Low birth weight programs adult bone deficits and increases obesity risk, which can alter bone metabolism. Pregnancies in females born small, further complicated by obesity can exacerbate pre-existing bone deficits. Exercise intervention prior to pregnancy can reverse negative effects of obesity in growth restricted offspring. We aimed to determine if a high fat diet (HFD) exacerbates bone deficits during pregnancy in females born small and whether endurance exercise prior to and during pregnancy would attenuate these deficits.
Uteroplacental insufficiency was induced on embryonic day 18 (E18) in WKY rats using bilateral uterine vessel ligation (Restricted) or sham (Control) surgery (F0 generation). F1 females consumed standard chow or HFD (23% fat) from age 5 weeks, ad libitum, and were mated at 20 weeks. Female rats exercised on treadmills for 4 weeks prior to and during pregnancy or remained sedentary. Femora and plasma were collected at post-mortem (E20) for pQCT and bone marker analysis.
Sedentary Restricted females had decreased trabecular and cortical content, cortical thickness, periosteal and endosteal circumferences and bending strength (p<0.05), irrespective of diet compared to Controls. HFD increased trabecular density in Control and Restricted Sedentary females. Exercise prevented these deficits, as there were no differences between Control and Restricted females consuming either diet. Osteocalcin was increased in Sedentary Restricted females compared to Control (p<0.05). HFD reduced osteocalcin and increased CTX-1 in Sedentary females compared to chow-fed females (p<0.05). Bone turnover markers were not different in pregnant chow and HFD females with exercise intervention.
HFD did not exacerbate bone deficits in Restricted females, however the changes observed in bone markers in Sedentary HFD females highlights the possibility of altered bone metabolism. Exercise prevented development of maternal bone deficits in late gestation; highlighting exercise as a therapy for females born small who are at risk of developing bone deficits.