IntroductionPhotobiomodulation was assessed as a novel treatment of Alzheimer’s disease (AD) by the use of a new device RGn500 combining photonic and magnetic emissions in a mouse model of AD.MethodsFollowing the injection of amyloid β 25-35 peptide in male Swiss mice, RGn500 was applied once a day for 7 days either on the top of the head or the center of abdomen or both.ResultsRGn500 daily application for 10 min produced a neuroprotective effect on the neurotoxic effects of amyloid β 25-35 peptide injection when this type of photobiomodulation was applied both on the head and on the abdomen. Protection was demonstrated by memory restoration and on the normalization of key markers of AD (amyloid β 1-42, pTau), oxidative stress (lipid peroxidation), apoptosis (Bax/Bcl2) and neuroinflammation.DiscussionRGn500 displays therapeutic efficacy similar to other pharmacological approaches evaluated in this model of AD.

The sigma(1) receptor-mediated behavioral effect is dependent not only on rapid Ca(2+) influx, as observed for a classical antidepressant, but also on intracellular Ca(2+) mobilization.

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Recent reports suggest an interaction between neuro‐(active)steroids and sigma1 (σ1) receptors, affecting biochemical parameters as well as physiological responses mediated by σ1 ligands in the rodent brain. In this study, we examined the modulation by neurosteroids of the haloperidol‐sensitive in vivo (+)‐[3H]SKF‐10,047 binding to σ1 sites in the mouse hippocampus and cortex. Progesterone (PROG; 2–40 mg/kg), pregnenolone sulfate (PREGS; 10–40 mg/kg), and dehydroepiandrosterone sulfate (DHEAS; 10–40 mg/kg) were administered systemically 10 min before the radioactive tracer. The total amount of (+)‐[3H]SKF‐10,047 bound in each structure was significantly affected by PROG and PREGS only at the highest dose tested and was unaffected by DHEAS. However, bound to free (B/F) radioactivity ratios were highly significantly decreased by 30–40% in each structure by PROG and PREGS. DHEAS, at 40 mg/kg, induced a significant 20% decrease in the hippocampus. Furthermore, the in vivo (+)‐[3H]SKF‐10,047 binding parameters were diminished in pregnant female mice compared to non‐pregnant or male mice. These results confirm the in vitro binding results, bring a direct in vivo demonstration of the interaction between neurosteroids and σ1 receptors, and show that physiologic modulations of the steroidal concentrations affect the σ1 systems. © 1996 Wiley‐Liss, Inc.

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