How to interpret the results of a full factorial experiment in biology when two factors separately act unidirectionally, but acting together suppress each other? What is the possible logic of a causal relationship at the molecular-cellular and organ level? I obtained a result of this type when performing a neurobiological experiment on rats. I administered two substances (factors) to rats and measured the change in dopamine secretion in the nucleus accumbens in response to the administration. Having received such a result, I am confused what is the possible interpretation in the paradigm of physiology.