An acute, non-therapeutic dose of methylphenidate disrupts partner preference in female rats.
The present study was designed to test the effects of an acute, high dose of methylphenidate (MPH; trademarked as Ritalin) on sexual behavior in female Long-Evans rats. In Experiment 1, naturally cycling subjects in estrus were tested for partner preference 20min after receiving an i.p. injection of MPH 10mg/kg (n=8) or saline (n=7). During the partner-preference test, female subjects were given the choice to interact with a sexually active male stimulus or a sexually receptive female stimulus. Physical contact was limited by placing the stimulus animals behind a wire mesh during the no-contact phase of the test, whereas physical contact was not limited during the contact phase. Female subjects that received MPH spent significantly less time with the male stimulus than the saline-treated subjects during both phases (no-contact and contact) of the partner-preference test. This acute dose of MPH did not affect visits to the female stimulus; however, MPH-treated subjects made fewer visits to the male stimulus than the saline-treated subjects during the contact phase of the partner-preference test. Consistent with previous findings, MPH increased line crossings when subjects were tested in an open field immediately after the partner-preference test. In Experiment 2, female subjects were ovariectomized (OVX), primed with estradiol benzoate and progesterone, and tested for partner preference 20min after receiving an injection of MPH 10mg/kg (n=8) or saline (n=8). Similar to the results of Experiment 1, OVX hormone-primed subjects that received MPH spent significantly less time with the male stimulus than the saline-treated subjects during both phases of the partner-preference test. Although MPH-treated subjects were sexually receptive, they displayed fewer proceptive behaviors (i.e., hops and darts) than saline-treated subjects. Two-weeks later, the subjects from Experiment 2 were tested in an open field 20min after receiving an injection of MPH 10mg/kg or saline (counterbalancing previous MPH exposure). Once again MPH increased locomotor activity. In conclusion, the effects of MPH were equally as robust in naturally cycling subjects as in the more commonly used OVX-hormone primed subjects. The results of the present study suggest that an acute, non-therapeutic dose of MPH disrupts approach and interest in a male stimulus during a test of partner preference. This avoidance of the male stimulus may be the result of a decrease in the incentive value of a sexual partner.
Department of Psychology, Southwestern University, Georgetown, TX 78626, USA.
Alexa
A
Gomez
Department of Psychology, Southwestern University, Georgetown, TX 78626, USA.
Alexandra N
AN
Petrucci
Department of Psychology, Francis Marion University, Florence, SC 29506, USA.
Lauren
L
Dance
Department of Psychology, Southwestern University, Georgetown, TX 78626, USA.
Jessica
J
Morales-Valenzuela
Department of Psychology, Southwestern University, Georgetown, TX 78626, USA.
Nicole
N
Gibbs
Department of Psychology, St. Edward's University, Austin, TX 78704, USA.
Cara C
CC
Dahlhausen
Department of Psychology, St. Edward's University, Austin, TX 78704, USA.
Jessica R
JR
Villatoro
Department of Psychology, St. Edward's University, Austin, TX 78704, USA.
Russell F
RF
Frohardt
Department of Psychology, Southwestern University, Georgetown, TX 78626, USA. Electronic address: guarracf@southwestern.edu.
Fay A
FA
Guarraci
D000818:Animals; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D012726:Sexual Behavior, Animal / Q000187:drug effects*
C074283:estradiol 3-benzoate; D008774:Methylphenidate; D011374:Progesterone; D004958:Estradiol
Locomotion; Open field; Proceptive behaviors; Psychomotor stimulants; Ritalin; Sexual behavior; Sexual motivation