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In the present investigation, the authors aimed to evaluate the role of cytokines in intestinal postnatal maturation induced by dietary polyamines. Neonatal rats were administered either saline or spermine (8 μmol) orally. Spermine increased interleukin-1β (IL-1β), IL-6, and TNF-α plasma concentration. The maximum concentrations of IL-1β, IL-6, and TNF-α were, respectively, observed at 4, 4, and 8...
Estrogen or progesterone replacement in ovariectomized rats is an often-used experimental system for determination of the specific effects of these hormones. In this study, two different delivery systems and two different dosage levels of estrogen, progesterone or a combination of the two have been used. Estrogen and progesterone in the circulation have been measured in response to each treatment...
Continuous withdrawal of hypophyseal portal blood from unrestrained sheep has permitted detailed assessments of the pulsatile secretion of gonadotrophin-releasing hormone (GnRH). To determine if this blood can also be used to characterize the secretory dynamics of pituitary hormones, patterns of luteinizing hormone (LH) in the hypophyseal portal blood of ovariectomized ewes was compared with previous...
An ovary implanted into the spleen of an ovariectomized rat develops into a luteinized tumor, growing in response to gonadotrophins. Previously, it was shown that in vivo Buserelin, a gonadotrophin-releasing hormone (GnRH) analog, inhibited tumor growth. To determine if GnRH had a direct effect on tumor cells, the presence of GnRH receptors as well as the endocrine effects of buserelin were studied...
The effect of stress on serum corticosteroid-binding globulin (CBG) was studied in adult male Sprague-Dawley rats. CBG was measured either by a homologous radioimmunoassay (RIA) or by a binding assay (BA) using 3H-corticosterone. Exposure of adult male rats to a severe stressor such as immobilization (IMO) for 1 h did not alter serum CBG levels, but a significant decrease was found after 6 and especially...
The aim of the present study was to investigate the regulation of the in vitro DNA synthesis of ovarian cells recovered from prepubertal rats 48 h after administration of pregnant mare’s serum gonadotrophin alone (granulosa cells) or followed by human chorionic gonadotrophin (luteal cells). Isolated granulosa cells were cultured in serum-free medium, different stimuli added for periods of 48 h, and...
Bisphosphonates are compounds derived from pyrophosphate, a byproduct of cellular cleavage of adenosine triphosphate (ATP), and are resistant to alkaline phosphatase by virtue of replacement of oxygen by carbon. The high affinity of the P-C-P structure for hydroxyapatite accounts for deposition in bone. Modification of the two side chains of carbon alters the potency of the drugs. Of those that have...
Thyrotropin-releasing hormone (TRH) and its mRNA have been identified in the rat heart, and TRH can enhance cardiomyocyte contractility in vivo. At present, little is known about cardiac TRH gene transcriptional regulation in the heart. Hormones and neurotransmitters, including thyroid hormone (T3), glucocorticoids, testosterone, and 5-HT initiate effects not only in the cardiovascular system, but...
The authors have recently demonstrated that an inhibitor of protein phosphorylation, staurosporine (SSP), can dramatically enhance follicle-stimulating hormone (FSH) stimulated cyclic adenosine monophosphate (cAMP) accumulation in rat granulosa cell line (GFSHR-17) overexpressing about 20-fold FSH receptor than primary granulosa cells. Moreover, incubation with SSP can partially release the cells...
Nasal calcitonin is a newly approved treatment for established osteoporosis that increases lumbar spine bone mass, is safe, and well tolerated. Fracture efficacy data is not yet available, although preliminary results are promising. The dose for established osteoporosis is 200 IU. The dose for prevention of postmnopausal osteoporosis has not been established. Nasal calcitonin may be analgesic to bone...
Protein kinase C (PKC) is a key regulatory enzyme involved in the transduction of extracellular growth signals to the cell nucleus. It occurs in several isoforms, the exact functional roles of which have not been established as yet. The tumor-promoting agent 12-O-tetradecanoyl-phorbol acetate (TPA) is the classic activator of PKC and modulates the activity of the activating protein-1 (AP-1) transcription...
There are physiological and skeletal changes that occur during pregnancy to accommodate the increased calcium needs of late pregnancy and lactation in the rat. Endochondral bone growth is accelerated during early to midpregnancy, but the endocrine basis of this is not clear. The purpose of this study was to define the role, if any, of placental factors in changes in endochondral growth by comparing...
In young birds, growth hormone (GH) administration has been found to have only a small or even no effect on circulating concentrations of insulin-like growth factor-I (IGF-I). This is in obvious contrast to the situation in mammals. The present study examines the effect of continuous administration of GH in adult male chickens. Plasma concentrations of IGF-I were markedly elevated (2.5–3.0-fold,p<0...
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