Primed-burst potentiation occludes the potentiation phenomenon and enhances the epileptiform activity induced by transient pentylenetetrazol in the CA1 region of rat hippocampal slices.
The effects of pentylenetetrazol (PTZ) following induction of long-term potentiation (LTP) on population spikes in CA1 of hippocampal slices were investigated. Population spikes were evoked by activation of Schaffer collaterals with a range of stimulation intensities. LTP was induced using &theta;-pattern primed burst tetanic stimulation. Changes in the population spike amplitude and number of population spikes were used as indices to quantify the effects of PTZ exposure in the control (non-tetanized) and LTP (tetanized) conditions. The amplitude of population spike was measured 20 min before, during 20 min chemical application (3 mM), and also after 30 or 60 min washout period. In non-tetanized slices, the population spike input-output curve was significantly increased 20 min after PTZ application and persisted at least for 60 min. Multiple population spikes or after potentials also appeared, but did not persist. When PTZ was applied on tetanized slices, 60 min after LTP induction, the amplitude increase produced by PTZ was smaller than the increase seen in the control condition. Also LTP induction preceding PTZ exposure increased the number of population spikes evoked by stimulation of Schaffer collaterals. It is concluded that a transient PTZ application produces a long-lasting increase in population spike amplitude. Primed burst LTP occludes PTZ-induced potentiation while also increasing the epileptogenic effect of PTZ.
Omrani
A
A
Department of Physiology, School of Medical Sciences, Tarbiat Modarres University, P.O. Box: 14115-111, Tehran, Iran.
Fathollahi
Y
Y
Mohajerani
H R
HR
Semnanian
S
S
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D004827:Epilepsy / Q000139:chemically induced* / Q000503:physiopathology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D008297:Male; D010433:Pentylenetetrazole / Q000494:pharmacology; D017966:Pyramidal Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D010433:Pentylenetetrazole