The parasympathetic cardiac ganglion of Necturus maculosus (mudpuppy) will be used to investigate the histochemical organization and synaptic integration occurring in a vertebrate cardiac ganglion. The mudpuppy cardiac ganglion contains two neuron types: postganglionic cells and intrinsic SIF cells. These two cell types can be identified in living preparations providing a unique opportunity to analyze the role of SIF cells within autonomic ganglia. The morphological and physiological basis for the effects of acetylcholine, catecholamine, serotonin (5-HT) and substance P on postganglionic neurons will be studied. The following specific questions will be addressed: 1) Identify the chemical nature of the synaptic profiles on postganglionic neurons. In preliminary studies, fibers and cells were found containing serotonin, catecholamines, and a substance P-like peptide in the mudpuppy cardiac ganglion. The synaptology in the ganglion of terminals immunolabeled for these substances will be determined using electron microscopy. 2) Determine the influence of substance P, 5-HT, and catecholamines on the membrane properties of postganglionic neurons and on synaptic transmission between the preganglionic fibers and postganglionic cells. Intracellular recording techniques and voltage-clamp procedures will be used to investigate the action of these transmitter substances on synaptic transmission between the preganglionic and postganglionic cells as well as on the conductance properties of individual postganglionic neurons. 3) Correlate electrophysiological response to applied neuroactive substances with synaptic terminal type and distribution to individual ganglion neurons. Following intracellular recording, neurons will be injected with HRP or lucifer yellow in order to understand the relationship of structure and function in synaptic integration. 4) Determine the effect(s) of SIF cell activity on the properties of adjacent postganglionic neurons. Individual SIF cells will be stimulated intracellularly to determine the influence of SIF cell activation on adjacent parasympathetic neurons and/or on transmission between preganglionic fibers and postganglionic cells. The results of this project should provide significant information about: a) the mechanism(s) of interaction of neurotransmitters on an identified postsynaptic cell, b) the role(s) of SIF cells in autonomic ganglia, and c) the type(s) of integration occurring in vertebrate cardiac ganglia for local reflex control of cadiac function.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS023978-01
Application #
3408163
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1986-09-01
Project End
1989-08-31
Budget Start
1986-09-01
Budget End
1987-08-31
Support Year
1
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of Vermont & St Agric College
Department
Type
Schools of Medicine
DUNS #
066811191
City
Burlington
State
VT
Country
United States
Zip Code
05405
Braas, K M; Rossignol, T M; Girard, B M et al. (2004) Pituitary adenylate cyclase activating polypeptide (PACAP) decreases neuronal somatostatin immunoreactivity in cultured guinea-pig parasympathetic cardiac ganglia. Neuroscience 126:335-46
Parsons, Rodney L; Barstow, Karen L; Scornik, Fabiana S (2002) Spontaneous miniature hyperpolarizations affect threshold for action potential generation in mudpuppy cardiac neurons. J Neurophysiol 88:1119-27
Calupca, Michelle A; Locknar, Sarah A; Parsons, Rodney L (2002) TRPC6 immunoreactivity is colocalized with neuronal nitric oxide synthase in extrinsic fibers innervating guinea pig intrinsic cardiac ganglia. J Comp Neurol 450:283-91
Scornik, F S; Merriam, L A; Parsons, R L (2001) Number of K(Ca) channels underlying spontaneous miniature outward currents (SMOCs) in mudpuppy cardiac neurons. J Neurophysiol 85:54-60
Calupca, M A; Locknar, S A; Zhang, L et al. (2001) Distribution of cocaine- and amphetamine-regulated transcript peptide in the guinea pig intrinsic cardiac nervous system and colocalization with neuropeptides or transmitter synthetic enzymes. J Comp Neurol 439:73-86
Calupca, M A; Prior, C; Merriam, L A et al. (2001) Presynaptic function is altered in snake K+-depolarized motor nerve terminals containing compromised mitochondria. J Physiol 532:217-27
May, V; Beaudet, M M; Parsons, R L et al. (2000) PACAP modulates rat sympathetic neuron depolarization through IP3. Ann N Y Acad Sci 921:186-94
Beaudet, M M; Parsons, R L; Braas, K M et al. (2000) Mechanisms mediating pituitary adenylate cyclase-activating polypeptide depolarization of rat sympathetic neurons. J Neurosci 20:7353-61
Calupca, M A; Vizzard, M A; Parsons, R L (2000) Origin of neuronal nitric oxide synthase (NOS)-immunoreactive fibers in guinea pig parasympathetic cardiac ganglia. J Comp Neurol 426:493-504
Parsons, R L; Rossignol, T M; Calupca, M A et al. (2000) PACAP peptides modulate guinea pig cardiac neuron membrane excitability and neuropeptide expression. Ann N Y Acad Sci 921:202-10

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