Seasonal Change in Adiponectin Associated with Ovarian Morphology and Function in Wild Ground Squirrels (Citellus dauricus Brandt)

Abstract

The goal of this study is to explore the relationship between altered circulating adiponectin concentration, ovarian tissue morphology, ovarian steroidogenesis, and sex hormone production in ovaries of wild ground squirrels. The ovarian mass differed significantly during the breeding and non-breeding seasons, and the circulating estradiol and progesterone concentrations were significantly higher in the breeding season, while the circulating adiponectin level was significantly lower. The expression levels of gonadotropin receptors (FSHR and LHR) and steroidogenic enzymes (StAR, P450scc, P450arom, and 3β-HSD) were significantly higher during the breeding season. Comparing the ovarian transcriptome data of wild ground squirrels between the two periods, we found that some differentially expressed genes were enriched for ovarian steroidogenesis and the adipocytokine signaling pathway, which correlated with our present results. Notably, the MAPK signaling pathway was also enriched and its related genes (Erk1, p38 Mapk, Jnk) were up-regulated by qPCR during the non-breeding season. These findings suggested that adiponectin may be involved in the regulation of seasonal changes in the ovarian function of wild ground squirrels, possibly by acting on the MAPK signaling pathway to regulate sex steroidogenesis in the ovaries.

Seasonal patterns of prolactin, prolactin receptor, and STAT5 expression in the ovaries of wild ground squirrels (<em>Citellus dauricus</em> Brandt)

“… 23 Our previous studies have demonstrated the seasonal expressions of follicle-stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), estrogen receptors α (ERα), and estrogen receptors β (ERβ) in the ovaries of wild ground squirrels. 22 , 24 Moreover, the concentrations of FSH, LH, progesterone, and estrogen were higher during the breeding season in comparison to the non-breeding season. 25-27 These findings indicate the potential roles of gonadotropins and sexual steroid hormones in driving the seasonal changes in ovarian functions of wild ground squirrels.…”

“…The wild ground squirrel ( Citellus dauricus Brandt) is a quintessential seasonal breeding mammal, displaying an annual reproductive cycle. 22 During the breeding season (April to May), germ cells maturation and mating, birthing, and pup-rearing activities occur, which are absent during the non-breeding season (June to March). 23 Our previous studies have demonstrated the seasonal expressions of follicle-stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), estrogen receptors α (ERα), and estrogen receptors β (ERβ) in the ovaries of wild ground squirrels.…”

Regulation and Role of Adiponectin Secretion in Rat Ovarian Granulosa Cells

“…Tissues were further processed with a goat anti-rabbit IgG/HRP kit (KGOS60, KeyGEN BioTECH Biotechnology, Nanjing, China), stained with the diaminobenzidine solution (30 mg DAB, 150 mL 0.05 M pH 7.6 Tris HCl solution, 25 µL H 2 O 2 ) and counterstained with hematoxylin [52]. We scored the positive signals of the DAB staining of ovarian tissue with ImageJ (1.53k, National Institutes of Health, Bethesda, MD, USA) (− represents a negative, +++ represents a strong positive) [53].…”

Seasonal Variation in Gut Microbiota of the Wild Daurian Ground Squirrel (Spermophilus dauricus): Metagenomic Insights into Seasonal Breeding

“…There are some studies on the seasonal breeding behavior of wild Daurian ground squirrels. Our previous studies showed that the expression levels of sex hormone receptors and other hormones were seasonally different in the hypothalamus, testes, ovaries, and other HPG axis-related organs of wild Daurian ground squirrels [ 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Wild Daurian ground squirrels also show some seasonal differences in their gut [ 35 ].…”