Endocrine changes associated with the human aging process: II. Effect of age on the number and size of thyrotropin immunoreactive cells in the human pituitary.

The thyrotropin immunoreactive cells in the pituitaries of 40 patients of varying ages were quantified after immunocytochemical staining. Thyrotroph hypertrophy and relative hyperplasia were both present in aged pituitaries. No consistent relation with the histologic features of the thyroid or adrenal, or with the cause of death, was demonstrable.

Thyroglobulin and calcitonin immunoreactivity in canine thyroid carcinomas.

Although thyroid gland neoplasms are well-recognized entities in dogs, the diagnosis and classification of these tumors often is difficult. In contrast to human thyroid carcinomas, which are predominantly of the papillary or follicular types, a relatively high proportion of the canine tumors contain compact cellular areas and resemble, to some extent, medullary thyroid carcinomas. In order to assess the value of immunohistochemical techniques in the identification and classification of these neoplasms, 21 canine thyroid carcinomas were examined for the presence of thyroglobulin and calcitonin using the peroxidase-antiperoxidase technique. Four major patterns of thyroglobulin immunoreactivity were present in the tumors, including diffuse cytoplasmic positive reaction, apical staining in the cells bordering the neoplastic follicular lumens, intracytoplasmic droplet staining, and staining of intrafollicular colloid. All follicular and mixed compact cellular/follicular tumors contained immunoreactive hormone, while only four of six compact cellular carcinomas were thyroglobulin-positive. The extent of thyroglobulin reactivity was consistently greater in tumors of the follicular and mixed patterns than in carcinomas of the purely compact cellular type. Two of four metastases, each of which retained the mixed pattern of the primary tumors, were thyroglobulin-positive. No medullary thyroid carcinomas were identified, but scattered calcitonin-positive cells in one mixed and in one compact cellular tumor were interpreted as entrapped nonneoplastic C cells. Immunohistochemical localization of thyroglobulin should facilitate the diagnosis of canine tumors of suspected thyroid follicular cell origin, particularly those arising in ectopic sites (i.e., heart base) and those presenting as metastases.

Serum and bone marrow radioimmunoassay of acid phosphatase in prostatic cancer.

Use of radioimmunoassay (RIA) for determinations of prostatic acid phosphatase has recently received considerable attention because of reported higher sensitivity and specificity than previous enzymatic assays. We have compared the sensitivity and specificity of a commercially available RIA to a highly specific enzymatic assay (thymolphthalein monophosphate) using 37 patients with prostatic cancer and 34 patients with surgically proved benign prostatic hyperplasia. Seventeen of the cancer patients and all 34 of the BPH patients were studied prospectively. We further evaluated specificity by performing the RIA on 25 specimens of bone marrow from patients with nonprostatic disease. Our results indicate the radioimmunoassay is not, at this time, an adequate screening tool, and we question its accuracy in staging patients anymore reliably than by enzymatic assay.

Immunohistologic techniques in surgical pathology - a spectrum of "new" special stains.

Immunoperoxidase techniques, applied to fixed paraffin sections, provide a wide range of highly specific special stains of value to the surgical pathologist in diagnostic practice and in investigative studies. The application of "immunostains" provides an independent method of cell identification against which traditional subjective morphologic criteria may be compared: histopathology may thereby be transformed from something of an art to more of a science.

The effect of weight reduction on blood pressure, plasma renin activity, and plasma aldosterone levels in obese patients.

We investigated the relation between changes in the renin-aldosterone axis and reduction in blood pressure in 25 obese patients placed on a 12-week reducing diet; sodium intake was either medium (120 mmol) or low (40 mmol). Plasma renin activity (PRA) declined with weight loss, so that by 12 weeks there was a significant decrease in PRA (P less than 0.01) as well as plasma aldosterone (P less than 0.05), regardless of sodium intake. Weight loss with low sodium intake was equal to that with medium intake. The reduction in PRA but not in aldosterone correlated with weight loss in both sodium-intake groups (r = 0.58). Mean arterial pressure fell significantly and equally in both groups, correlating with weight loss throughout the study (r = 0.56) and with PRA from the fourth through 12th weeks (r = 0.48) These results demonstrate that weight loss is accompanied by reductions in PRA and aldosterone; PRA reductions, irrespective of sodium intake, may contribute to the decline in blood pressure.

Role of adrenals and estrogen in regression of mammary tumors during postpartum lactation in the rat.

The effects of bilateral adrenalectomy or estradiol benzoate treatment were observed on growth of 7,12-dimethylbenz(a)-anthracene-induced mammary tumors during postpartum lactation. In the control and estradiol benzoate-treated postpartum lactating rats, the mammary tumors decreased approximately 40% in size by Day 5 postpartum and continued to regress to 50% of their average original diameter by Day 25 postpartum. Adrenalectomy on Day 3 postpartum prevented mammary tumor regression and resulted in renewed mammary tumor growth. By Day 10 postpartum, average mammary tumor size in the adrenalectomized rats reached prepartum diameter and continued to increase in size until Day 25. Although serum prolactin concentrations were significantly higher in the lactating rats with mammary tumors than in the nonlactating rats with mammary tumors, there were no significant differences in serum corticosterone values. Adrenalectomy resulted in a significant increase in serum prolactin levels and in a marked fall in serum corticosterone levels. It is concluded that in rats adrenocortical activity is primarily responsible for reduced mammary tumor growth during postpartum lactation.

Evidence for a role of endorphins in stress- and suckling-induced prolactin release in the rat.

Injection of the opiate antagonist naloxone completely prevented the rise of serum prolactin induced by ether stress in intact male rats. Naloxone also led to a 50--95% inhibition of the marked elevation of plasma prolactin levels induced by suckling. These data suggest that endogenous opiates (endorphins) are involved in the stimulation of prolactin release induced by both stress and suckling in the rat.

Inhibition of ovarian luteinizing hormone (LH) and follicle-stimulating hormone receptor levels with an LH-releasing hormone agonist during the estrous cycle in the rat.

A single injection of the luteinizing hormone (LH)-releasing hormone (LHRH) agonist [D-Ala6,des-Gly-NH2(10)]LHRH ethylamide to female rats on diestrus I produced a marked reduction in ovarian LH/human chorionic gonadotropin (hCG) and follicle-stimulating hormone (FSH) receptor levels, uterine weight, and plasma progesterone levels measured 2 days later on expected proestrus. A maximal inhibitory effect was seen after a dose of only 40 ng of the peptide. No consistent effect of the LHRH analog was seen on ovarian prolactin receptors. When the analog was injected on day 7 of pregnancy, the inhibition of ovarian LH/hCG receptors was of shorter duration and was much less sensitive than that in nonpregnant animals. These data indicate that ovarian LH and FSH receptors levels are highly sensitive to changes in endogenous gonadotropin secretion and suggest that the gonadotropin surge occurring spontaneously on proestrus may play an important role in the regulation of ovarian gonadotropin receptors during the estrous cycle.

Inhibitory effect of a luteinizing hormone (LH)-releasing hormone agonist on rat ovarian LH and follicle-stimulating hormone receptor levels during pregnancy.

When injected at the daily dose of 100 microgram on days 7 through 12 of pregnancy, the luteinizing hormone (LH)-releasing hormone (LHRH) agonist [D-Ala6, des-Gly-NH2(10)] LHRH ethylamide led to complete suppression of pregnancy and a 45% to 60% decrease in plasma progesterone concentration. The antifertility effect of the LHRH analog was accompanied by an early and almost complete inhibition of ovarian LH/human chorionic gonadotropin and follicle-stimulating hormone receptor levels. These data suggest that the antifertility effects of LHRH agonists are mediated by down-regulation of ovarian gonadotropin receptors and decreased luteal function.

Effects of high hoses of estrogen on prolactin-binding activity and growth of carcinogen-induced mammary cancers in rats.

Specific binding sites for prolactin (PRL) were present in membrane preparations from 7,12-dimethylbenz(a)-anthracene-induced rat mammary tumors. The specific binding of PRL was time and temperature dependent. A significant negative correlation was noted between administered doses of estrogen and the subsequent binding of PRL to tumor cell membranes. Injections of 10 or 25 mug estradiol benzoate daily for 10 days effectively inhibited mammary tumor growth and significantly reduced specific PRL binding to mammary tumor cell membranes.

Prolactin and estrogen dependency of rat mammary cancers at early and late stages of development.

An attempt was made to separate estrogen from prolactin dependency of 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumors at 2.5 and 5 months after DMBA injection. Ovariectomy and drug and/or hormone treatments were used to produce an estrogen or prolactin deficiency for 2 weeks, followed by a 2-week period in which the deficiency was corrected. Tumors were classified as estrogen or prolactin dependent based upon regression in the absence of the hormone and resumption of growth upon hormone replacement. At 2.5 months and 5 months after DMBA injection, about 29 and 33% of the tumors, respectively, were classified as prolactin dependent, and 35 and 45%, respectively, were classified as estrogen dependent. However, the percentage of estrogen-dependent tumors was reduced to 2.2 and 9.7%, respectively, when prolactin levels were maintained after ovarierctomy. These results indicate that most DMBA-induced mammary tumors in Sprague-Dawley female rats are dependent on both estrogen and prolactin but that ovariectomy or estrogen administration do not accurately reflect estrogen dependency, since prolactin secretion also is altered by these procedures.

Estrogen and prolactin receptor concentrations in rat mammary tumors and response to endocrine ablation.

Estrogen and prolactin receptor concentrations were measured in 24 carcinogen-induced rat mammary tumors and correlated with the tumor response to host ovariectomy or hypophysectomy. It was found that essentially all of the tumors contained some specific estrogen receptor, and all but three contained prolactin receptor. The values for each receptor comprised a continuum from very low to relatively high concentrations, suggesting that previous considerations of hormone dependence on the basis of presence or absence of hormone receptors may be oversimplified. The concentration of each receptor tended to be lower in the hormone-independent than in the hormone-dependent tumors, but there were a number of hormone-independent tumors with higher receptor levels than some of the hormone-dependent tumors had. A better correlation of tumor response to endocrine ablation resulted from a combination of the 2 receptor levels than from either receptor concentration alone. These results suggest that there is a complex relationship between mammary tumor response to endocrine ablatin and levels of estrogen and prolactin receptors and that some tumors may be dependent upon 1 or both of these hormones for growth.

Effects of estrogen and testosterone on specific prolactin binding in the kidneys and adrenal of rats.

The effects of estradiol benzoate in the female rat, testosterone propionate in the male rat, and castration in both sexes on specific prolactin binding sites in the particulate membranes of the kidneys and adrenals were studied. Castration resulted in a significant increase in PRL binding activity in the kidneys of both males and females, and in a significant increase in PRL binding activity in the adrenals of the females. The increase in PRL binding with castration and the decrease seen with testosterone treatment were similar in both immature and mature rats. Progesterone administration to castrate females failed to alter PRL binding in both tissues. The present results suggest that estrogen and testosterone participate in the PRL osmoregulatory system in rat.

Effects of castration, testosterone, estradiol, and prolactin on specific prolactin-binding activity in ventral prostate of male rats.

Lactoperoxidase-catalyzed 125I-labeled ovine prolactin (PRL) was found to bind specifically to particulate membrane fractions of rat ventral prostate. Unlabeled PRL readily displaced the labeled PRL, whereas ovine GH, LH, FSH, or TSH showed no such competition. Castration reduced the binding of 125I-labeled PRL to about 1/6 of that in intact rats, and injections of testosterone propionate (TP) increased PRL binding to values as great or greater than those in intact controls. Injections of TP into intact immature and mature rats also increased PRL binding. In vitro binding of labeled PRL was inhibited in prostatic tissue removed from intact immature rats 2 h after injecting unlabeled PRL, but not in ventral prostates from rats killed 26 or 74 h after injecting unlabeled prolactin. PRL injected together with TP in castrated rats produced no greater increase in prolactin binding than TP alone, while estrogen appeared to decrease PRL binding beyond that produced by castration alone.

Prolactin binding activity on the crop sacs of juvenile, mature, parent and prolactin-injected pigeons.

Specific prolactin (PRL) binding activity of lactoperoxidase catalyzed 125I-labeled ovine-PRL was determined in a membrane-rich particulate fraction of pigeon crop sacs. Levels of TSH, LH or FSH as high as 1000 ng each were unable to displace the 125I-o-PRL bound to 600 mug of crop sac microsomal protein, whereas competitive displacement was achieved with as little as 0.5 ng unlabeled PRL. Ovine GH exhibited some cross reactivity when incubated in amounts greater than 500 ng, but this could be accounted for by its stated PRL contamination. Specific PRL binding activities were determined in juvenile and mature pigeons with unstimulated crop sacs, and parent pigeons with 'crop milk' and mature birds injected with PRL for 4 days. Crop sacs from juvenile birds contained approximately twice as much binding activity as crop sacs from mature pigeons. Parent and PRL injected pigeons, each with proliferated crop sac epithelium, exhibited 4-5 times as much specific PRL binding as the non-proliferated crops from juvenile or mature birds. These results show that the pigeon crop sac contains specific binding sites for PRL, and that the crop sac response to PRL is associated with an increase in PRL binding activity.