Effects of Growth Hormone on Circulating Resistin Levels in Mice

Adipose tissue, along with its traditional role in lipid storage, also exhibits an extensive endocrine function secreting a number of anti- and proinflammatory hormones collectively known as adipokines. With obesity, the balance shifts towards an increase in proinflammatory hormones. One such adipokine, resistin, is found to have a positive correlation with inflammation and with insulin resistance. The aim of this study was to investigate circulating resistin levels in three mouse lines with altered growth hormone (GH) action. Bovine growth hormone (bGH) mice are giant, lean with lower insulin sensitivity while growth hormone antagonist (GHA) mice and growth hormone receptor knockout (GHR-/-) mice are dwarf and obese with either normal or higher insulin sensitivity, respectively. Blood plasma samples from three male mice lines: bGH, GHA, GHR-/- along with their littermate wild type (WT) control groups were collected following an overnight fast. The bGH mice (n = 6) were compared to WT controls (n = 5) at the age of 29 weeks, while 8 weeks bGH mice (n = 6) were compared to WT controls (n = 6). The GHA mice (n = 11) were matched to WT controls (n = 11) at the ages of 14, 26, 52 and 72 weeks. The GHR-/- mice (n = 6) were compared to WT controls (n = 10) at the age of 24 weeks. Mouse resistin immunoassay kits were used to quantify the resistin levels in the above mentioned mice. Leptin, adiponectin, insulin and body fat composition data have been reported from these mice previously. The resistin levels were found to be significantly higher in GHA mice when compared to controls at all ages except 14 weeks. Resistin levels remain relatively constant at four age points in GHA mice. Additionally, GHR-/- mice also had significantly higher resistin levels at the age of 24 weeks compared to controls. No significant differences were found in bGH mice for resistin levels when compared to controls. Positive and significant correlations were found for circulating resistin and adiponectin, leptin, insulin and fat mass in male GHA mice while resistin had a negative and significant correlation with body weight. On the other hand resistin was found to have a significant positive correlation with adiponectin in male GHR-/- mice. No differences in resistin levels were found in male bGH mice. Since GH is a diabetogenic hormone, it can be concluded that GH causes insulin resistance independent of circulating resistin levels.

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Food and Nutrition Sciences (Health Sciences and Professions)

Grantor dc:publisher

Ohio University

Year dc:date

2012

Author dc:creator

• Vijeyta, Fnu

Contributors dc:contributor

• Berryman, Darlene

• Endocrinology
• Food Science
• Nutrition
• Resistin
• growth hormone
• transgenic mice

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1346947127

OAI identifier oai:identifier

oai:etd.ohiolink.edu:ohiou1346947127