Cholinergic neurochemical development of normal and deafferented antennal lobes during metamorphosis of the moth, Manduca sexta

Abstract

Sensory neurons with somata in the antennae of the moth, Manduca sexta, make synapses in the antennal lobes of the brain. These lobes develop during metamorphosis of the pupa to the adult while the antennae themselves develop and send presumably cholinergic sensory fibers into the lobes. Levels of acetylcholine, choline acetyltransferase, and acetylcholinesterase rise dramatically in the lobes as sensory axons grow from the antennae to the lobes through the antennal nerves. An [125I]alpha-bungarotoxin-binding activity, which may represent ACh-receptors, develops in the lobes with a time course different from that of the other cholinergic components, rising gradually throughout metamorphosis. This activity is specific to nervous tissue and is blocked by cholinergic agents (carbamylcholine, atropine, curare, and nicotine). Levels of acetylcholine, choline acetyltransferase, and acetylcholinesterase, but not of toxin-binding activity, are greatly reduced in lobes deafferented by amputation of developing antennae.