The biochemistry of metabolic depression: a history of perceptions.

Our interest in animals that 'turn off' dates back at least 300 years. This phenomenon has been reported in most of the major invertebrate phyla and in all vertebrate classes, and has implications for our understanding of a wide range of homeostasis and metabolic control issues. Surprisingly however, it took 20 years of biochemical research before the realization dawned that metabolic depression is the frontline strategy utilized by these animals to survive environmental stress. In this essay, the history of this research is treated in five stages, defined in terms of how the phenomenon now known as metabolic depression was perceived at the time. The two initial stages clearly show that the researchers involved were refractory to the concept of metabolic depression until about 1982 (stage 3). The two stages after 1982 reflect the impact of the acknowledgement of metabolic depression per se and show how research is now being directed towards both the mechanisms involved in, and the cellular targets of metabolic depression.