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R S Calandra

Publications and source records attributed to R S Calandra.

At least 55 records · Page 3Linked to original sources
PubMed1988

Effects of thyroxine on oestrogen receptor concentrations in anterior pituitary and hypothalamus of hypothyroid rats.

The effects of thyroxine (T4) were studied on the concentration of oestrogen receptors in the anterior pituitary gland and hypothalamus of ovariectomized euthyroid and hypothyroid rats. A group of rats was made hypothyroid by the administration of 131I. Seven days after ovariectomy, animals were separated into five groups: I, euthyroid controls; II, hypothyroid controls; III, hypothyroid and injected with oestradiol benzoate (10 micrograms/day for 10 days); IV, hypothyroid and injected with T4 (4 micrograms/day for 10 days) and V, hypothyroid and injected with both oestradiol and T4 as described above. In group I, oestrogen receptor levels in pituitary cytosol were 44.4 +/- 3.4 (S.D.) fmol/mg protein and in the nucleus 47.7 +/- 4.0 fmol/mg DNA. In group II the respective values were 12.8 +/- 1.7 fmol/mg protein (P less than 0.01) and 12.7 +/- 1.7 fmol/mg DNA (P less than 0.01 compared with group I). In group III, cytosolic receptor concentrations decreased when compared with those in group II (P less than 0.05), whereas nuclear receptor concentrations rose significantly (P less than 0.01). Group IV had both pituitary cytosolic and nuclear receptors increased (P less than 0.01 compared with group II). In group V there were no changes in cytosolic receptor concentrations but a significant (P less than 0.01) rise in nuclear receptors as compared with group II. Hypothalamic oestrogen receptors in untreated hypothyroid rats (group II) were unchanged in the cytosol and diminished (P less than 0.01) in the nucleus in relation to euthyroid controls (group I). Thyroxine, but not oestrogen, was effective in increasing the concentration of cytosolic receptors (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Effect of GABA and benzodiazepines on testicular androgen production.

We have evaluated the effect of Ro5-4864, a selective probe to label peripheral type benzodiazepine receptor, on "in vitro" testicular androgen production. Decapsulated testes from adult rats showed a significant increase in the basal and hCG-stimulated testosterone secretion into the medium in response to 10(-5) M, 10(-6) M, and 10(-7) M Ro5-4864. In addition, we have studied the changes in testicular GABA content at three different ages and we found its highest concentration at 31 days of age. When we evaluated the effect of GABA on "in vitro" androgen production at different stages of gonadal maturation we observed that the highest concentration of GABA (10(-6) M) was able to modify the basal and hCG-stimulated androgen production from adult (60 days) and pubertal (45 days) testes. In addition, when prepubertal testes (31 days) were incubated under basal conditions, 10(-6) M GABA induced a significant increment of androstanediol production, while the stimulatory effect of hCG was reduced in the presence of the same GABA concentration. The present results suggest that GABA plays a physiological role in the regulation of rat testicular androgen production depending on the stage of sexual maturation.

Age Factors↗
PubMed1987

Androgen-dependence of ornithine decarboxylase in the rat epididymis.

Ornithine decarboxylase (ODC) activity was measured in epididymides of 45-day-old rats. Higher ODC activity was detected in the corpus and cauda than in the caput epididymidis. Bilateral castration for 7 days caused epididymal ODC to fall to undetectable values, whereas testosterone restored activity to normal values. The effect of the androgen was significantly inhibited by cyproterone acetate. The caput was more sensitive to the action of testosterone than were the corpus and caudal segments. Unilateral castration for 4 or 8 days did not affect ODC on the control or castrated side, but the activity fell in epididymides of both sides after removal of the remaining testis. These results show that epididymal ODC activity is androgen-dependent.

Animals↗
PubMed1987

Effect of phosphatase inhibitors on estrogen receptors in the rat testis.

Testicular estrogen receptors were measured in the presence of phosphatase inhibitors, molybdate (MoO4=), wolframate (WO4=) and fluoride (F-), under different experimental conditions. At 0-4 degrees C, MoO4= was able to partially replace the stabilizing action of dithiothreitol (DTT) on cytosolic estrogen binding activity, suggesting a protective effect on reduced sulfhydryl groups. At 25 degrees C in the presence of DTT, the effect of MoO4= was observed in homogenates and low speed supernatants, being uneffective in cytosol. A possible mechanism of action through inhibition of phosphatase activity was supported by the use of WO4=. Acid phosphatase activity was inhibited in the presence of these agents, whereas alkaline phosphatase was unaffected. The addition of MoO4= also caused a significant inhibition of proteolytic activity. These results suggest that MoO4= would stabilize testicular estrogen binding activity through, at least, three mechanisms: 1) protection of reduced sulfhydryl groups; 2) inhibition of acid phosphatase, and 3) inhibition of proteolytic activity.

Animals↗
PubMed1985

Prolactin binding sites in the brain and kidneys of the toad, Bufo arenarum Hensel.

(125I)-ovine prolactin (oPRL) binding was found in several brain areas of the toad, Bufo arenarum Hensel. The olfactory bulb, cerebral hemispheres, and both dorsal and ventral mesencephalic regions showed saturable, high affinity, (125I)-oPRL binding, ranging between 5.6 to 29.9 fmol/mg protein, while the association constant (Ka) by Scatchard analysis was between 4.0 to 8.7 x 10(9) M-1. This binding was compared with the Scatchard plot of the kidney, which has been already described by other groups, and gave 41.7 fmol/mg protein and Ka 2.5 x 10(9) M-1. Liver showed no binding and in the cerebral hemispheres (125I)-oPRL was not displaced by non-lactogenic hormones, indicating that binding was hormone and tissue specific.

Animals↗
PubMed1985

Effect of median eminence lesions and hormonal replacement on the prolactin receptors in the adrenal gland and Langerhans islets from ovariectomized adult rats.

The effect of hyperprolactinemia induced by median eminence lesions (MEL) and ACTH and glucocorticoid replacement on prolactin (Prl) receptors was studied in the adrenal, isolated Langerhans islets and the liver. Adult rats were ovariectomized 15 days before MEL and they were divided in the following groups: 1) SHAM: injected with saline solution 3 times in alternate days; 2) MEL: saline solution; 3) MEL + ACTH: 50 micrograms: 10 IU/rat, s.c. (Synacthen) and 4) MEL + DEXA: 10 micrograms/rat (dexamethasone). For measuring total lactogenic binding sites an in vitro treatment of the membrane fraction with 4M MgCl2 was used. MEL originated a significant increase in Prl serum levels, which was not altered by injections of ACTH or dexamethasone. In contrast, serum corticosterone (B) levels in MEL rats were significantly lowered, and it was restored by ACTH. Unexpectedly, B levels increased when dexamethasone was administered to MEL rats. Prl receptors were diminished in the adrenal gland and Langerhans islets from MEL animals, as compared with the SHAM group. ACTH and glucocorticoid administration did not affect the pancreatic Prl receptors, while the adrenal gland exhibited a further lowering of Prl binding sites during ACTH treatment. Since no effect was found when dexamethasone was injected, a possible direct action of ACTH is suggested. On the other hand, Prl receptors were induced in the liver by MEL, and this action was abolished by dexamethasone and ACTH. Binding affinity in every tissue studied remained unchanged. Our data suggest that endogenous Prl is able to regulate its own receptors not only in the liver, but also in the adrenal gland and pancreatic islets.

Adrenal Glands↗
PubMed1984

Effects of prolactin, bromocriptine and sulpiride on estrogen and lactogenic receptors in the rat adrenal gland.

In prepubertal male rats, the injection of bromocriptine (Br) for 10 days caused an increase in adrenal weight (Br 0.75 mg/kg BW (Br I): 2.83%; Br 1.5 mg/kg BW (Br II): 12.1% and Br 3 mg/kg BW (Br III): 24.7%), and this effect was only significant at the highest dose. Sulpiride (S, 30 mg/kg BW/day) for 10 days produced a significant decrease in adrenal weight (18.6%), whereas ovine prolactin (oPRL) administered at doses of 0.5 or 5 mg/kg BW/day for 10 had no effect on this parameter. The action of these drugs on corticosterone serum levels was for Br III a 50.6% increase and for S a 29.2% decrease. Bromocriptine caused a significant increment of cytosolic available estrogen receptors C: 7.65 +/- 0.36 (SE); Br I: 10.2 +/- 0.36; Br II: 11.0 +/- 0.23 and Br III: 13.3 +/- 0.35) and total lactogenic receptors in the adrenal gland (C: 125.2 +/- 2.84; Br I: 203.8 +/- 4.43; Br II: 213.1 +/- 7.58 and Br III: 251.3 +/- 10.4), and this effect was dose-related. oPRL diminished adrenal estrogen receptors only at the highest dose used (C: 11.1 +/- 1.73; PRL 5: 8.2 +/- 0.75) as did S (C: 11.2 +/- 1.84 and S: 5.2 +/- 1.07); while the former originated a marked decrease in lactogenic adrenal binding sites at both doses (C: 198.7 +/- 12.2; PRL 0.5: 52.9 +/- 5.00 and PRL 5: 38.8 +/- 4.76), S also had a highly significant diminution over these receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1984

Incidence of estrogen, progesterone and prolactin receptors in human breast cancer.

Analysis of estrogen and progesterone cytosolic receptors (ER, PR) has been studied in human breast carcinoma. ER were assayed by sucrose density gradients and dextran coated-charcoal method. In a series of 109 ER+ breast tumors, 64.2% exhibited the 8S form, 25% the 4S and 11% both the 8S and 4S components. From a total number of 970 specimens, 776 (80%) were primary and 194 (20%) metastatic lesions. In the whole group, ER was positive in 77.6% and PR in 61.4%, while both receptors were found simultaneously in 59%. The concentration of ER was higher in postmenopausal women in comparison to premenopausal women. On the other hand, the levels of PR were rather similar in both groups. In primary lesions, PR was more frequently seen than in secondary tumors and the same holds true for the presence of ER and PR and the frequency of negative tumors. Specific prolactin (PRL) binding assay was performed in a group of 50 breast tumors. Positive and negative distribution was almost equal (48 vs 52%) and there was not correlation between PRL-R and ER. In addition, a limited group of male breast cancer, showed that three out of five patients possess only androgen receptors, whereas the remaining two cases were exclusively ER+. In summary, the present results indicate that the local incidence of steroid receptors in female breast carcinoma, are very likely similar to previous reports either in premenopausal and postmenopausal women and in primary and secondary lesions. The importance of PRL-R assay requires a further evaluation.

Breast Neoplasms↗
PubMed1981

Specific prolactin binding in the rat adrenal gland: its characterization and hormonal regulation.

Rat adrenal prolactin receptors possess the same hormonal specificity as those in the prostate gland and liver, but are less stable during storage and after freezing. There is a gradual decrease in specific prolactin binding to the adrenal during sexual maturation in male rats; maximum binding capacity of 980 fmol/mg protein is at 25 days of age decreasing to approximately 100 fmol/mg protein at day 90. Prolactin receptors in the prostate are high at 25 days of age (700 fmol/mg protein), decrease sharply by day 30 (180 fmol/mg protein) and then gradually increase. Ovariectomy resulted in a significant rise in total prolactin binding in the adrenal gland, while the administration of oestradiol or testosterone reduced the binding, the reverse of changes in prolactin binding in the liver. Only oestrogen increased serum levels of prolactin in female rats. Ovine prolactin (500 micrograms) given to female rats resulted in a rapid increase over a period of 2-8 h total prolactin receptors in the adrenal, and these then decreased to normal levels, indicating a possible positive regulation of prolactin receptors by homologous hormone.

Adrenal Glands↗
PubMed1981

Testosterone, dihydrotestosterone, and zinc concentrations in human testis and epididymis.

Tissue testosterone, dihydrotestosterone, and zinc concentrations have been determined in testis and epididymis of 13 patients with carcinoma of the prostate, 1 patient with carcinoma of the penis, and 3 patients with carcinoma of the prostate on estrogens. The 13 patients not receiving estrogens had the following testicular levels: testosterone, of 529 +/- 63.1 ng/g (mean +/- SE); dihydrotestosterone, 23.7 +/- 2.58 ng/g; and zinc 62.2 +/- 7.6 micrograms/g. The epididymal levels were as follows: testosterone, 40.6 +/- 3.4 ng/g; dihydrotestosterone, 20.5 +/- 2.36 ng/g; and zinc, 67.2 +/- 11.1 micrograms/g. Patients on estrogen therapy showed much lower androgen values in the two organs but zinc was not changed significantly. Concentrations of androgens were not significantly different in the epididymal fractions of caput, corpus, and cauda. In testis, there was a positive correlation between zinc and androgens contents, while the opposite was suggested by the data in the epididymis. Even though these patients were not normal, there was no evidence of testicular or epididymal disturbances.

Aged↗