2.12 | Angiotensin II-induced aortic aneurysm
Male WT and SKI mice in LDLR−/− background at 7 weeks
old (18–22 g) were fed on a Western diet (21% w/w milk fat, 0.15% w/w
cholesterol, Beijing Keao Xieli Feed Corporation) for 7 days and then
received subcutaneous implantation of ALZET osmotic pumps (Model 2004,
DURECT Corporation, USA), delivering angiotensin II (1.44
mg·kg−1·day−1, dissolved in
saline)(Bhamidipati et al., 2014). Before implantation, mice were given
buprenorphine (0.08 mg·kg−1, s.c.) as analgesic, and
during pump implantation, they were anaesthetised with isoflurane
(1.5%) inhalation. The mouse back was depilated with depilatory
ointment. After disinfection with iodophor, the pump was implanted
subcutaneously into the back of the mouse. The incision was sealed with
sterile sutures and disinfected with iodophor. Buprenorphine (0.08
mg·kg−1, s.c., every 8 hr) was given to the mouse the
first day after surgery. The mice were monitored every day in the first
week after operation. Seven days after angiotensin II infusion, SKI mice
were randomly given pioglitazone
(15 mg·kg−1·day−1, suspended in 200
μL sterile water, n = 11) or solvent control sterile water (200
μL, n = 11), and WT mice were given sterile water (200 μL,n = 11). They were given by gavage once a day. Western diet was
applied during the whole experiment. 28 days after the infusion of
angiotensin II, mice were killed and perfused with ice-cold PBS, and
then the connective tissue was removed to expose the whole aorta and its
collateral branches and digital images were acquired for aneurysm
analysis using an Olympus microscope (model SZX16).
Aneurysms are defined as
enlargements > 50% diameter compared to littermate
controls without angiotensin II infusion. The composition of aneurysms
was evaluated according to the type of aneurysm, including the ruptured
aneurysm, unruptured aneurysm, and non-aneurysm. The survival rate and
incidence of aneurysm were monitored and calculated. The number of
aneurysms per mouse was counted. The length of aneurysm was measured
according to the scale with CellSens standard software 1.12
(RRID:SCR_014551 , Olympus).