Background:Prior research has established that exposure to low temperatures adversely affects ovarian function,yet the precise mechanisms remain to be elucidated.Methods:Thirty experimental rats,each demonstrating two...Background:Prior research has established that exposure to low temperatures adversely affects ovarian function,yet the precise mechanisms remain to be elucidated.Methods:Thirty experimental rats,each demonstrating two regular estrous cycles,were assorted randomly into three distinct groups:a control group,a cold exposure group,and a group treated with 4-phenylbutyric acid(4-PBA).To mimic the conditions of cold exposure,rats in the cold exposure and 4-PBA groups were subjected to immersion in ice water for 21 days.After 7 days of exposure to ice water,the 4-PBA group received intraperitoneal injections of a 20 mg/mL solution of 4-PBA at a dose of 100 mg/kg/day for 14 days.Estrous cycles were monitored via analysis of vaginal secretion smears.Serum hormone levels were measured using enzyme-linked immunosorbent assay(ELISA)kits.Ovarian morphology and the ultrastructure of granulosa cells(GCs)were evaluated using hematoxylin and eosin(HE)staining,and transmission electron microscopy(TEM),respectively.Apoptotic levels in GCs were quantified using a terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling(TUNEL)kit.Expression of apoptotic markers,endoplasmic reticulum stress(ERS)indicators,and molecules associated with relevant pathways were assessed through immunohistochemistry,western blot,and quantitative realtime polymerase chain reaction(qRT-PCR).Results:Dysregulation of the estrous cycle was notable in rats exposed to cold.The cold exposure group exhibited significantly reduced levels of estradiol(E2)and progesterone(P)compared to controls,alongside an increase in follicular atresia and a reduction in the count of developing follicles.After cold exposure,enhanced apoptosis and ERS were evident,with activation of the protein kinase RNA-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2α(eIF2α)/activating transcription factor 4(ATF4)signaling pathway in ovarian.Notable changes were also observed in the ultrastructure of ovarian GCs,where both apoptosis and ERS levels were increased.Conversely,treatment with 4-PBA alleviated disturbances in the estrous cycle and hormonal imbalances,improved ovarian morphology,and alleviated apoptosis and ERS,effectively inhibiting the PERK/eIF2α/ATF4 pathway.Additionally,4-PBA treatment significantly improved the ultrastructure of GCs and alleviated apoptosis and ERS in these cells within the cold exposure group.Conclusion:These findings suggest that ERS plays a significant role in ovarian dysfunction induced by cold exposure,primarily through promoting apoptosis.展开更多
基金supported by the National Natural Science Foundation of China(Nos.82174426,82104740)the Natural Science Foundation of Hebei Province of China(No.H2021423020)the Innovation Funding Program for doctoral students in Hebei Province(No.CXZZBS2022098).
文摘Background:Prior research has established that exposure to low temperatures adversely affects ovarian function,yet the precise mechanisms remain to be elucidated.Methods:Thirty experimental rats,each demonstrating two regular estrous cycles,were assorted randomly into three distinct groups:a control group,a cold exposure group,and a group treated with 4-phenylbutyric acid(4-PBA).To mimic the conditions of cold exposure,rats in the cold exposure and 4-PBA groups were subjected to immersion in ice water for 21 days.After 7 days of exposure to ice water,the 4-PBA group received intraperitoneal injections of a 20 mg/mL solution of 4-PBA at a dose of 100 mg/kg/day for 14 days.Estrous cycles were monitored via analysis of vaginal secretion smears.Serum hormone levels were measured using enzyme-linked immunosorbent assay(ELISA)kits.Ovarian morphology and the ultrastructure of granulosa cells(GCs)were evaluated using hematoxylin and eosin(HE)staining,and transmission electron microscopy(TEM),respectively.Apoptotic levels in GCs were quantified using a terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling(TUNEL)kit.Expression of apoptotic markers,endoplasmic reticulum stress(ERS)indicators,and molecules associated with relevant pathways were assessed through immunohistochemistry,western blot,and quantitative realtime polymerase chain reaction(qRT-PCR).Results:Dysregulation of the estrous cycle was notable in rats exposed to cold.The cold exposure group exhibited significantly reduced levels of estradiol(E2)and progesterone(P)compared to controls,alongside an increase in follicular atresia and a reduction in the count of developing follicles.After cold exposure,enhanced apoptosis and ERS were evident,with activation of the protein kinase RNA-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2α(eIF2α)/activating transcription factor 4(ATF4)signaling pathway in ovarian.Notable changes were also observed in the ultrastructure of ovarian GCs,where both apoptosis and ERS levels were increased.Conversely,treatment with 4-PBA alleviated disturbances in the estrous cycle and hormonal imbalances,improved ovarian morphology,and alleviated apoptosis and ERS,effectively inhibiting the PERK/eIF2α/ATF4 pathway.Additionally,4-PBA treatment significantly improved the ultrastructure of GCs and alleviated apoptosis and ERS in these cells within the cold exposure group.Conclusion:These findings suggest that ERS plays a significant role in ovarian dysfunction induced by cold exposure,primarily through promoting apoptosis.
