Electrical Stimulation of Guinea Pig Cochlea: Effects on Primary Fibers

Mast cells express the substance P (SP) neurokinin 1 receptor and the calcitonin gene-related peptide (CGRP) receptor in guinea pig and human small intestine. Enzyme-linked immunoassay showed that activation of intramural afferents by antidromic electrical stimulation or by capsaicin released SP and CGRP from human and guinea pig intestinal segments. Electrical stimulation of the afferents evoked slow excitatory postsynaptic potentials (EPSPs) in the enteric nervous system. The slow EPSPs were mediated by tachykinin neurokinin 1 and CGRP receptors. Capsaicin evoked slow EPSP-like responses that were suppressed by antagonists for protease-activated receptor 2. Afferent stimulation evoked slow EPSP-like excitation that was suppressed by mast cell-stabilizing drugs. Histamine and mast cell protease II were released by 1) exposure to SP or CGRP, 2) capsaicin, 3) compound 48/80, 4) elevation of mast cell Ca2+ by ionophore A23187, and 5) antidromic electrical stimulation of afferents. The mast cell stabilizers cromolyn and doxantrazole suppressed release of protease II and histamine when evoked by SP, CGRP, capsaicin, A23187, electrical stimulation of afferents, or compound 48/80. Neural blockade by tetrodotoxin prevented mast cell protease II release in response to antidromic electrical stimulation of mesenteric afferents. The results support a hypothesis that afferent innervation of enteric mast cells releases histamine and mast cell protease II, both of which are known to act in a diffuse paracrine manner to influence the behavior of enteric nervous system neurons and to elevate the sensitivity of spinal afferent terminals.

Download Full-text

Effectiveness of Middle Ear Electrical Stimulation for Activating Central Auditory Pathways

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348948209100312 ◽

1982 ◽

Vol 91 (3) ◽

pp. 285-291 ◽

Cited By ~ 15

Author(s):

Ben M. Clopton ◽

Martha M. Bosma

Keyword(s):

Electrical Stimulation ◽

Guinea Pig ◽

Middle Ear ◽

Spiral Ganglion ◽

Auditory Pathways ◽

Low Frequencies ◽

Central Auditory Pathways ◽

Stimulation Of

Electrical stimulation of afferent auditory elements through electrodes placed in the middle ear was investigated in acute guinea pig preparations. Thresholds for auditory activation were current-dependent for low frequencies (<1 kHz) and charge-dependent at higher frequencies. Threshold currents were 3–5 times those for intracochlear stimulation. Mechanisms of activation were examined with removal of cochlear fluids and injection of neomycin, Xylocaine, saline, and artificial perilymph with different calcium concentrations. Neurons of the spiral ganglion are indicated as mediators of this stimulation.

Download Full-text

Diverse responses of single auditory afferent fibres to electrical stimulation of the inferior colliculus in guinea-pig

Experimental Brain Research ◽

10.1007/s00221-004-2003-1 ◽

2004 ◽

Vol 160 (2) ◽

pp. 235-244 ◽

Cited By ~ 17

Author(s):

W. H. A. M. Mulders ◽

D. Robertson

Keyword(s):

Electrical Stimulation ◽

Guinea Pig ◽

Inferior Colliculus ◽

Stimulation Of

Download Full-text

Use of NK1 receptor antagonists in the exploration of physiological functions of substance P and neurokinin A

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y95-124 ◽

1995 ◽

Vol 73 (7) ◽

pp. 903-907 ◽

Cited By ~ 6

Author(s):

M. Qtsuka ◽

K. Yoshioka ◽

M. Yanagisawa ◽

H. Suzuki ◽

F.-Y. Zhao ◽

...

Keyword(s):

Spinal Cord ◽

Electrical Stimulation ◽

Substance P ◽

Guinea Pig ◽

Saphenous Nerve ◽

Ventral Root ◽

Neonatal Rat ◽

Neurokinin A ◽

Receptor Antagonists ◽

Stimulation Of

Tachykinin NK1 receptor antagonists were used to explore the physiological functions of substance P (SP) and neurokinin A (NKA). Pharmacological profiles of three NK1 receptor antagonists, GR71251, GR82334, and RP 67580, were examined in the isolated spinal cord preparation of the neonatal rat. These tachykinin receptor antagonists exhibited considerable specificities and antagonized the actions of both SP and NKA to induce the depolarization of ventral roots. Electrical stimulation of the saphenous nerve with C-fiber strength evoked a depolarization lasting about 30 s of the ipsilateral L3 ventral root. This response, which is referred to as saphenous-nerve-evoked slow ventral root potential (VRP), was depressed by these NK1 receptor antagonists. In contrast, the saphenous-nerve-evoked slow VRP was potentiated by application of a mixture of peptidase inhibitors, including thiorphan, actinonin, and captopril in the presence of naloxone, but not after further addition of GR71251. Likewise, in the isolated coeliac ganglion of the guinea pig, electrical stimulation of the mesenteric nerves evoked in some ganglionic cells slow excitatory postsynaptic potentials (EPSPs), which were depressed by GR71251 and potentiated by peptidase inhibitors. These results further support the notion that SP and NKA serve as neurotransmitters producing slow EPSPs in the neonatal rat spinal cord and guinea pig prevertebral ganglia.Key words: substance P, neurokinin A, neurotransmitter, tachykinin antagonist, spinal cord.

Download Full-text