1974 Volume 24 Issue 1 Pages 11-20
Cycloheximide (Naramycin named by the Tanabe Phamaceutical Company) is known to have a strong rat repellent action. Rats were trained to discriminate between water containing one odour, and water containing the other odour and cycloheximide. The relative abilities of olfactory discrimination were studied in the following types of rats; the normal rats and the rats with the anterior limbs of the anterior commissure (AC) sectioned, the lateral olfactory tracts (LOT) sectioned, the AC plus the LOT sectioned and the olfactory bulbs (OB) removed bilaterally.
1. The above rats' reactions were tested between the normal tap water and the water containing two drops of 0.02% cycloheximide. The rates of successful discrimination were all about 60%, and no difference was found among the above groups. Consequently, it was concluded that the odour of cycloheximide itself does not interfere with the results of the following discrimination experiments.
2. When the concentrations of anise and camphor were diluted in four steps, the rates of success decreased gradually in each of the above groups of rats (Table 2). But a difference was found in the discriminative ability between the rats with the OB removed, and the other groups of rats even in the lowest concentrations of odours used.
3. The discrimination tests were performed on rats between dl-camphor (10-3%) and each of the eight odours used (Table 3, 4 and 5). The discriminative ability decreased in this order, from the normal, to the AC sectioned, the LOT sectioned, the AC plus LOT sectioned and finally the OB removed rats.
4. The discriminative abilities of rats with the OB removed were examined between the stimulants and non-stimulants of the trigeminal nerve. Thus, considerable contribution of the trigeminal nerve was proved to the discrimination of some odours (Table 6).
5. A clear difference of discriminative ability was found between the AC plus LOT sectioned and the OB removed rats. The origin of this difference was considered.
