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Rat Pineal Exhibits Two Electrophysiological Patterns of Response to Microiontophoretic Norepinephrine Application
Author(s) -
ReyesVazquez C.,
PrietoGomez B.,
Aldes L. D.,
Dafny N.
Publication year - 1986
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1986.tb00744.x
Subject(s) - stimulation , norepinephrine , electrophysiology , propranolol , superior cervical ganglion , chemistry , medicine , endocrinology , anesthesia , dopamine
The spontaneous activity of 117 pineal units was recorded in urethane‐anesthetized rats. The pineal units exhibited a wide range of firing rates of which 50% were on average slower than 14 spikes per second. Superior cervical ganglion (SCG) stimulation was studied in 76 pineal units; this stimulation caused excitation in 55% of the units. Microiontophoretic application of norepinephrine (NE) induced changes of firing rates in 61% of the pineal units tested. Two patterns of activity following NE microiontophoresis was observed: increase in firing rate (64%) and decrease in firing rate (36%). NE‐induced excitation was observed only in those units excited by SCG stimulation. When NE and SCG stimulation were applied together, partial summation of the excitation induced by each one alone was observed. None of the units in which NE depressed the firing rate responded to SCG stimulation. Local application of propranolol blocked the excitation initiated by SCG stimulation as well as the excitation and the depression induced by NE microiontophoresis.