Discriminative response control by naloxone in morphine pretreated rats

✍ Scribed by Stephen Miksic; Gary Sherman; Harbans Lal

• Publisher: Springer
• Year: 1981
• Tongue: English
• Weight: 621 KB
• Volume: 72
• Category: Article
• ISSN: 0033-3158
• DOI: 10.1007/bf00431653

✦ Synopsis

In an operant procedure using a lever press response 12 male, hooded rats were trained to discriminate 1.25 mg/kg naloxone from a saline injection. On certain days, according to a counterbalanced training schedule, naloxone was administered 8 h after 40 mg/kg morphine and 10 rain prior to a trial in which food was available on an FRI0 schedule from one of two levers in a dual lever operant chamber. On other days saline was administered 10 rain prior to a trial in which food was made available by pressing the other lever. After criterion performance for acquisition of the discrimination had been reached, tests were carried out to determine its nature. Discrimination of naloxone was dose-dependent and was significantly diminished when naloxone was administered 36 h after morphine. Partial generalization of cyclazocine with naloxone was observed. Spontaneous withdrawal from morphine, tested during trials preceeded by an injection of saline instead of naloxone at various time intervals after morphine, did not generalize with the naloxone discriminative stimulus.