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Biomedical subjects

E J Roy

Publications and source records attributed to E J Roy.

53 records · Page 3Linked to original sources
PubMed1979

Antiestrogen inhibits the induction of progestin receptors by estradiol in the hypothalamus-preoptic area and pituitary.

Estradiol treatment of ovariectomized-adrenalectomized rats produced an increase in cytosol progestin binding in the hypothalamus-preoptic area (HPOA), pituitary, and uterus. In the HPOA and pituitary, this induction of progestin receptors by estradiol was inhibited by the antiestrogen CI-628 under a variety of dose and time conditions. In the uterus, inhibition of the full effect of estradiol on progestin binding was observed after 3 days of injection of antiestrogen and estradiol. In the absence of estradiol, the antiestrogen produced a slight induction of progestin receptors in the HPOA and pituitary and a substantial induction of progestin receptors in the uterus. The results suggest that the induction of progestin receptors could be a key intermediate step in some behavioral and neuroendocrine actions of estradiol.

Animals↗
PubMed1979

Oestrogen receptors in cell nuclei of the hypothalamus-preoptic area-amygdala following an injection of oestradiol or the antioestrogen CI-628.

Oestrogen receptors were measured by an exchange assay in cell nuclei of the hypothalamus-preoptic area-amygdala (HPA) of ovariectomized-adrenalectomized (OVX-ADX) rats following an intravenous injection of oestradiol or an antioestrogen, CI-628. Receptors were translocated to the nucleus by both compounds. Receptors translocated by the antioestrogen were specific for oestrogens; testosterone, corticosterone and progesterone were not bound by these receptors. Several properties of antioestrogen- and oestradiol-receptor complexes were compared. The time-course in cell nuclei in vivo showed that receptors were still present in HPA nuclei 24 h after administration of CI-628 but not 24 h after oestradiol. This prolonged increase of nuclear receptors after the antioestrogen treatment was attributed to the continued presence of CI-628 and its metabolites in plasma. The maximum level of receptors produced in the HPA cell nuclei following CI-628 treatment was lower than the peak level of nuclear receptors following oestradiol. The dissociation rate in vitro of nuclear antioestrogen-receptor complexes formed in vivo was more rapid at 0 degrees C than that of nuclear oestradiol-receptor complexes. This property may be related to the lower peak level of binding after CI-628 treatment and to the inhibitory actions of antioestrogens.

Adrenalectomy↗
PubMed1977

Binding of [3-H]estradiol by brain cell nuclei and female rat sexual behavior: inhibition by antiestrogens.

The antiestrogens MER-25, CI-628, and nafoxidine inhibit the uptake of [3H]-estradiol in whole homogenates and isolated cell nuclei tissues and the pituitary, and inhibit estradiol-induced female sexual behavior. The antiestrogens were injected intraperitoneally 2 h prior to an intravenous injection of [3H]estradiol, and the animals were killed 2 h after the estradiol. CI-628 reduces radioactivity in whole homogenates and isolated cell nuclei of cerebral cortex, hypothalamus, preoptic area -septum and pituitary. Nafoxidine reduces uptake in cell nuclei of the hypothalamus, preoptic area-septum and pituitary. In this paradigm, MER-25 inhibited uptake only in the pituitary. In the analogous behavioral experiments, with antiestrogens injected 2 h prior to an intravenous injection of unesterified estradiol, CI-628 and nafoxidine totally inhibited lordosis responding. MER-25 shows no inhibition of behavior in this paradigm. However, when MER-25 is injected 12 h prior to the estradiol, it inhibits retention of [3H]estradiol at 2 h in brain and pituitary cell nuclei, and lordosis responding is also inhibited. Additionally, the antiestrogens can apparently displace previously bound [3H]estrdiol. When the antiestrogens are injected 2 h prior to an injection of [3H]estradiol, MER-25, CI-628 and nafoxidine all show greater inhibition of nuclear estradiol retention at 12 h after the [3H]estradiol injection than 2 h. Analogously, when CI-628 is injected 2 h after an intravenous injection of [3H]estradiol, it displaces most of the radioactivity present in hypothalamic-preoptic area nuclei at 12 h after the estradiol injection. These results indicate that antiestrogens can prevent or reverse the nuclear concentration of estradiol in brain cells and are consistent with a role of the cell nucleus in the induction of estrous behavior by estradiol.

Animals↗
PubMed1977

An exchange assay for estrogen receptors in cell nuclei of the adult rat brain.

A nuclear exchange assay was developed for brain estrogen receptors. The assay employs an extraction procedure which solubilizes essentially all of the estradiol from brain cell nuclei: purified cell nuclei are evenly dispersed in a hypotonic buffer prior to the addition of an equal volume of 0.8M KC1. Experiments with an in vivo injection of 3H-estradiol established that this procedure extracts even normally salt-resistant binding. For exchange, aliquots of the extract are incubated with 3H-estradiol or 3h-estradiol plus 100-fold excess unlabeled estradiol. Bound 3H-estradiol is separated from free 3H-estradiol on Sephdex LH-20 columns. Loss of estradiol binding activity can occur with brain nuclear extracts under conditions required for exchange. This loss of binding is inhibited by the addition of bacitracin to the incubation buffer. The exchange is complete within 5 hrs at 25 degrees C and specific binding activity is stable for at least 16 hrs. The assay was validated by comparing levels of macromolecular-bound radioactivity after an in vivo injection of 3H-estradiol and levels determined by exchange after an injection of unlabeled estradiol. Scatchard analysis confirmed the high affinity nature of the binding measured by exchange.

Animals↗
PubMed1976

Effects of ovariectomy and estradiol on body weight and food intake in gold thioglucose-treated mice.

Two experiments investigated the effects of ovariectomy and estradiol replacement on the body weight and food intake of mice that had previously been treated with either gold thioglucose or saline. Ovariectomy and estradiol benzoate injections altered food intake in gold thioglucose-treated mice as much as in saline controls. Ovariectomy increased body weight in saline controls but it was without effect on the body weight of gold thioglucose-treated mice.

Animals↗
PubMed1976

Estrogenic effects of an antiestrogen, MER-25, on eating and body weight in rats.

Ethamoxytriphetol, MER-25, which acts as an estrogen antagonist on other estrogen-sensitive behaviors and in peripheral tissues, was found to be fully estrogenic with respect to eating behavior and body weight regulation. The MER-25 causes decreases in eating and weight gain that are not due to toxicity, as indicated by its failure to induce a learned aversion to saccharin and by its failure to alter spontaneous activity. Estradiol benzoate (EB) and MER-25 similarly affect eating and body weight in gonadectomized rats: Both cause a transient decrease in food intake and a permanent decrease in body weight relative to controls; the eating and body weight effects of both MER-25 and EB are attenuated by progesterone; and both MER-25 and EB affect females more than males. Because of its full estrogenicity, MER-25 fails to antagonize the effects of EB on eating and body weight while simultaneously antagonizing effects of EB on sexual behavior, the uterus, and the vagina. The results indicate that the systems mediating the effects of estrogens on eating and body weight differ biochemically from other behavioral and somatic estrogen-sensitive systems.

Animals↗
PubMed1975

Role of estrogens in androgen-induced spontaneous activity in male rats.

Three experiments tested the hypothesis that testosterone may be aromatized to an estrogen to stimulate running-wheel activity in rats. Aromatizable (testosterone propionate: TP) and nonaromatizable (dihydrotestosterone propionate; DHTP) androgens were compared with estradiol benzoate (EB) for the ability to induce running in castrated male rats. The DHTP had no effect on running. The TP increased running, but EB was more than 100 times as effective. A relatively small dose of a specific estrogen antagonist, MER-25, was shown to attenuate the effects of both EB and TP on male running. The MER-25 did not affect the running of castrated, oil-treated male rats and did not inhibit the running induced by food deprivation.

Animals↗
PubMedDate not supplied

Single-chain Fv/folate conjugates mediate efficient lysis of folate-receptor-positive tumor cells.

Bispecific antibodies that bind to a tumor antigen and the T cell receptor (TCR) redirect cytotoxic T lymphocytes (CTL) to lyse tumor cells which have escaped normal immune recognition mechanisms. One well-characterized tumor antigen, the folate receptor (FR), is expressed on most ovarian carcinomas and some types of brain cancer. Recently, it was shown that conjugates of folate and anti-TCR antibodies are extremely potent bispecific agents that target tumor cells expressing the high-affinity folate receptor, but not normal cells expressing only the reduced folate carrier protein. In this paper, it is shown that the size of these conjugates can be reduced to the smallest bispecific agent yet described (30 kDa) by attaching folate to a single-chain antibody, scFv, of the anti-TCR antibody KJ16. The scFv/folate conjugates are as effective as IgG/folate conjugates in mediating lysis of FR4 tumor cells by CTL. The optimal folate density was in the range of 5-15 folate molecules per scFv or IgG molecule, which yielded half-maximal lysis values (EC50) of approximately 40 pM (1.2 ng/mL for scFv). Finally, the scFv/folate conjugates could efficiently target tumor cells even in the presence of free folic acid at concentrations that are normally found in serum. Compared to conventional bispecific antibodies, the small size of scFv/folate conjugates may prove advantageous in the ability to penetrate tumors and in reduced immunogenicity.

Animals↗