Document Type

Thesis - University Access Only

Award Date

2010

Degree Name

Master of Science (MS)

Department / School

Animal Science

Abstract

Genistein is a bioactive isoflavone, which has been shown to have estrogenic effects in pigs. Previously it has been demonstrated that administration of genistein to barrows increases anterior pituitary (AP) concentrations of insulin-like growth factor I (IGF-1) and luteinizing hormone (LH) and increased expression of AP IGF receptor, indicating genistein has an effect on the IGF-1 system in barrows. However, whether similar changes occur in ovariectomized gilts remains to be determined. Therefore, the objective of this experiment was to determine if short term administration of genistein alters the IGF-I system in ovariectomized gilts. Sixteen crossbred gilts of similar weight (x= 95.5 kg) were ovariectomized and assigned to either control (C; n=8) or genistein (G; n=8) groups. The genistein pigs received 800 mg of genistein in DMSO while C pigs received an equal volume of DMSO i.m. on d 0, 1, 2, and 3. Blood samples were obtained by jugular venipuncture on d 0, 1, 2, and 3. Pigs were slaughtered on day 4 when blood, AP, and medial basal hypothalami (MBH) were collected. Serum and AP concentrations of LH and IGF-1 were determined by RIA. Serum concentrations of IGF-1 were not different (P>0.05) between C and G pigs on d O through d 4. Serum concentrations of LH were not different (P>0.05) in G pigs compared to C pigs on d 0, 1, 2, 3 and 4. No difference was detected (P>0.05) in anterior pituitary concentrations of IGF-1 between C and G pigs. Anterior pituitary concentrations of LH tended to be greater (P>0.06) in G pigs compared to C pigs. Anterior pituitary glands were collected and total RNA was isolated using TriReagent. The resulting RNA was reverse transcribed into cDNA. Specific primers for porcine IGF-1, insulin-like growth factor type 1 receptor (IGF-IR), insulin-like growth factor binding protein-2 (IGFBP-2), insulin-like growth factor binding protein-3 (IGFBP- 3), insulin-like growth factor binding protein-5 (IGFBP-5), gonadotropin releasing hormone receptor (GnRH receptor), luteinizing hormone beta subunit (LH~ subunit), and estrogen receptor alpha (ERa) were designed using the software supplied by integrated DNA technologies. Real-Time semi-quantitative PCR was used to measure the resulting quantity of mRNA for each gene of interest. Gene expression of porcine IGF-1, IGF-IR, IGFBP-2, IGFBP-3, IGFBP-5, GnRH receptor, LH~ subunit, and ERa in the AP were quantified and normalized to the amount of GAPDH. Porcine gene expression of ERa in the MBH was quantified and normalized to the amount of β-actin. Genistein treatment increased (P< 0.05) relative expression of AP IGF-1 in G pigs versus C pigs. Relative expression of anterior pituitary IGF-IR, IGFBP-2 and IGFBP-3 did not differ (P>0.05) in C and G pigs. Relative expression of AP IGFBP-5 increased (P< 0.05) in G pigs compared to C pigs. Genistein treatment increased (P< 0.05) expression of GnRH receptor in G pigs versus C pigs. Relative expression of AP LH~ and ERa did not differ between C and G pigs. Medial basal hypothalamus relative expression of ERa did not change (P>0.05) in C pigs and G pigs. These preliminary data suggest that short term administration of genistein increases some IGF-1 system components in ovariectomized gilts, however genistein is far less potent than estradiol and may not be able to initiate all the biological functions that are caused by estradiol.

Keywords: Genistein, Insulin-like Growth Factor, Estradiol, Gilts

Library of Congress Subject Headings

Sows

Genistein

Estrogen -- Physiological effect

Somatomedin

Insulin-like growth factor-binding proteins

Format

application/pdf

Number of Pages

89

Publisher

South Dakota State University

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