Abstract

Aqueous extract of leaves of Nelumbo nucifera was investigated on acute stress (immobilization stress)-induced biochemical alterations in Swiss mice. The animals were also subjected to acute physical stress (swimming endurance test) and acute chemical stress (writhing test) to gauge the antistress potential of the extract. Further to evaluate the antistress activity of Nelumbo nucifera in chronic stress condition, fresh Wistar rats were subjected to cold restraint stress (4° for 1 h) for 7 days after 21 days of pretreatment with the extract. Stimulation of hypothalamus pituitary adrenal axis in stressful condition alters plasma glucose, triglyceride, cholesterol, total protein and corticosterone levels. Pretreatment with the extract significantly ameliorated the stress-induced variations in these biochemical levels in both acute and chronic stress models. The extract treated animals showed increase in swimming endurance time and reduced number of writhes in physical and chemical-induced stress models respectively. Treatment groups also reverted back perturbed neurotransmitter levels (norepinephrine, dopamine and 5-hydroxytryptamine) in brain as well as increase in adrenal gland weights and atrophy of spleen caused by cold chronic stress. In mice immunized with sheep red blood cells, treatment groups subjected to restraint stress prevented the humoral immune response to the antigen. Histopathological studies of adrenal gland of stress control group revealed vacuolar degeneration, loss of architecture and formation of lesions in the cortex, which was reversed by extract treatment. The results indicate that aqueous extract of Nelumbo nucifera has significant adaptogenic activity against a variety of biochemical, histological, physiological and immunological perturbations in acute and chronic stress models.