Electrical kindling of the hippocampus is associated with functional activation of neuropeptide Y-containing neurons.
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 Ca2+ but was reduced by 38 +/- 3.6% (P < 0.05) during 20 min incubation with 5 microM 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 Ca2+. 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.(ABSTRACT TRUNCATED AT 250 WORDS)
Rizzi
M
M
Laboratory of Neuropharmacology, Mario Negri Institute for Pharmacological Research, Milano, Italy.
Monno
A
A
Samanin
R
R
Sperk
G
G
Vezzani
A
A
D000704:Analysis of Variance; D000818:Animals; D004558:Electric Stimulation; D004569:Electroencephalography; D007839:Functional Laterality; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D007696:Kindling, Neurologic; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009478:Neuropeptide Y / Q000032:analysis / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013779:Tetrodotoxin / Q000494:pharmacology
D009478:Neuropeptide Y; D013779:Tetrodotoxin; D011189:Potassium Chloride