Effect of pentobarbital sodium on the behavior of rats in the Krech Hypothesis Apparatus.

A search for relations between brain chemistry and behavior.

“…The use of this drug was suggested by the fact that in appropriate small concentrations it has been shown in vitro to reduce the rate of synthesis of ACh (Mc-Lennan & Elliott, 1951), and we therefore expected it to lower adaptive capacity. The behavioral effect was in accordance with our prediction, and Moroz (1959) found that pentobarbital could also fixate animals on spatial preferences. Nevertheless, we do not now know how much weight should be given to this evidence, for the following reasons: we did not determine whether the rate of synthesis of ACh was actually reduced in the brains of our animals, and extrapolation from the in vitro to the in vivo condition is problematical ; pentobarbital has other effects in the brain which also tend to reduce the brain's responsiveness.…”

“…Thus, for example, one could alter the rate of ACh synthesis or the level of ChE activity by the use of drugs and see whether predicted changes would occur in behavior. We had used such an approach when we employed pentobarbital sodium to inhibit ACh synthesis and predicted that the injected animals would show less adaptive problem-solving behavior than control animals (Moroz, 1959;Rosenzweig, et al, 19S6). The behavioral results had been consistent with our assumptions about the role of ACh functioning, but, as we have indicated, these results cannot be interpreted unambiguously.…”