Role of cAMP/PKA/CREB pathway and β-arrestin 1 in LH induced luteolysis in pregnant rats

Abstract

Luteal dysfunction in pregnant women is associated with early pregnancy loss, making the study of structure and function of the corpus luteum (CL) critical. Luteinizing hormone (LH) plays a crucial role in the mammalian female reproduction majorly by regulating luteal development. In rats, the luteotropic roles of LH have been widely investigated but its role in the process of luteolysis has received little attention. In this study, we explored the luteolytic actions of LH during different stages of pregnancy in rats. Repeated administration of LH during the late and mid-stages of pregnancy led to functional luteolysis during both stages, while structural luteolysis was observed only during the late-stage. We analyzed the involvement of cAMP/PKA/CREB pathway, MAP kinases and β-arrestins to elucidate the molecular mechanism of LH-mediated luteolysis. The results indicate that the repeated administration of LH causes LH/CGR desensitization along with an increase in β-arrestin 1 expression, while luteal expression of MAP kinases remained unaffected. Further, siRNA-mediated depletion of β-arrestin 1 in primary luteal-cell cultures prevents initiation of the luteolysis process to some extent during both the stages of pregnancy, underscoring its role in LH mediated-luteolysis. In conclusion, the luteolytic actions of LH appear to involve more than one signaling pathway and cAMP/PKA/CREB pathway appears to be the key regulator. This is the first report to show a positive correlation between β-arrestin 1 and 20α-hsd expression. These findings have implications for our understanding of the molecular pathways that regulate luteolysis.

Role of intraluteal and intrauterine prostaglandin signaling in LH-induced luteolysis in pregnant rats

“…The results suggests that endogenous PGF 2α signaling may not play a significant role in the LH induced luteolysis during mid-pregnancy (Farina et al ., 2004). It was demonstrated in the lab previously that the serum levels of P 4 do not change upon repeated LH treatment during mid-stage of pregnancy (Vashistha et al ., 2021). The limited role of PGF 2α signaling during mid-pregnancy can be explained as the inhibitory effects of P 4 are still intact and prevents the activation of PGF 2α signaling during repeated LH treatment.…”

“…Repeated LH administration has been shown to activate luteolytic events both in-vivo and in-vitro via desensitization of the cAMP/PKA/CREB pathway (Vashistha et al ., 2021). PGF 2α is a well-established luteolysin in rodents and is known to interact with the cAMP/PKA/CREB pathway (Astle et al ., 2005).…”

“…We carried out studies in the late (DOP 19) and mid-stage (DOP 8-10) pregnant rats. Previously published protocol was followed (Vashistha et al ., 2021). Briefly, late-stage pregnant rats were assigned into two groups with three animals/group.…”

“…qPCR Total RNA from CL tissues was isolated using TRI reagent as per the manufacturer's recommendations. The qPCR analysis was performed as described previously (Vashistha et al, 2021). Table 2 contains the list of primers used in the qPCR analysis.…”

“…In female mammals, the process of luteolysis is complex and varies from species to species. Luteinizing hormone (LH) induces luteolysis in rats during the mid and late-stage of pregnancy (Vashistha et al ., 2021). Stocco and colleagues emphasized the role of intraluteal prostaglandin (PG) F 2α in LH-induced luteolysis (Stocco and Deis, 1998).…”