Biomaterial Database

Inhibitory innervation of a lobster muscle. 1990

J P Walrond, and T J Wiens, and C K Govind

Department of Anatomy and Neurobiology, Colorado State University, Fort Collins 80523.

Inhibitory neuromuscular synapses formed by the common inhibitor (CI) neuron on the distal accessory flexor muscle (DAFM) in the lobster, Homarus americanus, were studied with electrophysiological and electron-microscopic (thin-section and freeze-fracture) techniques. Postsynaptic inhibition as indicated by inhibitory junctional potentials was several-fold stronger on distal compared to proximal muscle fibers. This difference correlated with the results of serial thin-section studies, which showed more inhibitory synapses on distal fibers than on their proximal counterparts. Effects of postsynaptic inhibition on excitatory junctional potentials via current shunting had a morphological correlate in the spatial relationship between inhibitory and excitatory synapses on the distal fibers. Inhibitory synapses were larger than their excitatory counterparts and had fewer glial processes. In freeze-fracture views, inhibitory synapses did not appear as raised plateaus in the P-face as do excitatory synapses, and their active zones were more widely scattered. The intramembrane particles in the inhibitory postsynaptic membrane - representing neurotransmitter receptors - are arranged in parallel rows in the sarcolemmal P-face and have complementary furrows in the sarcolemmal E-face. Altogether, our findings help to describe a population of inhibitory neuromuscular synapses formed by the CI neuron in lobster muscle.

UI	MeSH Term	Description	Entries
D008121	Nephropidae	Family of large marine CRUSTACEA, in the order DECAPODA. These are called clawed lobsters because they bear pincers on the first three pairs of legs. The American lobster and Cape lobster in the genus Homarus are commonly used for food.	Clawed Lobsters,Homaridae,Homarus,Lobsters, Clawed,Clawed Lobster,Lobster, Clawed
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009433	Neural Inhibition	The function of opposing or restraining the excitation of neurons or their target excitable cells.	Inhibition, Neural
D009469	Neuromuscular Junction	The synapse between a neuron and a muscle.	Myoneural Junction,Nerve-Muscle Preparation,Junction, Myoneural,Junction, Neuromuscular,Junctions, Myoneural,Junctions, Neuromuscular,Myoneural Junctions,Nerve Muscle Preparation,Nerve-Muscle Preparations,Neuromuscular Junctions,Preparation, Nerve-Muscle,Preparations, Nerve-Muscle
D005614	Freeze Fracturing	Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.	Fracturing, Freeze,Fracturings, Freeze,Freeze Fracturings
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia