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Bombesin excites a subpopulation of 5‐hydroxytryptamine‐sensitive neurones in the rat dorsal raphe nucleus in vitro.
Author(s) -
Pinnock R D,
Woodruff G N
Publication year - 1991
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1991.sp018695
Subject(s) - dorsal raphe nucleus , serotonergic cell groups , bombesin , raphe nuclei , dorsum , nucleus , neuroscience , in vitro , raphe , serotonin , chemistry , biology , anatomy , medicine , neuropeptide , receptor , serotonergic , biochemistry
1. The effects on dorsal raphe neurones of the peptides bombesin, gastrin‐releasing peptide and neuromedin B were studied using intracellular recording techniques from slices of rat brain maintained in vitro. The peptides were added to the solutions perfusing the slices. 2. The peptides bombesin, gastrin‐releasing peptide and neuromedin B depolarized neurones in the dorsal raphe nucleus. The same neurones were depolarized by phenylephrine and hyperpolarized by 5‐hydroxytryptamine (5‐HT) but were insensitive to sulphated cholecystokinin octapeptide (CCK). 3. The responses to the peptides were not blocked by CCKA, CCKB and alpha 1‐adrenoreceptor antagonists. 4. The response to the peptides persisted in the presence of tetrodotoxin (TTX) and low‐calcium, high‐magnesium‐containing artificial cerebrospinal fluid (ACSF). 5. Under voltage clamp conditions the peptides caused a decrease in membrane conductance accompanied by an inward current. The reversal potential for the event was the same as that for 5‐HT. 6. The results of the present study demonstrate that bombesin and the structurally related peptides gastrin‐releasing peptide (GRP) and neuromedin B depolarized a subpopulation of raphe 5‐HT neurones by acting on a postsynaptically located receptor linked to potassium channels.