The Upsurge of China

372hal,;17 c

Hewlet-Packard scanjet 5590 [CD]/ Hewlet-Packard

552 M

Social habituation and dishabituation in CD-1 mice treated with the norepinephrine neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4)

Male CD-1 mice between postnatal days 60 and 90 were injected intraperitoneally (i.p) with either water vehicle (controls) or 50$\mu$g/g of the norepinephrine neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4). They were tested 3 to 6 days later on the odors of adult males in a four-trial habituation/dishabituation paradigm. There were four groups: group CSS were water injected and exposed to the same male on all four trials; group CSN were water injected and exposed to the same male on the first three trials and a novel one on the fourth; group DSN were DSP-4 treated and exposed the same male on the first three trials and a novel one on the fourth; and group D0-N were exposed to the empty apparatus on the first three trials and to a novel male on the fourth. All groups showed a significant decline in screen investigation time between the first and second trials, an indication of habituation to the overall testing environment. Group CSS demonstrated a progressive decrease in screen investigation time with the least investigation time occurring on trial 4. Group CSN demonstrated a similar pattern of diminishing screen investigation time over the first three trials, but stopped diminishing on the fourth trial when a new stimulus animal was placed in the cage. Animals from the DSN group did not demonstrate a quantitative change in screen investigating time at all. Screen investigation time of the D0-N group decreased progressively over the first three trials but increased sharply on trial 4 to trial 1 levels. These results suggest that animals from the CSN group could distinguish between the odors of a familiar and novel animal while those from the DSN group could not. Thus DSP-4 treatment may have impaired the ability of the animals to recognize the odors of a familiar versus an unfamiliar conspecific. This failure of recognition was not due to anosmia since animals from the D0-N group habituated to the testing environment showed a strong dishabituation response when exposed to a novel animal. In addition, on an olfactory preference test, all groups showed a preference for a familiar botanical odor (hardwood) over a nonfamiliar one (pine). Taken together, these results suggest that central NE is a modulator of intermale social olfaction