The Effects of Mobile Phone Radiofrequency Radiation on Cochlear Stria Marginal Cells in Sprague-Dawley Rats.

To investigate the possible mechanisms for biological effects of 1,800 MHz mobile radiofrequency radiation (RFR), the radiation-specific absorption rate was applied at 2 and 4 W/kg, and the exposure mode was 5 min on and 10 min off (conversation mode). Exposure time was 24 h short-term exposure. Following exposure, to detect cell DNA damage, cell apoptosis, and reactive oxygen species (ROS) generation, the Comet assay test, flow cytometry, DAPI (4',6-diamidino-2-phenylindole dihydrochloride) staining, and a fluorescent probe were used, respectively. Our experiments revealed that mobile phone RFR did not cause DNA damage in marginal cells, and the rate of cell apoptosis did not increase (P > 0.05). However, the production of ROS in the 4 W/kg exposure group was greater than that in the control group (P < 0.05). In conclusion, these results suggest that mobile phone energy was insufficient to cause cell DNA damage and cell apoptosis following short-term exposure, but the cumulative effect of mobile phone radiation still requires further confirmation. Activation of the ROS system plays a significant role in the biological effects of RFR. Bioelectromagnetics. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.

[Effects of extrastimulation on morphofunctional state of cochlear stria vascularis]. / Osobennosti spontannogo nistagma pri supratentorial'nykh ishemicheskikh ochagakh golovnogo mozga.

An electron-microscopic study of the response of cochlear stria vascularis (CSV) cells to an electric impact of physiotherapeutic parameters was made in 26 guinea-pigs. Twelve guinea-pigs (group 1) have undergone 9 sessions of bilateral endaural electrostimulation with square bipolar impulses (4 ms, 0.1-0.4 mA, 50 Hz, 20 min). Fourteen guinea-pigs of group 2 have undergone a 12-18-day course of intramuscular ototoxic antibiotic canamycin in a dose 200-400 mg/day followed by the above electrostimulation. Nine anesthesized guinea-pigs of group 3 were inserted an electrode into the niche of the round window of the right ear. After a 10-day course of canamycin (200 mg/day) they were exposed to electrostimulation (8 sessions) with impulsed alternative current (100 Hz, 1 ms, 0.08 mA, 30 min). Five guinea-pigs served control. Morphofunctional state of CSV was assessed at electronograms by analyzing cell ultrastructure and counting the number of secretory vacuoles in the apical region of marginal cell cytoplasm. In group 1 there was intensification of biosynthetic processes in all CSV cells and a significant (p<0.01) increase of vacuole number in the marginal cells (53.9+/-3.8) vs normal value (33.9+/-1.5). In group 2 ultrastructure of all CSV cells was less affected and secretory activity was almost normal (31.4+/-2.9). CSV cell condition was similar to ultrastructure of the cells in group 2. The number of vacuoles in CSV marginal cells of the right (28.9+/-1.98) and left (29.1+/-5.4) cochleas was similar. Thus, electrostimulation activates biosynthetic processes in CSV structures and enhances secretory activity of marginal cells.

Role of acoustic striae in hearing: discrimination of sound-source elevation.

After years of systematic experimentation, we finally uncovered one thing the dorsal system contributes to hearing which the ventral system may not -- the mechanism for orienting to an elevated sound source [Sutherland, D.P., Masterton, R.B., Glendenning, K.K. (1998) Behav. Brain Res. in press]. This paper follows up this one positive result on a historical background of uniformly negative results. The focus of this report is on the fusiform cells of the dorsal cochlear nucleus whose axons course through the dorsal acoustic stria (DAS). Because electrophysiological studies have shown that the cues for sensing the elevation of a sound source would seem to be best analyzed by the dorsal cochlear nucleus, we tested, behaviorally, normal cats and cats deprived of their DAS or intermediate acoustic stria, bilaterally or ipsilaterally (with or without their contralateral ear deafened), for their ability to orient to elevated sources of broad-band noise. For behavioral testing, we made use of a conventional shock-avoidance procedure. The results lead to the conclusion that DCN and DAS may play no role in learned elevation discriminations. This result builds on that of another of our papers which suggests that a deficit in reflexive discrimination of elevation is strictly auditory in nature [Sutherland, D.P., Masterton, R.B., Glendenning, K.K. (1998) Behav. Brain Res. in press].

Strial dysfunction in a melanocyte deficient mutant rat (Ws/Ws rat).

A homozygous mutant rat at the white spotting (Ws) locus showing a deficiency of melanocytes has recently been found (4, 5). The function and morphology of the inner ear of the Ws/Ws rat were examined by auditory brainstem response (ABR), endocochlear DC potential (EP), and electron microscopy. The mean ABR threshold of the Ws/Ws rat was significantly higher than that of the control +/+ rat. Most Ws/Ws rats showed no or very little EP. In electron microscopy, the stria vascularis of the Ws/Ws rat proved to be very thin and flat with poor interdigitation of marginal cells, and absence of intermediate cells. The organ of Corti appeared to be intact in both the +/+ rat and the Ws/Ws rat. These electrophysiological and morphological findings suggest that the Ws/Ws rat suffered from severe hearing loss caused by strial dysfunction.

Cochlear strial blood circulation.

The present immunohistologic study demonstrates that cochlear strial blood circulation is markedly damaged in guinea pigs subjected to intense acoustic stimulation. In contrast, autonomic unbalance of the inner ear induced by resection or electric stimulation of the superior cervical ganglion has no appreciable effect on cochlear strial blood flow. In consequence, although strial blood circulation in the cochlea is susceptible to pathological change in some conditions, it does not appear to be affected by autonomic unbalance alone.