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Outward current produced by somatostatin (SRIF) in rat anterior cingulate pyramidal cells in vitro
Author(s) -
Hicks G A,
Feniuk W,
Humphrey P P A
Publication year - 1998
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0701824
Subject(s) - agonist , endocrinology , medicine , somatostatin , chemistry , anterior cingulate cortex , receptor , somatostatin receptor , cingulate cortex , antagonist , pyramidal cell , biology , neuroscience , central nervous system , hippocampus , cognition
A high density of receptors for somatostatin (SRIF) exists in the anterior cingulate cortex but their function is unknown. Whole‐cell patch clamp recordings were made from visualized deep layer pyramidal cells of the rat anterior cingulate cortex contained in isolated brain slices to investigate the putative effects of SRIF and to identify the receptor subtype(s) involved. SRIF (1–1000 n M ) produced a concentration‐dependent outward current which was associated with an increased membrane conductance, was sensitive to Ba 2+ (300 μ M –1 m M ), and was absent in the presence of a maximal concentration of the GABA B receptor agonist, baclofen (100 μ M ). These observations suggest the outward current was carried by K + ions. SRIF analogues also elicited outward currents with a rank potency order of (EC 50 , n M ): octreotide (1.8)>BIM‐23027 (3.7)>SRIF (20)=L‐362,855 (20). BIM‐23056 was without agonist or antagonist activity. Responses to L‐362,855 were unlike those to the other agonists since they were sustained for the duration of the application. The sst 2 receptor antagonist, L ‐Tyr 8 Cyanamid 154806 (1 μ M ), had no effect alone but partially reversed responses to submaximal concentrations of SRIF (100 n M , 44±6% reversal) and L‐362,855 (100 n M , 70±6% reversal) and fully reversed the response to BIM‐23027 (10 n M ). In contrast, L ‐Tyr 8 Cyanamid 154806 did not antagonize the response to baclofen (10 μ M ). We conclude that SRIF activates a K + conductance in anterior cingulate pyramidal neurones via an action predominantly at sst 2 receptors.