Earlier studies have shown significant reduction in ACh content and elevation of AChE activity in the discrete areas of brain in rats subjected to acute (100 dB) noise stress. Results of the present study indicate that the pretreatment of animals with OS extract has significantly brought back the noise stress altered values of these cholinergic parameters to the normal levels. Singh et al. have shown that the OS extract prevented the stress induced changes in the adrenergic neurotransmitters in rat brain.
So, it is evident now that ethanolic extract of OS prevents the stress induced changes not only in the stress indices like plasma corticosterone level, leukocyte count, leukocyte functions and organ weight but also in central nervous system. The central nervous system plays an important
role in the development of stress induced ulcers and OS was found to prevent the development of ulcers during stress conditions . In the light of all these observations, it could be speculated that the central nervous system might be one of the important sites of actions of OS extract.