Reproduction

Polge, Chris

doi: 10.1530/jrf.0.1000001pmid: N/A

Cook, Brian

doi: 10.1530/jrf.0.1000002pmid: N/A

Small annual meetings on reproduction, from which the Society for the Study of Fertility (SSF) was to develop, started in 1944. The proceedings of these meetings were first published in 1947 by the Family Planning Association under the title Conference on Infertility. From 1949 to 1953, Heffers published the Proceedings of the Society for the Study of Fertility and, from 1954, Blackwell Scientific Publications continued with Studies on Fertility. As early as 1952, the possibility of producing a quarterly journal was raised, but finance proved a major obstacle. In 1956, Alan Parkes proposed, on behalf of the SSF, that the Journal of Endocrinology should become the official organ of the SSF, and that it should be renamed the Journal of Endocrinology and Reproduction. Solly Zuckerman supported this initiative, but views of members of the Society for Endocrinology on the proposal were so divided that the idea was abandoned.In 1957,

Urbanski, H. F.; Fahy, M. M.; Daschel, M.; Meshul, C.

doi: 10.1530/jrf.0.1000005pmid: 8182610

Although the excitatory amino acid (EAA) receptor agonist N-methyl-d-aspartate (NMDA) can exert profound stimulatory effects on the neuroendocrine reproductive axis of Syrian hamsters, the exact relationship between NMDA receptors and LHRH neurones is unclear. In the present study, in situ hybridization histochemistry was performed on sections of hamster brain using an 35S-labelled riboprobe to the EAA receptor gene, NMDAR1. A high content of NMDA receptor mRNA was detected not only in brain areas classically associated with specific NMDA binding (for example, hippocampus and cerebral cortex) but also in the hypothalamus, in particular the ventromedial–arcuate area; diffuse hybridization of the riboprobe also occurred in the medial–septal area and diagonal band of Broca, regions of the hamster brain in which the LHRH neuronal perikarya are primarily located. In a separate experiment, RNA was extracted from immortalized LHRH neurones (GT1–1 and GT1–7 cells) and used for northern analysis with a 32P-labelled NMDAR1 riboprobe. Clear-cut hybridization occurred with RNA bands of approximately 4.2 and 4.4 kb from the two LHRH neuronal subtypes. These findings suggest that at least some of the stimulatory action of EAAs on LHRH secretion is likely to be exerted directly at the level of the LHRH neurones rather than being mediated through interneurones. Furthermore, the demonstration of abundant NMDA receptor gene expression within hypothalamic areas that lie outside the blood–brain barrier adds plausibility to the concern that EAAs of dietary origin, such as monosodium glutamate, have the capacity to perturb the normal secretory activity of neuroendocrine circuits of the hypothalamus.

Asher, G. W.; Veldhuizen, F. A.; Morrow, C. J.; Duganzich, D. M.

doi: 10.1530/jrf.0.1000011pmid: 8182577

The effects of administration of exogenous melatonin to pregnant red deer hinds on prolactin secretion, lactogenesis and reproductive seasonality were studied. Mature hinds (n = 23) were allocated to one of four treatments. Hinds in treatment 1 (n = 6) each received two subcutaneous melatonin implants (Regulin) at monthly intervals starting on 2 October, about 80 days before expected parturition. Hinds in treatment 2 (n = 6) received similar treatment starting on 2 November, about 40 days before calving, whereas hinds in treatment 3 (n = 5) received treatment starting on the actual day of calving (about 10 December). Final implants were delivered on 1 February, with overall treatment durations of 150, 120 and 90 days for treatments 1–3, respectively. Hinds in treatment 4 (n = 6) served as controls and received no melatonin treatment. Blood samples were taken twice a week from September to May, and plasma was analysed for progesterone and prolactin. Mammary development was assessed by palpation score (0–5) twice a week from October to April inclusive, and liveweights were recorded at least every two weeks throughout the trial. Calving occurred between 28 November and 24 December, with no significant differences among treatments (P > 0.10). Hinds in treatment 1 exhibited significant retardation of mammary gland development and liveweight gain leading up to parturition (P < 0.01). Furthermore, sex-adjusted calf birth weights were on average 3 kg lighter for treatment 1 (P < 0.05), with all calves either removed for bottle-rearing or having died within a few hours of birth. Failure of lactogenesis in treatment 1 was characterized by the presence of underdeveloped, hard mammary tissue devoid of expressible milk. Hinds in treatments 2–4 all exhibited full lactation and successfully reared their calves, and there were no significant differences in calf weaning weight and growth rates. Likewise, there were no significant differences in mean liveweight or lactation score profiles. Mean plasma prolactin concentrations varied significantly between treatments (P < 0.05), and control hinds exhibited a marked seasonal pattern of secretion which reached a peak at calving. However, hinds in treatments 1 and 2 failed to show any discernible seasonal increase in mean plasma prolactin concentrations, whereas there was a marked increase in mean prolactin concentrations in hinds in treatment 3 up to parturition, but concentrations decreased rapidly thereafter relative to those of control hinds. Melatonin treatment significantly advanced the date of first oestrus and decreased the postpartum–oestrus interval (P < 0.05). It was concluded that initiation of melatonin implant treatment about 80 days before parturition compromises mammary and fetal development in red deer hinds. However, the role of prolactin was not demonstrated conclusively.

Miyoshi, K.; Funahashi, H.; Okuda, K.; Niwa, K.

doi: 10.1530/jrf.0.1000021pmid: 8182591

Rat one-cell embryos recovered from naturally mated females were cultured in modified hamster embryo culture medium 1 without amino acids. In the presence of 0.4 mmol phosphate l−1 (NaH2PO4), no embryos developed beyond the two-cell stage, regardless of the presence of 5.0 mmol glucose l−1. This inhibition was dose dependent at very low concentrations of phosphate in the medium supplemented with 7.5 mmol glucose l−1 and osmolarity adjusted to 244 mosmol; development to the blastocyst stage was not inhibited at 0.001–0.01 μmol phosphate l−1, but development to the morula and four-cell stages was markedly inhibited at 0.1 and 1.0 μmol phosphate l−1. In the medium without phosphate, glucose did not inhibit or promote development to the morula stage, but adequate concentrations of glucose were necessary for the development of morulae to the blastocyst stage; the percentage of one-cell embryos that developed to the blastocyst stage at 7.5 mmol glucose l−1 (67%) and 10.0 mmol glucose l−1 (60%) were not statistically different from the percentage at 5.0 mmol glucose l−1 (46%), but was significantly greater than the percentage at 2.5 mmol l−1 (33%). When osmolarity of the medium with 5.0 mmol glucose l−1 was varied by adjusting the amount of NaCl added, more (82–98%) of the one-cell embryos developed to the four-cell stage at 212–276 mosmol, but development was greatly inhibited at 304 mosmol. Development to the blastocyst stage was largely dependent on osmolarities; at 244 mosmol, 61% of embryos developed to the blastocyst stage, although this percentage was not significantly different from the percentage (43%) at 264 mosmol.

Adams, G. P.; Evans, A. C. O.; Rawlings, N. C.

doi: 10.1530/jrf.0.1000027pmid: 8182600

Eleven age-matched (±4 days) Hereford heifers were examined by transrectal ultrasonography daily for 18 days beginning 20 weeks (5 months) before puberty (first ovulation) to determine the suitability of the transrectal ultrasound technique for imaging the ovaries of prepubertal heifers and to test the hypothesis that ovarian follicular development occurs in waves in prepubertal heifers. Satisfactory ovarian images were obtained during preliminary ultrasound examinations conducted 4 weeks before the observational period (that is 32 weeks of age), during which a semirigid probe extension was used to allow external manipulation of the intrarectally placed ultrasound transducer. Daily examinations commencing at 36 weeks of age were accomplished by intrarectal placement of the operator's hand and transducer, without complication, in all 11 heifers throughout the observational period. Periodic increases in the number of follicles detected (day effect, P < 0.02) were inversely related to the diameter of the largest follicle (r = −0.3, P < 0.03). Portions of three anovulatory follicular waves were detected in all heifers during the observational period (first and third waves in part and second wave in whole). Individual follicles destined to assume a dominant or subordinate position in a wave were retrospectively identified and monitored beginning at a diameter of 4–5 mm. The interval between the emergence of dominant follicles of successive waves (interwave interval) was 8.0 ± 0.4 days and the interval between successive maxima in the number of follicles per heifer per day was 8.1 ± 0.5 days. The growing phase of the dominant follicles best fit a quadratic curve. The growing phase of the largest subordinate follicles, and the static and regressing phases of dominant and subordinate follicles best fit simple linear expressions. Periodic surges in serum concentrations of FSH (day effect, P < 0.0001), but not of LH (day effect, not significant), were associated with follicular wave dynamics. FSH surges (increase and decrease, respectively, best fit quadratic curves) spanned a mean of 3 days and reached maximum values 0.9 ± 0.3 days before emergence of the wave. Results supported the hypothesis that follicular development occurs in waves in prepubertal heifers. Mechanisms controlling the well-ordered phenomena of wave emergence, follicle selection and follicle regression, similar to those of sexually mature heifers, were present in 36-week-old prepubertal heifers.

Skutelsky, E.; Ranen, E.; Shalgi, R.

doi: 10.1530/jrf.0.1000035pmid: 8182608

The lectin-binding patterns of mammalian zonae pellucidae were investigated to determine whether differences reflected their characteristic carbohydrate distribution patterns. Ovaries isolated from rodents (mouse, rat and hamster), rabbits, cats, dogs and pigs were fixed with glutaraldehyde and embedded in paraffin wax. Sections 5 μm, were deparaffinized, rehydrated and labelled with ten different biotinylated lectins as probes and avidin–biotin– peroxidase complex as visualant. The zonae pellucidae of all animals studied exhibited species-specific variations in lectin-binding patterns, whereas the lectin binding of their granulosa cells and follicular fluids were identical. Phylogenetically close species, such as the rodents and rabbits demonstrated high similarity in zona pellucida saccharides, expressed in binding of succinylated wheatgerm agglutinin and peanut agglutinin. Lectins such as Dolichos biflorus agglutinin, which binds only to mouse, Griffonia simplicifolia (GS-I), which binds to mouse and rat but not hamster and rabbit and soybean agglutinin, which binds only to rodents, reflect characteristic differences between phylogenetically related mammals.

Zakar, T.; Teixeira, F. J.; Hirst, J. J.; Guo, F.; MacLeod, E. A.; Olson, D. M.

doi: 10.1530/jrf.0.1000043pmid: 8182609

Since glucocorticoids decrease and protein kinase C (PKC) activators increase amniotic PGE2 production, the possibility that they regulate the activity of prostaglandin endoperoxide H synthase (PGHS), the rate-limiting enzyme of prostaglandin synthesis from arachidonate, was investigated. Glucocorticoids inhibited the production of PGE2 from exogenous arachidonate specifically and in a concentration dependent fashion. Furthermore, cortisol decreased PGHS activity and the amount of PGHS protein in amnion microsomes, and reduced the rate of recovery of PGHS after acetylsalicylic acid (ASA) pretreatment. Actinomycin D blocked the inhibition of PGHS recovery by cortisol, but did not suppress the spontaneous recovery of the enzyme, indicating that the glucocorticoid induced a post-transcriptional inhibitor of PGHS synthesis. PKC-activating phorbol esters, such as 12-tetradecanoyl phorbol 13-acetate (TPA) increased the synthesis of PGE2 from exogenous arachidonate, also in a specific and concentration dependent manner. PGHS recovery after ASA treatment was enhanced by TPA. PGHS activity and protein concentrations were increased by phorbol ester treatment; however, this was apparent only in tissues in which the concentrations of PGHS were initially low. These results show that the synthesis of PGHS is positively and negatively regulated in the human amnion by PKC and glucocorticoids, respectively, and suggest that effectors using these pathways may regulate the enzyme in vivo.

Al-Gubory, K. H.; Driancourt, M-A.; Antoine, M.; Martal, J.; Neimer, N.

doi: 10.1530/jrf.0.1000051pmid: 8182611

Porcine and ovine follicular tissues were used to investigate, in vitro, the effect of charcoal-treated aqueous extract from ovine corpora lutea of pregnancy on aromatase activity as determined by the conversion of [3H]testosterone to oestradiol by follicular walls and measurement of 3H2O release. Extract (500 μg protein) prepared from corpora lutea of day 112 of pregnancy but not extract (500 μg) prepared from ovine fetal cotyledonary tissue obtained at a similar time significantly decreased (P < 0.02) aromatase activity of pig follicles in the absence of FSH. These results demonstrate that a non-steroidal factor in the corpora lutea of late pregnancy directly inhibits aromatase activity. When the effects of different doses (300, 600 or 1200 μg) of luteal extract from corpora lutea of day 100 of pregnancy on aromatase activity of pig follicles were studied, the dose by treatment (presence or absence of FSH) interaction was not significant. Luteal extract dose at 300 μg did not affect aromatase activity but a significant decrease in activity occurred at 600 μg of luteal extract (600 versus 300 μg, P < 0.02). There was no further significant increase in the inhibitory effect with 1200 μg luteal extract. When the effects of 600 μg luteal extract from corpora lutea of days 15, 75 or 100 of pregnancy on aromatase activity of pig follicles were studied, a significant (P < 0.05) stage of pregnancy effect was detected, but the stage of pregnancy by treatment (presence or absence of FSH) interaction was not significant. No effect was noted with day 15 or day 75 luteal extract. In contrast, aromatase activity in the presence of day 100 luteal extract was significantly reduced compared with that of control (P < 0.01) and day 15 luteal extract (P < 0.05). A significant (P < 0.05) stage of pregnancy effect was also observed on aromatase activity of sheep follicles. Aromatase activity of sheep follicles was significantly reduced in the presence of day 100 luteal extract compared with that of control (P < 0.05) and day 15 luteal extract (P < 0.02). These data suggest that the stimulus triggering the synthesis of the aromatase inhibitor appears after mid-pregnancy. The aromatase-inhibiting activity was lost from luteal extract of corpora lutea of day 100 of pregnancy after treatment with proteolytic enzymes, demonstrating the proteic nature of the aromatase inhibitor. These experiments provide evidence for the existence in ovine corpora lutea of late pregnancy of a non-steroidal factor that reduces follicular aromatase activity. We propose the term aromatase-inhibiting factor or AIF to describe this activity.

Shakil, T.; Snell, A.; Whitehead, S. A.

doi: 10.1530/jrf.0.1000057pmid: 8182612

The effects of stimulating the immune system with lipopolysaccharide (LPS) or suppressing the immune system with cyclosporin (CS) on reproductive functions in the female rat were investigated. Animals were either treated acutely with LPS (2 mg kg−1) or cyclosporin (20 mg kg−1) on dioestrus day 1 and 2 or treated chronically over a period of 6 days (on alternate days with LPS, daily with CS). Chronic LPS treatment induced a state of constant dioestrus and decreased circulating concentrations of progesterone and oestradiol. Chronic CS treatment induced some irregularity in the 4-day vaginal smear pattern in a minority of animals and, while it had no effect on circulating concentrations of progesterone, oestradiol concentrations were suppressed compared with those measured in pro-oestrous animals. LH responses to GnRH were reduced in both perifused pituitary fragments and cultured pituitary cells obtained from animals pretreated with either LPS or CS. In contrast, a low dose of LPS (20 μg kg−1) given over 6 days did not disrupt ovarian cycles and reduced, but did not abolish, the second phase primed LH response. Neither drug had a direct effect on the pituitary LH responses to GnRH, except that pituitary cells exposed to high doses of CS for periods greater than 48 h did show attenuated LH responses to GnRH. This finding was not paralleled with high doses of LPS. The differential count of ovarian follicles from histological studies showed that LPS treatment was associated with significantly fewer large preovulatory follicles, whereas animals treated with CS showed a similar distribution of follicular volumes compared with controls. Results suggest that the hypothalamic–pituitary control of ovarian function is impaired by both LPS and CS treatment, and LPS appears to have an additional effect in suppressing ovarian functions, possibly via an inhibitory action on steroidogenesis.