A Comparative Study of Excitatory and Inhibitory Amino Acids in Three Different Brainstem Nuclei |
| |
Authors: | Waleed M Renno Moussa Alkhalaf Alyaa Mousa Reem A Kanaan |
| |
Institution: | (1) Department of Anatomy, Faculty of Medicine, Kuwait University, P.O. Box 24923, Safat, 13110, Kuwait;(2) Department of Biochemistry, Faculty of Medicine, Kuwait University, P.O. Box 24923, Safat, 13110, Kuwait;(3) Faculty of Pharmacy, Al-Zaytoonah University, Amman, Jordan |
| |
Abstract: | This study was designed to shed more light onto the three different brainstem regions which are implicated in the pain pathway
for the level of various excitatory and inhibitory neurotransmitters before and following neuronal stimulation. The in vivo
microdialysis technique was used in awake, freely moving adult Sprague-Dawley rats. The neurotransmitters studied included
aspartate, glutamate, GABA, glycine, and taurine. The three brainstem regions examined included the mid-brain periaqueductal
gray (PAG), the medullary nucleus raphe magnus (NRM), and the spinal trigeminal nucleus (STN). Neuronal stimulation was achieved
following the administration of the sodium channel activator veratridine. The highest baseline levels of glutamate (P < 0.0001), aspartate (P < 0.0001), GABA (P < 0.01), taurine (P < 0.0001), and glycine (P < 0.001) were seen in the NRM. On the other hand, the lowest baseline levels of glutamate, GABA, glycine, and taurine were
found in the PAG, while that of aspartate was found in the STN. Following the administration of veratridine, the highest release
of the above neurotransmitters except for the aspartate and glycine was found in the PAG where the level of glutamate increased
by 1,310 ± 293% (P < 0.001), taurine by 1,008 ± 143% (P < 0.01), and GABA by 10,358 ± 1,920% (P < 0.0001) when comparison was performed among the three brainstem regions and in relation to the baseline levels. The highest
release of aspartate was seen in the STN (2,357 ± 1,060%, P < 0.001), while no significant difference was associated with glycine. On the other hand, the lowest release of GABA and
taurine was found in the STN (696 ± 91 and 305 ± 25%, respectively), and glutamate and aspartate in the NRM (558 ± 200 and
874 ± 315%, respectively). Our results indicate, and for the first time, that although some differences are seen in the baseline
levels of the above neurotransmitters in the three regions studied, there are quite striking variations in the level of release
of these neurotransmitters following neuronal stimulation in these regions. In our opinion this is the first study to describe
the pain activation/modulation related changes of the excitatory and inhibitory amino acids profile of the three different
brainstem areas. |
| |
Keywords: | Aspartate Glutamate GABA Glycine Taurine Periaqueductal gray Nucleus raphe magnus Spinal trigeminal nucleus Pain |
本文献已被 PubMed SpringerLink 等数据库收录! |
|