Acute cold stress improved the transcription of pro-inflammatory cytokines of Chinese soft-shelled turtle against Aeromonas hydrophila

Chinese soft-shelled turtle, Pelodiscus sinensis, is widely cultured in East and Southeast Asian countries. It frequently encounters the stress of abrupt temperature changes, which leads to mass death in most cases. However, the mechanism underlying the stress-elicited death remains unknown. We have suspected that the stress impaired the immune function of Chinese soft-shelled turtle, which could result in the mass death, as we noticed that there was a clinical syndrome of infection in dead turtles. To test our hypothesis, we first performed bioinformatic annotation of several pro-inflammatory molecules (IL-1β, TNFα, IL-6, IL-12β) of Chinese soft-shelled turtle. Then, we treated the turtles in six groups, injected with Aeromonas hydrophila before acute cold stress (25 °C) and controls, after acute cold stress (15 °C) and controls as well as after the temperature was restored to 25 °C and controls, respectively. Subsequently, real-time PCR for several pro-inflammatory cytokines (IL-1β, TNFα, IL-6, IL-12β, IL-8 and IFNγ) was performed to assess the turtle immune function in spleen and intestine, 24 hours after the injection. We found that the mRNA expression levels of the immune molecules were all enhanced after acute cold stress. This change disappeared when the temperature was restored back to 25 °C. Our results suggest that abrupt temperature drop did not suppress the immune function of Chinese soft-shelled turtle in response to germ challenge after abrupt temperature drop. In contrast, it may even increase the expression of various cytokines at least, within a short time after acute cold stress.

Cannabinoids in acute gastric damage and pancreatitis

Recent studies have shown that stimulation of cannabinoid 1 (CB1) receptor reduces the area of ischemic myocardial necrosis and affects activity of the digestive tract. The aim of the present study was to check whether the administration of CB1 receptor agonist or antagonist affects the stress-induced gastric ulceration and development of edematous pancreatitis.

METHODS

Experiments were performed on rats. Gastric lesions were induced by water immersion and restrain stress (WRS). Acute pancreatitis was induced by cerulein. Prior to WRS or before and during cerulein administration, a natural endogenous ligand for CB1 receptor, anandamide was administered intraperitoneally at the dose of 0.8, 1.5 or 3.0 micromol/kg. A synthetic CB1 receptor antagonist, AM 251 (ALEXIS(R) Biochemicals) was administrated at the dose of 4 micromol/kg i.p. alone or in combination with anandamide at the dose of 1.5 micromol/kg.

RESULTS

Administration of anandamide reduced gastric lesions and this effect was associated with am increase in gastric mucosal blood flow and mucosal DNA synthesis; whereas serum level of pro-inflammatory interleukin-1 beta was reduced. Treatment with AM 251 aggravated gastric damage and reversed protective effect of anandamide administration. Opposite effect was observed in the pancreas. Administration of anandamide increased dose-dependently the severity of pancreatitis. In histological examination, we observed an increase in pancreatic edema and inflammatory infiltration. Also, treatment with anandamide augmented the pancreatitis-induced increase in serum level of lipase, amylase, poly-C ribonuclease, and pro-inflammatory interleukin-1 beta; whereas pancreatic DNA synthesis was reduced. Treatment with AM 251 reduced histological and biochemical signs of pancreatic damage and reversed deleterious effect of anandamide in cerulein-induced acute pancreatitis.

CONCLUSIONS

Activation of CB1 receptors evokes opposite effects in the stomach and pancreas: in the stomach, exhibits protective effect against stress-induced gastric mucosal lesions; whereas in the pancreas, increases the severity of cerulein-induced pancreatitis.