Knockdown of prolactin receptors in a pancreatic beta cell line: effects on DNA synthesis, apoptosis, and gene expression.

Prolactin (PRL) and placental lactogen stimulate beta cell replication and insulin production in vitro and in vivo. The molecular mechanisms by which lactogens promote beta cell expansion are unclear. We treated rat insulinoma cells with a PRL receptor (PRLR) siRNA to determine if PRLR signaling is required for beta cell DNA synthesis and cell survival and to identify beta cell cycle genes whose expression depends upon lactogen action.

The interplay of prolactin and the glucocorticoids in the regulation of beta-cell gene expression, fatty acid oxidation, and glucose-stimulated insulin secretion: implications for carbohydrate metabolism in pregnancy.

Carbohydrate metabolism in pregnancy reflects the balance between counterregulatory hormones, which induce insulin resistance, and lactogenic hormones, which stimulate beta-cell proliferation and insulin production. Here we explored the interactions of prolactin (PRL) and glucocorticoids in the regulation of beta-cell gene expression, fatty acid oxidation, and glucose-stimulated insulin secretion (GSIS). In rat insulinoma cells, rat PRL caused 30-50% (P < 0.

Effects of lactogen resistance and GH deficiency on mouse metabolism: pancreatic hormones, adipocytokines, and expression of adiponectin and insulin receptors.

We recently described a novel mouse model that combines resistance to lactogenic hormones with GH deficiency (GHD). The GHD/lactogen-resistant males develop obesity and insulin resistance with age. We hypothesized that altered production of pancreatic hormones and dysregulation of adipocytokine secretion and action contribute to the pathogenesis of their insulin resistance.

Short stature in children with sickle cell anemia correlates with alterations in the IGF-I axis.

Children with sickle cell anemia (SCA) frequently have short stature. We propose that alterations in the IGF-I axis are involved in their growth failure. We investigated the IGF-I axis in children with SCA and height below the 25th percentile (n = 15) and compared it with that of children with SCA and height above the 50th percentile (n = 7).

Lactogenic and somatogenic hormones regulate the expression of neuropeptide Y and cocaine- and amphetamine-regulated transcript in rat insulinoma (INS-1) cells: interactions with glucose and glucocorticoids.

Lactogenic hormones stimulate food intake in rodents, ungulates, and birds. To test the hypothesis that lactogens regulate expression of neuropeptides that control appetite, we used the prolactin (PRL)-responsive rat insulinoma (INS-1) cell line as an experimental paradigm. INS-1 cells express mRNA for neuropeptide Y (NPY) and cocaine- and amphetamine-regulated transcript (CART) but little or no agouti-related peptide or proopiomelanocortin.

Growth hormone and prolactin receptors in adipogenesis: STAT-5 activation, suppressors of cytokine signaling, and regulation of insulin-like growth factor I.

Growth hormone GH stimulates lipolysis in mature adipocytes and primary preadipocytes but promotes adipogenesis in preadipocyte cell lines. The lactogenic hormones (prolactin PRL and placental lactogen) also stimulate adipogenesis in preadipocyte cell lines but have variable lipolytic and lipogenic effects in mature adipose tissue. We hypothesized that differences in expression of GH receptors GHR and PRL receptors PRLR during adipocyte development might explain some of the differential effects of the somatogens and lactogens on fat metabolism.

Leptin in the newborn mouse. Plasma concentrations, characterization of the circulating hormone, and tissue source.

Previous studies suggested that brown adipose tissue (BAT) provides a source of circulating leptin in the newborn mouse. However, we detected no leptin mRNA in newborn BAT or in newborn liver or stomach. In contrast, leptin expression was detected readily in newborn white adipose tissue (WAT).

Targeted deletion of the PRL receptor: effects on islet development, insulin production, and glucose tolerance.

PRL and placental lactogen (PL) stimulate beta-cell proliferation and insulin gene transcription in isolated islets and rat insulinoma cells, but the roles of the lactogenic hormones in islet development and insulin production in vivo remain unclear. To clarify the roles of the lactogens in pancreatic development and function, we measured islet density (number of islets/cm(2)) and mean islet size, beta-cell mass, pancreatic insulin mRNA levels, islet insulin content, and the insulin secretory response to glucose in an experimental model of lactogen resistance: the PRL receptor (PRLR)-deficient mouse. We then measured plasma glucose concentrations after ip injections of glucose or insulin.