Olfactory denervation: its biological and behavioral effects in infant rats.

Two-week-old infant rats were treated with intranasal ZnSO4 and compared with littlemate controls 24 hr later. When infants were returned to their mother and littermates, those with olfactory deficits lost weight, had reduced cardiac and respiratory rates and lower body temperatures, and showed increased locomotor behavior in an unfamiliar test area. Subsequent experiments showed that in the absence of the mother and also in isolation, differences between ZnSO4-treated and control infants involved fewer systems were less marked, and presented different patterns. Isolated infants given oral ZnSO4 did not differ from controls on any measures. Olfactory denervation appears to produce these effects by disrupting nursing, by altering littermate interaction, and by other central nervous system effects that are independent of social interaction.