Steroids 69 (2004) 687–696 Non-invasive repeated measurement of urinary progesterone, 17-estradiol, and testosterone in developing, cycling, pregnant, and postpartum female mice Denys deCatanzaro a,∗ , Cameron Muir b,c , Elliott A. Beaton a , Michelle Jetha a a Department of Psychology, McMaster University, Hamilton, Ont., Canada L8S 4K1 b Department of Immunology, CIDtech Research, Cambridge, Ont., Canada N1R 6T5 c Brock University, St. Catharines, Ont., Canada L2S 3A1 Received 26 January 2004; received in revised form 13 July 2004; accepted 20 July 2004 Available online 11 September 2004 Abstract Excretory samples from adult female mice were collected non-invasively during development, estrous cycling, pregnancy, and postpartum. In initial studies, urinary measures were statistically more dynamic over days than were fecal measures; thus subsequent studies focused on urine. Higher 17-estradiol levels were present in isolated females than in those exposed to males. In cycling females, urinary 17-estradiol was more variable than were measures of testosterone or progesterone, showing peaks with an approximate 5-day periodicity. When urinary estradiol and progesterone were monitored in conjunction with vaginal smear cell counts, patterns were idiosyncratic; most females showed distinct peaks in urinary steroids, not in clear synchrony with vaginal cell cornification. Levels of progesterone rose markedly during the first 10 days of pregnancy, then declined before birth. Estradiol showed a substantial peak on days 7–8 of gestation in all females measured. Urinary testosterone was not dynamic during pregnancy, but rose in immediate prenatal and postpartum measures. During post-weaning, pre-pubertal development, urinary levels of progesterone remained constant but levels of estradiol rose substantially over time. © 2004 Elsevier Inc. All rights reserved. Keywords: Estradiol; Progesterone; Mice; Pregnancy; Urine; Non-invasive 1. Introduction In small species, measurement of steroid dynamics in blood can require invasive techniques that prevent repeated measures, given the likelihood that steroids will be sensitive to human handling and blood loss. Thus, characterization of steroids in blood over time and during development requires cross-sectional multi-subject designs, which may obscure individual differences and prevent profiling of individuals’ steroid levels over time and across circumstances. In contrast, non-invasive measures from excretions may allow repeated measures from individuals, and insofar as these ∗ Corresponding author. Tel.: +1 905 525 9140x23014; fax: +1 905 529 6225. E-mail address: decatanz@mcmaster.ca (D. deCatanzaro). reflect systemic levels they may provide individual profiling. Furthermore, as excretions such as urine are a medium for pheromones, and exogenous steroids can influence conspecifics’ physiology and behavior in laboratory rodents [1–4], levels of steroids in excretions may be of interest in their own right. Measures of steroids in excretions have been successful for several mammals and birds [5–8], and data from larger mammals, where blood can be sampled less invasively, show substantial correlation of measures of blood steroids with the same steroids or their conjugates in urine and feces [9–12]. We have recently adapted such non-invasive excretory procedures for laboratory mice [13–15]. We have found un- conjugated 17-estradiol and testosterone in all urinary and fecal samples taken from both sexes, however conjugate lev- els were relatively low in females and undetectable in males 0039-128X/$ – see front matter © 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.steroids.2004.07.002