Table 1. Effects of treatment with a selective agonist kappa-opioid receptor (U69593) on maternal behavior on day 5 of lactation.

Groups	Latency to sniff the 1st pup (s)	Retrieving 1st pup	Retrieving all pups	Grouping	Crouching	Full maternal behavior
Saline	10 ± 2.8	100	100	100	100	100
U69593 (0.15 mg/kg)	12 ± 3.4	50*	0*	0*	0*	0*

Data are reported as percentage of animals observed showing the listed behaviors during the first 30 min. Latency to sniff the first pup is reported in seconds (s).

^*P < 0.05 compared to the saline group (Fisher test).