Effects of single and long-term administration of nifedipine on nociception and stereotyped behavior of rats.
In the present investigation, nociception and stereotyped behavior were evaluated in 3-month old male Wistar rats after a single nifedipine dose (2.5 and 5.0 mg/kg, ip, 1 h before testing, 6-7 rats per group for stereotypy studies and 15 animals per group for nociception experiments) or after long-term nifedipine treatment (2.5 mg/kg, ip, twice daily for 30 days, with testing performed 72 or 96 h after the last injection, 7 rats per group for stereotypy studies and 14-16 animals per group for nociception experiments). Stereotypy was induced with 2.5 mg/kg amphetamine, ip, and nociception was measured by the tail-immersion test. Administration of a single nifedipine dose did not modify nociception or amphetamine-induced stereotypy (with a mean +/- SEM tail-withdrawal latency of 4.5 +/- 0.5 s for control, 4.4 +/- 0.3 s for 2.5 mg/kg nifedipine and 4.7 +/- 0.7 s for 5.0 mg/kg nifedipine and with mean +/- SEM sum of stereotypy scores of 32.5 +/- 1.6 for control, 29.1 +/- 1.0 for 2.5 mg/kg nifedipine and 29.1 +/- 1.6 for 5.0 mg/kg nifedipine). Withdrawal from long-term nifedipine treatment did not affect stereotyped behavior (with mean +/- SEM sum of stereotypy scores of 28.7 +/- 1.6 for control and 30.7 +/- 1.3 for nifedipine-treated rats) but significantly increased tail-withdrawal latencies (with a mean +/- SEM tail-withdrawal latency of 4.1 +/- 0.3 s for control and 6.4 +/- 0.6 s for nifedipine-treated rats). Therefore, long-term nifedipine treatment induced plastic modifications in nociception but not in stereotyped behavior.(ABSTRACT TRUNCATED AT 250 WORDS)
Mattia
N F
NF
Departamento de Farmacologia, Escola Paulista de Medicina, São Paulo, Brasil.
Maiolini Júnior
M
M
Conceição
I M
IM
Chang
Y H
YH
Smaili
S
S
Frussa-Filho
R
R
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D008297:Male; D009543:Nifedipine / Q000008:administration & dosage* / Q000494:pharmacology; D010147:Pain Measurement / Q000187:drug effects*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D013239:Stereotyped Behavior / Q000187:drug effects*; D013997:Time Factors
D009543:Nifedipine