30 Evolution of cerebrovascular changes in mouse cortex during normal pregnancy by in vivo two-photon imaging

Introduction Past studies have shown that cerebral autoregulation is a physiologic process that maintains blood flow at an appropriate level. Impairment of cerebral autoregulation during pregnancy may contribute to further diseases like preeclampsia and eclampsia. However, little is known about the normative cerebrovascular adaptation during pregnancy. Objectives In the present study we observed adaptive changes in the blood flow and vessel diameter from prepregnancy to late pregnancy by in vivo two-photon imaging. Methods 12 female C57 mice were randomly divided into four groups: non-pregnancy, early-pregnancy, middle-pregnancy, late pregnancy. After the animals were anesthetized, a mouse head holder was used to hold the head. A thinned skull window was made (1–2 mm in diameter) over the motor cortex. One day later, Rhodamin B dissolved in saline (3 mg/ml, 0.2 ml/20 kg) was injected intraperitoneally to label the vessels 15 min before beginning the imaging experiments. The animal was anesthetized and placed under two photon microscope to observe; blood flow signal pictures were taken using line-scan and analyzed by blood flow analysis software programmed. Results The blood flow velocity of arteriovenous vessels and capillaries increased significantly in middle and late pregnancy compared to non-pregnancy and early-pregnancy; vascular diameters in middle and late pregnancy also became bigger than that in non-pregnancy and early-pregnancy. Conclusions Both the blood flow velocity and diameter of cortical micro vessels increased significantly from non-pregnancy and early-pregnancy to middle and late pregnancy. Such results demonstrated a progressive cerebrovascular adaptation from prepregnancy to late pregnancy.