The influence of steroid hormones on the uterine cervix during pregnancy

This paper reviews the evidence concerning the actions of steroid hormones on the connective tissues of the pelvis. Most available data concern the effects of steroids on the cervix. The time course of cervical softening in rats, sheep and humans suggests the possibility that the changes in connective tissue biochemistry that underlie the physiological phenomenon of cervical softening are under hormonal control. Both oestrogens and progestogens have been implicated in the control of cervical softening. However, recent experiments using inhibitors of 3 beta-hydroxysteroid dehydrogenase suggest that cervical softening can be produced in both sheep and humans by progesterone withdrawal in the absence of high circulating concentrations of oestradiol-17 beta.     

The influence of exogenous steroid hormones on steroid receptors, uterine histological structure and the bacterial flora of the normal bitch.

Oestrogen (ER) and progesterone (PR) receptors have been shown to vary in both concentration and distribution during the oestrous cycle of the bitch, influenced by the normal changes in endogenous reproductive hormones. The influence of exogenous steroid hormones on steroid receptors and the histological structure of the uterus was studied in two groups of parous Beagle bitches. Group A (n = 6) were treated with progesterone (P4) in oil i.m. (3 mg/kg) in late metoestrus on the day that peripheral plasma P4 concentrations were first identified as <10 ng/ml, and subsequently once weekly on three other occasions. Group B (n = 6) were treated with a single i.m. injection of MPA (50 mg, 4.2-5.6 mg/kg) following the same protocol. Full-thickness uterine wall biopsies were obtained from the mid part of one horn 2-7 days after the last (fourth) injection of P4 or MPA. During the subsequent oestrus, when peripheral plasma P4 concentrations were between 8 and 10 ng/ml, each bitch in both groups (n = 12) received a single injection of oestradiol benzoate (ODB) in oil i.m. (7.5 mg, 0.63-0.84 mg/kg). All bitches had an ovariohysterectomy 7 days later. Full-thickness uterine wall samples were obtained from the mid part of the intact horn and other parts of the uterus. Swabs were taken from the uterine lumen for bacteriological examination; all were sterile. Tissue samples were sectioned and examined for evidence of lesions, and stained for ER and PR receptors using an immunocytochemical method. The immunoreactivity was scored semiquantitatively, incorporating both the intensity and distribution of specific staining of the receptors using a simplified histoscore (H-score). At the time of ovariohysterectomy, fluid had accumulated in the isolated section of the uterine horn distal to the point of biopsy; the volume was greater in the MPA-treated bitches. There was also evidence in some sections of histological changes in the endometrium. Variations in the expression of both ER and PR were seen between bitches, which may have been due to some not being in mid-metoestrus at the time of treatment. In general, ER scores were low after P4 and MPA treatment, but following ODB there was a significant (P<0.05) increase in ER expression in all parts of the endometrium. PR scores were zero in the glandular epithelium of all 12 bitches after P4, MPA and ODB treatment, whereas in the other parts of the endometrium they were generally moderate to high. Following treatment with ODB, PR generally increased in the three regions of the endometrium where PR were present. The study shows that ER and PR distribution and expression in the endometrium of bitches can be modified by P4, MPA and ODB, with evidence of individual variation.     

The influence of mantle cavity fluid on the aerial oxygen consumption of some intertidal gastropods

The intertidal gastropods Gibbula cineraria (L.), Nucella lapillus (L.), and Littorina littorea (L.) have been investigated. Animals that had attached to a plastic surface under sea water were exposed to air and rapidly frozen. Fluid was found to be retained within the mantle cavity in contact with the gill. For each species the weight of the mantle cavity fluid retained in air was related to the whole weight of the animal. There was no significant difference between the weight of fluid held by animals in the laboratory and that held by animals on the shore 2 h after aerial exposure. The oxygen consumption of inactive individuals in air was measured by two techniques which did not produce significantly different results. The aerial oxygen consumption of all three species was lowered by the loss of mantle cavity fluid. This also reduced the temperature coefficient. A correlation is suggested between a large weight of mantle cavity fluid, the presence of a gill in the mantle cavity and a large reduction in oxygen consumption upon the loss of fluid.     

Effect of ovarian sex hormones on the pool of free amino acids in maternal tissues of pregnant rats fed a protein-free diet.

The effects of s.c. injections of 5 mug oestrone/kg and 50 mg progesterone/kg on Days 5-7 of gestation were investigated in rats fed a protein-free diet. The decrease in essential and non-essential amino acid concentrations in maternal liver and the implantation site caused by dietary protein deficiency was restored to control values, whereas the alterations of the plasma free amino acid concentrations, except for arginine and glycine, were not reversed by hormone treatment.