Figure 5.

In vitro GSIS and insulin/proinsulin content of male GHRH-KO islets Insulin and proinsulin content (A), basal (2.8mM glucose) insulin secretion (B), 16.8mM GSIS (C), and gene expression (D) of islets from 16- to 18-week-old control (open columns) and GHRH-KO (crosshatched columns) mice. Insulin, proinsulin content, and insulin secretion were normalized with islet protein content assessed by Bradford and are represented as percentage of control values within experiments (set at 100%). GSIS (fold induction) is the ratio of insulin concentration in 16.8mM and 2.8mM glucose-KRHB after 30 minutes of incubation. All values are means ± SEM of 4–5 independent experiments with 4–8 independent wells/genotype with the exception of gene expression analysis (n = 2). Asterisks indicate significant differences between GHRH-KO and controls. ***, P < .001. NF, normalization factor; INS-2, insulin; Pdx-1, pancreatic and duodenal homeobox; Glut-2, glucose transporter 2; Gck, glucokinase.