Search

Estrogen Is known to affect the regulation of all six of the established anterior pituitary gland (AP) hormones, but little is known of the specifics of its regulation of the AP hormones, their isoforms, and nonhormonal AP proteins. We used difference gel electrophoresis in conjunction with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and peptide mass fingerprinting to quantify the effects of estrogen on the AP-soluble protein fraction in rats. Two-month-old rats were ovariectomized and used at 6 months of age. They were injected subcutaneously with sesame oil vehicle or 50 μg estradiol valerate in vehicle and studied 48 hrs later, approximately 3 hrs before the time of the anticipated onset of the estrogen-induced surges of gonadotropins in blood. The APs were pooled, and the soluble protein fraction was examined in replicate analyses. After DeCyder software analysis, we identified 26 protein spots that had a 1.5-fold or greater average increase in the experimental group relative to the controls. Nineteen showed a 1.5-fold or greater decrease. Estrogen increased levels of the more acidic isoforms of growth hormone and prolactin and of proteins involved in protein synthesis, folding, and secretion (e.g., eukaryotic translation elongation factor 2, ERp57, ERp29, Hsc70-ps1, calreticulin, coatomer delta subunit, and secretogranin II) and of some metabolic enzymes (e.g., arginosuccinate synthetase, enolase 1, creatine kinase B, phosphoglycerate mutase, malate dehydrogenase, pyruvate kinase, and aldolase A). The majority of the downregulated proteins were involved in RNA or DNA interactions (e.g., five heterogeneous nuclear ribonucleoproteins, DEAD-box proteins 17 and 48, ssDNA binding protein PUR-alpha, PTB-associated splicing factor, and Pigpen protein), but isovaleryl coenzyme A dehydrogenase, mitochondrial aldehyde dehydrogenase, stathmin 1, vinculin, radixin, and secretogranin III were also reduced. Our results indicate that estrogen acts in vivo within 48 hrs to modulate levels of a significant number of AP proteins.

SummaryThe ACTH-releasing activity of hypothalamic extract and rat plasma was examined with the dispersed rat pituitary cell technique of Swallow and Sayers (8). Although both plasma and serum caused ACTH release which was dose-related, stress did not enhance the ACTH releasing activity. Furthermore, separation studies of plasma using ultrafiltration and gel separation suggest that the CRF activity in plasma is associated with molecules of a molecular weight greater than 15,000.The hypothalamic extract used in this study was kindly provided by the National Institute of Arthritis, Metabolism and Digestive Diseases (NIAMDD) Rat Pituitary Hormone Distribution Program.

SummaryThe effects of infusion of synthetic thytropin releasing hormone (TRH) into a hypophysial portal vessel on the release of prolactin and growth hormone (GH) were investigated in normal male rats under urethane anesthesia. Significant increases in serum prolactin and GH levels were consistently observed after the infusion of 100 ng or larger doses of synthetic TRH, but smaller doses had no effect. Pretreat-ment of rats with 50 fig estradiol in oil raised the basal levels of prolactin and GH, but the net increase after TRH remained the same for prolactin and was somewhat reduced for GH.The authors are indebted to Mrs. J. Gauthier and Mrs. M. Esslinger for their excellent technical assistance, Dr. Abba J. Kastin for his help in preparing the manuscript, and NIAMD Rat Pituitary Hormone Program for the supply of rat GH and Prolactin RIA Kits.

SummaryThe iv infusion of dopamine (250 or 500 ng/min) or epinephrine (500 or 1000 ng/min) into adult female cycling rats in each instance caused a threefold elevation in the equilibrium concentration of prolactin (PRL) in the plasma resulting from the continuous infusion of 200 ng rat PRL/min. A single iv injection of 1 μg dopamine had no effect upon equilibrium PRL levels. The metabolic clearance rate of PRL was significantly reduced from 1.35 to 0.44 ml/min as a result of infusing either 250 or 500 ng dopamine/min, and from 1.14 to 0.37 and from 1.56 to 0.65 ml/min from infusing 500 and 1000 ng/min, respectively, of epinephrine.I am grateful to the National Institute of Arthritis, Metabolism and Digestive Diseases (NIAMDD) Rat Pituitary Hormone Distribution Program for the gift of rat PRL, and to Tanya McGee for expert technical assistance.

SummaryThe testes of immature ring doves are measurably stimulated by implants of 1 immature (29-44 days) rat pituitary daily for 10 days; one adult common pigeon pituitary daily for 10 days gives much greater stimulation; stimulation can be obtained from fewer than 5 adult pigeon pituitaries 30 pituitaries of immature but nearly full grown pigeons (1.8 to 2.3 months from beginning development) implanted in groups of 3 daily for 10 days give no detectable stimulation. These results confirm an earlier indication from growth rate of testes in these birds : Pigeons less than 2.3 months old (1.8 months after hatching) and ring doves of less than 3.0 months (2.5 months after hatching) are to be considered as animals in which the production of F.S.H. has not yet been initiated. When anterior pituitary hormones, or extracts of this tissue, are injected into these birds it must be granted that their action is obtained on an intact organism free from follicle-stimulating hormone, and that the injected material ser...

ConclusionsThe injection of Progynon-B into rats with their ovaries intact augmented the lactogen content of their pituitary glands. The pituitary glands from, ovariectomized rats injected with 1000 i.u. of Progynon-B daily for 15 days were significantly larger than those from rats with their ovaries intact and similarly treated, but the lactogen content per pituitary was similar.

SummaryAnterior pituitary explants from female immature, mature and postpartum lactating rats were cultured in vitro on “199” or Trowell T-8 medium at 35 ± 1°C for periods of 6-14 days. Medium was assayed for prolactin by the intradermal pigeon crop method. Pituitary explants from mature female rats, gassed continuously with 95% O2 − 5% CO2 released 5-10 times more prolactin into medium each day than explants exposed only to air atmosphere. The amount of prolactin per AP recovered each day from the culture medium, under continuous gassing, was 2-3 times greater than that present in a fresh AP prior to culture. This proves that prolactin was actively synthesized and released and not merely “leached” out from AP explants. Explants from immature rats elaborated about half as much prolactin per AP per day as explants from mature rats, and ex-plants from lactating rats about twice as much as explants from mature rats. Assays of some explants at the end of culture revealed a low prolactin content, indicating ra...

SummaryCastration of adult male rats resulted in a 5-fold increase in pituitary LH concentration, but no change in pituitary FSH concentration. Estrone, testosterone, δ 4 Androstenedione and dehydroepiandrosterone inhibited the post-castration increase in pituitary LH and there was a relationship between dose and degree of inhibition. Those steroids which exhibited an androgenic effect increased the pituitary FSH concentration in the castrate pituitary, but a dose-response relationship was not discernible.

SummaryPituitary tissue and rat pituitary extracts were incubated with dopamine in vitro. The results indicate that dopamine chemically inactivates ACTH and FSH when incubated in high concentration with these hormones for prolonged periods. The data fail to support a direct effect of dopamine on the pituitary release of ACTH and FSH, and dopamine does not alter the pituitary response to hypothalamic extract.

SummaryA specific rabbit anti-sheep LH serum (A/S) was implanted into the rat hypothalamic median eminence (ME) to investigate the mode of action of a “short” feedback of endogenous LH by neutraliz...

The initial rapid increase in the rate of prolactin release from rat pituitary cells in monolayer cultures following medium replacement can be attributed entirely to the “mechanical” stress associated with the replacement maneuver itself.

SummaryThe concentration of prolactin in the plasma of lactating rats increased from 24 to 74 ng/ml following acute ether stress as the length of the preceding period of nonsuckling diminished from 12 to 8 hr. In a second experiment the prolactin concentration increased from 24 to 79 to 104 ng/ml as the frequency of 10-min sucklings during a 12-hr period was altered from once at the end of the twelfth hr to once every 6 hr to once every 4 hr and the mothers then exposed to ether 12 hr after the last suckling. These results indicate that more frequent activation of the prolactin-releasing mechanism facilitates the subsequent release of prolactin in response to ether stress.We are grateful to the NIAMDD Rat Pituitary Hormone Distribution Program for the rat prolactin radioimmunoassay kit, and to Mrs. Tanya McGee for technical assistance.

SummaryFollowing protracted injection in 16 rabbits of gonadotropic hormone derived from different sources we succeeded in one case in producing a progonadotropic serum, after treatment consisting of daily injections for a period of 5 months. 0.025 cc of this serum was able to multiply by 8 the gonadotropic effect of an aqueous extract of rat pituitaries, Control experiments showed that this augmentary effect was specific: it was neither obtained with normal serum acting on extracts of the rat pituitary, nor with progonadotropic serum acting on gonadotropic hormones of a different origin, Viz., of human pituitaries.

SummaryEvidence is offered that the essential factor for the production of pregnancy cells in the anterior pituitary of the rat is contained in the luteinized ovary and, further, that this factor is not sex specific.

We reported1 that the normal male rat pituitary contains an appreciable amount of the lactogenic hormone and that the injection of the estrogenic hormone definitely increases the galactin content o...

SummaryThe prolactin and thyrotrophin content of various transplantable pituitary tumors was studied. 1. Prolactin was found in stilbestrol induced and stilbestrol dependent rat pituitary tumor and also in an autonomous mammotrophic mouse tumor in concentrations only 10% or less that found in bovine pituitaries. These tumors contained little or no thyrotrophin. 2. Two autonomous adrenotrophic tumors contained no detectable prolactin or thyrotrophin. 3. Two dependent thyrotrophic tumors contained no detectable prolactin while the thyrotrophin concentration was ten times that of bovine pituitaries. A five gram thyrotrophic tumor contains 5,000 times more thyrotrophin than one mouse pituitary. Blood levels of thyrotrophin were 2,000 times normal.

Engle1 has shown that the anterior hypophysis of the castrate rat is more potent in gonad-stimulating hormone than that of the normal animal. Evans and Simpson2 confirmed this and demonstrated that glands from cryptorchid rats have more than normal potency. Severinghaus3 showed that the same holds for the castrate guinea pig.In the present experiments anterior lobes from normal and castrate (4 to 12 months) adult male and female, and experimental cryptorchid (6 to 14 months) guinea pigs were implanted intramuscularly into immature female rats and mice. In all, 235 animals were used as donors and 83 as hosts. The relative impotency of the guinea pig pituitary in gonadotropic hormone made it necessary to implant considerable amounts in the rat. The amount of guinea pig anterior lobe (fresh gland weight) required to induce a significant increase in the immature rodent ovary was found to be approximately 4 times that of rat pituitary. In the case of the five types of guinea pig pituitaries mentioned above fro...

SummaryChicken and rat hypophyseal extracts were compared with a purified beef growth hormone preparation in the hypophysectomized, immature female rat using the tibial cartilage assay and hematological alterations. The avian adenohypophysis contains 1/8th of the growth-promoting material found in an equivalent amount of rat hypophyseal extract. Significant depression in hematocrit and WBSG levels occurs at doses of avian extracts which are unable to promote epiphyseal cartilage growth.

Implants of rat pituitaries were made into 98 male and 40 female chicks as part of a program of study of the pituitary-gonad inter-relationship. The results were unexpected, and we believe of general interest because of possible bearing on the problem of species specificity of hormone action. The bird affords an excellent test for experiments involving pituitary hormones of animals in different classes because: (1) of the marked response of the immature testis to the “follicle stimulating’ hormone (F.S.H.),1 and, (2) since it was reported by one of us,2 that the testes of chicks given the pituitary luteinizing principle differed histologically from those of chicks which received F.S.H.Young adult rats weighing 180225 gm. were used as donors and those castrated were operated upon 9 weeks previous to the time of implantation, Weights of pituitaries used corresponded closely to those tabulated for Wistar rats of similar weight.3 Single pituitaries were implanted subcutaneously into the chicks on the 5th and ...

ConclusionsAssays of male and female rat hypophyses were made by injecting acetone dried glands into normal and hypophysectomized immature female rats. Male hypophyses stimulated follicular development only, unless large amounts of the desiccated glands were administered. The hypophyses of adult female rats induced luteinization at all dose levels.

SummaryThe ovaries of 24- to 26-day-old rats and the testes of day-old White Leghorn chicks showed an increase in weight following the injection of a suspension of a single male rat pituitary gland in 8 divided doses over a 4-day period. The average increase in ovarian weight was 309% and that of the testes was 62%.

ConclusionThe stimulus of suckling of the removal of milk from the mammary glands markedly decreases the galactin content of the rat pituitary gland.

The ratio of the amounts of thyrotropic hormone in rat and beef hypophyses is entirely different from the ratio of the interrenotropic content in pituitaries of these 2 animal forms. Per unit of weight, adult male rat hypophyses are 7 to 9 times as potent in thyrotropic hormone as beef glands, whereas bovine pituitaries exceed male rat hypophyses in the ability to hypertrophy the adrenal cortex of adult male rats.Intramuscular implants into immature male guinea pigs and subsequent histological study of the thyroids showed that as good a response can be elicited with 6 mg. of male rat pituitary as with 50 mg. of beef.The adrenal weight is almost doubled when 1800 mg. of bovine glands are implanted over a 5 to 10 day period into adult male rats, provided the recipients have not been thyroidectomized.1 On the other hand, as many as 200 (about 1600 mg.) adult male rat hypophyses implanted into intact rats produced no adrenal enlargement whatsoever; however, 350 whole glands administered to one rat did induce ...

SummaryFractions isolated from rat pituitary homogenates by differential centrifugation have been assayed for growth-promoting activity by the tibia test. The supernatant fraction contained a relatively high proportion of the activity, but no sharp localization was evident.

SummaryA modified tissue culture technic for rat pituitary was used for assaying the ACTH releasing activity of commercial Pitressin and purified vasopressin. Pitressin increased ACTH release whereas highly purified arginine-vasopressin had no effect. The ACTH hypophysotrope activity of commercial Pitressin is attributed to a contaminant of vasopressin of probable hypothalamic origin.

ConclusionThe injection of rat pituitary extract into rats gives rise to an antithyrotropic substance in the serum of these animals. This was detected by the depressing effect of the serum upon the O2 consumption of guinea pigs receiving a standard dose of thyrotropic hormone.

McQueen-Williams1 has demonstrated that one normal male rat pituitary contains sufficient galactin to induce a good response in a one-month-old pigeon when implanted subcutaneously over the crop gland. Better results have been obtained in our laboratory by injecting the macerated pituitary intradermally over the crop gland as described by Lyons and Page.2In order to study the effect of estrone upon the galactin content of male rat pituitaries, 16 animals were paired upon the basis of body weight. One of each pair was injected subcutaneously daily for 15 days with 500 International Units of the benzoate of hydroxyestrin (Oestroform B). At the end of 15 days all of the animals were sacrificed, their pituitaries removed and weighed. Each pituitary was then macerated, using an agate mortar and pestle, and suspended in 0.4 cc. of distilled water. This suspension was then injected intradermally over the right crop gland of a common rock pigeon at the rate of 0.1 cc. per day. The left crop gland was used as a co...