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Polycystic ovary syndrome (PCOS) is one of the most common ovarian diseases among women of reproductive age. The reproductive and metabolic traits of PCOS are underpinned by adipocyte dysfunction, especially diminished adiponectin secretion. Based on evidence that niacin stimulates adiponectin secretion, this study evaluated the effects of niacin on adiponectin concentrations and reproductive traits in a rat model of PCOS. PCOS was induced by single injection of 4mg kg-1 oestradiol valerate (i.m.), and PCOS groups were administered orally with saline or niacin (10 or 25mg kg-1) daily for 30 days after PCOS induction. The control group received 0.2mL sesame oil (i.m.) only. At the end of the experimental period, serum samples and ovaries were collected for adiponectin, histological and molecular analyses. Niacin reduced the bodyweight gain and increased ovary weights in PCOS rats. Niacin also increased the number of normal antral follicles and corpora lutea while reducing the number of cystic follicles and the thickness of theca interna. Moreover, niacin significantly increased serum adiponectin concentration and the gene expression of adiponectin and its type 1 receptor. In conclusion, this study indicates that niacin reduces cystic follicles and improves ovulation in PCOS rats. Adiponectin signalling may have contributed, in part, to the beneficial effects.

Overexposure to glucocorticoids during fetal development alters fetal organ growth and maturation patterns, which can result in adverse programming outcomes in adulthood. The aim of this study was to determine whether exposure to dexamethasone (Dx) during the fetal period programmed ovary development and function in infant (16-day-old) and peripubertal (38-day-old) female offspring. Pregnant Wistar rats were separated into control and Dx-treated (0.5mg kg-1) groups and were injected with Dx or an equivalent volume of vehicle on Days 16, 17 and 18 of gestation. Ovaries from 16- and 38-day-old female offspring were prepared for histological and stereological examination. The volume of the ovary and the number of primordial and primary follicles were significantly reduced in prenatally Dx-exposed infant and peripubertal female offspring compared with control offspring. The number of multilaminar follicles was decreased in infant female offspring. In peripubertal females, prenatal exposure to Dx increased the number of multilaminar and large follicles of all classes. Because vaginal opening did not occur up to Day 38 postpartum in the Dx-exposed offspring, the absence of ovulation and corpora lutea is confirmation that the onset of puberty had been delayed. We can conclude that overexposure to glucocorticoids early in life programs ovary development, which may affect fertility in adulthood.

This study was designed to determine whether prenatal dexamethasone treatment has an effect on follicular development and atresia in the ovary of spiny mouse (Acomys cahirinus) offspring. Dexamethasone (125µg kg -1 bodyweight per day) was administered to pregnant spiny mice from Day 20 of gestation to parturition. The processes of follicle loss were analysed using classical markers of apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling reaction, active caspase-3) and autophagy (Lamp1). The present study indicated that dexamethasone reduced the pool of healthy primordial follicles. Moreover, the oocytes from these follicles showed intensive caspase-3 and Lamp1 staining. Surprisingly, dexamethasone caused an increase in the number of secondary follicles; however, most of these follicles were characterised by extensive degeneration of the oocyte and caspase-3 and Lamp1 labelling. Western-blot analysis indicated that the glucocorticoid receptor as well as apoptosis and autophagy markers were more strongly expressed in the DEX-treated group than in the control. On the basis of these findings, we have concluded that dexamethasone impairs spiny mouse folliculogenesis and enhances follicular atresia through induction of autophagy or combined autophagy and apoptosis.

High-producing dairy cows are subfertile; however, the mechanisms responsible for the decreased fertility are unknown. The aim of the present study was to test the hypothesis that culled dairy cows (4-8 years old) characterised by 'Lo' ovaries (i.e. those with <10 mid-antral follicles) are affected by premature ovarian senescence. Cows in which both ovaries were 'Lo' ovaries represented 5% of the total population analysed, and exhibited reduced ovarian size (P<0.001) and increased perifollicular stroma (P<0.05) compared with age-matched controls (i.e. cows in which both ovaries had >10 mid-antral follicles; 'Hi' ovaries). The total number of follicles, including healthy and atretic primordial, primary, secondary and small antral follicles, was lower in Lo ovaries (P<0.01). Interestingly, the primordial follicle population in Lo ovaries was lower (P<0.05) than in the control. Finally, the follicular fluid of mid-antral follicles from Lo ovaries had reduced oestradiol and anti-Müllerian hormone levels (P<0.05), but increased progesterone concentrations (P<0.05). Together, these data account for the reduced fertility of cows with Lo ovaries and are in agreement with previous observations that oocytes isolated from Lo ovaries have reduced embryonic developmental competence. Cows with a specific Lo ovary condition may represent a suitable model to address the causes of low fertility in high-yielding dairy cows, as well as the condition of premature ovarian aging in single-ovulating species.

This study assessed carry-over effects of energy level during the early antral phase and subsequent follicular phase on follicle recruitment and ovulation rate. Gilts (n=45) were fed a standard diet to a low (L, ~1.2kg day(-1)) or high (H, ~2.7kg day(-1)) level during the early antral (luteal) phase, and subsequently fed a H or L feed level during the follicular phase, resulting in four treatment groups (HH, HL, LH and LL). Follicle size at the end of the luteal phase was greater for gilts fed a high feed level previously (3.3vs3.0mm; P<0.05). During the follicular phase, high feeding increased follicle size at Day 5 (6.9vs6.2mm; P<0.005) and plasma oestradiol concentration (P<0.05). Nevertheless, a low feed level during the luteal phase reduced ovulation rate (14.4vs13.2; P<0.05) and embryo number (12.6vs10.5; P<0.05), and this was not counteracted by feed level during the follicular phase. Plasma progesterone concentration after ovulation was lower for LL gilts than for other treatments (P<0.05). These results indicate that undernutrition during early antral follicle development may have a residual effect on follicle recruitment and quality.

A follicular wave and luteolysis were induced in mares by ablation of follicles > or =6 mm and treatment with prostaglandin F(2alpha) (PGF) on Day 10 (where ovulation = Day 0). The incidence of haemorrhagic anovulatory follicles (HAFs) in the induced waves (20%) was greater (P < 0.007) than in preceding spontaneous waves (2%). Hormone and follicle dynamics were compared between induced follicular waves that ended in ovulations (ovulating group; n = 36) v. HAFs (HAF group; n = 9). The day of the first ovulation or the beginning of HAF formation at the end of an induced wave was designated as post-treatment Day 0. The mean 13-day interval from Day 10 (PGF and ablation) to the post-treatment ovulation was normalised into Days 10 to 16, followed by Day -6 to Day 0 relative to the post-treatment ovulation. Concentrations of LH were greater (P < 0.05) in the HAF group than in the ovulating group on Days 10, 11, 12, 14, -3 and -2. The HAF group had greater (P < 0.003) LH concentrations on Day 10 of the preceding oestrous cycle with spontaneous ovulatory waves. The diameter of the largest follicle was less (P < 0.05) in the HAF group on most days between Day 13 and Day -1 and this was attributable to later (P < 0.002) emergence of the future largest follicle at 6 mm in the HAF group (Day 12.4 +/- 0.5) than in the ovulating group (Day 11.3 +/- 0.1). The results indicate that the high incidence of HAFs after PGF and ablation was associated with later follicle emergence and immediate and continuing greater LH concentration after PGF treatment, apparently augmented by an inherently high pretreatment LH concentration.