Temporal and spatial expression of preprotachykinin A mRNA in the developing filial mice brain after maternal administration of monosodium glutamate at a late stage of pregnancy.
In the early stages of brain development, exposure of excessive monosodium glutamate (MSG) to neurons causes animal functional and behavioral disorders in adulthood. To investigate the effects of excessive MSG during pregnancy on the neurons in the developing brain, in situ hybridization was used. In mice, the expression of preprotachykinin A mRNA (PPT A mRNA) was assessed in neurons of in the brain after MSG treatment. Brain tissue sections were hybridized with specific digoxigenin-labeled RNA probes. The number of cells that expressed PPT A mRNA gradually decreased from 10-day-old (10d) to 60-day-old (60d) MSG-treated and normal animals. In the MSG-treated and normal mice, the PPT A mRNA-positive neurons almost disappeared in 90-day-old (90d) mice. The expression of PPT A mRNA significantly decreased at 10d in most of the brain regions of MSG-treated mice including the cerebral cortex (CC), hippocampal subregions of CA1, CA2 (CA1, CA2), habenula nucleus (HAB), hypothalamic periventricular nucleus (PE), hypothalamic arcuate nucleus (AR), median eminence (ME), amygdala nucleus (AMY), endopiriform nucleus (EN), and hypothalamic ventromedial nucleus (VMH) and dorsomedial nucleus (DMH). In the hippocampal CA4 subregions (CA4), paraventricular nucleus (PV) and caudate putamen (CPU), however, they were not significantly altered. Furthermore, in CC, hippocampal CA3 subregion (CA3), PE and EN regions the number of PPT A mRNA-positive neurons decreased at 20 days old (20d), but increased significantly in CA2 and CPU. At 30 days old (30d), the positive neuron number decreased in AMY, and they did not change in other regions. At 60d, the number of positive neurons significantly decreased in PV and ME, but increased in AMY. In the other observed regions, no changes were found. These results show that maternal administration of excessive MSG at a late stage of pregnancy significantly decreases PPT A mRNA expression in most of the brain regions of filial mice. This suggests that glutamate-induced excitotoxicity may affect the metabolism of precursors of substance P in developing brain neurons. The present study provides insights into the plasticity and vulnerability of neuron in different brain regions to glutamate excitotoxicity.
Xu
L
L
Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University, Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China.
Zhao
Y
Y
Zhan
S-Q
SQ
Tang
X-D
XD
Guo
Y
Y
Wang
H-S
HS
Yang
C
C
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000196:embryology* / Q000254:growth & development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D051379:Mice; D008815:Mice, Inbred Strains; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012970:Sodium Glutamate / Q000494:pharmacology*; D015320:Tachykinins / Q000235:genetics*
D011498:Protein Precursors; D012333:RNA, Messenger; D015320:Tachykinins; C044206:preprotachykinin; D012970:Sodium Glutamate