Preserved olfactory short-term memory after combined cholinergic and serotonergic lesions using 192 IgG-saporin and 5,7-dihydroxytryptamine in rats.

Young adult Long-Evans female rats were subjected to intracerebroventricular injections of 150 microg 5,7-dihydroxytryptamine (5,7-DHT), 2 microg 192 IgG-saporin, or a combination of both neurotoxins. All rats were tested for olfactory recognition (short-term memory) using a task based on spontaneous exploration of odor sources. Compared with animals undergoing sham operations, 5,7-DHT reduced the concentration of serotonin by 60-80% in the frontoparietal cortex, hippocampus, striatum and the olfactory bulbs. After 192 IgG-saporin treatment, acetylcholine concentrations were reduced by approximately 40% in all these structures, except the striatum. Neither lesion induced a significant deficit in olfactory recognition. These data suggest that combined lesions of cholinergic and serotonergic neurons in the rat brain do not alter olfactory perception or olfactory short-term memory.