The Nutrition of the Central Nervous System in the Cockroach, Periplaneta Americana L. the Exchange and Metabolism of Sugars

The insect central nervous system is enveloped by a continuous cellular and fibrous membrane, the perilemma, which has been shown to be a barrier to the inward diffusion of sodium and potassium ions (Hoyle, 1952, 1953; Twarog & Roeder, 1956), acetylcholine (Twarog & Roeder, 1956) and dyes (Wigglesworth, i960). On the other hand, this structure must also, as Wigglesworth (1959, i960) has pointed out, be specialized to allow exchanges of nutritive and excretory substances to take place between the central nervous system and the haemolymph. This important role of the perilemma has been little studied and no quantitative observations have been made on the entry of nutritive substances into the insect central nervous system. In this investigation an attempt has been made to throw some light on these processes by studying the uptake of some C-labelled sugars in the abdominal nerve cord of the cockroach. Relatively little is known of the biochemical events occurring within the insect central nervous system, and the opportunity has been taken to learn something of these processes by following the metabolic fate of the C-labelled compounds in the abdominal nerve cord of this insect. These observations form part of a wider investigation being carried out in this laboratory in collaboration with Prof. V. B. Wigglesworth. The parallel histological and histochemical aspects of this problem are dealt with in a separate study on the central nervous system of this insect (Wigglesworth, i960).