Microglia activation and neuronal injury were assessed in brain sections by immunofluorescence using specific antibodies against CD68 and active caspase-3, respectively. RNA (mRNA) expression was measured by quantitative real-time PCR (qRT-PCR) in laser-captured cortical neurons. Microglia activation and neuronal injury were assessed in brain sections by immunofluorescence using specific antibodies against CD68 and active caspase-3, respectively. In the vestibulomotor and cognitive (MWM) tests, NPLT-treated animals performed significantly better than the untreated blast group and similarly to sham animals. NPLT upregulated mRNA encoding BDNF and downregulated the pro-apoptotic protein caspase-3 in cortical neurons. Immunofluorescence demonstrated that NPLT inhibited microglia activation and reduced the number of cortical neurons expressing activated caspase-3. NPLT also increased expression of BDNF in the hippocampus and the number of proliferating progenitor cells in the dentate gyrus. Our data demonstrate a neuroprotective effect of NPLT and prompt further studies aimed to develop NPLT as a therapeutic intervention after traumatic brain injury (TBI). strong class=”kwd-title” Keywords:?: blast injury, near-infrared light, neuroprotection, non-invasive transcranial laser therapy, optoacoustics, traumatic brain injury Introduction Over the past two decades, blast-induced neurotrauma (BINT) has become a prevalent health concern due to the increasing incidence of blast-induced traumatic brain injury (TBI) sustained by soldiers in combat.1C4 Many victims of closed-head, blast injury experience persistent post-concussive symptoms5 and chronic cognitive and emotional deficits secondary to the initial TBI.6,7 Although the understanding of TBI pathophysiology has improved, current treatment options for BINT remain limited. Recently, transcranial low-level laser therapy (LLLT) has gained recognition as an alternative to existing TBI treatments.8C10 LLLT uses near-infrared light (600C1000?nm) to stimulate, repair, regenerate, and protect injured tissue. Initial studies of LLLT focused on stimulation of wound healing and reduction of pain and inflammation in various orthopedic conditions.11 Recently, several reports demonstrated beneficial effects of LLLT in reducing neuroinflammation, brain lesion volume, and edema in animal models of TBI.12 Specifically, they showed a significant neuroprotective effect of transcranial LLLT Dolastatin 10 generated by LED or laser sources (both continuous and pulsed) using controlled cortical impact and closed-head-injury rodent models of TBI. More recently, some clinical case reports tested the therapeutic effect of LLLT for the treatment of chronic TBI patients and showed small but significant improvements in cognitive and motor functions13C15; however, as of today, no studies have tested LLLT on animal models of BINT. In the past few years, new evidence emerged pointing Dolastatin 10 to a potential therapeutic use of non-invasive low-intensity, low-frequency (0.44C0.67?MHz) ultrasound waves for treatment of TBI. Specifically, recent studies have shown that transcranial delivery of low-intensity pulsed ultrasound stimulation reduces brain injury caused by focused ultrasound-induced bloodCbrain barrier permeablity and reduces edema in a closed-head weight-drop model of TBI.16,17 We Dolastatin 10 propose to use optoacoustics to combine the therapeutic effects of light and ultrasound. Optoacoustic waves can be generated in tissues by short (typically, hundreds of nanoseconds or shorter) optical pulses.18C21 Absorption of light energy in tissue or any other absorbing medium is followed by temperature rise. Thermal expansion of the irradiated medium induces Rabbit Polyclonal to AKAP8 mechanical stress (pressure rise) upon the condition of stress confinement. This mechanism is referred to as the thermo-optical mechanism of pressure generation. The condition of stress confinement means that there is insignificant stress relaxation in the irradiated volume during the optical pulse. To provide this condition in tissues, the duration of the optical pulse should be shorter than the time of stress propagation out of the irradiated tissue volume.18C20 Nanosecond laser pulses can be used to generate conditions of Dolastatin 10 stress confinement for many optoacoustic applications in tissues including the proposed nano-pulsed laser therapy (NPLT). Such light plus ultrasound combination may be more efficient for therapy than light or ultrasound alone. Moreover, a synergistic effect may be produced when light pulses and light-induced ultrasound (optoacoustic) waves are applied simultaneously resulting in a better therapeutic response. We developed a novel, medical-grade optoacoustic system for the transcranial delivery of near-infrared light pulses (808?nm) and detection of low-level optoacoustic (ultrasound) waves. This system generates pulses with a duration of 10?nsec, energy of up to 15?mJ, and pulse repetition rate of 20?Hz. It can produce wide-band low-energy optoacoustic waves in tissue via thermoelastic mechanism under stess-confined irradiation conditions. Thus, our system, originally designed to monitor blood oxygenation in the brain22C24 has significant therapeutic potential for the treatment of brain injuries because it combines.