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Electrical Kindling of the Hippocampus is Associated with Functional Activation of Neuropeptide Y‐containing Neurons
Author(s) -
Rizzi M.,
Monno A.,
Samanin R.,
Sperk G.,
Vezzani A.
Publication year - 1993
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1993.tb00222.x
Subject(s) - kindling , dentate gyrus , hippocampus , neuropeptide y receptor , endocrinology , medicine , hippocampal formation , chemistry , stimulation , tetrodotoxin , neuropeptide , receptor
The release of neuropeptide Y (NPY) was measured from hippocampal slices of rats at stage 2 (preconvulsive stage) and stage 5 (full seizure expression) of electrical kindling of the dorsal hippocampus (upper blade of the dentate gyrus). Spontaneous release in naive rats (9.0 ± 0.8 fmol/ml every 10 min) was independent of external Ca 2+ but was reduced by 38 ± 3.6% ( P < 0.05) during 20 min incubation with 5μM tetrodotoxin. Spontaneous efflux in naive rats did not differ from that in shams (implanted with electrodes but not stimulated) or in rats kindled to stage 2 and stage 5. Twenty‐five, 50 and 100 mM KCl induced a concentration‐dependent release of NPY ( P < 0.05 and P < 0.01 at 25 and 50–100 mM respectively) from slices of shams. The effect of 100 mM KCl was reduced by 94 ± 1% ( P < 0.01) in the absence of Ca 2+ . Two days after the last stage 2 stimulation and 1 week after the last stage 5 seizure, NPY release was significantly larger than in shams at all KCl concentrations in the stimulated and contralateral hippocampus ( P < 0.05 and P < 0.01). Forty‐eight hours after one single after‐discharge and 1 month after the last stage 5 seizure, 50 mM KCl induced a significantly larger release of NPY in the stimulated and contralateral hippocampus ( P < 0.01 and P < 0.05), although the effect was less than during kindling. The tissue concentration of NPY increased significantly in both hippocampi at stage 2 and 1 week after stage 5 (2.6 times on average, P < 0.01) but no significant differences were found 1 month after stage 5. The present results provide the first evidence of enhanced neuronal release of NPY during kindling, suggesting that this neuropeptide may have a potential role in epileptogenesis.