Synaptic mechanisms in sympathetic preganglionic neurons

1992 ◽  
Vol 70 (S1) ◽  
pp. S86-S91 ◽  
Author(s):  
N. J. Dun ◽  
S. Y. Wu ◽  
E. Shen ◽  
T. Miyazaki ◽  
S. L. Dun ◽  
...  
Keyword(s):  
Excitatory Amino Acid ◽  
Neonatal Rat ◽  
Excitatory Postsynaptic Potentials ◽  
Sympathetic Preganglionic Neurons ◽  
Postsynaptic Potentials ◽  
Preganglionic Neurons ◽  
Inhibitory Postsynaptic Potentials ◽  
Ventral Roots ◽  
Adult Cat ◽  
Synaptic Mechanisms

Intracellular recordings from sympathetic preganglionic neurons (SPNs) in adult cat and neonatal rat spinal cord slices reveal four types of synaptic potentials, namely, excitatory postsynaptic potentials (EPSPs), inhibitory postsynaptic potentials (IPSPs), and slow EPSPs in both preparations, and a slow IPSP in cat SPNs. Pharmacological studies show that glutamate or a related excitatory amino acid and glycine are the probable mediators of EPSPs and IPSPs. There may be heterogenous mediators of slow EPSPs; substance P, serotonin, norepinephrine, and epinephrine are all probable mediators of slow EPSPs in subpopulations of SPNs. In the case of slow IPSPs, norepinephrine appears to be the likely transmitter. Finally, stimulation of ventral roots elicits a synaptic potential that appears to be caused by glutamate released from afferent fibers in the ventral roots. Our results indicate that a multitude of synaptic mechanisms exist in the rat SPNs by means of which inputs arising from sensory and supraspinal neurons are processed in a timely and orderly manner, thus ensuring highly organized but differentiated outputs to multiple peripheral target cells.Key words: sympathetic preganglionic neurons, excitatory postsynaptic potentials, inhibitory postsynaptic potentials, slow excitatory postsynaptic potentials, glutamate, glycine.

Further identification of multiple responses mediated by dopamine in the CNS of Planorbis corneus

1978 ◽  
Vol 56 (1) ◽  
pp. 7-18 ◽  
Author(s):  
J. F. MacDonald ◽  
M. S. Berry
Keyword(s):  
Neuroleptic Drugs ◽  
Intracellular Recordings ◽  
Excitatory Postsynaptic Potentials ◽  
Multiple Responses ◽  
Gastropod Mollusc ◽  
Postsynaptic Potentials ◽  
Synaptic Potentials ◽  
Inhibitory Postsynaptic Potentials ◽  
Planorbis Corneus ◽  
Synaptic Responses

Intracellular recordings from neurones, receiving monosynaptic contacts from a dopamine-containing (DA-containing) neurone in the central ganglia of the gastropod mollusc Planorbis corneus, revealed that there are at least three DA-mediated responses. These are 'fast' excitatory postsynaptic potentials (EfPSPs) (200 ms), 'slow' excitatory postsynaptic potentials (EsPSPs) (900 ms), and inhibitory postsynaptic potentials (IPSPs) (200–900 ms). Various combinations of these synaptic potentials were recorded from postsynaptic neurones: EsPSPs, EfPEPs, EsEfPSPs, or EfIPSPs. Neurones receiving such connections also responded appropriately to iontophoresized DA with a 'fast' depolarization (EfPSPs), a 'slow' depolarization (EsPSPs), or a hyperpolarization (IPSPs). These responses could be distinguished on the basis of function (excitation or inhibition), duration, rate of desensitization, and sensitivity to apomorphine, D-LSD, and tubocurarine. The neuroleptic drugs (DA antagonists) haloperidol, fluphenazine, and metoclopramide reduced both excitatory and inhibitory DA transmission. This investigation strongly supports the hypothesis that DA is the transmitter mediating multiple synaptic responses in Planorbis.

Potentiation of NMDA Currents by Pituitary Adenylate Cyclase Activating Polypeptide in Neonatal Rat Sympathetic Preganglionic Neurons

1997 ◽  
Vol 78 (2) ◽  
pp. 1175-1179 ◽  
Author(s):  
S. Y. Wu ◽  
N. J. Dun
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Phosphodiesterase Inhibitor ◽  
Neonatal Rat ◽  
Sympathetic Preganglionic Neurons ◽  
Preganglionic Neurons ◽  
Whole Cell Patch Clamp ◽  
Pituitary Adenylate Cyclase ◽  
Inward Currents ◽  
Induced Currents

Wu, S. Y. and N. J. Dun. Potentiation of NMDA currents by pituitary adenylate cyclase activating polypeptide in neonatal rat sympathetic preganglionic neurons. J. Neurophysiol. 78: 1175–1179, 1997. Whole cell patch-clamp recordings were made from sympathetic preganglionic neurons (SPNs) in the intermediolateral cell column of thoracolumbar spinal cord slices of 12- to 16-day-old rats, and the effects of pituitary adenylate cyclase activating polypeptide (PACAP)-38 on N-methyl-d-aspartate (NMDA)- and kainate (KA)-induced inward currents were examined. PACAP, in concentrations (10–30 nM) that caused no significant change of holding currents, reversibly increased NMDA-induced currents but not KA-induced currents. At higher concentrations (>30 nM), the peptide produced a sustained inward current. The potentiating effect of PACAP was nullified by prior incubation of the slices with the adenylate cyclase inhibitor MDL-12,330A (25 μM). Further, superfusing the slices with the membrane-permeable cyclic AMP analogue N6,2′-0-dibutyryladenosine 3′:5′-cyclic monophosphate (100–300 μM) in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (700 μM) increased the NMDA currents. This result suggests that PACAP selectively increases NMDA-receptor-mediated responses in the rat SPNs, probably via a cyclic-AMP-dependent mechanism, providing evidence that the peptide may be involved in synaptic plasticity.

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