Advanced type 1 diabetes is associated with ASIC alterations in mouse lower thoracic dorsal root ganglia neurons.

Acid-sensing ion channels (ASICs) from dorsal root ganglia (DRG) neurons are proton sensors during ischemia and inflammation. Little is known about their role in type 1 diabetes (T1D). Our study was focused on ASICs alterations determined by advanced T1D status. Primary neuronal cultures were obtained from lower (T9-T12) thoracic DRG neurons from Balb/c and TCR-HA(+/-)/Ins-HA(+/-) diabetic male mice (16 weeks of age). Patch-clamp recordings indicate a change in the number of small DRG neurons presenting different ASIC-type currents. Multiple molecular sites of ASICs are distinctly affected in T1D, probably due to particular steric constraints for glycans accessibility to the active site: (i) ASIC1 current inactivates faster, while ASIC2 is slower; (ii) PcTx1 partly reverts diabetes effects against ASIC1- and ASIC2-inactivations; (iii) APETx2 maintains unaltered potency against ASIC3 current amplitude, but slows ASIC3 inactivation. Immunofluorescence indicates opposite regulation of different ASIC transcripts while qRT-PCR shows that ASIC mRNA ranking (ASIC2 > ASIC1 > ASIC3) remains unaltered. In conclusion, our study has identified biochemical and biophysical ASIC changes in lower thoracic DRG neurons due to advanced T1D. As hypoalgesia is present in advanced T1D, ASICs alterations might be the cause or the consequence of diabetic insensate neuropathy.

TRPV1 properties in thoracic dorsal root ganglia neurons are modulated by intraperitoneal capsaicin administration in the late phase of type-1 autoimmune diabetes.

Pharmacological therapies in type 1 diabetes for efficient control of glycemia and changes in pain alterations due to diabetic neuropathy are a continuous challenge. Transient receptor potential vanilloid type 1 (TRPV1) from dorsal root ganglia (DRG) neurons is one of the main pharmacological targets in diabetes, and its ligand capsaicin can be a promising compound for blood-glucose control. Our goal is to elucidate the effect of intraperitoneal (i.p.) capsaicin administration in type 1 diabetic mice against TRPV1 receptors from pancreatic DRG primary afferent neurons. A TCR(+/-)/Ins-HA(+/-) diabetic mice (dTg) was used, and patch-clamp and immunofluorescence microscopy measurements have been performed on thoracic T(9)-T(12) DRG neurons. Capsaicin (800 µg/kg, i.p. three successive days) administration in the late-phase diabetes reduces blood-glucose levels, partly reverses the TRPV1 current density and recovery time constant, without any effect on TRPV1 expression general pattern, in dTg mice. A TRPV1 hypoalgesia profile was observed in late-phase diabetes, which was partly reversed to normoalgesic profile upon capsaicin i.p. administration. According to the soma dimensions of the thoracic DRG neurons, a detailed analysis of the TRPV1 expression upon capsaicin i.p. treatment was done, and the proportion of large A-fiber neurons expressing TRPV1 increased in dTg capsaicin-treated mice. In conclusion, the benefits of low-dose capsaicin intraperitoneal treatment in late-phase type-1 diabetes should be further exploited.

Double transgenic mice--a suitable model for studying oxidative stress in type 1 diabetes mellitus.

Type 1 diabetes mellitus (T1DM), one of the most prevalent chronic diseases is characterized by the progressive destruction of pancreatic beta cells, leading to insulin deficiency and hyperglycemia. Studies performed on diabetic subjects with prolonged hyperglycemia showed the oxidative stress occurrence followed by molecular, cellular and tissue damage. Currently, reducing the oxidative stress represents a therapeutic target, in order to reduce its complications in diabetic patients. An adequate experimental model of type 1 diabetes represents a prerequisite in oxidative stress study, therefore, we assessed oxidative status in polymorphonuclear cells (PMNs) and peritoneal macrophages using a double transgenic (dTg) mouse model of type 1 diabetes. Our results revealed the increased production of reactive oxygen species (superoxide anion and H2O2) and nitrogen (nitric oxide) species in diabetic mice leading to the idea of oxidative stress model for the study of its complications in type 1 diabetes.

Capsaicin short term administration effect on different immune parameters.

Type 1 diabetes is an autoimmune disease affecting a higher and higher number of persons; for this reason, the study of diabetes, and its complications, has shown a major interest. In order to highlight the modifications appeared in this disease, it is essential to use a suitable model. In "Cantacuzino" NIRDMI there is a double transgenic murine model which develops a fulminating form of type 1 diabetes. Previous studies indicate the usefulness of this diabetic murine model in order to study neuropathy. Capsaicin treatment is one method to reduce neuropathic pain. This study was based on the assumption that intraperitoneal administration of a low dose of capsaicin, on a short period of time, can decrease pain sensations generation and transmission. If from the neurological point of view, capsaicin effects are known, its effects on the immune system are not clear yet. Therefore, in this study we have investigated capsaicin effects on oxygen and nitrogen free radicals generation by phagocytic immune cells, in lymphocyte populations, and also capsaicin effects on plasmatic protein oxidation. Our results point to minor modifications in oxygen reactive species production, simultaneous with a significantly decrease in nitric oxide generation, without affecting lymphocyte populations. Therefore, capsaicin short term administration can be used to reduce pain sensations, without the impairment of immune parameters.

Antibody and splenocyte proliferation response to whole inactivated Streptococcus pneumoniae serotype 1, 3 and 6B in mice.

Animal models of infection and protection on the topic of the Streptococcus pneumoniae (S. pneumoniae) have encountered many difficulties generated by low immunogenicity, a characteristic of polysaccharide capsular bacteria and difference of virulence between serotypes and strains. We have explored the immune response after immunization with heat inactivated S. pneumoniae serotype 1, 3 and 6B in C57BL/6 mice by IgM and IgG detection, and by splenocyte in vitro 5-ethynyl-2'-deoxyuridine (EdU) incorporation after antigen specific stimulation, as a proposed method of cellular immune response evaluation. Antibody titer persistence after immunization was not lengthy while antigen specific proliferation response detected by EdU assay was remnant. Intraperitoneal (i.p.) challenge with serotype 6B S. pneumoniae proved that antibody titers and the detected specific cellular immune response do not cover seroprotective necessity and do not confer improved immunologic memory in comparison to non-immunized mice, which show natural resistance.

Evaluation of the efficacy of a specific hyperimmune serum in experimental influenza infection in mice.

Serotherapy still remains a way of treatment in some diseases, and it could be consider superior to any other mode of action because the protecting substances of the body are the products of the organism itself. The aim of the study was to establish an "in vivo" method for testing the efficacy of therapeutic serum. Hyperimmune serum for influenza A/PR8/34 viral strain, was prepared in sheep, and tested for inhibition of haemagglutination and microneutralisation. Seroprotection was evaluated in mice one day after being challenged with a lethal dose of the same virus. Our study shows that protection occurred in all mice treated with undiluted hyperimmune serum one day post infection (no clinical signs, faster recovery of the body weight after the first three days of the infection, all mice survived).