Materials and methods control and kindled group.
A .S. Bazyan et al. Brain Research 888 2001 212 –220
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mechanisms in kindling seizures retrieval after very long 2.2.1. Three to four-months-old rats
times of acute administration of subconvulsive doses of The first series comprised the rats, in which a convulsive
convulsants. dose of PTZ 50 mg kg resulted in seizure scores of 4–5
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Previously, we have found [29] that changes in [ H]- points. They were decapitated 60 min 30 min after the
diazepam binding are maximal in the cerebellar cortex, termination of seizures or 48 h later and on day 7 after the
rather than in the neocortex, of the kindled rats. It has been injection n536, including control rats.
shown that 81 of the total BDZ receptors in cerebellar The second series comprised the rats, in which a
cortex contain high-affinity sites for PTZ [6]. In the subconvulsive dose of PTZ 20 mg kg elicited kindled
forebrain, only 34 of the total BDZ receptor population seizures scoring 4–5 points, followed by decapitation 60
bear high-affinity sites for PTZ. At the same time, the min 30 min after the termination of seizures or 48 h later
cerebellar cortex actualizes movement control. The cere- and on day 7 after the last injection n548, including
bellar cortex exerts its influence by inhibiting and dis- control rats.
inhibiting motor control action, in the premotor networks The third series comprised the rats endogenously sensi-
of the brainstem, sensomotor cortex, and spinal cord [19– tive and insensitive to the convulsant. One group of
22,24]. On the other hand, the cerebellum and its associ- animals n525 was treated with 25 mg kg PTZ and the
ated brainstem circuitry does appear to be essential neces- second group with 30 mg kg n525. Then, the rats were
sary and sufficient for learning and memory of the selected according to their sensitivity: the first subgroup
conditioned response [32,33,62–64,68]. This indicates that n56 with seizures 2 points provoked by 25 mg kg
long-term reactions are inherent to the neurons of cere- PTZ; and the second subgroup n56 with no seizures
bellum; for instance, in long-term depression [23]. provoked by 30 mg kg PTZ. Both groups were decapitated
The goal of the present investigation was to study on day 7 after the injection.
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long-term characteristics of [ H]-diazepam binding in cerebellar cortex after an acute injection of PTZ in
2.2.2. After 6 months about 10-months-old rats convulsive doses, after kindling development; peculiarities
For the period of 6 months both the control and kindled
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of the retrieval of kindled seizures and of [ H]-diazepam rats were kept in the breeding facility. Their weights at the
binding 6 months after the termination of kindling, follow- second stage of experiments reached 360–450 g.
ing a challenge with a subconvulsive dose of PTZ. At the second stage, the persistence of kindling was
studied. Two control groups and two groups of kindled rats were treated with 20 and 30 mg kg PTZ n525 in each