[Problem of controls in physiology and pharmacology: psychophysiological and morphofunctional effects of chronic saline administration].

The psychophysiological and morphofunctional effects of chronic administration of saline, which is commonly used as an active control, to Wistar rats were analyzed at different levels. The active control proved to be complicated by signs of stress manifested as increased corticosterone levels, changes in the homeostatic system, blood cytometric indices, morphofunctional states of the thymus and spleen, sharp suppression of the cognitive activity, and decrease in the motivational and locomotor activities. Pain expectation developed in animals after the second saline injection in the tail-flick test--pain sensitivity sharply increased in the session prior to the injection. These signs of stress should be taken into account for interpretation of the effects in drug tests.