Possible mechanism of adaptogenic activity of seabuckthorn (Hippophae rhamnoides) during exposure to cold, hypoxia and restraint (C-H-R) stress induced hypothermia and post stress recovery in rats

The present study was carried out to investigate mechanism of adaptogenic activity of seabuckthorn dry leaves aqueous lyophilized extract, administered in rats at a dose of 100 mg/kg body weight prior to cold (5 °C)-hypoxia (428 mm Hg)-restraint (C-H-R) exposure up to fall of T_rec 23 °C and recovery (T_rec 37 °C) from C-H-R induced hypothermia. The effect of extract treatment was studied on key metabolic regulatory enzymes in blood, liver and muscle and tissue glycogen in rats on attaining T_rec 23 °C and post stress recovery of T_rec 37 °C. In control rats during C-H-R exposure on attaining T_rec 23 °C there was significant decrease in enzyme activities of blood hexokinase (HK), citrate synthase (CS) and glucose-6-phosphate dehydrogenase (G-6-PD); liver CS; and in muscle glycogen, and CS and G-6-PD activities. In control rats on recovery of T_rec 37 °C there was also a significant decrease in liver and muscle glycogen levels along with decreased enzyme activities of blood G-6-PD; liver CS; and liver and muscle G-6-PD. This suggested that during severe stressful exposure to C-H-R and post stress recovery the aerobic metabolism as well as hexose monophosphate (HMP) pathway is suppressed. The single and five doses extract treatment restricted the decrease or better maintained tissue glycogen and enzyme activities, viz. HK, phosphofructokinase (PFK), CS and G-6-PD, in blood, liver and muscle, during C-H-R exposure (T_rec 23 °C) and recovery of T_rec 37 °C. The results suggest that seabuckthorn extract treatment caused a trend for shifting anaerobic metabolism to aerobic during C-H-R exposure and post stress recovery.