Functional Restoration of Pituitary after Pituitary Allotransplantation into Hypophysectomized Rats.

Long-term hormone replacement therapy due to panhypopituitarism can lead to serious complications and thus, pituitary transplantation is considered a more desirable. We investigated functional restoration after allotransplatation of the pituitary gland. We transplanted extracted pituitary gland into the omentum of an hypophysectomized rat. Two experiments were performed: (1) to confirm the hypophysectomy was successful and (2) to assess functional restoration after pituitary transplantation. Pituitary hormone level and weight change were consecutively assessed. Electron microscopic (EM) examinations were performed to identify morphological changes at 3 days after transplantation. We confirmed that pituitary gland was properly extracted from 6 rats after sacrifice. The findings showed (1) a weight loss of more than 3% or (2) a weight change of less than 2% along with a decreased growth hormone (GH) level by more than 80% at 2 weeks post-hypophysectomy. A further four rats underwent pituitary transplantation after hypophysectomy and were compared with the previously hypophysectomized rats. All showed rapid weight gain during the two weeks after transplantation. The thyroid-stimulating hormone, prolactin, and GH levels were restored at one week post-transplantation and maintained for 10 weeks. Hypophyseal tissue architecture was maintained at 3 days after transplantation, as indicated by EM. These data suggest that a transplanted pituitary gland can survive in the omentum with concomitant partial restoration of anterior pituitary hormones.

Effect of thyroxin on cell morphology and hormone secretion of pituitary grafts in rats.

INTRODUCTION: Growth hormone and prolactin secretion is affected by thyroid hormones. To see if this influence is subsidiary to the hyptothalamus, we investigated the effects of thyroxin (T4) on hormone secretion and histology of sellar pituitaries and pituitary grafts detached from the hypothalamus (autografted or allografted under the kidney capsule). MATERIALS AND METHODS: Male Wistar rats were divided into eight groups: control, thyroidectomised, pituitary autografted, pituitary allografted, and four additional groups that were injected with T4 for two weeks, starting four weeks after surgery. At sacrifice, adenohypophysial hormone blood levels were assessed, and tissue from sellar and grafted pituitaries were investigated by histology and electron microscopy. RESULTS: Growth hormone and prolactin blood levels, as well as the number of growth hormone immunopositive cells increased in T4-treated groups. Both pituitary auto- and allo-grafts showed lactotroph hyperplasia and displayed spongiform areas containing cells with vesicles in their cytoplasm resembling thyroidectomy cells. This phenomenon was minimized in their respective T4-treated group. Thyroidectomy cells were identified in pituitary grafts, indicating that hypothalamic control was not essential to induce them. DISCUSSION AND CONCLUSION: It is intriguing that the pituitary allografted group, even maintaining normal T4 blood levels, developed thyroidectomy cells in their grafts, suggesting that a long- term deficit of vascularization (>4 weeks) prevented T4 from reaching the graft. After 6 weeks, post T4 treatment of two weeks seemed to be the determining factor to minimize thyroidectomy cells in both pituitary autografted + T4 and pituitary allografted + T4 grafts compared to the untreated groups, although more time and/or higher T4 doses may be required to fully restore the euthyroid morphology.

From Pituitary Stem Cell Differentiation to Regenerative Medicine.

The anterior pituitary gland is comprised of specialized cell-types that produce and secrete polypeptide hormones in response to hypothalamic input and feedback from target organs. These specialized cells arise during embryonic development, from stem cells that express SOX2 and the pituitary transcription factor PROP1, which is necessary to establish the stem cell pool and promote an epithelial to mesenchymal-like transition, releasing progenitors from the niche. Human and mouse embryonic stem cells can differentiate into all major hormone-producing cell types of the anterior lobe in a highly plastic and dynamic manner. More recently human induced pluripotent stem cells (iPSCs) emerged as a viable alternative due to their plasticity and high proliferative capacity. This mini-review gives an overview of the major advances that have been achieved to develop protocols to generate pituitary hormone-producing cell types from stem cells and how these mechanisms are regulated. We also discuss their application in pituitary diseases, such as pituitary hormone deficiencies.

Effect of prolactin on the water-salt balance in rat females in the model of cholestasis of pregnancy.

We studied the possibility of prolactin involvement in the regulation of water-salt metabolism in female rats in the model of cholestasis of pregnancy. For simulation of the prolactin level during pregnancy, hyperprolactinemia was simulated by transplantation the pituitary under the renal capsule of the recipient; for modeling cholestasis of pregnancy, a combination of induced hyperprolactinemia and bile duct obstruction was used. Diurnal diuresis, expression of aquaporin 1-4 mRNA in the renal medulla, glomerular filtration rate, and diurnal sodium excretion were evaluated in these models. Diuretic and natriuretic effects of prolactin in the model of cholestasis of pregnancy were demonstrated. These data and the fact that prolactin has no effect on glomerular filtration rate and aquaporin expression suggest that prolactin modulates activity of sodium transporters in the kidney.

Harvey Cushing's attempt at the first human pituitary transplantation.

BACKGROUND: This case study illustrates Harvey Cushing's pioneering work in pituitary transplantation in the early 20th century and the essential relationship between laboratory research and clinical practice. In 1911, a 48 year-old man presented at Johns Hopkins Hospital with bitemporal hemianopsia, hypothermia, hypersomnolence, decreased libido, polydypsia and polyuria. INVESTIGATION: A review of the Johns Hopkins Hospital surgical records from 1896-1912 on a patient with hypopituitarism secondary to a suprasellar mass, in whom the first documented pituitary gland transplantation was performed. DIAGNOSIS: A diagnosis of hypopituitarism was made. Postmortem examination revealed a cystic cavity lined with squamous epithelium. MANAGEMENT: The patient was treated with whole-gland pituitary extract, which improved his symptoms only temporarily. Cushing transplanted a pituitary gland obtained from a spontaneously aborted fetus into the cerebral cortex of the patient, who showed marked improvement of his somnolence and confusion, whereas his polyuria and polydypsia persisted. A recurrence of symptoms after 6 weeks prompted Cushing to attempt a second transplant of a fetal pituitary gland, without improvement. The patient resumed hormonal supplementation with whole-gland pituitary extract, but died a month after the second transplant from respiratory complications.

Effects of hyperprolactinemia on toxicological parameters and proliferation of islet cells in male rats.

Prolactin has a wide variety of biological effects. Consequences of hyperprolactinemia on islet B cell proliferation as well as general toxicological parameters were here examined using anterior pituitary-grafted rats. Three or six anterior pituitary glands were implanted under single renal capsules of F344 male rats and left there for 13 weeks afterward. Clinical observation along with measurement of body weight and food consumption was conducted during the observation period, and subsequently hematology, blood biochemistry, gross pathology, organ weights and histopathology were examined. In addition, the proliferation rate of islet B cells was measured by a 5-bromo-2'-deoxy-uridine (BrdU) labeling technique. Serum prolactin concentrations at week 13 were 36, 70, 75 and 105 ng/ml in the sham-operated, 3-pituitary-grafted groups from male or female donors, and 6-pituitary-grafted group from male donors, respectively. Higher cholinesterase and total cholesterol values, lower trigriceride and leutenizing hormones (LH) values, and higher adrenal weights compared to those in the sham-operated group were apparent in the 3- and/or 6-pituitary-grafted groups. Also, the study revealed that mammary gland structure was transformed with change of differentiation from a male to a female acinar pattern. Furthermore a specific increase of islet cell proliferation rate was found, positively correlated with serum prolactin concentration. These findings suggest that elevation of serum prolactin level over 13 weeks induces islet cell proliferation and changes in toxicological parameters, including cholinesterase activity, elements of lipid metabolism and histopathology/morphology of the adrenals and mammary glands in male rats.

[Transplantation of hormone-producing cells into the testicular paravasal fat hole in secretory infertility and gonadal hypoplasia].

Intratesticular cell transplantation is an effective surgical method in the treatment of patients with secretory infertility in chronic orchoepididymitis accompanied and not accompanied with marked testicular hypoplasia. This treatment in patients with secretory infertility and testicular hypoplasia enlarges gonads by more than 60% (from 3 to 5 mm3). The density of spermatozoa on the spermogram of males both with and without testicular hypoplasia increased by more than 70%--from 7.2 to 12.2 mln/ml in patients with gonad hypoplasia and from 14.2 to 25.5 mln/ml in patients with normal testicular size. The number of active mobile spermatozoa rose by 76 and 32% in patients with and without testicular hypoplasia, respectively, the number of pathological cells in ejaculate decreased from 61.8 to 51.4% and from 48.2 to 41.2%, respectively. Cell transplantation enabled a wife of each seventh man with secretory infertility to have a child, even in case of severe bilateral testicular hypoplasia in two of the men.

High physiological prolactin induced by pituitary transplantation decreases BMD and BMC in the femoral metaphysis, but not in the diaphysis of adult female rats.

High physiological prolactin (PRL) stimulated intestinal calcium absorption and renal calcium uptake in mammals. Previous histomorphometric study revealed a significant increase in bone turnover in the trabecular part of the PRL-exposed long (cortical) bone; however, whole-bone densitometric analysis was unable to demonstrate such effect. We therefore studied differential changes in bone mineral density (BMD) and contents (BMC) of the femoral diaphysis and metaphysis in adult female rats exposed to high PRL induced by anterior pituitary (AP) transplantation. The estrogen-dependent effects of PRL on the femur were also investigated. We found that chronic exposure to PRL had no effect on BMD or BMC of the femoral diaphysis, which represented the cortical part of the long bone. It is interesting that 7 weeks after an AP transplantation, BMD and BMC of the femoral metaphysis were significantly decreased by 8% and 14%, respectively. Ovariectomy (Ovx) for 2, 5, and 7 weeks also decreased BMD and BMC in the femoral metaphysis, but not in the diaphysis. However, the AP transplantation plus Ovx (AP+Ovx) produced no additive effects. Nevertheless, 2.5 microg/kg 17beta-estradiol (E2) supplementation abolished the osteopenic effects of both Ovx and AP+Ovx on the femur. As for the L5-6 vertebrae, BMD and BMC were not affected by PRL exposure, but were significantly decreased by Ovx and AP+Ovx, and such decreases were completely prevented by E2 supplementation. It could be concluded that high physiological PRL induced a significant osteopenia in the trabecular part, i.e., the metaphysis, of the femora of adult female rats in an estrogen-dependent manner. Since PRL had no detectable effect on the vertebrae, the effects of PRL on bone appeared to be site-specific.

Long-term, homologous prolactin, administered through ectopic pituitary grafts, induces hypothalamic dopamine neuron differentiation in adult Snell dwarf mice.

Pituitary prolactin (PRL) secretion is inhibited by dopamine (DA) released into the portal circulation from hypothalamic tuberoinfundibular DA (TIDA) neurons. Ames (df/df) and Snell (dw/dw) dwarf mice lack PRL, GH, and TSH, abrogating feedback and resulting in a reduced hypophysiotropic TIDA population. In Ames df/df, ovine PRL administration for 30 d during early postnatal development increases the TIDA neuron number to normal, but 30 d PRL treatment of adult df/df does not. The present study investigated the effects of homologous PRL, administered via renal capsule pituitary graft surgery for 4 or 6 months, on hypothalamic DA neurons in adult Snell dw/dw mice using catecholamine histofluorescence, tyrosine hydroxylase immunocytochemistry, and bromodeoxyuridine immunocytochemistry. PRL treatment did not affect TIDA neuron number in normal mice, but 4- and 6-month PRL-treated dw/dw had significantly increased (P < or = 0.01) TIDA (area A12) neurons compared with untreated dw/dw. Snell dwarfs treated with PRL for 6 months had more (P < or = 0.01) TIDA neurons than 4-month PRL-treated dw/dw, but lower (P < or = 0.01) numbers than normal mice. Periventricular nucleus (area A14) neuron number was lower in dwarfs than in normal mice, regardless of treatment. Zona incerta (area A13) neuron number was unchanged among phenotypes and treatments. Prolactin was unable to induce differentiation of a normal-sized A14 neuron population in dw/dw. Bromodeoxyuridine incorporation was lower (P < or = 0.01) in 6-month PRL-treated normal mice than in 6-month PRL-treated dwarfs in the subventricular zone of the lateral ventricle and in the dentate gyrus, and lower (P < or = 0.05) in 4-month untreated dwarfs than in 4-month untreated normal mice in the median eminence and the periventricular area surrounding the third ventricle. Thus, a PRL-sensitive TIDA neuron population exists in adult Snell dwarf mice when replacement uses homologous hormone and/or a longer duration. This finding indicates that there is potential for neuronal differentiation beyond early developmental periods and suggests plasticity within the mature hypothalamus.

High-calcium diet modulates effects of long-term prolactin exposure on the cortical bone calcium content in ovariectomized rats.

High physiological prolactin induced positive calcium balance by stimulating intestinal calcium absorption, reducing renal calcium excretion, and increasing bone calcium deposition in female rats. Although prolactin-induced increase in trabecular bone calcium deposition was absent after ovariectomy, its effects on cortical bones were still controversial. The present investigation, therefore, aimed to study the effect of in vivo long-term high physiological prolactin induced by either anterior pituitary (AP) transplantation or 2.5 mg/kg prolactin injection on cortical bones in ovariectomized rats. Since the presence of prolactin receptors (PRLR) in different bones of normal adult rats has not been reported, we first determined mRNA expression of both short- and long-form PRLRs at the cortical sites (tibia and femur) and trabecular sites (calvaria and vertebrae) by using the RT-PCR. Our results showed the mRNA expression of both PRLR isoforms with predominant long form at all sites. However, high prolactin levels induced by AP transplantation in normal rats did not have any effect on the femoral bone mineral density or bone mineral content. By using (45)Ca kinetic study, 2.5 mg/kg prolactin did not alter bone formation, bone resorption, calcium deposition, and total calcium content in tibia and femur of adult ovariectomized rats. AP transplantation also had no effect on the cortical total calcium content in adult ovariectomized rats. Because previous work showed that the effects of prolactin were age dependent and could be modulated by high-calcium diet, interactions between prolactin and these two parameters were investigated. The results demonstrated that 2.0% wt/wt high-calcium diet significantly increased the tibial total calcium content in 9-wk-old young AP-grafted ovariectomized rats but decreased the tibial total calcium content in 22-wk-old adult rats. As for the vertebrae, the total calcium contents in both young and adult rats were not changed by high-calcium diet. The present results thus indicated that the adult cortical bones were potentially direct targets of prolactin. Moreover, the effects of high physiological prolactin on cortical bones were age dependent and were observed only under the modulation of high-calcium diet condition.

Deiodinase type 1 activity is expressed in the prostate of pubescent rats and is modulated by thyroid hormones, prolactin and sex hormones.

The aim of this study was to characterize the type of 5'-deiodinase activity in the prostate of pubescent rats (7-8 weeks), to establish its distribution in the lobes (ventral, dorsolateral, and anterior), and to analyze its modulation by prolactin (PRL), testosterone, dihydrotestosterone (DHT), and 17beta-estradiol (E(2)). Our results showed that the enzymatic activity was highly susceptible to inhibition by 6-n-propyl-2-thiouracil and gold thioglucose, its preferential substrate was reverse tri-iodothyronine (rT(3)), it exhibited a low dithiothreitol requirement (5 mM), and the apparent K(m) and V(max) values for substrate (rT(3)) were approximately 0.25 microM and 9.0 pmol liberated/mg protein per hour, respectively. All these characteristics indicate the preferential expression of type 1 deiodinase (D1), which was corroborated by demonstrating the presence of D1 mRNA in prostate. D1 activity was detected in all lobes and was most abundant in the dorsolateral. Although we detected type 2 deiodinase (D2) mRNA expression, the D2 activity was almost undetectable. D1 activity was enhanced in animals with hyperthyroidism and hyperprolactinemia, in intact animals treated with finasteride (inhibitor of local DHT production), and in castrated animals with E(2) replacement. In contrast, activity diminished in castrated animals with testosterone replacement. Our results suggest that thyroid hormones, PRL, and E(2) exert a positive modulation on D1 activity, while testosterone and DHT exhibit an inhibitory effect. D1 activity may be associated with prostate maturation and/or function.

Effects of partial decerebration and hypophyseal allograft in the thymus of chicken embryos: thymostimulin localization and enzymatic activities.

Changes in chicken embryo thymus after partial decerebration (including the hypophysis) and hypophyseal allograft were investigated. Chicken embryos were partially decerebrated at 36-40 hr of incubation and on day 12 received a hypophyseal allograft from 18-day-old donor embryos. The embryonic thymuses were collected on day 18 and examined with histological methods, tested for the anti-thymostimulin-like immune-reaction, and for histoenzymatic activities and compared with normal and sham-operated embryos at the same age. After partial decerebration, the thymic cortical and medullary compartments diminished markedly in size. Anti-thymostimulin, succinic dehydrogenase and ATPase enzymatic activities tested, yielded negative reactions. In partially decerebrated hypophyseal allografted embryos, the same thymic compartments improved and anti-thymostimulin-like immune-reaction and enzymatic activities partially recovered. These findings confirmed the key role of hypophysis in thymic ontogenic development and provided new information in metabolic enzymatic pathways and synthesis of a thymostimulin-like substance in the thymus.

Experimental adenomyosis.

Adenomyosis has been reported in a number of different animal species, whereas endometriosis appears limited to humans and non-human primates. This suggests a different aetiology of the two conditions. Adenomyosis develops spontaneously in certain strains of laboratory mice. Its incidence in mice can be markedly enhanced by systemic exposure to various hormonal agents, including prolactin, progesterone, synthetic progestins, certain oestrogenic agents, as well as tamoxifen and toremifene. The precise hormonal changes necessary remain unclear, although the evidence suggests that adenomyosis in this model is not due to a simple oestrogenic effect. Study of the pathological and molecular alterations in this model indicates that disturbances to the uterine stroma, blood vessels and myometrium are also important factors in the development of adenomyosis.

[Analysis of different mutations in regulatory sequence of prolactin gene during the formation of 17 beta-estradiol-induced prolactinoma in eutopic and ectopic pituitary of rats].

OBJECTIVE: To analyze different mutations in regulatory sequence of prolactin (PRL) gene during the formation of 17 beta-estradiol (E2 ) -induced prolactinoma in eutopic and ectopic pituitary of rats. METHODS: Male Sprague-Dawley rats transplanted with an isologaus pituitary under renal capsule were treated with subcutaneous implantation of an empty or E2-laden silastic capsule. Reverse transcription-polymerase chain reaction was employed to evaluate the expression of PRL mRNA in pituitary glands, and DNA sequencing was used to analyze the mutation in regulatory sequence of PRL gene. RESULTS: After treated with E2 for 120 days, both the eutopic and ectopic pituitaries were three times more heavier than those from control group (P < 0. 01) , and the body weight of rats was decreased to 42. 90% of the control group (P < 0 01 ). The PRL mRNA expressions in glands from the eutopic and ectopic pituitaries 120 days after treated with E2 were much more than those in untreated pituitary glands (P <0. 01). DNA sequencing showed seven mutations in the regulatory sequence of PRL gene in the eutopic pituitaries 120 days after treated with E2 , while the mutation in the ectopic pituitaries was decreased. CONCLUSIONS: Prolactinomas can be induced by chronic treatment with E2 in both the eutopic and the ectopic pituitaries transplanted under renal capsule distant from the hypothalamus. Different mechanisms exist in the formation of eutopic and ectopic prolactinomas.

Mice lacking the amplified in breast cancer 1/steroid receptor coactivator-3 are resistant to chemical carcinogen-induced mammary tumorigenesis.

Amplified in breast cancer 1 (AIB1; steroid receptor coactivator-3, p/CIP, RAC3, ACTR, TRAM-1, or NCoA-3) is a transcriptional coactivator for nuclear receptors and certain other transcription factors and is a newly defined oncogene overexpressed in human breast cancer. Although the role and molecular mechanism of AIB1 in normal physiology and in breast cancer are currently under intensive investigation, the role of AIB1 in determination of the susceptibility of mammary gland to chemical carcinogens remains uncharacterized. In this study, we used back-crossed FVB wild-type (WT) and AIB1 mutant mice to assess the role of AIB1 in mammary gland development and in carcinogen-induced tumorigenesis. We show that mammary ductal growth was delayed in AIB1-/- mice with FVB strain background, and mammary ductal outgrowths emanating from the AIB1-/- mammary epithelial transplants in WT mice also were attenuated, indicating that the role of AIB1 in mammary ductal growth is a mammary epithelial autonomous function. In mice treated with the chemical carcinogen 7,12-dimethylbenz[a]anthracene (DMBA), AIB1 deficiency protected the mammary gland, but not the skin, from tumorigenesis. AIB1 deficiency suppressed the up-regulation of the insulin receptor substrate (IRS)-1 and IRS-2 and thereby inhibited the activation of Akt, expression of cyclin D1, and cell proliferation. The suppression of these components for insulin-like growth factor-I signaling might be partially responsible for the decreased DMBA-induced mammary tumor initiation and progression in AIB1-/- mice. Our results suggest that AIB1 may serve as a potential target for prevention of carcinogen-induced breast cancer initiation and for treatment of breast cancer progression.

Probucol, a hypocholesterolemic agent, prevents the development of uterine adenomyosis induced by pituitary grafting in mice.

This in vivo experimental study was designed to investigate the effects of probucol, a hypocholesterolemic agent, on uterine adenomyosis which is frequently induced by pituitary grafting in mice. SHN mice, which are known to develop uterine adenomyosis spontaneously, and much sooner after pituitary grafting, were used and histopathological study on the uteri in pituitary gland-implanted mice with or without probucol treatment was performed. Four out of 10 pituitary gland-implanted mice developed uterine adenomyosis with dilated blood vessels, but none of the probucol-treated mice. There were no differences between pituitary-grafted mice with or without probucol treatment in body weight and wet weights of uterus, ovaries, kidney and liver except spleen. Probucol markedly reduced the serum levels of total cholesterol, free cholesterol, free fatty acids, phospholipids and triglycerides and, thus, this agent inhibited the incidence of uterine adenomyosis induced by pituitary grafting in mice.

Superior cervical ganglionectomy differentially modifies median eminence and anterior and mediobasal hypothalamic GABA content in male rats: effects of hyperprolactinemia.

This work was undertaken to analyze the changes in GABA concentrations in the anterior and mediobasal hypothalamus and in the median eminence after acute or chronic superior cervical ganglionectomy (SCGx), and whether high prolactin levels interfere with the effects of SCGx on GABA content. Acute but not chronic SCGx increased GABA content in all the areas studied, as compared to controls. The presence of a pituitary graft abolished the effects of acute SCGx in the median eminence and anterior hypothalamus, as compared to controls, but potentiated its effects in the mediobasal hypothalamus. Chronic SCGx increased GABA content in the mediobasal and anterior hypothalami, as compared to pituitary grafted controls. Acute SCGx decreased plasma prolactin and GH levels, but chronic surgery did not modify these hormone plasma levels. Acute SCGx increased plasma ACTH levels, whereas chronic SCGx did not modify them. Pituitary grafting increased circulating values of prolactin, ACTH and GH, as compared to controls. Acute SCGx did not modify plasma prolactin levels in grafted animals, although it increased plasma GH levels and decreased those of ACTH in this experimental group. Chronic SCGx further increased both plasma prolactin and GH levels, without modifying plasma ACTH levels. These results suggest that SCGx differentially modifies GABA content within the hypothalamus and median eminence. Induction of hyperprolactinemia in the neonatal age interferes with SCGx effects on both GABA content within the hypothalamus and median eminence and the secretory patterns of the pituitary hormones studied.

Cortactin-binding protein 90 (CBP90) expression in the mouse mammary glands during prolactin-induced lobuloalveolar development.

We have previously performed suppression subtractive hybridization to identify genes that were induced during prolactin (PRL)-driven lobuloalveolar development of the mammary gland. This suggested that cortactin-binding protein 90 (CBP90), which is known to be a brain-specific protein that binds to cortactin, was expressed under the regulation of PRL in the mammary glands (preliminary observation). In this study, the expression of CBP90 was examined in the mammary glands of mice under manipulated hormonal circumstances. PRL treatment by 9 days of pituitary grafting induced CBP90 expression in the normal mammary glands but not in the cleared fat pads, while cortactin was expressed constitutively in both the normal mammary glands and the cleared fat pads. Unlike milk proteins, longer treatment with PRL (36 days of pituitary grafting) did not increase the expression level of CBP90 mRNA, while it slightly increased the cortactin mRNA level. Mammary CBP90 mRNA expression was induced by pituitary grafting but not by progesterone treatment in PRL-deficient mice, while pituitary grafting induced mammary CBP90 expression in ovariectomized PRL-deficient mice only when estrogen and progesterone were appropriately supplemented to permit the formation of alveolar buds. The CBP90 protein was detected by immunohistochemistry in the luminal epithelium of the alveolar buds and more faintly in the ductal epithelium. Thus, from the unique expression pattern, CBP90 may be useful as a molecular marker for the hormone-stimulated development of mammary alveolar buds.

Fos immunoreactivity in the suprachiasmatic nuclei of golden hamsters bearing an ectopic pituitary graft.

Young male golden hamsters, made hyperprolactinemic by a pituitary graft under the kidney capsule, were exposed to a light pulse (1,000 lx/30 min) at Zeitgeber time (ZT) 18. Controls included hamsters receiving a sham graft (muscle). Fos immunoreactive cells were counted in both suprachiasmatic nuclei (SCN) of each animal, using an image analyzer system. The Fos immunoreactivity (Fos-ir) of the ventrolateral and dorsomedial SCN regions was greater in the pituitary-grafted hamsters. Indeed, light induced the greatest response in grafted animals in both SCN regions. However, the SCN of pituitary-grafted hamsters in the absence of light showed the lowest Fos-ir in both regions. The results support the occurrence of a dual effect of hyperprolactinemia on Fos-ir in the SCN of hamsters at ZT 18, with inhibition of Fos expression in the absence of light and potentiation of early gene expression when animals were exposed to a light pulse.

Age-associated loss of bone marrow hematopoietic cells is reversed by GH and accompanies thymic reconstitution.

Deterioration of the thymus gland during aging is accompanied by a reduction in plasma GH. Here we report gross and microscopic results from 24-month-old Wistar-Furth rats treated with rat GH derived from syngeneic GH3 cells or with recombinant human GH. Histological evaluation of aged rats treated with either rat or human GH displayed clear morphologic evidence of thymic regeneration, reconstitution of hematopoietic cells in the bone marrow, and multiorgan extramedullary hematopoiesis. Quantitative evaluation of formalin-fixed, hematoxylin and eosin-stained sections of bone marrow from aged rats revealed at least a 50% reduction in the number hematopoietic bone marrow cells, compared with that of young 3-month-old rats. This age-associated decline in bone marrow leukocytes, as well as the increase in bone marrow adipocytes, was significantly reversed by in vivo treatment with GH. Restoration of bone marrow cellularity was caused primarily by erythrocytic and granulocytic cells, but all cell lineages were represented and their proportions were similar to those in aged control rats. On a per-cell basis, GH treatment in vivo significantly increased the number of in vitro myeloid colony forming units in both bone marrow and spleen. Morphological evidence of enhanced extramedullary hematopoiesis was observed in the spleen, liver, and adrenal glands from animals treated with GH. These results confirm that GH prevents thymic aging. Furthermore, these data significantly extend earlier findings by establishing that GH dramatically promotes reconstitution of another primary hematopoietic tissue by reversing the accumulation of bone marrow adipocytes and by restoring the number of bone marrow myeloid cells of both the erythrocytic and granulocytic lineages.