Biomedical subjects
Publications and source records attributed to T Palfai.
Reserpine produced amnesia for a one-trial passive avoidance task when given 2, 3, 4, 5 hr before but not when given 1, 8, 12, 24 hr or 30 min before, immediately, 90 min or 2, 4, 5, 6, 8, 9, 12, 24 hr following training. The results were discussed in terms of the reserpine effect on biogenic amines and their possible role in memory formation.
Random bred Swiss mice showed preference for water over 10% ethanol solution when unlimited food was available. When partially food deprived, the preference was reversed in 5 out of 8 animals. About half of the naive mice, however, ingested substantial amounts of this ethanol solution at the very first exposure when partially food deprived for 12 days. It is suggested that while the caloric value of ethanol is reinforcing, food deprivation might make the sensory effects of ethanol also reinforcing.
A discriminated escape training paradigm was used to study the effects of reserpine on learning and memory in mice. Intraperitoneal injection of reserpine before reversal training had no effect on acquisition but did produced a time-and dose-dependent impairment of retention test performance 10 days later. These results suggested that reserpine may have interfered with some aspect of memory storage. Retention impairments observed when a 2.0 mg/kg reserpine injection was given 2 hr before reversal training were not attenuated by readministering the drug before testing, a finding that provides no support for a state-dependency interpretation. Furthermore, animals treated with reserpine exhibited inferior retention of previous training, regardless of the pharmacological state present during that learning. This was interpreted as a drug-induced impairment of memory retrieval. In addition, performance during the initial discriminated escape training session suggested that reserpine may also impair acquisition under some conditions. In the last experiment, it was found that when the catecholamine precursor L-dihydroxyphenylalamine (100 mg/kg) and the indole amine precursor D,L-5-hydroxytryptophan (125 mg/kg) were both given after reserpine treatment, subsequent retention performance was not significantly impaired. The results are discussed in terms of the possible roles of biogenic amines in arousal, learning, and memory.
In this study, the possible role of overt convulsions following pentylenetetrazol (PTZ) in retrograde amnesia was investigated. Following a single passive avoidance conditioning, when overt convulsions were blocked with sodium pentobarbital (Nem), the amnesic effect of pentylenetetrazol was also blocked. Subconvulsive doses of the drug did not produce amnesia. Animals that received a typically convulsive dose of the drug but failed to convulse were not amnesic; only animals with overt convulsions were different from saline controls. The data suggest that overt convulsions may be necessary for the development of pentylenetetrazol-induced retrograde amnesia.
The effects of various dose levels of Metrazol on retention and electrocorticogram (ECoG) were investigated. Mice given a subconvulsive 30 mg/kg or a convulsive 50 mg/kg dose of Metrazol 15 min before reversal training in a discriminated escape learning task showed retention impairment of reversal training retention. Lower dose levels (5 or 10 mg/kg) had no effect. The 30 mg/kg dose produced asymmetrical dissociation. The convulsive dose (50 mg/kg), previously reported to result in symmetrical dissociation, produced ECoG changes that were still evident 15 min following the injection, i.e. at the time when training or testing usually took place. With lower doses (10 or 30 mg/kg), no apparent ECoG effects were observed at this interval. The implications of the findings were discussed with respect to the state-dependent hypothesis.
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The effects of 40 mg/kg Metrazol on a conditioned saccharin aversion produced by LiCl were studied in two experiments. In Experiment 1, it was found that Metrazol administered 10 min before or after LiCl did not impair conditioned aversion to saccharin. In Experiment 2, Metrazol was given 2 min before, 9 or 3 min after the administration of LiCl. Under these conditions, impairment did occur. It was concluded that Metrazol may impair conditioned taste aversion in a time-dependent manner. The present findings are discussed in terms of their relationship to ECS as an interfering agent and retroactive and proactive effects on the CS and/or the UCS.