Hmt. Barros et Ka. Miczek, WITHDRAWAL FROM ORAL COCAINE IN RATS - ULTRASONIC VOCALIZATIONS AND TACTILE STARTLE, Psychopharmacology, 125(4), 1996, pp. 379-384
While anxiety appears to characterize humans who administer high doses
of cocaine or experience withdrawal from cocaine, it is difficult to
capture this aspect of cocaine effects in animals. The present study i
nvestigated if acute or protracted withdrawal from prolonged low-dose
cocaine that is self-administered via the oral route could be detected
in tactile startle and vocal ''distress'' responses of rats. Adult ma
le Long-Evans rats had access to cocaine solution (0.1 mg/ml) either f
or 24 or 4 h/day using the two-bottle choice technique. The amount of
solution consumed from each bottle was measured daily for 30 or 60 day
s. On days 1, 3, 7, 14, 21, 28 of withdrawal, startle and ultrasonic v
ocal responses (USV, 15-35 <Hz) were measured in response to 18 air-pu
ff stimuli (20 psi). Rats drank an average of 5-20 mg/kg per day of th
e cocaine solution. On average, about half of the daily liquid was con
sumed from the cocaine solution-containing bottle. USVs were emitted a
t significantly increased rates on day 3 of withdrawal from 30 or 60 d
ays of cocaine drinking. Startle reactions were slightly, but non-sign
ificantly increased on day 1 of withdrawal. Comparable to withdrawal f
rom ethanol, morphine, and diazepam treatments, withdrawal from oral s
elf-administration of low to moderate doses of cocaine increases the r
ate of ultrasonic vocalizations while increasing minimally the amplitu
de of startle responses to low-intensity tactile stimuli. Nevertheless
, no correlation between the total amount of cocaine self-administered
or the duration of treatment with the intensity of the withdrawal man
ifestations could be detected.