Sex differences in a mouse model of multiple sclerosis: neuropathic pain behavior in females but not males and protection from neurological deficits during proestrus

Background

Multiple sclerosis (MS), a demyelinating disease of the central nervous system, is one of the most prevalent neurological disorders in the industrialized world. This disease afflicts more than two million people worldwide, over two thirds of which are women. MS is typically diagnosed between the ages of 20–40 and can produce debilitating neurological impairments including muscle spasticity, muscle paralysis, and chronic pain. Despite the large sex disparity in MS prevalence, clinical and basic research investigations of how sex and estrous cycle impact development, duration, and severity of neurological impairments and pain symptoms are limited. To help address these questions, we evaluated behavioral signs of sensory and motor functions in one of the most widely characterized animal models of MS, the experimental autoimmune encephalomyelitis (EAE) model.

Methods

C57BL/6 male and female mice received flank injection of complete Freund’s adjuvant (CFA) or CFA plus myelin oligodendrocyte glycoprotein 35-55 (MOG_35-55) to induce EAE. Experiment 1 evaluated sex differences of EAE-induced neurological motor deficits and neuropathic pain-like behavior over 3 weeks, while experiment 2 evaluated the effect of estrous phase in female mice on the same behavioral measures for 3 months. EAE-induced neurological motor deficits including gait analysis and forelimb grip strength were assessed. Neuropathic pain-like behaviors evaluated included sensitivity to mechanical, cold, and heat stimulations. Estrous cycle was determined daily via vaginal lavage.

Results

MOG_35-55-induced EAE produced neurological impairments (i.e., motor dysfunction) including mild paralysis and decreases in grip strength in both females and males. MOG_35-55 produced behavioral signs of neuropathic pain—mechanical and cold hypersensitivity—in females, but not males. MOG_35-55 did not change cutaneous heat sensitivity in either sex. Administration of CFA or CFA?+?MOG_35-55 prolonged the time spent in diestrus for 2 weeks, after which normal cycling returned. MOG_35-55 produced fewer neurological motor deficits when mice were in proestrus relative to non-proestrus phases.

Conclusions

We conclude that female mice are superior to males for the study of neuropathic pain-like behaviors associated with MOG_35-55-induced EAE. Further, proestrus may be protective against EAE-induced neurological deficits, thus necessitating further investigation into the impact that estrous cycle exerts on MS symptoms.

     

RNA Binding to CBP Stimulates Histone Acetylation and Transcription

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Selenomethionine protects against adverse biological effects induced by space radiation

Ionizing radiation-induced adverse biological effects impose serious challenges to astronauts during extended space travel. Of particular concern is the radiation from highly energetic, heavy, charged particles known as HZE particles. The objective of the present study was to characterize HZE particle radiation-induced adverse biological effects and evaluate the effect of D-selenomethionine (SeM) on the HZE particle radiation-induced adverse biological effects. The results showed that HZE particle radiation can increase oxidative stress, cytotoxicity, and cell transformation in vitro, and decrease the total antioxidant status in irradiated Sprague-Dawley rats. These adverse biological effects were all preventable by treatment with SeM, suggesting that SeM is potentially useful as a countermeasure against space radiation-induced adverse effects. Treatment with SeM was shown to enhance ATR and CHK2 gene expression in cultured human thyroid epithelial cells. As ionizing radiation is known to result in DNA damage and both ATR and CHK2 gene products are involved in DNA damage, it is possible that SeM may prevent HZE particle radiation-induced adverse biological effects by enhancing the DNA repair machinery in irradiated cells.     

Lack of nitric oxide synthase depresses ion transporting enzyme function in cardiac muscle

Nitric oxide (NO*) is produced endogenously from NOS isoforms bound to sarcolemmal (SL) and sarcoplasmic reticulum (SR) membranes. To investigate whether locally generated NO* directly affects the activity of enzymes mediating ion active transport, we studied whether knockout of selected NOS isoforms would affect the functions of cardiac SL (Na+ + K+)-ATPase and SR Ca2+-ATPase. Cardiac SL and SR vesicles containing either SL (Na+ + K+)-ATPase or SR Ca2+-ATPase were isolated from mice lacking either nNOS or eNOS, or both, and tested for enzyme activities. Western blot analysis revealed that absence of single or double NOS isoforms did not interrupt the protein expression of SL (Na+ + K+)-ATPase and SR Ca2+-ATPase in cardiac muscle cells. However, lack of NOS isoforms in cardiac muscle significantly altered both (Na+ + K+)-ATPase activity and SR Ca2+-ATPase function. Our experimental results suggest that disrupted endogenous NO* production may change local redox conditions and lead to an unbalanced free radical homeostasis in cardiac muscle cells which, in turn, may affect key enzyme activities and membrane ion active transport systems in the heart.     

Routes to improving the reliability of low level DNA analysis using real-time PCR

Background  

Accurate quantification of DNA using quantitative real-time PCR at low levels is increasingly important for clinical, environmental and forensic applications. At low concentration levels (here referring to under 100 target copies) DNA quantification is sensitive to losses during preparation, and suffers from appreciable valid non-detection rates for sampling reasons. This paper reports studies on a real-time quantitative PCR assay targeting a region of the human SRY gene over a concentration range of 0.5 to 1000 target copies. The effects of different sample preparation and calibration methods on quantitative accuracy were investigated.     

Oncogene expression in vivo by ovarian adenocarcinomas and mixed-mullerian tumors

Six-micron paraffin sections of paraformaldehyde-fixed specimens of 24 ovarian benign and neoplastic specimens were assayed for tumor cell-specific oncogene expression by a sensitive, quantitative in situ hybridization technique with probes for 17 oncogenes, beta-actin, and E. coli beta-lactamase. In the benign, borderline, and invasive adenocarcinomas, multiple oncogenes, including neu, fes, fms, Ha-ras, trk, c-myc, fos, and PDGF-A chains, were expressed at significant levels relative to a housekeeping gene (beta-actin). In the mixed-Mullerian tumors, a rather different pattern of oncogene expression was observed, characterized primarily by expression of sis (PDGF-B chain). For the adenocarcinomas, statistical analysis demonstrated that expression of several genes (fms, neu, PDGF-A) was closely linked to others (c-fos, c-myc) known to have important roles in the control of cell proliferation, but only one gene, fms, correlated very strongly with clinicopathologic features (high FIGO histologic grade and high FIGO clinical stage) predictive of aggressive clinical behavior and poor outcome. The authors discuss the role that tumor epithelial cell expression of the fms gene product might play in the auto- and paracrine control of growth and dissemination of ovarian adenocarcinomas.