High gastrin cell activity and low ghrelin cell activity in high-anxiety Wistar Kyoto rats

Abstract

Ghrelin is produced by gastric A-like cells and released in response to food deprivation. Interestingly, psychological stress also raises circulating ghrelin levels. This study compared plasma ghrelin levels in Sprague-Dawley (SPD) rats and high-anxiety Wistar Kyoto (WKY) rats. The two strains were also compared with respect to plasma gastrin, a gastric hormone with a pre-and postprandial release pattern opposite to that of ghrelin, and to the activity of the gastrindependent, histamine-forming ECL cells in the gastric mucosa. The rats were killed after being freely fed or after an over-night fast. The stomachs were weighed and tissue samples were collected for histological and biochemical analysis. Plasma ghrelin and gastrin levels were determined by RIA. While fasted SPD rats had higher plasma ghrelin levels than fasted WKY rats (P!0 . 001), plasma ghrelin did not differ between freely fed rats of the two strains. Gastrin levels were higher in fed WKY rats than in fed SPD rats (P! 0 . 001). Despite the higher plasma gastrin level, the oxyntic mucosal histidine decarboxylase (HDC) activity (a marker of ECL-cell activity) in fed rats and the mucosal thickness did not differ between the two strains. In a subsequent study, rats were subjected to water-avoidance stress for 60 min, causing plasma gastrin to increase in WKY rats (P!0 . 001) but not in SPD rats. In conclusion, high-anxiety WKY rats had lower circulating ghrelin and higher gastrin than SPD rats in both the fasted and fed state, while the ECL-cell activity (HDC activity) was only moderately affected.

Ghrelin's Roles in Stress, Mood, and Anxiety Regulation

“…Thus, we proposed that ghrelin has anxiolytic-like effects and that ghrelin signaling is required for the anxiolytic-like effects of caloric restriction [9]. Our observations seem to be supported by a report showing that Wistar Kyoto rats, which are thought to display more anxiety-like behaviors than Sprague-Dawley and other rat strains, have lower plasma levels of ghrelin than Sprague-Dawley rats [24]. Furthermore, although stress-induced elevations in circulating ghrelin have been noted in both Wistar Kyoto and Sprague-Dawley rat strains, the magnitude of those elevations was significantly lower in the anxiety-prone Wistar Kyoto animals than in the Sprague-Dawley animals [11].…”

Ghrelin, a Gastric Hormone with Diverse Functions

“…In contrast to these observations, increasing circulating ghrelin has been reported to produce anxiolytic-like responses, while no longer were these anxiolytic-like behavioral responses observed when GHSR-null mice were calorie restricted (Lutter et al, 2008). These findings are consistent with a report showing low ghrelin cell activity in high-anxiety Wistar Kyoto rats (Kristensson et al, 2007). The reasons for the conflicting results are currently unknown (Andrews, 2011).…”

Effects of Toxoplasma gondii infection on anxiety, depression and ghrelin level in male rats

“…Calorie-restricted wild-type mice showed anxiolytic-and antidepressant-like behavior in the elevated plus maze and forced swim test, respectively, as compared to wild-type mice (Lutter et al 2008). Also, high-anxiety WKY rats had lower circulating ghrelin than SPD rats in both the fasted and fed state (Kristensson et al 2007). Masayuki Kanehisa reported that in forced swimming tests, rats that received antisense DNA for ghrelin, immobilization time decreased.…”