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Hormone treatment facilitates penile erection in castrated rats after sleep deprivation and cocaine.
Andersen ML, Bignotto M, Tufik S.
Universidade Federal de Sao Paulo, Sao Paulo, Brazil.
J Neuroendocrinol (2004) Feb;16(2):154-9.[link]

...we conducted two experiments to determine whether sleep deprivation and cocaine administration could also induce spontaneous penile erection in castrated rats ...

...these data show that progesterone treatment facilitates penile erection in sleep deprived-cocaine castrated rats."