Figure 1.

Experimental timeline in months for middle (Mid)-aged (17–20 months) and Old (26–30 months) female F344BN rats. Rats acclimated to their environment and were trained for tail-cuff blood pressure measures during the month prior to undergoing bilateral oophorectomy (OVX) or sham procedures (indicated by the gray bar). A 1-month washout period followed the surgery (indicated by the stippled bar). At the age of 28 months, Old-OVX rats were subdivided to receive either daily subcutaneous injections of the GPER agonist, G1 (100 μg/kg; Old-OVX+G1) or vehicle (soybean oil; Old-OVX), whereas sham-operated, gonadal intact rats (Old-intact) received vehicle only, for 8 weeks (indicated by hashed bar). At 19 months of age, sham-operated, gonadal intact and OVX middle-aged rats received daily injections of vehicle only, for 4 weeks. At the end of the study, when Mid-aged and Old rats were at 20 and 30 months, respectively, transthoracic echocardiograms were performed with anesthesia. Body weights were recorded weekly and conscious systolic blood pressure measures were obtained bimonthly throughout the study protocol.