Summary. The concentrations of progesterone and oestradiol in the oviducal fluid during oestrus and pseudopregnancy were measured. Progesterone concentrations ranged from 0·55 ± 0·17 ng/ml during oestrus to a maximum of 2·86 ± 0·82 on Day 12 of pseudopregnancy. Serum progesterone concentrations were similar to those found in oviduct fluid during oestrus, but by Day 12 serum levels had risen to 14·13 ± 1·97 ng/ml. Daily oviducal fluid oestradiol values ranged from 48·3 ± 6·4 pg/ml to 119·7 ± 23·6 pg/ml and were similar to serum concentrations.
Laura L. Richardson and G. Oliphant
M. K. Vaughan, B. A. Richardson, L. J. Petterborg, G. M. Vaughan and R. J. Reiter
Summary. Adult female hamsters were injected each afternoon for 9 weeks with 2·5, 15 or 25 μg of melatonin or 6-chloromelatonin (CM). Each drug resulted in a significant dose-related depression in uterine, ovarian and anterior pituitary gland weights. Additionally, plasma and pituitary concentrations of prolactin fell with increasing dose of either indole whereas pituitary levels of LH and FSH were positively correlated with dose. There was no difference in effectiveness between the two drugs.
Adult male hamsters treated for 10 weeks with daily afternoon injections of melatonin and a blank beeswax pellet had depressed testicular and accessory organ weights and plasma and pituitary concentrations of prolactin. Implantation of a 1 mg melatonin or CM beeswax pellet in hamsters concurrently receiving daily afternoon injections of melatonin prevented the organ weight and hormonal changes, except for plasma prolactin.
Adult male hamsters treated for 10 weeks with daily afternoon injections of CM and a blank beeswax pellet had depressed reproductive organ weights and pituitary and plasma concentrations of prolactin; this depression in hormonal values and organ weights was totally prevented if the CM-injected hamsters were also bearing a beeswax–melatonin pellet.
In conclusion, 6-chloromelatonin is as effective as melatonin with regards to antigonadotrophic and counter-antigonadotrophic effects in male and female Syrian hamsters.
L Richardson, J P Hanrahan, T Tharmalingam, S D Carrington, P Lonergan, A C O Evans and S Fair
The aim of this study was to investigate the properties and to functionally characterize the cervical mucus that modulates sperm transport through the cervix by using ewe breeds with a divergent pregnancy rate (Belclare and Suffolk; high and low, respectively) following cervical insemination using frozen-thawed semen. Sperm number, as well as sialic acid and fucose content in both the channels and in the lumen of different regions of the cervix were quantified in inseminated Belclare and Suffolk ewes. Expression of glycosyltransferase and MUC genes, glycosidase activity and sialic acid speciation in follicular phase cervical tissue and mucus were assessed. More spermatozoa were found in the cervical channels in the region closest to the cervical os in Belclare than Suffolk ewes (P < 0.05) and Suffolk ewes had a higher sialic acid content in the cervical channels than Belclare ewes (P < 0.05) in all regions of cervix. Suffolk ewes had significantly higher expression of FUT1, ST6GAL1 and MUC5AC than Belclare ewes. There was no difference between the breeds in glycosidase activity (P > 0.05). Levels of Neu5Ac were higher in Belclare than Suffolk ewes (P < 0.05) and levels of Neu5Gc was higher in Suffolk than Belclare ewes (P < 0.05). Competitive sperm penetration assays demonstrated that frozen-thawed sperm progression increased when cervical mucus was incubated with sialyllactose prior to a sperm penetration test (P < 0.05). These results suggest that the difference between Belclare and Suffolk ewes in sperm transport with frozen-thawed semen is due to the higher concentration of sialic acid within channels, which binds to spermatozoa and reduces their ability to traverse the cervix.