Biomedical subjects

Sarah Stanley

Publications and source records attributed to Sarah Stanley.

8 recordsLinked to original sources

PubMed2005

Hormonal regulation of food intake.

Our knowledge of the physiological systems controlling energy homeostasis has increased dramatically over the last decade. The roles of peripheral signals from adipose tissue, pancreas, and the gastrointestinal tract reflecting short- and long-term nutritional status are now being described. Such signals influence central circuits in the hypothalamus, brain stem, and limbic system to modulate neuropeptide release and hence food intake and energy expenditure. This review discusses the peripheral hormones and central neuronal pathways that contribute to control of appetite.

Animals↗

PubMed2005

Appetite control.

Our understanding of the physiological systems that regulate food intake and body weight has increased immensely over the past decade. Brain centres, including the hypothalamus, brainstem and reward centres, signal via neuropeptides which regulate energy homeostasis. Insulin and hormones synthesized by adipose tissue reflect the long-term nutritional status of the body and are able to influence these circuits. Circulating gut hormones modulate these pathways acutely and result in appetite stimulation or satiety effects. This review discusses central neuronal networks and peripheral signals which contribute energy homeostasis, and how a loss of the homeostatic process may result in obesity. It also considers future therapeutic targets for the treatment of obesity.

Adipose Tissue↗

PubMed2004

Gastrointestinal satiety signals III. Glucagon-like peptide 1, oxyntomodulin, peptide YY, and pancreatic polypeptide.

Many peptides are synthesized and released from the gastrointestinal tract and pancreas, including pancreatic polypeptide (PP) and the products of the gastrointestinal L cells, glucagon-like peptide 1 (GLP-1), oxyntomodulin, and peptide YY (PYY). Whereas their roles in regulation of gastrointestinal function have been known for some time, it is now evident that they also influence eating behavior. This review considers the anorectic peptides PYY, PP, GLP-1, and oxyntomodulin, which decrease appetite and promote satiety in both animal models and humans.

Digestive System↗

PubMed2004

The gut and regulation of body weight.

Signals generated by the gastrointestinal tract are able to regulate appetite and influence body weight. Ghrelin is an orexigenic peptide produced by the stomach. Satiety signals derived from the intestine and pancreas include peptide YY, pancreatic polypeptide, glucagon-like peptide 1, oxyntomodulin, and cholecystokinin. Signals from the gut and adipose tissue are integrated in the central nervous system to provide energy homeostasis. Knowledge of the body's control of appetite is important because we strive to combat obesity in man.

Animals↗

PubMed2003

Basal chromatin modification at the IL-4 gene in helper T cells.

Chromatin immunoprecipitations in naive CD4, but not CD8, T cells, demonstrated association of the IL-4 promoter with acetylated histone. Histone modifications and rapid IL-4 transcription were absent in conserved noncoding sequence 1 (CNS-1)(-/-) cells lacking an 8-kb-distant enhancer in the IL-4/IL-13 intergenic region, but also in CD4(-/-) and Itk(-/-) cells, which have similar Th2 deficiencies. Histones associated with the IL-13 promoter were not similarly acetylated in naive T cells, but became acetylated in differentiated Th2 cells. Conversely, Th1 differentiation induced histone methylation at the type 2 cytokine locus. Like CD4(-/-) and Itk(-/-) mice, CNS-1(-/-) BALB/c mice were highly resistant to the Th2-inducing protozoan, Leishmania major. CNS-1 deficiency led to failure of IL-4 gene repositioning to heterochromatin after Th1 polarization, possibly related to the presence of reiterative Ikaros binding sites in the intergenic element. Hyperacetylation of nonexpressed genes may serve to mark lineage-specific loci for rapid expression and further modification.

Animals↗

PubMed2003

Galanin-like peptide stimulates the release of gonadotropin-releasing hormone in vitro and may mediate the effects of leptin on the hypothalamo-pituitary-gonadal axis.

Leptin regulates the hypothalamo-pituitary-gonadal axis in relation to nutritional status. The mechanism through which leptin mediates its effects on neuroendocrine reproductive circuits remains unclear. Galanin-like peptide (GALP) is a recently identified hypothalamic peptide, localized in the arcuate nucleus, which seems to be regulated by leptin and stimulates LH when administered centrally. Here, we demonstrate that leptin stimulates the release of GALP and GnRH in vitro from hypothalamic explants harvested from male rats. In addition, we show that GALP stimulates the release of GnRH from hypothalamic explants and GT1-7 cells. Furthermore, we demonstrate that GALP antiserum blocks the stimulatory action of leptin on GnRH release from hypothalamic explants. GALP is a ligand of the galanin receptors. We therefore investigated whether the effect of GALP on GnRH release may be mediated via a known galanin receptor. GALP-stimulated GnRH release from hypothalamic explants was attenuated (but not abolished) by the galanin receptor antagonist galantide. However, GALP-stimulated GnRH release from GT1-7 cells was not diminished by the coadministration of galantide. In addition, none of the cloned galanin receptors were expressed in GT1-7 cells by RT-PCR. These observations suggest that GALP may stimulate GnRH release through an indirect pathway involving a galanin receptor and via a direct action on GnRH neurons, possibly through a novel receptor. These findings suggest that GALP may mediate the actions of leptin on the reproductive axis and provide a link between nutrition and fertility.

Animals↗

PubMed2003

A role for arcuate cocaine and amphetamine-regulated transcript in hyperphagia, thermogenesis, and cold adaptation.

We have recently shown that injection of the hypothalamic peptide cocaine and amphetamine regulated transcript (CART) into discrete hypothalamic nuclei stimulates food intake. This stimulation was particularly marked in the arcuate nucleus. Here we show that twice daily intra-arcuate injection of 0.2 nmole CART peptide for 7 days was associated with a 60% higher daytime food intake, an 85% higher thermogenic response to the beta3 agonist BRL 35135, and a 60% increase in brown adipose tissue UCP-1 mRNA. In a separate study, using stereotactically targeted gene transfer, a CART transgene was delivered by using polyethylenimine to the arcuate nucleus of adult rats. Food intake was increased significantly during ad libitum feeding and following periods of food withdrawal and food restriction in CART over-expressing animals. CART over-expressing animals lost 12% more weight than controls following a 24-h fast. Brown adipose tissue uncoupling protein-1 (UCP-1) mRNA levels (collected Day 25) were 80% higher in CART over-expressing animals. Finally, by using quantitative in situ hybridization, we found that chronic cold exposure (20 days at 4oC) increased arcuate nucleus CART mRNA by 124%. Together with the orexigenic and thermogenic effects of CART, this finding suggests a role for arcuate nucleus CART in cold adaptation.

Adaptation, Physiological↗

PubMed2003

Effects of galanin-like peptide on food intake and the hypothalamo-pituitary-thyroid axis.

Galanin-like peptide (GALP) is a novel hypothalamic peptide synthesised in neurons in the arcuate nucleus which project to the paraventricular nucleus (PVN). GALP has recently been identified as an orexigenic peptide. In this study we aimed to further characterise the hypothalamic action of this peptide in energy homeostasis. Firstly, we investigated the orexigenic effect of GALP in the PVN and compared its effects with galanin and galanin 2-29. Secondly, we examined the effect of PVN administration of GALP and galanin on circulating thyroid-stimulating hormone (TSH). PVN administration of GALP significantly increased the food intake of satiated rats 1 h after administration at doses of 0.3, 1 and 3 nmol. In comparison with paraventricular administration of galanin, GALP was a more potent orexigen, whereas galanin 2-29, the relatively selective GAL R2 agonist, had no effect on food intake. Both GALP and galanin administration (1 nmol) into the PVN significantly decreased the level of circulating TSH. To investigate the mechanism of these effects, we examined the effect of GALP and galanin application on neuropeptide release from hypothalamic explants in vitro. GALP peptide (100 nM) stimulated the release of the orexigenic peptide neuropeptide Y from hypothalamic explants and decreased the release of the anorectic peptide cocaine-and-amphetamine-regulated transcript, whereas galanin (100 nM) peptide had no significant effect on the release of either peptide. Both GALP (100 nM) and galanin (100 nM) inhibited the release thyrotrophin-releasing hormone. These data suggest that in the PVN, GALP may play a role in energy homeostasis by stimulating food intake and suppressing TSH release.

Animals↗