Fig 1.

Schematic of the experimental design. All hamsters were cannulated, and half were ovariectomized (OVX) while the other half remained intact. Half of the animals in each of these groups were then implanted with osmotic pumps that infused either saline, or GnIH, into the lateral ventricle for the duration of the experiment. OVX females were then injected with estradiol (E2) and progesterone (P4) on a four day schedule that maintains the expression of reproductive behaviors. Females were tested for sexual motivation, vaginal scent marking, and lordosis. Finally, on day 15, females received 5 intromissions in a mating test, and were perfused 60 minutes later.