It is still unclear whether Testosterone (T) increases sexual desire through a stimulation of the androgen receptor in relevant brain regions or through its conversion to estrogens. The aim of this study was to clarify the mechanisms of T facilitation of female sexual desire by assessing the effect of a non-aromatizable androgen (Dihydrotestosterone, DHT) in a validated animal model. Ovariectomized (OVX) Long-Evans rats were treated with oil (O) + O, 10 mcg Estradiol Benzoate (EB) + O, 10 mcg EB + 500 mcg Progesterone (P), O + 500 mcg DHT or 10 mcg EB + 500 mcg DHT (n = 12 per group). EB was administered 48 h, while P and DHT 4 h, prior to 4 sexual behavioral testing sessions in bisected unilevel pacing chambers. Appetitive behaviors (the frequencies of hops/darts and solicitations) were considered as the main outcome measure. Sexual receptivity indexes [lordosis magnitude, expressed as lordosis rating (LR), and lordosis quotient (LQ)], rejection responses, as well as mounts, intromissions and ejaculations received from the male were also coded. The probability of transition among sexual behaviors was evaluated by Transition Matrices; T-Pattern analysis was performed to detect hidden repeated temporal behavioral sequences. Preliminary analyses found no statistically significant differences between the O + O and EB + O groups, therefore we excluded the EB + O group from further analyses. Rats treated with EB + DHT displayed significantly more appetitive behaviors compared to negative controls (O + O and O + DHT), whereas no difference was observed between EB + DHT rats and positive controls (EB + P); noteworthy, a higher number of appetitive behaviors was observed in the O + DHT group compared to the O + O group. Furthermore, rats treated with EB + DHT showed significantly higher receptivity measures (LR and LQ) and received more mounts, intromissions and ejaculations compared to negative controls (O + O and O + DHT), to levels equivalent to EB + P. No differences were detected in female-male mounts or rejection responses among the 4 groups. Under a qualitative perspective, full solicitation was found exclusively in T-patterns of the EB + DHT group, which was also the only one to display T-patterns of higher order encompassing appetitive behaviors-only events. In conclusion, the administration of DHT in EB-primed OVX Long-Evans rats enhances sexual behavior measures. Specifically, DHT seems to stimulate sequences of appetitive behaviors separated from copulative/reproductive measures. Our data support an independent role of androgens in the facilitation of female sexual desire.

中文翻译：

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非芳香化雄激素二氢睾酮 (DHT) 促进雌二醇引发的卵巢切除雌性大鼠的性行为

目前尚不清楚睾酮 (T) 是否通过刺激相关大脑区域的雄激素受体或通过其转化为雌激素来增加性欲。本研究的目的是通过评估非芳香化雄激素（双氢睾酮，DHT）在经过验证的动物模型中的作用，阐明 T 促进女性性欲的机制。用油 (O) + O、10 微克苯甲酸雌二醇 (EB) + O、10 微克 EB + 500 微克孕酮 (P)、O + 500 微克 DHT 或 10 微克 EB + 500 治疗去卵巢 (OVX) 长埃文斯大鼠mcg DHT（每组 n = 12）。EB 给药 48 小时，而 P 和 DHT 给药 4 小时，在 4 次性行为测试之前，在对开的单水平起搏室中进行。食欲行为（跳跃/飞镖和招揽的频率）被认为是主要的结果衡量标准。性接受指数[前凸程度，表示为前凸等级（LR）和前凸商数（LQ）]、排斥反应，以及从男性收到的坐骑、插入和射精也被编码。性行为间的转换概率由转换矩阵评估；进行 T 模式分析以检测隐藏的重复时间行为序列。初步分析发现 O + O 组和 EB + O 组之间没有统计学上的显着差异，因此我们将 EB + O 组排除在进一步分析之外。与阴性对照（O + O 和 O + DHT）相比，用 EB + DHT 治疗的大鼠表现出明显更多的食欲行为，而在 EB + DHT 大鼠和阳性对照（EB + P）之间没有观察到差异；值得注意的是，与 O + O 组相比，在 O + DHT 组中观察到更多的食欲行为。此外，与阴性对照（O + O 和 O + DHT）相比，用 EB + DHT 治疗的大鼠表现出显着更高的接受性测量（LR 和 LQ），并且接受了更多的坐骑、插入和射精，达到相当于 EB + P 的水平。 没有差异在 4 组中检测到雌雄坐骑或排斥反应。从定性的角度来看，完全吸引仅在 EB + DHT 组的 T 模式中发现，这也是唯一一个显示包含仅食欲行为事件的高阶 T 模式的模式。总之，在 EB 引发的 OVX Long-Evans 大鼠中施用 DHT 增强了性行为测量。具体来说，DHT 似乎刺激与交配/生殖措施分开的食欲行为序列。我们的数据支持雄激素在促进女性性欲方面的独立作用。