neuroprotective in models of neurodegenerative diseases and brain injuries, mainly due to anti-inflammatory and anti-apoptotic effects. However, it is not known if doxycycline has neurotrophic potential, which is relevant, considering the role of axonal degeneration at the early stages of neurodegeneration in Alzheimer's disease, Amyotrophic Lateral Sclerosis and Parkinson's disease as well as in normal aging. Axons are preceded by the formation of neurites, the hallmark of the neuronal differentiation induced by neurotrophins like NGF. Therefore, the modulation of neurotrophin receptors aimed at formation and regeneration of axons has been proposed as a strategy to delay the progression of neurodegeneration and has gained relevance as new techniques for early diagnosis arise. Based on these premises, we investigated the potential of doxycycline to mimic the effects of Nerve Growth Factor (NGF) with focus on the signaling pathways and neuronal modulators of neurite initiation, growth and branching. We used PC12 cells, a neuronal model widely employed to study the neurotrophic pathways and mechanisms induced by NGF. Results showed that doxycycline induced neurite outgrowth via activation of the trkA receptor and the downstream signaling pathways, PI3K/Akt and MAPK/ERK, without inducing the expression of NGF. Doxycycline also increased the expression of GAP-43, synapsin I and NF200, proteins involved in axonal and synaptic plasticity. Altogether, these data demonstrate, for the first time, the neurotrophic potential of doxycycline, which might be useful to restore the neuronal connectivity lost at the initial phase of neurodegeneration.

Photobiomodulation increases cell viability via AKT activation in an in vitro model of diabetes induced by glucose neurotoxicity.

Peripheral neuropathy (PN) is a serious complication of diabetes mellitus (DM) and is known to be resistant to conventional treatment. Photobiomodulation (PBM) is demonstrated to be effective in treating PN and in protecting nerve fiber damage. To better understand the mechanisms underlying the regenerative effects of PBM on diabetic neuropathy, we conducted a study in an in vitro model of diabetes induced by glucose neurotoxicity. Neuro 2A cells (1 × 104 cells/ well; N2A) were cultured in Minimum Essential Medium (MEM) supplemented with high glucose concentrations (100 mM) for 48 h and after the incubation period were submitted to either one or three consecutive applications of PBM, once a day (low-level InGaAlP, continuous wave mode, 660 nm, 30 mW, 1.6 J/cm2, 15 s, per well). Cell viability was measured by MTT method, neurotoxicity by LDH release, neurite outgrowth was evaluated through morphometric analysis, and AKT/ERK protein expression levels were assessed by western blotting. Results demonstrate that PBM increased N2A viability as well as induced neurogenesis observed by the increase in neurite outgrowth being this effect modulated by AKT activation. Data obtained herein reinforce the regenerative potential of PBM in the treatment of PN and strongly suggests that phototherapy should be considered adjuvant in the treatment of diabetes.

Vasoinhibin Suppresses Nerve Growth Factor-Induced Differentiation and Survival of PC12 Pheochromocytoma Cells.

BACKGROUND: Vasoinhibin, a protein derived from prolactin, regulates various vascular functions including endothelial cell survival. Of note, vasoinhibin is present in the central nervous system, where it triggers neuroendocrine and behavioral responses to stress. Moreover, vasoinhibin compromises nerve growth factor (NGF)-induced neurite outgrowth in primary sensory neurons of the peripheral nervous system. Nonetheless, information on the functions of vasoinhibin in developing neurons remains limited. The present study explored whether vasoinhibin affects the neurotrophic actions of NGF by measuring the cell differentiation and survival of PC12 pheochromocytoma cells. METHODS: The effects of recombinant or lentiviral vector-transduced human vasoinhibin were tested on differentiating PC12 cells. Neurite outgrowth was quantified by measuring their length and density. The MTT assay was employed to assess cell viability, and ELISA was used to quantify DNA fragmentation as an index of apoptosis. Phosphorylated Akt and ERK1/2 were analyzed by Western blotting. RESULTS: The addition of a human recombinant vasoinhibin, and the transduction of a lentiviral vector carrying a human vasoinhibin sequence, significantly reduced NGF-induced neurite outgrowth, cell survival, and phosphorylation of Akt and ERK1/2, and increased DNA fragmentation and caspase 3 activation in PC12 cells. CONCLUSIONS: Vasoinhibin downregulates NGF-induced differentiation and survival of PC12 cells, blocking tropomyosin receptor kinase A-triggered signaling pathways and increasing apoptosis. These results establish that vasoinhibin interaction with NGF and other neurotrophins may be critical in mediating pathways involved in neuronal survival and differentiation.

The Antidiabetic Drug Liraglutide Minimizes the Non-Cholinergic Neurotoxicity of the Pesticide Mipafox in SH-SY5Y Cells.

Organophosphorus (OPs) compounds have been widely used in agriculture, industry, and household, and the neurotoxicity induced by them is still a cause of concern. The main toxic mechanism of OPs is the inhibition of acetylcholinesterase (AChE); however, the delayed neuropathy induced by OPs (OPIDN) is mediated by other mechanisms such as the irreversible inhibition of 70% of NTE activity (neuropathy target esterase) that leads to axonal degeneration. Liraglutide is a long-lasting GLP-1 analog clinically used as antidiabetic. Its neurotrophic and neuroprotective effects have been demonstrated in vitro and in experimental models of neurodegenerative diseases. As in OPIDN, axonal degeneration also plays a role in neurodegenerative diseases. Therefore, this study investigated the protective potential of liraglutide against the neurotoxicity of OPs by using mipafox as a neuropathic agent (at a concentration able to inhibit and age 70% of NTE activity) and a neuronal model with SH-SY5Y neuroblastoma cells, which express both esterases. Liraglutide protected cells against the neurotoxicity of mipafox by increasing neuritogenesis, the uptake of glucose, the levels of cytoskeleton proteins, and synaptic-plasticity modulators, besides decreasing the pro-inflammatory cytokine interleukin 1ß and caspase-3 activity. This is the first study to suggest that liraglutide might induce beneficial effects against the delayed, non-cholinergic neurotoxicity of OPs.

Caffeic Acid Phenethyl Ester (CAPE) Protects PC12 Cells from Cisplatin-Induced Neurotoxicity by Activating the NGF-Signaling Pathway.

Cisplatin is a highly effective chemotherapeutic drug that is toxic to the peripheral nervous system. Findings suggest that axons are early targets of the neurotoxicity of cisplatin. Although many compounds have been reported as neuroprotective, there is no effective treatment against the neurotoxicity of cisplatin. Caffeic acid phenethyl ester (CAPE) is a propolis component with neuroprotective potential mainly attributed to antioxidant and anti-inflammatory mechanisms. We have recently demonstrated the neurotrophic potential of CAPE in a cellular model of neurotoxicity related to Parkinson's disease. Now, we have assessed the neurotrophic and neuroprotective effects of CAPE against cisplatin-induced neurotoxicity in PC12 cells. CAPE (10 µM) attenuated the inhibition of neuritogenesis and the downregulation of markers of neuroplasticity (GAP-43, synapsin I, synaptophysin, and 200-kD neurofilament) induced by cisplatin (5 µM). This concentration of cisplatin does not affect cell viability, and it was used in order to assess the early neurotoxic events triggered by cisplatin. When a lethal dose of cisplatin was used (IC50 = 32 µM), CAPE (10 µM) increased cell viability. The neurotrophic effect of CAPE is not dependent on NGF nor is it additive to the effect of NGF, but it might involve the activation of the NGF-high-affinity receptors (trkA). The involvement of other neurotrophin receptors such as trkB and trkC is unlikely. This is the first study to demonstrate the protective potential of CAPE against the neurotoxicity of cisplatin and to suggest the involvement of trkA receptors in the neuroprotective mechanism of CAPE. Based on these findings, the beneficial effect of CAPE on cisplatin-induced peripheral neuropathy should be further investigated.

Non-cytotoxic Concentration of Cisplatin Decreases Neuroplasticity-Related Proteins and Neurite Outgrowth Without Affecting the Expression of NGF in PC12 Cells.

Cisplatin is the most effective and neurotoxic platinum chemotherapeutic agent. It induces a peripheral neuropathy characterized by distal axonal degeneration that might progress to degeneration of cell bodies and apoptosis. Most symptoms occur nearby distal axonal branches and axonal degeneration might induce peripheral neuropathy regardless neuronal apoptosis. The toxic mechanism of cisplatin has been mainly associated with DNA damage, but cisplatin might also affect neurite outgrowth. Nevertheless, the neurotoxic mechanism of cisplatin remains unclear. We investigated the early effects of cisplatin on axonal plasticity by using non-cytotoxic concentrations of cisplatin and PC12 cells as a model of neurite outgrowth and differentiation. PC12 cells express NGF-receptors (trkA) and respond to NGF by forming neurites, branches and synaptic vesicles. For comparison, we used a neuronal model (SH-SY5Y cells) that does not express trkA nor responds to NGF. Cisplatin did not change NGF expression in PC12 cells and decreased neurite outgrowth in both models, suggesting a NGF/trkA independent mechanism. It also reduced axonal growth (GAP-43) and synaptic (synapsin I and synaptophysin) proteins in PC12 cells, without inducing mitochondrial damage or apoptosis. Therefore, cisplatin might affect axonal plasticity before DNA damage, NGF/trkA down-regulation, mitochondrial damage or neuronal apoptosis. This is the first study to show that neuroplasticity-related proteins might be early targets of the neurotoxic action of cisplatin and their role on cisplatin-induced peripheral neuropathy should be investigated in vivo.

Effects of GnRH on Neurite Outgrowth, Neurofilament and Spinophilin Proteins Expression in Cultured Spinal Cord Neurons of Rat Embryos.

It has been previously described the presence of GnRH receptor in spinal cord neurons of rat embryos and adult rats. However, the functional role of these receptors has not been studied. In this work, the effect of GnRH on neurite outgrowth and cytoskeletal protein expression in cultured spinal cord neurons of rat embryos was analyzed. Specifically, neurofilaments of 68 and 200 kDa by immunoblot assays and spinophilin mRNA expression by RT-PCR. Results show that GnRH stimulates neurite outgrowth in addition to an increase in neurofilaments and spinophilin expression. These findings suggest that GnRH may play a role as neuromodulator in neuronal plasticity and that could be considered as a potential factor for neuronal regeneration in spinal cord injuries.