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Query: UMLS:C0020505 (hyperphagia)
 6,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth hormone (GH) is an endocrine regulator of glucose and lipid metabolism as well as body growth. GH levels are decreased and a unique pulsatile secretory pattern becomes obvious after puberty particularly in males. Coincidentally with this, males tend to deposit body fat. Experimental and clinical evidence has accumulated that obesity is associated with a decrease in GH levels. A strain of transgenic rats has been generated with severe obesity but normal nose-to-tail length, which has low circulating GH levels without pulsatility (human growth hormone (hGH) transgenic rats). The present review mainly focuses on recent and current work analysing the relationship between the occurrence of obesity and low GH levels and/or the absence of GH pulsatility in this transgenic animal model. This model has elevated blood glucose, non-esterified fatty acid, insulin and leptin levels associated with hyperphagia, suggesting that these rats also carry insulin- and leptin-resistant characteristics. hGH transgenic rats were subjected to a pair-feeding treatment to normalize food intake and chronic GH replacement to normalize GH levels. While the pair-feeding for 8 weeks successfully suppressed body-weight gain, the fat pad : body weight ratio remained very similar to freely-eating control hGH transgenic rats, which indicates the hyperphagia is not the sole contributor to the excess fat accumulation in this model. However, continuous elevation of peripheral hGH levels (approximately 2-fold) for 8 weeks by means of a slow-release vehicle resulted in a significant decrease in the fat mass : body weight ratios by 30 %. This GH treatment altered neither food intake nor body-weight gain. Thus, two characteristic phenotypes observed in the hGH transgenic rats, hyperphagia and obesity, seem to be closely related to GH levels and GH secretory pattern. This relationship might be working in the regulation of changes in seasonal body composition in wild animals.
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PMID:Effects of pulsatile secretion of growth hormone (GH) on fat deposition in human GH transgenic rats. 1908 6

Physiological mechanisms underlying migration remain poorly understood, but recent attention has focused on the role of the glucocorticoid hormone corticosterone (CORT) as a key endocrine regulator of migration. The migration-modulation hypothesis (MMH) proposes that baseline plasma CORT levels are elevated in migratory birds to facilitate hyperphagia and lipogenesis and that further elevation of CORT in response to acute stress is suppressed. Consequently, CORT may be a poor indicator of individual condition or environmental variation in migratory birds. We tested the MMH by measuring baseline and stress-induced CORT in common yellowthroats (Geothlypis trichas) during fall migration over 2 consecutive years in the Revelstoke Reach drawdown zone, a migratory stopover site affected by local hydroelectric operations. Birds had low baseline CORT at initial capture (<5 ng/mL) and then showed a robust stress response, with CORT increasing to ca. 50 ng/mL within 10-20 min. Our data therefore do not support the MMH. Baseline CORT did not vary with body mass, time of capture, Julian day, or year, suggesting that variable flooding regimes did not affect baseline CORT. Individual variation in the rate of increase in CORT was correlated with Julian day, being higher later in the migration period. Our data suggest that plasma CORT can be a useful metric in migration studies.
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PMID:Variation in plasma corticosterone in migratory songbirds: a test of the migration-modulation hypothesis. 2524 81