Purpose:
@EN To test if p-chlorophenylalanine(PCPA) induced decrease of immobility time during forced swimming test in rats in an epiphenomenon related with PCPA-induced changes in anxiety level or learning ability.
@ES Method:
@EN 22 male rats(Sprague Dawley, weighting 180-280gm) were randomly assigned to PCPA or control group and treated with 300mg/kg of PCPA or saline i. p. at -72, -48, and -24 hrs, Number of segment(ACT0) entered with 4 limbs on the open
field(L100×W100×H40cm, 25 segments), time(ANX0, sec) spent on the open arm(L110×W10cm, 50cm from the ground) in the elevated plus maze, and step-through latency(STL0, cut-off time: 300sec) in the shuttle box(L76.2×W34.3×H50.8cm, 7.5w
electric
bulb
in the light chamber, 0.5mA for 3 sec in the dark chamber) were measured consequently at 24hrs after the last injection of PCPA saline. After 20min of rest, animals were forced to swim for 15 min(cylinder:φ18×H40cm: water: H15cm, 25℃). On the
next
day, the second trial of open field test(ACT1), elevated plus maze test(ANX1), passive avoidance learning test(STL1), and measurement of total immobility time(IT, sec) during the 5min of forced swim were done in the same manner as the first trial
except
that electrical shock was not given to the animals in the passive avoidance learning test and duration of forced swimming was shortened from 15min to 5min. To evaluate longterm effect of PCPA on maintenance of memory, measurement of stepthrough
latency
was repeated 7 days after the first trial(STL7).
@ES Result:
@EN 1) ACT1 was significantly decreased in the pooled sample, but the effect of PCPA on the general motor activity was not significant. 2) PCPA significantly prolonged the time spent on the open arms in the elevated plus maze test. 3) Comparing
to
STL0,
STL1 was significantly prolonged in both groups. PCPA did not affect STL0 or STL1. STL7 was significantly prolonged in the control group, but not in the PCPA group. 4) PCPA shortened IT significantly.
@ES Conclusion:
@EN PCPA-induced decrease of immobility time during the forced swimming test in rats seems to be related with disinhibition of stress-related behavioral suppression. PCPA does not affect acquisition and short-term maintenance of passive avoidance
learning, but necessity of further studies about its effect on long-term maintenance memory is raised.
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