The 24-h rhythm of metabolic activity of the cockroach circadian pacemaker.

In the cockroach, Leucophaea maderae, the optic lobes contain a circadian pacemaker. The metabolic activity of optic lobe neuropils was measured at 17 time points over a 24-h period in constant darkness, using cytochrome oxidase activity as functional marker. The results revealed a clear 24-h energy metabolism rhythm in neuropils and particularly in the lobula plate, a part of the region which is assumed to include a circadian pacemaker in this species.