Is it advisable to use sorbitans in the investigation of the brain mechanisms?

Injection of 0.1% saline solution of Tween 80 i.p. (3 X 3 cm3/kg/12 h) in the cat decreased the carbachol-induced growling response 36 h after the last injection. The content of 5-hydroxyindoleacetic acid (5-HIAA) increased in the hypothalamus, midbrain and amygdala, which indicates the increase in serotonin (5-HT) turnover and the 5-HT system activity. The results indicate that Tween 80 causes per se both behavioral and neurochemical changes. Therefore, it is inadvisable to add sorbitans to the solutions used in the investigation of the brain mechanisms.