Effects of copper-impregnated collagen implants on local pro- and anti-inflammatory and regenerative tissue reactions following implantation in rats.

Combining collagen, an established regenerative biomaterial, and copper (Cu) with its known antibacterial and angiogenic effects could improve wound healing. However, Cu is also cytotoxic. Thus, this study aimed at examining the tissue reactions after simultaneous intramuscular implantation of collagen discs either without Cu (controls) or impregnated in 2, 20, or 200 mmol/L Cu acetate in 24 rats. After 7, 14, and 56 days, implants with peri-implant tissue were retrieved from 8 rats/day for immunohistochemical detection of CD68+ monocytes/macrophages and CD163+ macrophages, MHC-II+ cells, T lymphocytes and nestin as tissue regeneration marker. CD68+ monocytes/macrophages around implants increased with Cu amount but decreased over time except for the highest Cu amount, while CD163+ macrophages increased over time around and within implants. MHC-II+ cells were similar to CD68+ monocytes/macrophages. T lymphocyte numbers around implants were higher for Cu-impregnated samples vs. controls on day 7 and highest on day 14, but declined afterwards. Nestin expression around and within implants was largely unaffected by Cu. In conclusion, pro-inflammatory reactions around implants were dose-dependently influenced by Cu but mostly decreased over time, while Cu did not negatively affect anti-inflammatory and regenerative reactions. These results suggest that Cu-impregnated collagen could be beneficial in wound treatment.

The in vivo inflammatory and foreign body giant cell response against different poly(l-lactide-co-d/l-lactide) implants is primarily determined by material morphology rather than surface chemistry.

Biomaterials can cause a chronic local inflammation called foreign body reaction, with formation of foreign body giant cells (FBGC) by monocyte/macrophage fusion. However, FBGC appearance and role for biomaterials with different physicochemical properties are not yet fully understood. This study aimed at examining FBGC and inflammatory cells after intramuscular implantation of poly(l-lactide-co-d/l-lactide) (PLA) as membranes and uncoated electro-spun fiber meshes or meshes with a positively charged plasma-polymer coating into rats. After 7, 14 and 56 days, CD68+ and CD163+ macrophages, T lymphocytes, MHC-II+ cells, FBGC, and nestin-stained tissue area as regeneration marker were morphometrically analyzed. FBGC occurrence was primarily determined by material morphology, as their numbers for meshes were 10-fold higher during acute and 50-fold higher during chronic inflammation than for membranes but comparable between uncoated and coated meshes. CD68+ macrophages decreased around and within meshes, while CD163+ macrophages and MHC-II+ cells increased within meshes. T lymphocytes within meshes were higher for coated meshes, suggesting that the peri-implant tissue immunological response is also influenced by surface chemistry. FBGC were predominantly CD68+ and CD163- , and nestin-stained tissue area was negatively correlated with CD68+ monocytes/macrophages numbers and positively correlated with CD163+ macrophages numbers, highlighting differing roles in FBGC formation and tissue regeneration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2726-2734, 2018.

A Cell-Adhesive Plasma Polymerized Allylamine Coating Reduces the In Vivo Inflammatory Response Induced by Ti6Al4V Modified with Plasma Immersion Ion Implantation of Copper.

Copper (Cu) could be suitable to create anti-infective implants based on Titanium (Ti), for example by incorporating Cu into the implant surface using plasma immersion ion implantation (Cu-PIII). The cytotoxicity of Cu might be circumvented by an additional cell-adhesive plasma polymerized allylamine film (PPAAm). Thus, this study aimed to examine in vivo local inflammatory reactions for Ti6Al4V implants treated with Cu-PIII (Ti-Cu), alone or with an additional PPAAm film (Ti-Cu-PPAAm), compared to untreated implants (Ti). Successful Cu-PIII and PPAAm treatment was confirmed with X-ray Photoelectron Spectroscopy. Storage of Ti-Cu and Ti-Cu-PPAAm samples in double-distilled water for five days revealed a reduction of Cu release by PPAAm. Subsequently, Ti, Ti-Cu and Ti-Cu-PPAAm samples were simultaneously implanted into the neck musculature of 24 rats. After 7, 14 and 56 days, peri-implant tissue was retrieved from 8 rats/day for morphometric immunohistochemistry of different inflammatory cells. On day 56, Ti-Cu induced significantly stronger reactions compared to Ti (tissue macrophages, antigen-presenting cells, T lymphocytes) and to Ti-Cu-PPAAm (tissue macrophages, T lymphocytes, mast cells). The response for Ti-Cu-PPAAm was comparable with Ti. In conclusion, PPAAm reduced the inflammatory reactions caused by Cu-PIII. Combining both plasma processes could be useful to create antibacterial and tissue compatible Ti-based implants.

Corrigendum to 'In vivo evaluation of copper release and acute local tissue reactions after implantation of copper-coated titanium implants in rats'.

In the "Materials and methods" chapter of the article given above, in section 2.1 titled "Implant samples and preparation" on page 2 (top paragraph of the right column), an incorrect value of 1 µg mm-2 for the average Cu load of the surface was inadvertently specified. This was due to an accidental mix-up of electronic data sets from examination of different implant series. The correct value is 0.2 µg mm-2. No other data given in the article are affected. The authors kindly apologize for this mistake.

Acute and chronic local inflammatory reaction after implantation of different extracellular porcine dermis collagen matrices in rats.

Two cross-linked acellular porcine dermal collagen matrices (Permacol and NRX) were implanted into rats and the acute and chronic local inflammatory tissue reactions were investigated after 7, 14, 28, and 112 days. Both membranes were stable in vivo for up to 112 days. All investigated immune cell populations (CD68+ macrophages, CD163+ macrophages, T lymphocytes, MHC class II positive cells, mast cells, and NK cells) were present. Their amount decreased significantly over time compared to day 7 after implantation. A change from an acute to a chronic inflammation and an associated shift from proinflammatory M1-like to anti-inflammatory M2-like macrophages were observed. In the early phase there was a significant correlation of T cells to CD68+ (M1-like) macrophages, whereas in the chronic phase T lymphocytes were positively correlated with CD163+ (M2-like) macrophages. The material NRX showed an enhanced inflammatory reaction in comparison to Permacol possibly caused by material characteristics such as a twofold higher thickness of the membrane, roughness, and water absorption capacity. Nevertheless, a more pronounced regenerative process as, for example, indicated by nestin expression demonstrated its possible suitability for applications as wound repair material.

Systemic IFNγ predicts local implant macrophage response.

Implantation of biomaterials can cause complications often associated with inflammatory reactions. However, repeated evaluation of the implant site would be burdening for patients. Alternatively, blood examinations with analysis of inflammatory serum markers could potentially be useful to reflect the local cellular response for detection and/or prediction of inflammation-related complications. Therefore, following intramuscular implantation of surface-modified Ti implants in rats, this study aimed at examining possible associations between the post-implantation time course of pro-inflammatory (INFγ, IL-2) and anti-inflammatory (IL-4, IL-10) cytokine serum concentrations and the local peri-implant tissue response after 56 days (pro-inflammatory CD68-positive monocytes/macrophages, anti-inflammatory CD163-positive macrophages, MHC class II-positive cells, activated natural killer cells and mast cells). Multivariate correlation analysis revealed a significant interaction between serum IFNγ and peri-implant tissue CD68-positive monocytes/macrophages (p = 0.001) while no interactions were found for other cytokines and cell types. Additional Pearson correlation analysis of IFNγ serum concentrations on each experimental day vs. the CD68-positive monocytes/macrophages response on day 56 demonstrated a consistently positive correlation that was strongest during the first three weeks. Thus, high early pro-inflammatory IFNγ serum concentration was associated with high late number of pro-inflammatory CD68-positive monocyte/macrophages and low early serum IFNγ with low late CD68-positive monocyte/macrophage numbers. Further studies aimed at examination of patient samples could establish the relevance of this association to predict clinical complications. After implantation of titanium samples, high early IFNγ serum concentrations were associated with a pronounced late pro-inflammatory CD68-positive monocyte/ macrophage (red circle) response, while no correlation was found for other investigated cytokines and inflammatory cells (green circle). In contrast, low early IFNγ serum concentrations were correlated with low late monocyte/ macrophage numbers.

In vivo evaluation of copper release and acute local tissue reactions after implantation of copper-coated titanium implants in rats.

Copper (Cu) based coatings can reduce infections for titanium (Ti) implants. However, Cu is also cytotoxic. To examine the balance of antibacterial versus adverse tissue effects, this study aimed at evaluating a Cu coating regarding in vivo Cu release and local inflammatory reactions for 72 h. TiAl6V4 plates received either plasma electrolytic oxidation only (Ti), or an additional galvanic Cu deposition (Ti-Cu). No Staphylococcus aureus were found in vitro on Ti-Cu after 24 h. Following simultaneous intramuscular implantation of two Ti and two Ti-Cu plates into nine rats, serum Cu was elevated until 48 h and residual Cu on explanted samples reduced accordingly after 48 h. Total and tissue macrophages around implants increased until 72 h for both series, and were increased for Ti-Cu. As numbers of total and tissue macrophages were comparable, macrophages were probably tissue-derived. MHC-class-II-positive cells increased for Ti-Cu only. T-lymphocytes had considerably lower numbers than macrophages, did not increase or differ between both series, and thus had minor importance. Tissue reactions increased beyond Cu release, indicating effects of either surface-bound Cu or more likely the implants themselves. Altogether, Ti-Cu samples possessed antibacterial effectiveness in vitro, released measurable Cu amounts in vivo and caused a moderately increased local inflammatory response, demonstrating anti-infective potential of Cu coatings.

Serum profile of pro- and anti-inflammatory cytokines in rats following implantation of low-temperature plasma-modified titanium plates.

Surface modification of Titanium (Ti) by low-temperature plasma influences cell-material interactions. Therefore, this study aimed at examining serum cytokine levels and associations after intramuscular implantation (n = 8 rats/group) of Ti-plates with Plasma Polymerized Allyl Amine (Ti-PPAAm), Plasma Polymerized Acrylic Acid (Ti-PPAAc), and without such layers (Ti-Controls). Pro-inflammatory (IL-2, IFNγ, IL-6) and anti-inflammatory (IL-4, IL-10, IL-13) cytokines were measured weekly for 56 days. Ti-PPAAm caused increased IL-2 (d7-14, d35), increased IFNγ (d35) and decreased IL-10 (d35, d49-56). Ti-PPAAc induced divergent anti-inflammatory cytokine changes with increased IL-4 (d28-56) and decreased IL-10 (d42-56). Ti-Controls elicited increased IL-2 (d42) and IFNγ (d35-42, d56). IL-6 was not detected and IL-13 only in three samples, thus they do not influence the response against these Ti implants. Correlation analysis revealed surface-dependent associations between cytokines indicating the involvement of different inflammatory cell populations. Concluding, different plasma modifications induce specific serum cytokine profiles and associations indicating distinct inflammatory responses.

Talin, vinculin and nestin expression in orofacial muscles of dystrophin deficient mdx mice.

The activity of cytoskeletal proteins like talin, vinculin and nestin increases in muscle that regenerates. Little is known about their role or at least their expression in the process of regeneration in masticatory muscles of mdx mice, a model of Duchenne muscular dystrophy. To determine a potential role of cytoskeletal proteins in the regeneration process of mdx masticatory muscles, we examined the expression of talin 1, talin 2, vinculin and nestin in 100-day-old control and mdx mice using quantitative RT-PCR, Western blot analyses and histochemistry. The protein expression of talin 1, talin 2, nestin and vinculin in mdx muscles remained unchanged as compared with normal mice. However, in mdx masseter it was found a relative increase of nestin compared to controls. The protein expression of talin 1 and vinculin tended to be increased in mdx tongue and talin 2 to diminish in mdx masseter and temporal muscle. In mdx mice, we found significantly lower percentage of transcripts coding for nestin, talin 1, talin 2 and vinculin in masseter (p < 0.05) and temporal muscle (p < 0.001). In contrast, the mRNA expression of nestin was found to be increased in mdx tongue. Activated satellite cells, myoblasts and immature regenerated muscle fibres in mdx masseter and temporal revealed positive staining for nestin. The findings of the presented work suggest dystrophin-lack-associated changes in the expression of cytoskeletal proteins in mdx masticatory muscles could be compensatory for dystrophin absence. The expression of nestin may serve as an indicator for the regeneration in the orofacial muscles.

Myogenic differentiation factor 1 and myogenin expression not elevated in regenerated masticatory muscles of dystrophic (mdx) mice.

BACKGROUND: Orofacial muscles in mdx mice, a model of Duchenne muscular dystrophy (DMD), undergo muscle necrosis followed by muscle regeneration. The activity of myogenic regulatory factors (MRF) in muscles that regenerate may reveal specific changes. Little is known about the role of MRF, particularly their expression after muscle necrosis in the orofacial muscles of mdx mice and in DMD. Patients suffering from DMD present characteristic malocclusions in association with orofacial dysfunctions. Investigating the role of MRFs in mdx masticatory muscles may help to develop preventive and therapeutic strategies for DMD. MATERIAL AND METHODS: Using Western Blot analysis, we examined the protein expression of MRFs (myogenin and MyoD1) in masticatory muscles such as masseter, temporal, and tongue muscle and one hindlimb muscle, the soleus of control and mdx mice (n = 6-7). The mean optical density (MOD) of proteins was measured for quantification. RESULTS: Myogenin and MyoD1 were detected in mdx and control mice. The amount of myogenin in masseter (MOD, mean ± standard error of the mean (SEM), control vs. mdx: 3.08 ± 0.67 vs. 1.83 ± 0.33), tongue (MOD control vs. mdx: 1.53 ± 0.22 vs. 1.41 ± 0.14), temporal (MOD control vs. mdx: 1.23 ± 0.16 vs. 1.43 ± 0.35), and soleus muscles (MOD, control vs. mdx: 1.95 ± 0.26 vs. 2.31 ± 0.42) did not differ between the mouse strains. MyoD1 amounts in mdx, similar to that of myogenin, remained unchanged when compared to control mice (MOD control vs. mdx: masseter 0.75 ± 0.09 vs. 0.86 ± 0.13; tongue 1.55 ± 0.25 vs. 1.41 ± 0.28; temporal 0.71 ± 0.10 vs. 0.73 ± 0.11; soleus 1.09 ± 0.26 vs. 1.03 ± 0.24). CONCLUSION: The results indicate that protein expression of MyoD1 and myogenin in mdx mice does not differ from controls, suggesting a secondary role of MyoD1 and myogenin in the regeneration stage of mdx orofacial muscles.

Caveolin-1, caveolin-3 and VEGF expression in the masticatory muscles of mdx mice.

Duchenne muscular dystrophy (DMD) and murine X-linked muscular dystrophy (mdx), its murine model, are characterized by muscle damage and muscle weakness associated with inflammation and new vessel formation. Caveolins, dystrophin-associated proteins, are involved in the pathogenesis of DMD, because increased numbers of caveolae are found in DMD and mdx hindlimb muscles. Caveolae influence angiogenesis due to their content of vascular endothelial growth factor (VEGF) receptors. Orofacial muscles in mdx mice undergo muscle necrosis followed by muscle regeneration. To ascertain the role of caveolins and VEGF in the pathogenesis of dystrophic masticatory muscles, we examined the expression of caveolin-1 (cav-1), caveolin-3 (cav-3) and VEGF in control and mdx mice. In mdx masticatory muscles, no changes in transcript and protein levels of VEGF were found, whereas cav-1 and cav-3 expression was increased. Using immunohistochemistry, a strong sarcolemmal staining of caveolin-3 in regenerated muscle fibers was found. Furthermore, immunohistochemistry with the caveolin-1 antibody showed an increase in the amount of blood vessels in areas with regenerating muscle fibers. Dystrophic masticatory muscles showed changes comparable to those of hindlimb muscles in the expression of cav-1 and cav-3. The angiogenesis seems to be unaffected in the jaw muscles of mdx mice. We speculate that the increased caveolin expression could cause extensive and efficient muscle regeneration.

Examination of the inflammatory response following implantation of titanium plates coated with phospholipids in rats.

Implantation of biomaterials like titanium (Ti) causes inflammatory reactions possibly affecting implant functionality. Surface modifications could improve biocompatibility and functionality of implants. Biomembrane-derived phospholipids might be useful as implant coating due to their biomimetic properties. In vitro studies demonstrated beneficial effects for 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphoethanolamin (POPE) as coating regarding interactions with cells and bacteria. Therefore, this in vivo study aimed at examining local inflammatory reactions after implantation of POPE-coated Ti plates. Ti implants with POPE attached non-covalently or covalent via octadecylphosphonic acid (OPA), with OPA alone and uncoated controls were simultaneously implanted intramuscularly in rats for 7, 14 and 56 days. The peri-implant tissue was quantitatively analyzed by immunohistochemistry for total macrophages, tissue macrophages, T cells, antigen-presenting cells and proliferating cells. Overall, both POPE-coated series were comparable to the controls. Furthermore, no differences were found between POPE coating on a covalently linked OPA monolayer and POPE coating dried from solution. Together with earlier in vitro results, this demonstrates the potential of phospholipids for implant surface modification.

The expression of myogenic regulatory factors and muscle growth factors in the masticatory muscles of dystrophin-deficient (mdx) mice.

The activities of myogenic regulatory factors (MRF) and muscle growth factors increase in muscle that is undergoing regeneration, and may correspond to some specific changes. Little is known about the role of MRFs in masticatory muscles in mdx mice (the model of Duchenne muscular dystrophy) and particularly about their mRNA expression during the process of muscle regeneration. Using Taqman RT-PCR, we examined the mRNA expression of the MRFs myogenin and MyoD1 (myogenic differentiation 1), and of the muscle growth factors myostatin, IGF1 (insulin-like growth factor) and MGF (mechano-growth factor) in the masseter, temporal and tongue masticatory muscles of mdx mice (n = 6 to 10 per group). The myogenin mRNA expression in the mdx masseter and temporal muscle was found to have increased (P < 0.05), whereas the myostatin mRNA expressions in the mdx masseter (P < 0.005) and tongue (P < 0.05) were found to have diminished compared to those for the controls. The IGF and MGF mRNA amounts in the mdx mice remained unchanged. Inside the mdx animal group, gender-related differences in the mRNA expressions were also found. A higher mRNA expression of myogenin and MyoD1 in the mdx massterer and temporal muscles was found in females in comparison to males, and the level of myostatin was higher in the masseter and tongue muscle (P < 0.001 for all comparisons). Similar gender-related differences were also found within the control groups. This study reveals the intermuscular differences in the mRNA expression pattern of myogenin and myostatin in mdx mice. The existence of these differences implies that dystrophinopathy affects the skeletal muscles differentially. The finding of gender-related differences in the mRNA expression of the examined factors may indicate the importance of hormonal influences on muscle regeneration.

Differential expression of myosin heavy chain isoforms in the masticatory muscles of dystrophin-deficient mice.

The dystrophin-deficient mouse (mdx) is a homologue animal model of Duchenne muscular dystrophy (DMD) and is characterized by slowly progressive muscle weakness accompanied by changes in myosin heavy chain (MyHC) composition. It is likely that the masticatory muscles undergo similar changes. The aim of this study was to examine the masticatory muscles (masseter, temporal, tongue, and soleus) of 100-day-old mdx and control mice (n = 8-10), and the fibre type distribution (by immunohistochemistry) as well as the expression of the corresponding MyHC messenger RNA (mRNA) (protein and mRNA expression, using Western blot or quantitative real-time polymerase chain reaction (RT-PCR)). Immunohistochemistry and western blot analysis revealed that the masticatory muscles in the control and mdx mice consisted mainly of type 2 fibres, whereas soleus muscle consisted of both type 1 and 2 fibres. In the masseter muscle, the mRNA in mdx mice was not different from that found in the controls. However, the mRNA content of the MyHC-2b isoform in mdx mice was lower in comparison with the controls in the temporal muscle [11.9 versus 36.9 per cent; P < 0.01; mean ± standard error of the mean (SEM), Student's unpaired t-test], as well as in the tongue muscle (65.7 versus 73.8 per cent; P < 0.05). Similarly, the content of MyHC-2x isoforms in mdx tongue muscle was lower than in the controls (25.9 versus 30.8 per cent; P < 0.05). The observed down-regulation of the MyHC-2x and MyHC-2b mRNA in the masticatory muscles of mdx mice may lead to changed fibre type composition. The different MyHC gene expression in mdx mice masticatory muscles may be seen as an adaptive mechanism to muscular dystrophy.

Histological changes in masticatory muscles of mdx mice.

OBJECTIVE: Duchenne muscular dystrophy (DMD) patients have distorted dentofacial morphology that could be a result of changed force balance of masticatory muscles due to unequal dystrophic changes in various masticatory muscles. Skeletal muscles of DMD patients and those of murine model of DMD - mdx mice - are both characterized by Ca(2+) induced muscle damage, muscle weakness and characteristic histological changes. Therefore, to determine the pathological changes in this animal model of DMD, we examined the masticatory muscles of the mdx mice for histological abnormalities including nuclei localization, fibre diameters, and collagen expression. DESIGN: Muscle sections from masseter (MAS), temporal (TEM), tongue (TON) and soleus (SOL) of mdx and control normal mice were stained with hemalaun/eosin or with Sirius Red and morphometrically analysed. Levels of collagen staining in normal and mdx muscles were measured using image analysis and the mean optical density (mod) was determined. RESULTS: Dystrophin deficient masticatory muscles contained 11-75% fibres with centralised nuclei. In mdx mice an increased mean fibre diameter was observed as compared to the age-matched control muscles (control vs. mdx; MAS: 33.44+/-0.49microm vs. 37.76+/-0.68microm, p<0.005; TEM: 32.93+/-0.4microm vs. 42.93+/-0.68microm, p<0.005; SOL: 33.15+/-0.29microm vs. 40.62+/-0.55microm, p<0.005; TON: 13.44+/-0.68microm vs. 15.63+/-0.18microm, p<0.005). Increased expression of collagen was found in MAS (mod control vs. mdx: 1.34 vs. 3.99, p<0.005), TEM (mod control vs. mdx: 3.11 vs. 4.73, p<0.01) and SOL (mod control vs. mdx: 2.36 vs. 3.49, p<0.01). CONCLUSION: Our findings revealed that mdx masticatory muscles are unequally affected by the disease process. The masticatory muscles of the mdx mice could present a useful model for further investigating the influence of dystrophin deficiency on muscles function.

Morphometric immunohistochemical examination of the inflammatory tissue reaction after implantation of calcium phosphate-coated titanium plates in rats.

Calcium phosphate (CaP) preparations are established coatings for titanium-based medical implants used for bone reconstruction. However, biodegradation of the coating can result in microparticles that subsequently cause inflammatory reactions. The present study was therefore aimed at investigating the inflammatory response to two series of CaP-coated titanium plates: Ti-brushite (Ti-B) and Ti-hydroxyapatite (Ti-H) implants. Fifteen male LEW.1A rats received one plate of each series and a pellet (5 x 2 mm) of sol-gel derived silica/CaP (SCP implants) implanted into the back musculature. After 7, 14 and 28 days, five rats were killed and the implants were removed with the surrounding tissue. Quantitative immunohistochemistry was performed on frozen sections. Total monocytes/macrophages, tissue macrophages, T-cells, MHC-class-II-positive cells and proliferating cells were counted. For the Ti-B implants, the number of monocytes/macrophages remained constant while the other cell populations increased. In contrast, for the Ti-H implants the number of monocytes/macrophages decreased while the other cell populations remained constant. The SCP implants demonstrated degradation and scattering into smaller particles with an increase for all cell populations except the proliferating cells. Human mesenchymal stem cells demonstrated adherence and a flat morphology on Ti-B and Ti-H implants and no remarkable difference between both implants. Taken together, the in vivo data demonstrate that the short-term inflammatory response against a hydroxyapatite coating is lower in comparison to a brushite coating, and that the morphology of cells growing in vitro is similar on both layers.

Heterogeneous distribution of TRPC proteins in the embryonic cortex.

The present study was initiated to gain some information about the tissue distribution of transient receptor potential proteins of C-type (TRPC), a family of voltage-independent cation channels, at the beginning of neurogenesis in the telencephalon of embryonic mice. The mRNAs of all known TRPCs (TRPC1-TRPC7) could be found in the cortex at E13. TRPC1, TRPC3 and TRPC5 were the main isoforms, whereas the mRNAs for TRPC2, TRPC4, TRPC6 and TRPC7 were less abundant. The distribution throughout the cortical wall of TRPC1, TRPC3 and TRPC6 was studied by means of immuno-histochemistry. The data collected pointed to a heterogeneous expression of the channels. Three groups were identified. The first one comprises TRPC1, specifically found in the preplate but only in some post-mitotic neurons. It was mainly observed in a subset of cells distinct from the Cajal-Retzius cells. The second group is composed of TRPC3. It was found in non-neuronal cells and also in dividing (5-bromo-2'-deoxyuridine-positive) cells, indicating that TRPC3 is present in precursor cells. The third group contains TRPC6 detected in neuronal and in dividing non-neuronal cells. Double immunostaining experiments showed that TRPC3-positive cells also express TRPC6. Collectively, this report highlights a specific TRPC expression pattern in the immature cortical wall.

Diacylglycerol analogues activate second messenger-operated calcium channels exhibiting TRPC-like properties in cortical neurons.

The lipid diacylglycerol (DAG) analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG) was used to verify the existence of DAG-sensitive channels in cortical neurons dissociated from E13 mouse embryos. Calcium imaging experiments showed that OAG increased the cytosolic concentration of Ca(2+) ([Ca(2+)]i) in nearly 35% of the KCl-responsive cells. These Ca(2+) responses disappeared in a Ca(2+)-free medium supplemented with EGTA. Mn(2+) quench experiments showed that OAG activated Ca(2+)-conducting channels that were also permeant to Ba(2+). The OAG-induced Ca(2+) responses were unaffected by nifedipine or omega-conotoxin GVIA (Sigma-Aldrich, Saint-Quentin Fallavier, France) but blocked by 1-[beta-(3-(4-Methoxyphenyl)propoxy)-4-methoxyphenethyl]-1H-imidazole hydrochloride (SKF)-96365 and Gd(3+). Replacing Na(+) ions with N-methyl-D-glucamine diminished the amplitude of the OAG-induced Ca(2+) responses showing that the Ca(2+) entry was mediated via Na(+)-dependent and Na(+)-independent mechanisms. Experiments carried out with the fluorescent Na(+) indicator CoroNa Green showed that OAG elevated [Na(+)]i. Like OAG, the DAG lipase inhibitor RHC80267 increased [Ca(2+)]i but not the protein kinase C activator phorbol 12-myristate 13-acetate. Moreover, the OAG-induced Ca(2+) responses were not regulated by protein kinase C activation or inhibition but they were augmented by flufenamic acid which increases currents through C-type transient receptor potential protein family (TRPC) 6 channels. In addition, application of hyperforin, a specific activator of TRPC6 channels, elevated [Ca(2+)]i. Whole-cell patch-clamp recordings showed that hyperforin activated non-selective cation channels. They were blocked by SKF-96365 but potentiated by flufenamic acid. Altogether, our data show the presence of hyperforin- and OAG-sensitive Ca(2+)-permeable channels displaying TRPC6-like properties. This is the first report revealing the existence of second messenger-operated channels in cortical neurons.

Endocrine pancreas histology of congenic BB-rat strains with reduced diabetes incidence after genetic manipulation on chromosomes 4, 6 and X.

Congenic BB.SHR rat strains were established by crossing of spontaneously diabetic BB/OK rats and diabetes-resistant SHR rats. Chromosomal regions on which the genes Iddm 4 (BB.6s), Iddm6 (BB.Xs) and Iddm 2 (BB.LL) are located were exchanged. As a result of genetic manipulation diabetes incidence was markedly reduced from 80% in BB/OK to 50% in BB.SHR (Chr. X), to 14% in BB.SHR (Chr. 6) and to 0% in BB.LL rats. Pancreata of these newly generated BB.SHR rats were investigated histologically. In newly diagnosed diabetic rats of congenic strains pancreatic insulin content (BB.6s: p < 0.05; BB.Xs p < 0.01) and relative volume of insulin-positive cells (BB.Xs: p < 0.001) were significantly higher than in BB/OK rats. The degree of insulitis was not different in 90-day-old and newly diagnosed diabetic animals. Surprisingly, in 30-day-old rats we observed an increase of the degree of insulitis with decreasing diabetes incidence. We suppose that by an earlier occurrence of the immunological beta-cell destruction, a part of the animals is able to develop a secondary diabetes resistance. The exchange of the BB-lymphopenia gene by that of SHR-rats prevented the development of hyperglycaemia without altering the auto-reactive immune response, which could be observed in all animals investigated.