Sex- and age- differences in the expression of critical blood-brain barrier regulators: a physiological context

Background Available evidence indicates that blood-brain-barrier (BBB) dysfunction exacerbates with the advancing age and is implicated in a variety of neurological diseases and that there are significant sex differences in these diseases. However, the sex differences and age-related changes in BBB structure and function are still unclear under physiological conditions. Methods In this study, the mRNA was extracted from the cortical tissues and brain microvessels of male and female mice aged 3 months and 10 months to detect the expression of important BBB-related genes by qPCR. Results Under physiological conditions, compared with age-matched male counterparts, female mice reported a significantly lower mRNA expression of tight junction-related genes (cldn5 and occludin), transporters (Glut1 and D-gp), pericyte marker (Pdgfrb), microvessel marker (Cd31), basement membrane component (Col4a2), glycocalyx-related genes (Hs3st1, Extl2, and Clgalt), vascular homeostasis-related genes (Hif1a, Ddit4, and Pik3ca), and some regulatory genes (Adm, Zfpm2 and Nr3c1). A similar outcome was found in the 10-month mice when compared with the 3-month counterparts. Conclusion This study systematically analyzes the expression characteristics of key BBB regulatory genes in different sexes and ages under physiological conditions and reveals a marked sex difference in the expression of BBB structure/function-related genes, which may persist with the advancing age. The findings may provide important theoretical insights into the pathogenesis of sex-and age-related neurological diseases.