Depressed nNOS expression during spine transition in the developing hippocampus of FMR1 KO mice

• Main Authors: Qin Xu, Zhiwei Zhu, Jialu Xu, Weizhong Gu, Zhengyan Zhao
• Format: Article
• Language: English
• Published: Associação Brasileira de Divulgação Científica 2012-12-01
• Series: Brazilian Journal of Medical and Biological Research
• Subjects: FXS; nNOS; NO; Dendritic spine; Hippocampus
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2012001200017
• ISSN: 0100-879X; 1414-431X

Nitric oxide (NO), synthesized as needed by NO synthase (NOS), is involved in spinogenesis and synaptogenesis. Immature spine morphology is characteristic of fragile X syndrome (FXS). The objective of this research was to investigate and compare changes of postnatal neuronal NOS (nNOS) expression in the hippocampus of male fragile X mental retardation 1 gene knockout mice (FMR1 KO mice, the animal model of FXS) and male wild-type mice (WT) at postnatal day 7 (P7), P14, P21, and P28. nNOS mRNA levels were analyzed by real-time quantitative PCR (N = 4-7) and nNOS protein was estimated by Western blot (N = 3) and immunohistochemistry (N = 1). In the PCR assessment, primers 5&#8217;-GTGGCCATCGTGTCCTACCATAC-3&#8217; and 5&#8217;-GTTTCGAGGCAGGTGGAAGCTA-3&#8217; were used for the detection of nNOS and primers 5&#8217;-CCGTTTCTCCTGGCTCAGTTTA-3&#8217; and 5&#8217;-CCCCAATACCACATCATCCAT-3&#8217; were used for the detection of &#946;-actin. Compared to the WT group, nNOS mRNA expression was significantly decreased in FMR1 KO mice at P21 (KO: 0.2857 ± 0.0150, WT: 0.5646 ± 0.0657; P < 0.05). Consistently, nNOS immunoreactivity also revealed reduced staining intensity at P21 in the FMR1 KO group. Western blot analysis validated the immunostaining results by demonstrating a significant reduction in nNOS protein levels in the FMR1 KO group compared to the WT group at P21 (KO: 0.3015 ± 0.0897, WT: 1.7542 ± 0.5455; P < 0.05). These results suggest that nNOS was involved in the postnatal development of the hippocampus in FXS and impaired NO production may retard spine maturation in FXS.