Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2006) 11 OC12

ECE2006 Oral Communications Steroids and reproductive endocrinology (8 abstracts)

Expression profiling of genes in the testis of rhesus macaques during development and aging

HF Urbanski , VT Garyfallou , DR Lemos , JL Downs & DI Brown


Oregon National Primate Research Center, Beaverton, Oregon, United States.


Men show an age-associated decline in 24-hour circulating testosterone levels, but the reason for this decline is unclear. To shed light on the possible cause we first established that male rhesus monkeys undergo a similar decline in testosterone with age. Testosterone from young adult (∼10 years) and old (∼26 years) unanaesthetized males was measured by RIA from blood samples collected remotely through a vascular catheter, every 30 minutes for 24 hours. In both young and old animals, plasma testosterone showed a robust circadian pattern, with a peak occurring at night and a nadir occurring in the middle of the day. As expected, the peak, nadir, and overall mean testosterone levels were all significantly lower (P<0.001) in the old animals than in the young animals. Next, to help elucidate a possible mechanism for this age-associated decline, we extracted RNA from testicular parenchyma of three immature (∼2 years), three young adult (∼6 years) and three old (∼25 years) animals, and subjected the samples to GeneChip microarray analysis (Affymetrix HG-U133A). The gene encoding 17-β hydroxysteroid? dehydrogenase 3 (17-β HSD) showed a significant (P<0.05) developmental increase, suggesting that this enzyme may play a key role in activating testosterone biosynthesis during puberty. In contrast, the gene encoding steroidogenic acute regulatory protein (StAR), a key regulatory enzyme for testosterone biosynthesis, showed a significant (P<0.05) age-related decrease, suggesting that it may contribute to the age-associated decline in circulating testosterone. Interestingly, the microarray analysis also revealed the expression of the following clock-mechanism genes in the testis: Clock, Bmal1, Per1, Per2, Cry1, Rev-Erbα, and CK1ε and showed that CK1∈ declined significantly (P<0.05) during old age. Taken together, these data emphasize the circadian pattern of testosterone secretion in a nonhuman primate species, and suggest that transcriptional changes within the testis may contribute to the age-associated attenuation of this endocrine rhythm.

Volume 11

8th European Congress of Endocrinology incorporating the British Endocrine Societies

European Society of Endocrinology 
British Endocrine Societies 

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