Acute effects of pulsed microwaves and 3‐nitropropionic acid on neuronal ultrastructure in the rat caudate‐putamen

Abstract

Ultrastructure of the medium sized "spiny" neuron in rat dorsal-lateral caudate-putamen was assessed after administration of 3-nitropropionic acid (3-NP) and exposure to pulsed microwaves. Sprague-Dawley male rats were given two daily intraperitoneal doses of 0 or 10 mg/kg 3-NP and 1.5 h after each dose were exposed to microwave radiation at a whole body averaged specific absorption rate (SAR) of 0 (sham exposure), 0.6, or 6 W/kg for 30 min. Microwave exposure consisted of 1.25 GHz radiation delivered as 5.9 micros pulses with repetition frequency 10 Hz. Tissue samples taken 2-3 h after the second sham or microwave exposure showed no injury with light microscope methods. Blinded qualitative assessment of ultrastructure of randomly selected neurons from the same samples did reveal differences. Subsequent detailed, quantitative measurements showed that, when followed by sham exposure, administration of 3-NP significantly increased endoplasmic reticulum (ER) intracisternal width, ER area density, and nuclear envelope thickness. Microwave exposure at 6 W/kg alone also significantly increased these measures. Exposure of 3-NP treated animals at 6 W/kg significantly increased effects of 3-NP on ultrastructure. Although exposure at 0.6 W/kg alone did not affect ultrastructure measures, exposure of 3-NP treated animals at 0.6 W/kg reduced the effects of 3-NP. We concluded that 3-NP changed neuronal ultrastructure and that the microwave exposures used here changed neuronal ultrastructure in ways that depended on microwave SAR and neuron metabolic status. The apparent cancellation of 3-NP induced changes by exposure to pulsed microwaves at 0.6 W/kg indicated the possibility that such exposure can protect against the effects of mitochondrial toxins on the nervous system.

The Histaminergic Signaling System Exerts a Neuroprotective Role against Neurodegenerative-Induced Processes in the Hamster

“…It was, however, at the ultrastructural level that substantial neurodegenerative processes induced by the different doses of 3-NP were shown to occur in a more selective manner. As a matter of fact, greater structural alterations consisting of an increased number of neurons that displayed an evident dark nucleus plus crenated cell membrane and phenomena of vacuolation appeared to prevalently characterize the different brain regions such as the striatum and cortex of the rat, which is in line with the very early acute damages involving membrane thickness and dilated cisternal formations in the former brain area of this same animal under the influence of the freckled milk vetch-derived neurotoxin (Seaman and Phelix, 2005). Conversely, a low number of unimpaired mitochondrial crests were instead reported for hamster brain areas such as the amygdala with respect to the greater number reported for the rat and other rodent brain areas for that matter (La Fontaine et al, 2000).…”

Exposure of rat brain to 915 MHz GSM microwaves induces changes in gene expression but not double stranded DNA breaks or effects on chromatin conformation

“…Recent data provided evidence for neuronal damage in both the cortex, the hippocampus and the basal ganglia in the brains of exposed rats [Salford et al, 2003;Ilhan et al, 2004]. Although exposure at 0.6 W/kg alone did not affect ultrastructure of neurons in rat brains, exposure of 3-nitropropionic acid (3-NP)-treated animals reduced the effects of 3-NP [Seaman and Phelix, 2005].…”

Services to Operate and Maintain a Microwave Research Laboratory

“…This included a lack of necrosis in the brain at this level of examination. In contrast, changes in neuronal ultrastructure have been observed for animals exposed at 6 W/kg, animals receiving 10 mg/kg 3-NP, and animals having both these treatments [Seaman & Phelix, 2003]. …”

“…Results from these aspects of the project are reported here, while results from electron microscopy of neuronal ultrastructure in the caudate-putamen are being reported separately [Seaman & Phelix, 2003]. …”

“…These solutions were used in anticipation of the electron microscopy of brain tissue [Seaman & Phelix, 2003]. The brain and samples of heart, lung, and liver were collected and immersed in 10% neutral buffered formalin.…”