Ovarian expression of melatonin Mel(1a) receptor mRNA during mouse development

Melatonin, secreted by the pineal gland, is involved in the regulation of many physiological functions of various species of animals. In the present study, the expression of gene for melatonin Mel(1a) receptor (MelR) was evaluated in the ovary, hypothalamus, and pituitary according to the developmental stages in female mice. Semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) and in situ PCR techniques were applied. According to the developmental stages, gene for MelR was differently expressed on ovary, hypothalamus, and pituitary. MelR gene was first expressed on pituitary prior to the expression in hypothalamus and ovary. Ovarian MelR gene started to express at birth. Unlike hypothalamic expression of MelR gene which was identified after birth, in pituitary, it was expressed at 16 days post coitum. In the ovary, the expression signal of MelR gene was identified on granulosa cells. However, the signal was not detected in the theca cells. It was weak in the primordial and atretic follicles. Taken together, it can be considered that melatonin has a pivotal role in the folliculogenesis.

Pentobarbital and ketamine suppress serum concentrations of sex hormones in the female rat

PURPOSE

To investigate the potential effects of pentobarbital and ketamine on serum concentrations of sex hormones, the present study was performed using pregnant mare serum gonadotropin (PMSG)-primed cyclic female Sprague-Dawley rats.

METHODS

Pentobarbital sodium (37 mg.kg(-1), i. p.) or ketamine-hydrochloride (229 mg.kg(-1), i. m.) was injected 2 and 3 days after PMSG treatment. At 0, 1, 2, 3, 4, and 5 days after PMSG treatment, sera were collected by cardiac puncture. The serum concentrations of progesterone (P(4)), testosterone (T), and estradiol-17 beta (E(2)) were determined by radioimmunoassay.

RESULTS

The serum concentrations of P(4) tended to be lower in both the pentobarbital- and the ketamine-treated groups compared with the control group. Significant differences were found on days 3 and 4 after pentobarbital and on days, 1, 4, and 5 after ketamine administration. Serum concentrations of T were also suppressed in both the pentobarbital and the ketamine-treated groups, whereas E(2) concentrations decreased only in the ketamine-treated group.

CONCLUSION

Pentobarbital and ketamine decrease serum sex hormone concentrations in PMSG-primed female rats.

Natural and radiation-induced degeneration of primordial and primary follicles in mouse ovary

The present study deals with the morphological changes of the degenerating primordial and primary follicles induced by gamma-radiation. Prepubertal female mice of 3 weeks old ICR strain were gamma-irradiated with the dose of LD(80(30)) (8.3 Gy). The ovaries were collected at 3, 6 and 12 h after irradiation. The largest cross-sections were prepared by histological semithin sections for microscopical observations. The ratio (%) of normal to atretic follicles decreased with time after the irradiation in primordial follicles and in primary follicles as well. At 6 h after irradiation, the number of degenerated primordial follicles increased. Germinal vesicles disappeared and lipid droplets increased in number. Granulosa cells became round in shape and apoptotic cells started to appear. The ooplasmic membrane was not recognizable. The ratio of normal to atretic primordial follicles in the control group was 62.5. Then it became lower with time after the irradiation. It went down to 51.6, 49.0, 11.1 and 7.1 at 0, 3, 6 and 12 h, respectively. The ratio of normal to atretic primary follicles in the control mouse ovary was 81.3. It was 80.0, 75.0, 45.5 and 33. 3 at 0, 3, 6 and 12 h after irradiation, respectively. It is concluded that the ionizing radiation acutely induces the degeneration of primordial and primary follicles. The pattern of degeneration is one of the following: (1) apoptosis of one or more granulosa cells with a relatively intact oocyte, (2) apoptosis of an oocyte with intact follicle cells, or (3) apoptotic degenerations of both kinds of cells. These results can provide morphological clues for the identification of the degenerating primordial and primary follicles in normal and irradiated mouse ovaries.

Gamma-radiation accelerates ovarian follicular atresia in immature mice

This study deals with the morphological degenerations of normal and atretic follicles based on artificially induced radiation apoptosis. ICR strain of 3 week-old female mice were whole body irradiated with 8.3 Gy and sacrificed by cervical dislocation. Ovaries were collected at 0 h, 6 h, 12 h, 1 d, 2 d, 4 d, and 8 d post irradiation and processed for morphological observation. Irradiated ovarian follicles showed such characteristics as faint connection between zona and cumulus thinning of granulosa layer, numerous apoptotic bodies, and increased cell debris in antrum. However, in normal ovaries about a half of the follicles were healthy. Within 6 h post irradiation, more than 95% of follicles steeply became apoptotic. At 4 d, severely damaged follicles with hypertrophed theca layer and fragmented oocytes were shown. At 8 d, normal shaped follicles were observed together with severely disrupted ones. The normal shaped follicles seemed to have grown from radioresistant ones. In conclusion, gamma-radiation had an additive or concomitant effect on atretic degeneration of mouse ovarian follicles.

Immunosuppression by corticosteroid has no effect on the pregnancy rate in routine in-vitro fertilization/embryo transfer patients

Immunosuppression by exogenous corticosteroids has been used to improve the rates of embryo implantation and pregnancy in in-vitro fertilization (IVF) patients who have micromanipulated embryos replaced. The present study was conducted, in a prospective design, to evaluate effects of corticosteroid on the pregnancy rate in IVF/embryo transfer patients who have non-micromanipulated embryos replaced. Infertile women < 40 years old with tubal factor were included in this study. Patients were grouped according to the different follicle stimulation protocols, and received various doses of 16 beta-methylprednisolone (0, 16 or 60 mg/day) for 4 days from the day of oocyte retrieval. The mean age, duration of infertility, length of folliculogenesis and serum oestradiol concentrations at the time of human chorionic gonadotrophin (HCG) injection were not significantly different between control and corticosteroid-treated groups of patients. Short-term immunosuppression by 16 beta-methylprednisolone administration did not show any effects on the pregnancy and miscarriage rates in IVF/embryo transfer patients. Also, immunosuppression showed no dose effects in any groups. There was no relationship between the types of follicle stimulation protocols and the effect of 16 beta-methylprednisolone. Therefore, we concluded that short-term immunosuppression by exogenous corticosteroids in IVF/embryo transfer patients who have embryos with intact zona pellucida replaced has neither positive nor negative effects on pregnancy rates.

Viability of Human Follicular Oocytes Collected from Unstimulated Ovaries and Matured and Fertilized in vitro

Immature human follicular oocytes were collected from unstimulated ovaries, matured and fertilized in vitro and then transferred to patients with no ovarian dysfunction such as premature ovarian failure. From 11 1 consenting donors, 422 immature oocytes were collected from 97 ovaries between January 1990 and October 1991. The number of oocytes collected from ovaries and their development were recorded so that comparisons could be made among donors of different ages and ovarian condition, such as menstrual cycle, cyclic and non-cyclic ovaries. The rate of fertilization in vitro showed a peak in the 31-40-year age group; however, there was no statistical difference in the rate of oocyte maturation and cleavage among the donors in the different age groups. Immature oocytes of the luted phase had a significantly higher maturation rate than those of the follicular phase. There was no significant difference in the number of recovered oocytes, or in the development of immature follicular oocytes, between cyclic and non-cyclic ovaries. Mature follicular fluid and peritoneal fluid had a significant effect on the development of immature follicular oocytes. Also, it was found that fertilized eggs cleaved more frequently in the medium containing hypoxanthine compared with the medium without hypoxanthine. Finally, from 21 transfer cycles, viable embryos were derived from immature follicular oocytes, resulting in two pregnancies, both leading to the birth of normal babies. These findings suggest that culture in vitro of immature follicular oocytes, from unstimulated ovaries, to a suitable condition, could be used optimally for clinical applications such as human ovum donation programmes.