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In vivo and in vitroeffects of IR1072 neuronal preconditioning: possible role of BDNF Non-thermal near infra-red (IR) has been shown to have a wide range of therapeutic effects on a number of cell types, including neurons. Previously published data from our laboratories show a beneficial effect of IR1072 exposure on the acquisition of working memory in the 3D maze in IR-treated middle aged (12 month) mice compared to sham-treated mice (Michalikova et al., 2008). Brain-derived neurotrophic factor (BDNF) has been implicated in memory acquisition, as well as neuroprotection. In this study, we have probed sham- or IR-treated CD-1 mouse (in vivo) brain tissue for BDNF protein expression, and primary rat cortical neurons (in vitro) for neuroprotective properties, in order to attempt to define the pharmacological effects of IR1072.
For in vivo IR treatments, 3 month old male CD-1 mice were exposed to 6 min, full body IR1072 treatment over a 10 day period, as previously described (Michalikova et al., 2008). Brains were dissected and the left hemicorticies were prepared and assayed by quantitative immunoblotting standardised with beta-actin (Chazot et al., 2002), using validated commercial antibodies. BDNF expression in IR treated mice (0.605± 0.048, n=5, p<0.01) was significantly reduced compared to sham-treated mice (0.779 ± 0.017, n=5). In correlation to this, a reduction in ERK 1 expression was also found in IR treated mice (0.377 ± 0.032, n=4) compared to sham-treated mice (0.573 ± 0.074 n=4). Results are represented as mean ± S.E.M. The level of protection achieved following pre-treatment of pure neuronal cultures with IR1072 was dependent on the level of insult achieved (Table 1), similar to previous data using anaesthetic preconditioning in the same culture system (Errington et al, 2004). A surprising decreased BDNF expression was observed in IR-treated 3 month old CD-1 mice compared to age-matched sham-treated CD-1 mice. It should be noted, however, that preliminary results showed that 7 month, in contrast to 13 month, CD-1 mice previously treated for a four month period with IR1072, displayed limited learning improvement. Further studies are required to assess BDNF expression in the older treated CD-1 mice, where learning improvement was reproducibly achieved with IR treatment. |
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