The association of changes in cerebral ganglion dopamine metabolism with ootheca development in Periplaneta americana

1.1. Dopamine levels and DOPA-decarboxylase activity were measured in cerebral ganglia and haemolymph of female Periplaneta americana.2.2. Measurements were made at four points in the oothecal cycle of cockroaches known to drop oothecae at regular three day intervals.3.3. Dopamine levels and DOPA-decarboxylase activity in haemocytes and plasma cycle in phase with ootheca formation; their levels in haemolymph are maximal when a half visible, untanned ootheca is present.4.4. In the cerebral ganglia dopamine levels and DOPA-decarboxylase also cycle in phase with ootheca formation suggesting that cerebral ganglion dopamine metabolism is under the same controls as dopamine metabolism associated with oothecal tanning.