Matrix metalloproteinase inhibition influences aspects of photoperiod stimulated ovarian recrudescence in Siberian hamsters

Abstract

Blocking matrix metalloproteinase (MMP) activity in vivo with inhibitor GM6001 impedes photostimulated ovarian recrudescence in photoregressed Siberian hamsters. Since direct and indirect effects of MMPs influence a myriad of ovarian functions, we investigated the effect of in vivo MMP inhibition during recrudescence on ovarian mRNA expression of steroidogenic acute regulatory protein (StAR), 3β-hy-droxysteroid dehydrogenase (3β-HSD), Cyp19a1 aromatase, epidermal growth factor receptor (EGFR), amphiregulin (Areg), estrogen receptors (Esr1 and Esr2), tissue inhibitors of MMPs (TIMP-1,-2,-3), proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor A (VEGFA), its receptor VEGFR-2, and angiopoietin-2 (Ang-2). Female Siberian hamsters were randomly assigned to one of four photoperiod groups: stimulatory long (LD) or inhibitory short (SD) photoperiods, or transferred from SD to LD for 2 weeks (post-transfer, PT). Half of the PT hamsters were injected (ip) daily with GM6001 (PTG). SD exposure reduced ovarian StAR, 3β-HSD, Cyp19a1, Esr1, Esr2, TIMPs 2–3, PCNA, VEGFR-2 and Ang-2 mRNA expression (p < 0.05), and 2 weeks of photostimulation restored mRNA expression of 3β-HSD and PCNA and increased Areg and VEGFA mRNA expression in the PT group. GM6001 treatment during photostimulation (PTG) increased TIMP-1, -2 and -3 and PCNA mRNA, but inhibited Areg mRNA expression compared to PT. Neither photoperiod nor GM6001 altered EGFR expression. Results of this study suggest that in vivo inhibition of MMP activity by GM6001 may impede ovarian recrudescence, particularly follicular growth, in two ways: (1) directly by partially inhibiting the release of EGFR ligands like Areg, thereby potentially affecting EGFR activation and its downstream pathway, and (2) indirectly by its effect on TIMPs which themselves can affect proliferation, angiogenesis and follicular growth.

Assessing recrudescence of photoregressed Siberian hamster ovaries using in vitro whole ovary culture

“…Photoregressed ovaries are different than cycling ovaries in many respects; reductions in mass, increases in atresia, a lack of tertiary follicles and corpora lutea, and reduced estradiol production typify ovaries from hamsters exposed to SD. In addition, SD ovaries show altered mRNA expression of key folliculogenic and steroidogenic factors compared with ovaries from LD‐exposed Siberian hamsters (Salverson et al, , Shahed & Young, , Shahed, Simmons et al, ). In normal mouse ovaries cultured with FSH, antrum formation was observed after 3 days (Boland, Humpherson, Leese, & Gosden, ), suggesting that our model of Siberian hamster ovaries differs from cultured ovaries from other cycling rodents.…”

“…Kitl and Fgf‐2 promote the primordial to primary follicle transition in cultured 4‐day old mouse ovaries (Nilsson & Skinner, ; Nilsson et al, ; Parrott & Skinner, ); however, in the current study, the addition of GT did not affect Fgf‐2 mRNA expression in photoregressed cSD ovaries and reduced the level of Fgf‐2 mRNA expression among cLD ovaries (Figure c). Similarly, ovarian Fgf‐2 mRNA expression decreases in vivo as FSH increases in Siberian hamsters are transferred from inhibitory to stimulatory photoperiods for 2–10 days (Shahed, McMichael et al ; Shahed, Simmons et al, ). Although the cause of this decline is unknown, it may be that the timing of collection after GT stimulation influences Fgf‐2 mRNA expression, as in vivo gonadotropin‐releasing hormone (GnRH) treatment increased Fgf‐2 mRNA in bovine preovulatory follicles at 4 hr but that increase had declined by 10 hr (Berisha, Steffl., Amselgruber, & Schams, ).…”

“…Estrogen and progesterone production in vitro peaks in the presence of GT (Gutiérrez, Campbell, & Webb, 1997;McNatty, Makris, Degrazia, Rapin, & Ryan, 1979;Roy & Greenwald, 1987) but can also be produced with or without the addition of FSH or LH to the culture media (Funkenstein, Nimrod, & Lindner, 1980, Uilenbroek, Woutersen, & van der Linden, 1983. Our previous in vivo studies have shown that plasma estradiol concentrations and mRNA expression of steroidogenic enzymes in Siberian hamster ovaries decline with exposure to SD photoperiod as compared with higher levels in both cycling LD hamsters and those undergoing photostimulated recrudescence (Shahed, McMichael et al 2015;Shahed, Simmons et al 2015). In contrast, changes in photoperiod exposure do not appear to alter plasma progesterone concentrations in hamsters in vivo (Moffatt-Blue et al, 2006).…”

“…Both GT and intraovarian factors respond quickly in vivo when female photoregressed hamsters are transferred to stimulatory long days (LD); plasma FSH concentrations, ovarian FSH receptor (Fshr), and inhibin α (Inh-α) messenger RNA (mRNA) expression increases significantly after 4 days of long photoperiod stimulation, suggesting the importance of these factors in the recrudescence process. In addition, in vivo mRNA expression of intraovarian growth factors such as anti-Müllerian hormone (Amh), bone morphogenic protein (Bmp-15), growth differentiation factor-9 (Gdf-9), vascular endothelial growth factor (Vegfa), angiopoietin-2 (Ang-2), epidermal growth factor receptor (Egfr), and amphiregulin (Shahed & Young, 2013;Shahed, Simmons, Featherstone, & Young, 2015) change with photoperiod in Siberian hamsters.…”

Lipotoxicity, neuroinflammation, glial cells and oestrogenic compounds

“…Interestingly, treatment with oestradiol reduced the development of this obese phenotype, demonstrating that these effects on the homeostasis of body weight are mediated mainly by the activation of ER . Humans or mice with mutations in the ER gene ( ESR1 ) are obese . Similalrly, oestradiol therapy was found to have no effect in mice subjected to ER suppression …”