This study is a little closer to the origin of the statement about dopamine.
Animal studies suggest that bremelanotide may affect female sexual desire by activating presynaptic [melanocortin receptor subtype 4] on neurons in the [medial preoptic area] of the hypothalamus, leading to increased release of [dopamine], an excitatory neurotransmitter that increases sexual desire.
I find selegiline and PT-141 to be quite dissimilar, even if both have some influence on dopaminergic activity. PT-141 did nothing for me but cause sleep-disrupting nocturnal erections. The intensity of this effect had me worrying about unintended side effects. Selegiline seems more controllable. It reduces my prolactin, while potentially improving mood, libido and sexual function. Animal studies suggest anti-aging properties.