Alteration of Brain Levels of Neurotransmitters and Amino Acids in Male F344 Rats Induced by Three-week Repeated Inhalation Exposure to 1-Bromopropane

Abstract

The present study investigated the effects of 1-bromopropane (1BP) on brain neuroactive substances of rats to determine the extent of its toxicity to the central nervous system (CNS). We measured the changes in neurotransmitters (acetylcholine, catecholamine, serotonin and amino acids) and their metabolites or precursors in eight brain regions after inhalation exposure to 1BP at 50 to 1,000 ppm for 8 h per day for 7 d per week for 3 wk. Rats were sacrificed at 2 h (Case 1), or at 19 h (Case 2) after the end of exposure. In Case 1, the level of 5-hydroxyindoleacetic acid (5HIAA) was lowered in some brain regions by 1BP exposure. The decrease of 5HIAA in the frontal cortex was statistically significant at 50 ppm 1BP exposure. In Case 2, γ-amino butyric acid (GABA) and taurine were decreased in many brain regions of exposed rats, and a significant decrease of taurine in the midbrain occurred at 50 ppm 1BP exposure. In both cases of 2-h and 19-h intervals from the end of exposure to sacrifice, aspartate and glutamine levels were elevated in many brain regions, but the acetylcholine level did not change in any brain region. Three-week repeated exposure to 1BP produced significantly changes in amino acid contents of rat brains, particularly at 1,000 ppm.

NMDA Receptor Antagonist MK801 Protects Against 1-Bromopropane-Induced Cognitive Dysfunction

“…Previous studies have shown that 1-BP exposure enhances neuronal excitability in the hippocampus through the over-activation of NMDARs [23,46]. Consistent with previous reports, we found that the concentrations of GABA and Tau were significantly decreased in 1-BP-intoxicated rats [47]. Meanwhile, 1-BP intoxication increased the levels of excitatory Asp in rats, although the levels of Glu remained unchanged.…”

Neurochemical profile of the mouse hypothalamus using in vivo1H MRS at 14.1T

“…1). In addition, these hallmarks of hypothalamic concentrations were consistent with previously reported biochemical values in rats (17) and mice (18,19), in particular the high GABA and low Glu concentrations, which could point to GABA as a dominant neurotransmitter in hypothalamus (20). Furthermore, the observed increased hypothalamic choline content mostly in the form of GPC was in excellent agreement with chromatographic measurements in mice (21).…”

Direct in vivo measurement of glycine and the neurochemical profile in the rat medulla oblongata

“…Relative to CO, ST and HI, Gly in MO showed a three‐fold higher concentration (Fig. 3a), which is in accordance with the reported Gly regional distribution in rat brain 20, 22. The high concentration of Gly in MO is consistent with its neurotransmitter function in this region.…”

“…1). An excellent agreement of the concentrations of Glu, Gln, GABA and Tau in MO was found with previously quantified values in tissue extracts 20.…”

“…3). The concentration of Gly in MO measured in this study is in the range of previous reports using biochemical assays 20, and is somewhat lower than the value published by Aprison et al . 21, possibly as a result of the age difference of the rats 22.…”