Open AccessSTUDIES OF CONNECTIONS BETWEEN LOCUS COERULEUS AND CEREBRAL CORTEX
Author(s) -
James H. Austin,
Shuji Takaori
Publication year - 1976
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.26.145
Subject(s) - locus coeruleus , stimulation , chemistry , inhibitory postsynaptic potential , propranolol , medicine , cerebral cortex , endocrinology , neuroscience , biology , central nervous system
Small tracking electrodes were inserted into the cat locus coeruleus (LC), and the effects of LC stimulation were determined on the transcallosal potential (TCP) evoked in cerebral cortex on the same side. LC stimulation at 8 volts inhibited TCP amplitude an average of 11%. Rostral LC placements appeared most effective. LC stimulation, without drugs, did not affect the peak latency of the TCP. dl-Propranolol and FLA-63 blocked LC inhibition of the TCP and also increased TCP amplitude per se. Propranolol first increased the latency of the TCP during LC stimulation, then decreased decreased it, while also prolonging the latency of the TCP per se. Phenoxybenzamine increased rather than blocked the LC inhibitory effect and also increased TCP amplitude. dl-Erythro-DOPS slightly increased the LC inhibitory effect, and substantially increased TCP amplitude. dl-Threo-DOPS produced somnolence in unanesthetized animals, led to increased norepinephrine levels in cortex and brain stem, and caused cortical potentials to fluctuate widely. A midbrain lesion of the dorsal ascending NE bundle blocked the LC inhibitory effect. LC stimulation alone, or in combination with evoked cortical stimulation, did not affect the interstimulus electrocorticogram or the heart rate. In the transcallosal system of the cortical regions studied, the LC appears to play mainly an inhibitory role.