Table 8.

Changes in copulatory behavior of sexually potent male rats induced by the D₄ receptor agonists PD 168,077 and ABT-724: comparison with apomorphine.

Treatments	ML	IL	EL	MF	IF	EF	PEI
PD 168,077	==	==	==	↓	==	↑	↓
ABT-724	==	==	==	↓	==	↑	↓
Apomorphine	== *	== *	↓	↓	↓	↑	==

Dopamine receptor agonists were given to male rats ten minutes before the introduction of a sexually receptive female rat into the mating cage and copulatory parameters measured for 60 min. Changes refer to rats treated subcutaneously with saline (controls). ML, IL and EL = mount, intromission and ejaculation latencies (e.g., the time interval between the introduction of the female in the mating arena and the first mount/intromission/ejaculation, respectively); MF and IF = mount and intromission frequencies (e.g., number of mounts/intromissions in the first series of copulatory activity), EF =ejaculation frequency, the number of ejaculation in the entire copulatory test; PEI = post ejaculatory interval, the time interval between the first ejaculation and the first mount of the second series of copulatory activity. == = no effect; ↑ = increase; ↓ = decrease). Experimental details and data are in [70]. * Note that in [70], no significant effect of apomorphine on ML and IL was found against the decrease in both parameters reported by other studies reviewed above [35,36,195]. This discrepancy might be due to differences in the number of rats used in these studies.