Table 1.

Influence of morphine exposure for various time periods after pellet implantation on the ratio of hypothermic and analgesic responses to morphine in vivo, maximum contractions to nicotine and inhibition of neurogenic twitches by DAMGO and 2-CADO of LM/MP preparations in vitro.

Response measured	Days after pellet implantation
	1 day	4 days	10 days	14 days
IN VIVO RESPONSES: RATIO OF MORPHINE TO PLACEBO TREATED GROUP RESPONSE
Hypothermia AUC	1.13 (4)	0.7 (4)	0.7 (4)	0.82 (4)
Analgesia AUC	1.88* (4)	2.56* (4)	1.75* (4)	1.1 (4)
IN VITRO EXCITATORY RESPONSES: RATIO OF MORPHINE TO PLACEBO TREATED GROUP RESPONSE
Nicotine Maximum	0.74 (4)	1.41* (4)	1.93* (4)	1.31 (4)
IN VITRO INHIBITORY RESPONSES: RATIO OF MORPHINE TO PLACEBO TREATED GROUP RESPONSE
DAMGO IC50 values	2.08 (4)	4.0* (4)	3.3* (4)	2.4 (4)
2-CADO IC50 values	1.7 (4)	3.2* (4)	7.7* (4)	4.1* (4)

Values depict the ratio of morphine to placebo treated group response.

The same animals or preparations obtained from those animals were used in each experiment so sample sizes are identical (n = 4) for each response being evaluated.

Values that are statistically significant (p ≤ 0.05) are indicated by *.