Protective Effect of Memantine on Bergmann Glia and Purkinje Cells Morphology in Optogenetic Model of Neurodegeneration in Mice

Spinocerebellar ataxias are a family of fatal inherited diseases affecting the brain. Although specific mutated proteins are different, they may have a common pathogenetic mechanism, such as insufficient glutamate clearance. This function fails in reactive glia, leading to excitotoxicity and overactivation of NMDA receptors. Therefore, NMDA receptor blockers could be considered for the management of excitotoxicity. One such drug, memantine, currently used for the treatment of Alzheimer’s disease, could potentially be used for the treatment of other forms of neurodegeneration, for example, spinocerebellar ataxias (SCA). We previously demonstrated close parallels between optogenetically induced cerebellar degeneration and SCA1. Here we induced reactive transformation of cerebellar Bergmann glia (BG) using this novel optogenetic approach and tested whether memantine could counteract changes in BG and Purkinje cell (PC) morphology and expression of the main glial glutamate transporter—excitatory amino acid transporter 1 (EAAT1). Reactive BG induced by chronic optogenetic stimulation presented increased GFAP immunoreactivity, increased thickness and decreased length of its processes. Oral memantine (~90 mg/kg/day for 4 days) prevented thickening of the processes (1.57 to 1.81 vs. 1.62 μm) and strongly antagonized light-induced reduction in their average length (186.0 to 150.8 vs. 171.9 μm). Memantine also prevented the loss of the key glial glutamate transporter EAAT1 on BG. Finally, memantine reduced the loss of PC (4.2 ± 0.2 to 3.2 ± 0.2 vs. 4.1 ± 0.3 cells per 100 μm of the PC layer). These results identify memantine as potential neuroprotective therapeutics for cerebellar ataxias.     

Experimental results on radiative cooling of submicron carbon-black particles

The change in the temperature of the submicron carbon-black particles formed behind the reflected shock wave as a result of the pyrolysis of ethylene was investigated by the photoemission method. It has been established that the temperature of the carbon black substantially differs (by a value of the order of 400–600 K) from the temperature of the gas medium in which it is formed and grown. It is shown with the use of scanning electron microscopy that the average diameter of the carbon nanoclusters forming the carbon black comprises 55–30 nm at a pyrolysis temperatures of 2100–2800 K. The porosity of the primary nanoparticles is equal to 0.95–0.97.     

An investigation of the temperature dynamics in pulsed heating by the photoemission pyrometry method

An instrument for investigating temperature processes of 30–5000 μsec duration with a time resolution of 2 μsec is described and examples of its use are given. __________ Translated from Izmeritel’naya Tekhnika, No. 9, pp. 46–49, September, 2006.     

Photoemission method of measuring temperature

A photoemission method of measuring temperature is presented, and the range of its application is indicated. Expressions are obtained for calculating the systematic error, and a nomogram is given for determining it.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 2, pp. 257–265, August, 1978.