Cortisol and testosterone in Filipino young adult men: Evidence for co-regulation of both hormones by fatherhood and relationship status

Abstract Objectives: Although cortisol (CORT) may suppress testosterone (T) production under stress, in many species males' T and CORT are co-elevated during mate acquisition or conspecific competition. It is presently unknown how CORT co-varies with T in relation to fatherhood/relationship status in men. Here we evaluate associations between waking (AM) and pre-bed (PM) salivary CORT and T, and with plasma total T and luteinizing hormone. We also test whether co-elevationor co-downregulation of CORT and T are present in men who are mating-oriented (non-pairbonded, non-fathers) and parenting-oriented (pairbonded and/or fathers), respectively. Methods: Data come from 630 of young adult Filipino males (21?23 years) enrolled in the Cebu Longitudinal Health and Nutrition Survey, a population-based birth cohort study in Cebu City, Philippines. Results: T and CORT were positively related in AM (r = 0.37) and PM (r = 0.30) saliva samples (both P < 0.001). The positive relationship between AM measures was strengthened as caloric intake improved (interaction P < 0.05). Mating-oriented men were more likely to have co-elevated PM CORT and T (P < 0.05), defined as being in the highest tertile for both hormones, while parenting-oriented men were more likely to have co-downregulated (lowest tertile for both hormones) AM (P < 0.05) and PM (P < 0.001) CORT and T. Conclusions: CORT and T are positively related upon waking and before bed and are more likely to be co-elevated in mating-oriented men and co-downregulated in parenting-oriented men. Our findings support the interpretation that CORT and T serve complementary roles in facilitating men's mating effort. Am. J. Hum. Biol. 2011. ? 2011 Wiley-Liss, Inc.