Expression of leptin receptor in the oviduct of Chinese brown frog (Rana dybowskii)

EGFR-ERK1/2 signaling and mitochondrial dynamics in seasonal ovarian steroidogenesis of the muskrats (Ondatra zibethicus)

The dynamic systems of mitochondria, including mitochondrial fusion and fission, are essential for ovarian endocrine and follicular development. Meanwhile, ERK1/2 signaling is an important mechanism mediating altered mitochondrial dynamics and steroidogenesis. The purpose of this study was to investigate the seasonal changes in ovarian steroidogenesis concerning EGFR-ERK1/2 signaling and mitochondrial dynamics of the muskrats (Ondatra zibethicus). The results showed that follicular development in the muskrats remained in the tertiary follicular stage during the non-breeding season, accompanied by a significant decrease in serum and ovarian concentrations of 17β-estradiol and progesterone from the breeding season to the non-breeding season. EGF, EGFR, ERK1/2, p-ERK1/2, and mitochondrial dynamics regulators were mainly localized in granulosa cells and theca cells of muskrats during the breeding and non-breeding seasons. The mRNA levels of Egfr, Erk1/2, Mfn1/2, Opa1, Drp1, and steroidogenic enzymes in the ovaries were remarkably higher during the breeding season. The 17β-estradiol concentrations in the serum and ovaries as well as the relative levels of Mfn1/2, Opa1, and Drp1 were positively associated with each other. Furthermore, transcriptomic analysis of the ovaries revealed that differentially expressed genes might be linked to steroid biosynthesis, estrogen signaling pathway, and mitochondrial membrane-related pathways. In conclusion, these results suggest that the up-regulation of mitochondrial dynamics regulators during the breeding season is closely associated with enhanced ovarian steroidogenesis in the muskrats, which may be regulated by upstream EGFR-ERK1/2 signaling.

Expression of cholesterol synthesis and steroidogenic markers in females of the Chinese brown frog (Rana dybowskii) during prespawning and prehibernation

The oviduct of the Chinese brown frog (Rana dybowskii) expands in prehibernation rather than in prespawning, which is one of the physiological phenomena that occur in the preparation for hibernation. Steroid hormones are known to regulate oviductal development. Cholesterol synthesis and steroidogenesis may play an important role in the expansion of the oviduct before hibernation. In this study, we investigated the expression patterns of the markers that are involved in the de novo steroid synthesis pathway in the oviduct of R. dybowskii during prespawning and prehibernation. According to histological analysis, the oviduct of R. dybowskii contains epithelial cells, glandular cells, and tubule lumens. During prehibernation, oviductal pipe diameter and weight were significantly larger than during prespawning. 3-Hydroxy-3-methylglutaryl CoA reductase (HMGCR), low-density lipoprotein receptor (LDLR), steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), and steroidogenic factor 1 (SF-1) were detected in epithelial cells in prehibernation and glandular cells during prespawning. HMGCR, LDLR, StAR, and P450scc protein expression levels were higher in prehibernation than during prespawning, but the SF-1 protein expression level did not significantly differ. HMGCR, LDLR, StAR, P450scc (CYP11A1), and SF-1 (NR5A1) mRNA expression levels were significantly higher in prehibernation compared with prespawning. The transcriptome results showed that the steroid synthesis pathway was highly expressed during prehibernation. Existing results indicate that the oviduct is able to synthesize steroid hormones using cholesterol, and that steroid hormones may affect the oviductal functions of R. dybowskii.

Seasonal expressions of COX-1, COX-2, and EP4 in the scent glands of muskrats (Ondatra zibethicus)

Prostaglandins (PGs) serve as signaling molecules that regulate various physiological processes, including inflammation, immune response, blood clotting, and reproduction. The aim of this study was to investigate the immunolocalizations and expression patterns of prostaglandin-E2 (PGE2), cyclooxygenase (COX)-1, and COX-2, as well as its receptor subtypes 4 (EP4) in the scent glands of muskrats (Ondatra zibethicus) during the breeding and nonbreeding periods. There were significant seasonal differences in the scent glandular mass, with higher values in the breeding season and relatively low in the nonbreeding season. PGE2, EP4, COX-1, and COX-2 have been immunolocalized in the scent glandular and epithelial cells in both breeding and nonbreeding seasons, whereas no immunostaining was observed in the interstitial cells. The protein and mRNA expression levels of EP4, COX-1, and COX-2 were higher in the scent glands of the breeding season than those of the nonbreeding season. The mean mRNA levels of EP4, COX-1, and COX-2 were positively correlated with the scent glandular weights. The circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), and PGE2, as well as scent glandular PGE2 and dihydrotestosterone (DHT) concentrations, were also significantly higher in the breeding season. In addition, the transcriptomic study in the scent glands identified that differentially expressed genes might be related to fatty carboxylic monocarboxylic acid, steroidogenic-related pathways, and prostanoid metabolic processes. These findings suggested that prostaglandin-E2 might play an essential autocrine or paracrine role in regulating seasonal changes in the scent glandular functions of the muskrats.

Effects of temperature on growth, development and the leptin signaling pathway of Bufo gargarizans

Climate change is one of the most important causes of the decline in amphibians. Changes in temperature have an important effect on the growth and development and energy metabolism of amphibians. The aim of this study is to unravel the effects of temperature on the leptin signaling pathway of Bufo gargarizans and its molecular mechanisms. Our results showed that high temperature accelerated the development rate of tadpoles, but reduced body size and mass, while low temperature deferred the development of tadpoles, but increased size and mass. Both high temperature and low temperature exposure caused pathological damage of the liver in B. gargarizans. The results of RT-qPCR revealed that the high temperature treatment significantly upregulated the transcript levels of genes related to thyroid hormone (DIO2 (D2), Thyroid Hormone Receptor-α (TRα)) and the leptin signaling pathway (Leptin Receptor (LepR), Janus kinase 1 (JAK1), Janus kinase 2 (JAK2), Tyrosine kinase 2 (TYK2), Signal Transducer And Activator Of Transcription 3 (STAT3), Signal Transducer And Activator Of Transcription 3.1 (STAT3.1), and Signal Transducer And Activator Of Transcription 6 (STAT6)), while there was a decrease of mRNA expression of these genes (TRα, Thyroid Hormone Receptor-Beta (TRβ), LepR, JAK1, and TYK2) in the liver of tadpoles exposed to high temperature compared with the intermediate temperature treatment. Therefore, our results suggested that temperature extremes might interfere with the thyroid and leptin signaling pathways and affect the growth and development of B. gargarizans. Furthermore, tissue injury of the liver could occur due to exposure to temperature extremes. This work promotes public awareness of environmental protection and species conservation needs, also provides valuable experimental data and a theoretical basis for the protection of amphibians.

17Beta-Estradiol Regulates NUCB2/ Nesfatin-1 Expression in Mouse Oviduct

NUCB2/nesfatin-1 known to regulate appetite and energy homeostasis is expressed not only in the hypothalamus, but also in various organs and tissues. Our previous reports also demonstrated that NUCB2/nesfatin-1 was expressed in the reproductive organs, including the ovaries, uterus, and testes of mice. However, it is yet known whether NUCB2/nesfatin-1 is expressed in the oviduct and how its expression is regulated. Therefore, we investigated the expression of NUCB2/nesfatin-1 in the oviduct and its expression is regulated by gonadotropin. Immunohistochemical staining results showed that nesfatin-1 protein was localized in epithelial cells of the oviduct. As a result of quantitative real-time PCR (qRT-PCR) and Western blot, NUCB2/nesfatin-1 was detected strongly in the oviducts. During the estrus cycle, NUCB2/nesfatin-1 expression in the oviducts was markedly higher in the proestrus stage than in other estrus stages. In order to elucidate whether the expression of NUCB2 mRNA is controlled by the gonadotropins, we injected PMSG and hCG and measured NUCB2 mRNA level in the oviduct after injection. Its level was increased in the oviduct after PMSG injection, but no significant change after hCG injection. In addition, NUCB2 mRNA levels were markedly reduced after ovariectomy, while recovered after 17β-estradiol (E2) injection, but not by progesterone (P4). This study demonstrated that NUCB2/nesfatin-1 is highly expressed in the oviduct of mouse and its expression is regulated by E2 secreted by the ovaries. These results suggest that NUCB2/nesfatin-1 expressed by the oviduct may affect the function of the oviduct regulated by the ovaries.

Walnut Polyphenol Extract Protects against Fenitrothion-Induced Immunotoxicity in Murine Splenic Lymphocytes

Fenitrothion (FNT), an organophosphate pesticide, exerts an immunotoxic effect on splenocytes. Dietary polyphenol compounds exert antioxidant, anticancer and antihypertensive effects. In this study, we investigated the effect of walnut polyphenol extract (WPE) on FNT-induced immunotoxicity in splenic lymphocytes in vitro. Treatment with WPE significantly increased the proliferation of FNT-exposed splenocytes, as evidenced by increases in the proportions of splenic T lymphocytes (CD3⁺ T cells) and T-cell subsets (CD8⁺ T cells), as well as the secretion of the T-cell-related cytokines interleukin (IL)-2, interferon-γ, IL-4 and granzyme B. These effects were associated with a reduction in oxidative stress, as evidenced by changes in the levels of hydroxyl radical, superoxide dismutase, glutathione peroxidase and malondialdehyde. Moreover, WPE decreased the FNT-induced overexpression of NADPH oxidase 2 and dual oxidase 1 by regulating Toll-like receptor 4 signaling in splenic T-cells. Taken together, these findings suggest that WPE protects against FNT-mediated immunotoxicity and improves immune function by inhibiting oxidative stress.