Abstract
Prolactin is associated with both maternal and paternal care and appears important in developing a bond between parent and infant. In contrast with oxytocin, another hormone important in infant care, there is scant information on the role of prolactin in maintaining adult heterosexual relationships. We present here the first results demonstrating a relationship between prolactin levels and sexual and contact affiliation behavior in a pair-bonded species. We studied cotton-top tamarins, a socially-monogamous, cooperatively-breeding primate. We measured chronic urinary prolactin levels over a four week period to include the entire female ovulatory cycle and correlated prolactin levels in males and females with simultaneous measures of contact affiliation and sexual behavior. Current mothers who were no longer nursing displayed lower amounts of sexual behavior and proximity than non-breeding females and also had marginally lower levels of prolactin. The prolactin levels of males and females were similar within pairs, and variation in prolactin levels for both sexes was explained both by the amount of sexual behavior and contact affiliation. The results parallel a previous study that compared oxytocin levels with sociosexual behavior in the same species, and supports the hypothesis that both prolactin and oxytocin are involved in pair-bonding as well as in infant care.
Highlights
Despite the many parallels between prolactin and oxytocin in parental care and the interest in oxytocin in promoting pair bonding in monogamous biparental species [1], it is surprising that there are few papers on the role of prolactin in promoting pair-bonds
Prolactin levels were significantly correlated with sexual behavior (RS = 0.679, N = 11, p = 0.022) and with scent marking (RS = 0.742, N = 11, p = 0.009) with non-significant trends with duration of contact affiliation (RS = 0.579, N = 11, p = 0.062) and a negative nonsignificant trend with proximity (RS = -0.574, N = 11, p = 0.065)
Male prolactin levels correlated significantly with the amount of sexual behavior (RS = 0.756, N = 8, p = 0.030) and with contact affiliation (RS = 0.714, N = 8, p = 0.047, Fig. 2) and female prolactin showed a non-significant trend with the duration of contact affiliation (RS = 0.667, N = 8, p = 0.07) as was seen in Study 1 as well
Summary
Despite the many parallels between prolactin and oxytocin in parental care and the interest in oxytocin in promoting pair bonding in monogamous biparental species [1], it is surprising that there are few papers on the role of prolactin in promoting pair-bonds. We have previously shown in the socially-monogamous, cooperatively-breeding cotton-top tamarin that peripheral oxytocin levels varied in both males and females and were correlated with sociosexual behavior (copulation, huddling and grooming) [2]. Oxytocin levels were highly correlated between males and females. Variation in male oxytocin was explained best by variation in amount of sexual behavior observed whereas variation in female oxytocin was best explained by variation in amount of huddling and grooming behavior. In the black-penciled marmoset, a PLOS ONE | DOI:10.1371/journal.pone.0120650. In the black-penciled marmoset, a PLOS ONE | DOI:10.1371/journal.pone.0120650 March 23, 2015
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
