Inhibitory effects of Aconiti Lateralis Radix Preparata on chronic intermittent cold-induced inflammation in the mouse hypothalamus

Abstract

Ethnopharmacological relevance: Aconiti Lateralis Radix Preparata (AR) is the most frequently used herb to generate heat and treat symptoms associated with coldness in Asia. Aims of the study: The hypothalamus is one of the master regulators to maintain constant core body temperature. Chronic exposure to cold stress disturbs homeostatic regulation, gradually resulting in hypothalamic inflammation. This study investigate the effects of AR, on the chronic intermittent cold (CIC)-induced release of pro-inflammatory signaling molecules in the mouse hypothalamus. Materials and methods: Aconiti Lateralis Radix Preparata extract (ARE) were solubilized in distilled water and diluted with saline before administration. Male ICR mice (7 weeks old, 30-32 g) were divided randomly into 6 groups: (1) control, (2) cold stress, (3) ARE 30, (4) ARE 100, (5) ARE 300, and (6) ARE 1000 mg/kg groups. Groups (2)-(6) were exposed to CIC stress once a day for 14 days. CIC stress was achieved by exposing the mice to 4 degrees C and 60 +/- 10% humidity for 120 min once a day. Rectal temperature was measured after terminating cold stress. Cortisol levels were measured from serum. Hypothalamus tissue was used for western blot analysis, and IL-9, IL-13, PGE1, and PGE2 levels were assessed. Results: ARE treatment prevented the CIC-induced decrease in rectal temperature and increase in serum cortisol level. ARE-treated CIC-exposed mice demonstrated decrease in nuclear c-Fos levels dose-dependently compared to CIC-exposed mice. Nuclear NF-kB expression showed significant increase in CIC-exposed mice. ARE treatment significantly blunted the increase in nuclear NF-kB expression. CIC-exposed mice had significantly increased levels of both IL-9 and IL-13. Treatment with ARE suppressed the elevated IL-9 and IL-13 levels. Between control and CIC-exposed mice PGE1 levels showed no difference. However ARE (1000 mg/kg)-treated CIC-exposed mice had a significant increase in PGE1 level compared to CIC-exposed mice. PGE2 levels were significantly higher in CIC-exposed mice compared to control mice. ARE treatment significantly attenuated the increase in PGE2 levels. Conclusions: Our findings suggest CIC stress disturbs the anti-inflammatory effect of cortisol and maintenance of the body temperature. Thus AR contributes to suppress the activated proinflammatory factors, IL-9, IL-13, and PGE-2, and to increase the heat production.