Studies in cell cultures, animals, and humans have revealed antifatigue, anti-stress, antihypoxic (protection against damaging effects of oxygen deprivation), anticancer, antioxidant, immune enhancing and coïtusual stimulating effects.
The systematic study of the pharmacological effects of R. rosea, begun in 1965, found that small and medium doses had a simulating effect, such as lengthening the time mice swim and remain on vertical perches to the limit of their abilities. In contrast, larger doses were found to have more sedative effects. Small doses increased the bioelectrical activity of the brain, presumably by direct effects on the brainstem ascending and descending reticular formation.23-26,38,39,41 Further studies showed that medium range doses, unlike tranquilizers, enhanced the development of conditioned avoidance reflexes in rats and facilitated learning based on emotionally positive reinforcement.18,42-46 Overall, in small and medium doses, R. rosea stimulated norepinephrine (NE), dopamine (DA), serotonin (5-HT), and nicotinic cholinergic effects in the central nervous system (CNS). It also enhanced the effects of these neurotransmitters on the brain by increasing the permeability of the blood brain barrier to precursors of DA and 5-HT.[/B]2,23,42,46-49 Consequently, the cognitive (thinking, analyzing, evaluating, calculating, and planning) functions of the cerebral cortex and the attention, memory, and learning functions of the prefrontal and frontal cortex are enhanced. Other neuronal systems also contribute to the many aspects of memory: encoding, sorting, storage, and retrieval. For example, the cholinergic system uses the neurotransmitter acetylcholine (Ach) and contributes to memory function via pathways ascending from the memory storage systems of the limbic system to various areas of the cerebral cortex (memory retrieval). Agents that block Ach suppress the activity of these ascending pathways and interfere with memory. R. rosea reverses this blockade.49,50 The deterioration of these systems with age results in age-associated memory loss.52 R. rosea may prevent or ameliorate some age-related dysfunction in these neuronal systems.
