GABAergic/glutamatergic-glial/neuronal interaction contributes to rapid adaptation in pacinian corpuscles.
Pacinian corpuscles (PCs) are tactile receptors composed of a nerve ending (neurite) that is encapsulated by layers of lamellar cells. PCs are classified as primary mechanoreceptors because there is no synapse between the transductive membrane and the site of action-potential generation. These touch receptors respond in a rapidly adapting manner to sustained pressure (indentation or displacement), which until now was believed to be attributable solely to the mechanical properties of the capsule. However, evidence of positive immunoreactivity for GABA receptors on the neurite, as well as evidence for gene expression of synaptobrevin in the lamellar cells led to the hypothesis that GABAergic inhibition originating from the lamellar cells is involved in the rapid adaptation process of PCs. Electrophysiological data from isolated PCs demonstrates that, in the presence of either gabazine or picrotoxin (GABA receptor antagonists), many action potentials appear during the static portion of a sustained indentation stimulus (similar to slowly adapting receptors) and that these "static" spikes completely disappear in the presence of GABA. It was consequently hypothesized that glutamate, released by either the neurite itself or the lamellar cells, caused these action potentials. Indeed, the glutamate receptor blocker kynurenate either decreased or totally eliminated the static spikes. Together, these results suggest that GABA, emanating from the modified Schwann cells of the capsule, inhibits glutamatergic excitation during the static portion of sustained pressure, thus forming a "mechanochemical," rather than purely mechanical, rapid adaptation response. This glial-neuronal interaction is a completely novel finding for the PC.
Pawson
Lorraine
L
Institute for Sensory Research, Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, USA.
Prestia
Laura T
LT
Mahoney
Greer K
GK
Güçlü
Burak
B
Cox
Philip J
PJ
Pack
Adam K
AK
D000200:Action Potentials / Q000502:physiology; D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D002415:Cats; D004247:DNA / Q000096:biosynthesis / Q000235:genetics; D017931:DNA Primers; D004594:Electrophysiology; D005260:Female; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000502:physiology*; D007150:Immunohistochemistry; D009457:Neuroglia / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D010141:Pacinian Corpuscles / Q000502:physiology*; D010852:Picrotoxin / Q000494:pharmacology; D011724:Pyridazines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D004247:DNA; D017931:DNA Primers; D018755:GABA Agonists; D018756:GABA Antagonists; D018698:Glutamic Acid; D010852:Picrotoxin; D011724:Pyridazines; D012333:RNA, Messenger; D005680:gamma-Aminobutyric Acid; C049853:gabazine