This project seeks to specify how ultradian, circadian and seasonal rhythms of androgen availability influence the development and subsequent maintenance of mammalian reproductive structures and behavior. The model species is the Siberian hamster, Phodopus sungorus sungorus. The number and duration of daily testosterone pulses necessary to induce and maintain sexual behavior and structure in male mammals is unknown. Nor do we understand how environmental factors present at different seasons impact on development of reproductive structures. To correct these deficiencies we aim to 1) determine the minimum daily durations of androgen treatments that support mating behavior in males and the manner in which hormone pulses synergize to control penile development, 2) establish the different androgen requirements for initial induction versus subsequent maintenance of sex behavior, 3) assess the relative contributions of local versus systemic actions of androgens on penile growth, 4) specify the neural circuit that mediates pulsatile effects of steroids on sex behavior and 5) determine whether effects of testosterone are mediated by androgen and/or estrogen receptors. In establishing the minimal number, lowest dose, and optimal spacing of daily androgen treatments necessary for normal reproductive development, the present work should lead to new insights and guidelines for treatment of children with insufficient phallic development, as well as treatment of adult hypogonadal men. This line of research should promote development of effective physiological interventions that will minimize undesirable side-effects associated with current pharmacological treatments for human disorders of androgen secretion.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Research Project (R01)
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Special Emphasis Panel (ZRG1-IFCN-2 (01))
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Lamar, Charisee A
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University of California Berkeley
Schools of Arts and Sciences
United States
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Piekarski, David J; Place, Ned J; Zucker, Irving (2010) Facilitation of male sexual behavior in Syrian hamsters by the combined action of dihydrotestosterone and testosterone. PLoS One 5:e12749
Piekarski, David J; Routman, David M; Schoomer, Elanor E et al. (2009) Infrequent low dose testosterone treatment maintains male sexual behavior in Syrian hamsters. Horm Behav 55:182-9
Park, Jin Ho; Paul, Matthew J; Butler, Matthew P et al. (2007) Short duration testosterone infusions maintain male sex behavior in Syrian hamsters. Horm Behav 52:169-76
Costantini, Ruth M; Park, Jin Ho; Beery, Annaliese K et al. (2007) Post-castration retention of reproductive behavior and olfactory preferences in male Siberian hamsters: role of prior experience. Horm Behav 51:149-55
Beery, Annaliese K; Trumbull, Justin J; Tsao, Jyeming M et al. (2007) Sex differences in the onset of seasonal reproductive quiescence in hamsters. Proc Biol Sci 274:281-6
Park, Jin Ho; Takasu, Nana; Alvarez, Maria I et al. (2004) Long-term persistence of male copulatory behavior in castrated and photo-inhibited Siberian hamsters. Horm Behav 45:214-21