Mechanism of action of Rhodiola imbricata Edgew during exposure to cold, hypoxia and restraint (C-H-R) stress induced hypothermia and post stress recovery in rats

Mechanism of rhodiola root extract adaptogenic activity was studied in rats. The extract was orally administered in rats (100 mg/kg body weight), 30 min prior to cold (5 degrees C)-hypoxia (428 mmHg)-restraint (C-H-R) exposure up to fall of T(rec)23 degrees C and recovery (T(rec)37 degrees C) from hypothermia. In untreated control rats serum lactate and non-esterified fatty acids (NEFA) increased on attaining T(rec)23 degrees C with decreased blood enzyme activities hexokinase (HK), phosphofructokinase (PFK), citrate synthase (CS) and glucose-6-phosphate dehydrogenase (G-6-PD), on attaining T(rec)23 degrees C and T(rec)37 degrees C. Decreases were also observed in liver and muscle tissues HK and G-6-PD enzyme activities and liver glycogen and CS on attaining T(rec)23 degrees C and recovery; muscle PFK during recovery; muscle CS on attaining T(rec)23 degrees C. Single and five doses of extract administration restricted increase in serum lactate values of rats on attaining T(rec)23 degrees C and maintained blood NEFA in single dose extract treated animals, indicating improved utilization of NEFA as energy fuel. The single and five doses extract treatment decreased or better maintained tissue glycogen and enzyme activities, viz. HK, PFK, CS and G-6-PD, in blood, liver and muscle, on attaining T(rec)23 degrees C and recovery. The results suggest that rhodiola extract treatment in rats shifted anaerobic metabolism to aerobic, during C-H-R exposure and post stress recovery. (C) 2009 Elsevier Ltd. All rights reserved.