Peripheral olfactory deafferentation of the primary olfactory system in rats using ZnSO4 nasal spray with special reference to maternal behavior

A modified method of applying ZnSO4 to the olfactory mucosa is described. Treated rats experienced severe nasal congestion that cleared within 24 h; more persistent morbidity did not occur. Nonpregnant females observed with male intruders 24 h following ZnSO4 showed no alterations in behavior other than a reduction in anogenital sniffing, indicating that they were not hypoactive or irritable. In other experiments, lactating females were observed in a hole-board apparatus; 2 days posttreatment anosmia was confirmed in 80% of bilaterally ZnSO4-treated females by the absence of preference for pup odors. After bilateral but not unilateral ZnSO4 treatment, initially activity scores and nose pokes were equivalent in all groups, but later they both were lower than in controls, probably due to a more rapid habituation to the novel apparatus. We conclude that intranasal ZnSO4 by small-volume spray is a useful experimental tool.