The prospects for hormonal sterilization.
Explore the source record for details and available documents.
SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
The study describes the effects of ACTH, prolactin and other protein hormones on the synthesis and secretion of steroid hormones by tissue from a feminising adrenocortical carcinoma removed from a post-menopausal female. Steroid production by the tissue was determined by high resolution-mass fragmentography and by radioimmunoassay. Prolactin and ACTH stimulated the synthesis of estrogens by the tissue whereas GH, LH and ACTH were more effective than prolactin in stimulating androgen synthesis. The effect of protein hormones, other than ACTH, on adenylate cyclase activity of this tumour tissue indicated a lack of specificity of the membrane receptor sites.
Explore the source record for details and available documents.
Experiments performed in cyclic female rats demonstrated an equal ovulation-inhibiting activity of the 19-norgestagens norethynodrel, lynestrenol and norethisterone acetate after injection in oestrus and metoestrus, and after daily administration from oestrus to pro-oestrus. The results furthermore show that, after application of the minimal ovulation-inhibiting doses during oestrus and metoestrus, these substances 1. induce an increase in prolactin secretion, 2., with the exception of norethisterone acetate, possess a hypophysial site of action, 3. are able to induce deciduoma formation following traumatization of the uterus, and 4. maintain the reactivity of the cyclic corpora lutea to the injection of prolactin. The findings suggest that the prolactin-releasing and luteotrophic action of the progestagens studied may form an essential part of the mechanisms that are responsible for the inhibition of ovulation observed in rats after administration over one cycle.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Prolactin is a mammotropic hormone essential for the initiation of lactation. It also influences ovarian function; during hyperprolactinemia hypogonadism occurs. This is true for pathological forms of hyperprolactinemia but also for the early puerperium when there is physiological hyperprolactinemia. Amenorrhea is a better parameter of hyperprolactinemia than galactorrhea. The mechanisms by which prolactin disrupts ovarian function are not as yet fully understood; it probably alters hypothalamic neurotransmitter content through a direct feedback mechanism resulting in a decrease of Gn-RH. However, the direct effect of prolactin-producing pituitary tumors on the capacity of the gonadotrophs or a direct interference of prolactin at the gonadal level are also possibilities. Hyperprolactinemia can be treated very effectively with bromocriptine and this drug appears to have become the favorite form of treatment. In the case of obvious tumors hypophysectomy is indicated. When there are smaller tumors irradiation of the pituitary gland previous to bromocriptine treatment may prevent expansion of the gland during subsequent pregnancy.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Castrated NMRI mice were laparotomized and a thread impregnated with beeswax-methylcholanthrene was inserted into the uterine cervix. Beginning on the day of operation and for a further 5 days the animals were injected with oestradiol, prolactin, oestradiol-prolactin, oestradiol-prolactin-progesterone, or the solvents for the hormones only. One group of animals were injected with oestradiol-prolactin for 6 days and later with progesterone every third day until death. The animals were killed one or 4 weeks after the operation. Among the one-week animals the number of cervices presenting epithelial downgrowths ("buds") into the stroma was higher after treatment with a combination of oestradiol and prolactin than after treatment with each hormone separately or among the controls. Four weeks after operation, the incidence of squamous cervical carcinomas was seen to be significantly higher among animals injected with both oestradiol and prolactin than in controls or in those injected with oestradiol or prolactin alone. Progesterone had no definite effect on the oestradiol-prolactin induced incidence. The mechanism behind the synergistic effect of prolactin and oestradiol is discussed.
The role of growth hormone (GH), as well as prolactin and ACTH, in the induction of the PRL receptor was investigated both in hypophysectomized male rat livers and in the livers of male rats bearing a GH secreting tumor. After 7 days of s.c. injections, specific binding (% SB) of PRL in controls and rats treated with oPRL, hGH, ACTH, hCG, estradiol (E2), or testosterone (T) was approximately 1%. Treatment with oPRL plus ACTH increased SB to 4%; adding E2 to this combination produced a further increase to 8%, whereas the addition of T decreased hepatic binding to 1%. Combination of hGH with ACTH was most effective, giving a SB of 33%, which is similar to that observed in the liver of rats bearing a GH secreting tumor (36%). These studies suggest that GH acts synergistically with PRL and/or ACTH to increase lactogenic binding sites in the male rat liver and that sex steroids have a modulating effect on this action.
Explore the source record for details and available documents.
Specific 125I-labeled prolactin binding was measured in membrane particles prepared from R3230AC mammary carcinoma and liver of tumor-bearing Fischer rats after either prolactin, estrogen, or lergotrile mesylate treatment, or after the induction of diabetes by streptozotocin. Hormone binding to tumors was decreased by treatment with prolactin (0.5 or 1 mg/day) or estradiol valerate (7.5 mg/kg/week). In contrast, prolactin treatment did not affect prolactin binding to liver membrane particles, but estradiol valerate treatment resulted in a four-fold increase in prolactin binding to this tissue. Lergotrile mesylate, which lowers plasma prolactin levels, did not affect tumor growth or prolactin binding to either tumor or liver. Prolactin binding to both tumor and liver was significantly reduced in diabetic rats, suggesting that insulin may play an important role in controlling tissue sensitivity to prolactin. Specific binding of 125I-labeled prolactin to enzymatically dissociated cells from R3230AC tumors was demonstrated in vitro. The binding capacity of the cells was found to be of the same order of magnitude as the binding capacity in membrane preparations when appropriate corrections were applied for yields of cells and membranes. R3230AC tumor, which is responsive to prolactin appears therefore to be a useful model system for further study aimed at elucidation of growth and metabolic response to the hormone prolactin in breast cancer.