Substance P selectively decreases paired pulse depression in the rat hippocampal slice.
BACKGROUND
Although being widespread in the hippocampus, the role tachykinins play in synaptic transmission is unclear. The effect of substance P on field potentials evoked by stimulation of the Schaffer collateral-commissural fibres and recorded from the CA1 region of the rat hippocampal slice were studied.


RESULTS
Perfusion of substance P (8 microM) had no effect on the fEPSP or population spike. Substance P did however cause a selective reduction in the paired pulse depression of population spikes evoked by paired stimulation at interpulse intervals of 20-80 msec. A comparison of the actions of other tachykinin receptor agonists gave an order of potency of substance P > [beta-Ala8]-neurokinin A (4-10) > senktide. The effect of substance P was reduced by the neurokinin-1 receptor antagonist SR140333, but not by the neurokinin-2 or neurokinin-3 receptor antagonists, MDL 29,913 or [Trp7, beta-Ala8]-neurokinin A (4-10).


CONCLUSIONS
The order of potency of the agonists, and the effects of the antagonists, both indicate that the effect of substance P on paired pulse depression is mediated by neurokinin-1 receptors.
Wease
Kerrie N
KN
Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK. k.wease@abdn.ac.uk
Davies
Stephen N
SN
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D018039:Receptors, Tachykinin / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology; D013373:Substance P / Q000494:pharmacology* / Q000502:physiology*
D018039:Receptors, Tachykinin; D013373:Substance P