Table 1.

Serum testosterone levels in gonadally intact and castrated male guinea pigs measured 2 or 24 h following injection with either TP (400 μg sc) or its sesame oil vehicle (0.1 ml sc)

Experimental Group	Testosterone, pg/ml
Gonadally intact	3,858.0 ± 724.6
Orch/vehicle (2 h)	365.0 ± 27.6
Orch/TP (2 h)	3,067.5 ± 329.0*
Orch/vehicle (24 h)	387.7 ± 81.4
Orch/TP (24 h)	1,085.3 ± 179.1*

Values are means ± SE of serum testosterone concentrations; n = 4–25. Orch, castrated; TP, testosterone propionate.

^*Values from TP-treated Orch animals that are significantly different (1-way ANOVA/least significant difference, P < 0.05) from those from vehicle-treated controls.