Some effects of the removal of the frontal ganglion on metabolism in locusta migratorla migratorioides r. and f.

Abstract

A study has been made on the effects of the removal of the frontal ganglion from adult Locusta migratoria migratorioides R & F on various aspects of metabolism. A decrease in lipid and carbohydrate reserves was observed in the fat body of operated animals although this was less marked when compared with starved specimens. This decrease in fat body reserves was not due to an increased release into the haemolymph nor to increased utilisation. Indeed oxygen consumption was significantly lower than in operated controls. The fine structural appearance of the fat body cells indicated a cessation of the normal functional development. This tended to be confirmed by the observation that fat body from operated animals showed a reduced ability to incorporate C(^14) glucose into triglycerides in vitro. Six digestive enzymes have been characterised and the optimal conditions for assay employed in determining the effects of frontal ganglion removal and starvation on the activities of these enzymes in various regions of the gut. Both treatments resulted in a reduction in amount of enzyme activity. The distribution of enzyme activity was also affected such that the foregut of starved and frontal ganglionectomised treatments had a smaller proportion of the activity than in the control. The fact that frontal ganglion removal effects a dramatic reduction in haemolymph volume was confirmed. Ultrastructural changes in the Malpighian tubules adds support to the suggestion that this reduced blood volume vas a result of chronic diuresis. However, this was shown not to be due to an effect on the activity of the Na (^+)K (^+)ATPase exchange pump. Removal of the frontal ganglion was shown to result in a cessation of growth and to reduce or prevent altogether the release of neurosecretory material from the corpus cardiacum, confirming previous work on larvae and adults. The above observations are discussed in the light of endocrine control of metabolism and the proposal that food passage through the gut is reduced in frontal ganglionectomised animals.