The correlation between intestinal gonadotropin-releasing hormone (GnRH) and proglucagon in hyperlipidemic rats and Goto-Kakizaki (GK) rats.
Our experiment investigated the mRNA expression of intestinal gonadotropin-releasing hormone (GnRH), proglucagon (PG), and glucagon-like peptide 1 receptor (GLP-1R) in the jejunum, ileum, and colon of rats fed with high-fat diet and Goto-Kakizaki (GK) rats and revealed the physiological role of intestinal GnRH. We found that the GnRH and PG mRNA levels in high-cholesterol (HCh) diet were higher than in the control. However, the GnRH receptor (GnRHR) and GLP-1R mRNA levels did not differ significantly between HCh and control. The GnRH, PG, and GLP-1R mRNA levels in GK rats were lower, respectively, than those in control rats, while the GnRHR levels did not differ significantly between GK rats and control rats. There were no difference in GnRH, PG, GnRHR, and GLP-1R mRNA levels in the ileum and colon tissue between HCh and control rats. The GnRH mRNA levels of GK rats were lower than those in control rats; however, the PG, GLP-1R, and GnRHR levels did not differ significantly between GK and control rats. The GLP-1R mRNA levels of GK rats were lower than those in control rats. The GnRH mRNA expression showed positive correlation with PG mRNA expression in different intestinal sections. The GnRH level in the jejunum showed a significant effect on blood glucose level, while the PG level in the jejunum showed a significant effect on insulin level. This may imply that, compared with the ileum and colon, the jejunum had greater impact on glucose metabolism; furthermore, GnRH might interact with intestinal GLP-1 and GLP-2 through the paracrine and autocrine ways and then regulate glucose metabolism and insulin secretion.
Wang
Li
L
Department of Endocrinology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
Wu
Jing
J
Cao
Hongwei
H
Chen
Rong
R
Zhang
Nanyan
N
Fu
Jianfang
J
Gao
Bin
B
Zhang
Jing
J
Hou
Rongrong
R
Tang
Chaowu
C
Ji
Qiuhe
Q
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002791:Cholesterol, Dietary / Q000008:administration & dosage; D003106:Colon / Q000737:chemistry; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D000067757:Glucagon-Like Peptide-1 Receptor; D005951:Glucose Tolerance Test; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D006949:Hyperlipidemias / Q000378:metabolism*; D007082:Ileum / Q000737:chemistry; D007328:Insulin / Q000097:blood; D007422:Intestines / Q000737:chemistry*; D007583:Jejunum / Q000737:chemistry; D008297:Male; D052336:Proglucagon / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D018027:Receptors, Glucagon / Q000235:genetics; D011966:Receptors, LHRH / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D001786:Blood Glucose; D002791:Cholesterol, Dietary; C000593835:Glp1r protein, rat; D000067757:Glucagon-Like Peptide-1 Receptor; D007328:Insulin; D012333:RNA, Messenger; D018027:Receptors, Glucagon; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D052336:Proglucagon