Down regulation of prolactin (PRL) receptors resulting from i.v. infusion of oPRL or human growth hormone (hGH) into female virgin rats was demonstrated. A decrease of over 85% in the number of free receptors was achieved within 15 - 30 min using infusion of oPRL or hGH at 25 micrograms/h and remained at this level until the end of infusion. Ovine growth hormone or recombinant bovine growth hormone at ten-fold higher concentration had no effect at all. The decrease in the specific binding resulted from a lower number of binding sites and not from change in the dissociation constants. The decrease in the total receptors in the liver was more gradual and leveled off at 40 - 50% of the initial value. Our results suggest that a change in blood PRL or hGH level may lead to a new steady state in the number, occupancy and distribution of prolactin receptors.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/0006-291x(83)90573-9 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Basal and stimulated inhibin B in pubertal disorders.
J Clin Endocrinol Metab
January 2025
3Department of Metabolism, Digestion and Reproduction, Imperial College London.
Pubertal disorders in the form of delayed puberty (DP) or precocious puberty (PP) can cause considerable anxiety to both children and parents. Since the clinical and biochemical signatures of self-limiting and permanent conditions overlap considerably, it can be hard to determine whether to offer them reassurance or intervention. Researchers have thus long been searching for a robust test to indicate that the process of endogenous puberty is underway and is likely to proceed to completion.
View Article and Find Full Text PDFLoss-of-function GHSR variants are associated with short stature and low IGF-I.
J Clin Endocrinol Metab
January 2025
Division of Pediatric Endocrinology, Department of Pediatrics, Willem-Alexander Children's Hospital, Leiden University Medical Centre, Leiden, The Netherlands.
Context: The growth hormone (GH) secretagogue receptor, encoded by GHSR, is expressed on somatotrophs of the pituitary gland. Stimulation with its ligand ghrelin, as well as its constitutive activity, enhances GH secretion. Studies in knock-out mice suggest that heterozygous loss-of-function of GHSR is associated with decreased GH response to fasting, but patient observations in small case reports have been equivocal.
View Article and Find Full Text PDFA weight of evidence review on the mode of action, adversity, and the human relevance of xylene's observed thyroid effects in rats.
Crit Rev Toxicol
January 2025
Product Stewardship, Science & Regulatory, Shell Global Solutions International B.V. The Hague, the Netherlands.
Xylene substances have wide industrial and consumer uses and are currently undergoing dossier and substance evaluation under Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) for further toxicological testing including consideration of an additional neurotoxicological testing cohort to an extended one-generation reproduction toxicity (EOGRT) study. New repeated dose study data on xylenes identify the thyroid as a potential target tissue, and therefore a weight of evidence review is provided to investigate whether or not xylene-mediated changes on the hypothalamus-pituitary-thyroid (HPT) axis are secondary to liver enzymatic induction and are of a magnitude that is relevant for neurological human health concerns. Multiple published studies confirm xylene-mediated increases in liver weight, hepatocellular hypertrophy, and liver enzymatic induction the oral or inhalation routes, including an increase in uridine 5'-diphospho-glucuronosyltransferase (UDP-GT) activity, the key step in thyroid hormone metabolism in rodents.
View Article and Find Full Text PDFPublic Health.
Alzheimers Dement
December 2024
Libin Cardiovascular Institute, Calgary, AB, Canada; Hotchkiss Brain Institute, Calgary, AB, Canada; University of Calgary, Calgary, AB, Canada.
There is growing recognition that exercise is a potent stimulus for improving cognitive and brain function in both humans and rodents. While the mechanisms underlying the effect of exercise on cognition are very likely multifactorial, it is clear that the secretion and function of several classical factors are involved. Work done in rodents implicates several growth factors, including BDNF, IGF-1, and VEGF, in the ability of exercise to induce neuroplastic changes within key brain regions associated with learning and memory.
View Article and Find Full Text PDFSingle-cell and spatial transcriptomic analyses reveal heterogeneity characteristics and specific cell subtype regulators in growth hormone-secreting pituitary adenomas.
Int J Surg
December 2024
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
Background: Growth hormone-secreting pituitary adenomas (GHPA) display diverse biological behaviors and clinical outcomes, necessitating the identification of tumor heterogeneity and prognostically relevant markers.
Methods: In this study, we performed single-cell RNA sequencing (scRNA-seq) on 10 GHPA samples, four of which also underwent spatial transcriptome sequencing, and used scRNA-seq data from four normal pituitary samples as controls. Cell subtype characterization in GHPA was analyzed using multiple algorithms to identify malignant bias regulators, which were then validated using a clinical cohort.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!