Fig 2: Serum testosterone level measured by ELISA in different groups, GI (CTL): normal control, GII (GM): gentamycin induced testicular damage, GIII (PIO5): pioglitazone treated (5 mg/kg/day), GIV (PIO10): pioglitazone treated (10 mg/kg/day) and GV (PIO20): pioglitazone treated (20 mg/kg/day). Values are as mean ± SEM. (a) compared to control group, (b) compared to a diseased group, (c) compared to PIO 5 (GIII) group, (d) compared to PIO 10 (G IV) group, (e) compared to PIO 20 (GV) group. Serum LH and FSH were significantly elevated in response to gentamycin treatment in (GII, GM) compared to (GI, CTL) (p < 0.01). While the treated groups (GIII, GIV) showed a significant reduction in serum LH and FSH compared to GII, GM (p < 0.01) for both. GIV, PIO10 and GV, PIO 20 showed a non- significant difference in LH level compared to GI, CTL (p = 0.05, p > 0.05) respectively, while only GV, PIO20 showed a non- significant difference in FSH level compared to GI, CTL (p > 0.05) (Table 6).

Fig 3: Seasonal change levels of FSH, LH and T (a-c) in the plasm of the wild ground squirrels. B, the breeding season; NB, the non-breeding season. Data are shown as the mean ± SEM. ***P<0.001.

Fig 4: Serum hormone level analysis. Levels of E2 (a), AMH (b), and FSH (c) were measured by ELISA at 0 (when the perimenopausal model was established), 14, 21, and 28 days after hUCMSCs transplantation. * P < 0.05 vs control group. AMH anti-Müllerian hormone, E 2 estradiol, FSH follicle-stimulating hormone

Fig 5: Female rats showed decreased memory ability and increased ferroptosis in the hippocampus after OVX. (A) Experimental diagram of oestrous cycle confirmation, grouping, OVX modelling and behavioural tests in female SD rats. (B) Weight gain of rats after modelling (n = 6). (C) Levels of reproduction-related serum hormones, including LH, FSH and E2 (n = 6). (D) Relative hippocampal volumes from brain MRI (cm3, n = 6). The hippocampal volume was the area times the layer thickness. (E) Representative MRI images and division of the hippocampus in various scanning layers from MRI images. White dotted lines are edges of the hippocampal region. (F) Representative traces of rats recorded in the MWM. (G) Swimming speed (cm/s, n = 6) in the MWM test. (H) Escape latency during the learning period in the MWM test (s, n = 6). (I) Platform crossover times during the probe test in the MWM (n = 6). (J) Percentage of the time or distance travelled in the platform quadrant or in the quadrant opposite the platform (n = 6). (K) Representative images of Prussian blue iron staining (enhanced with DAB) in the hippocampal region in female rats (n = 3, scale bar = 50 µm). (L) Measurement of iron content in hippocampal tissue (µg/mg, n = 6). (M) Representative images of western blots and quantitative analyses showing the expression levels of DHODH at 2, 4 and 10 weeks after modelling (n = 3). (N) Representative images of western blots and quantitative analysis showing the expression levels of DHODH, GPX4, TfR, ferritin, FPN1, PCBP1 and GAPDH in rat hippocampi at 10 weeks after modelling (n = 3). (O) Representative TEM images of the hippocampus in female rats (left, scale bar = 2 µm); yellow triangles indicate mitochondria (right, scale bar = 500 nm). *P < 0.05, OVX vs. sham, E2 and Lip-1; #P < 0.05, OVX vs. sham. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)