Gerald Melissa S, Higley Sue, Lussier I sabelle D, Westergaard Greg C, Suomi Stephen J, Higley J Dee
National Institute on Alcohol Abuse and Alcoholism, NIH Animal Center, Primate Unit, Poolesville, MD, USA.
Brain Behav Evol. 2002;60(2):117-24. doi: 10.1159/000065207.
In rhesus macaque males, lower than average cerebrospinal fluid (CSF) concentrations of the principle metabolite of serotonin, 5-hydroxyindoleacetic acid (5-HIAA), have been linked to impulsivity, involvement in escalated aggression, failure to elicit consort relationships, production of fewer sperm plugs, and a relatively early age of mortality. Given these potential fitness costs, we performed two studies aimed at elucidating the effects of CSF 5-HIAA on reproduction. Study 1 retrospectively evaluated over a four-year period, the relative reproductive outcome for pairs of adult male rhesus macaques (n = 15) who lived in social groups and who differed in concentrations of CSF 5-HIAA. Study 2 examined the relationship between CSF 5-HIAA and sperm motility and density (n = 12), as a potential mechanism for maintaining variability in CSF 5-HIAA. For Study 1, an average measure from two CSF 5-HIAA samples was calculated for the two males who were present during the time when conception most likely took place (offspring birth date -165 +/- 14 days). Within-pair comparisons of CSF 5-HIAA concentrations between the sire and the non-successful male were drawn for each of the 72 offspring in the study. We found that while sires were typically the male with relatively higher CSF 5-HIAA within the pair, there were no absolute differences in CSF 5-HIAA between males who sired at least one offspring (sires) and those who failed to reproduce (non-sires). Furthermore, while absolute age was not predictive of reproductive outcome, sires with relatively high CSF 5-HIAA also tended to be also relatively older than their competitors. By contrast, for the males with relatively low CSF 5-HIAA who reproduced, sires were relatively younger than the non-sires. These differences in reproductive outcome for males differing in CSF 5-HIAA could not be explained by variability in sperm quantity or quality as we did not find evidence of a relationship between CSF 5-HIAA and either sperm measure. The results of this study suggest that as serotonergic function affects many aspects of behavior and survivorship, it might also be associated with reproductive outcome and different life-history strategies for males differing in concentrations of CSF 5-HIAA.
在恒河猴雄性中，血清素的主要代谢产物5-羟吲哚乙酸（5-HIAA）的脑脊液（CSF）浓度低于平均水平，这与冲动性、参与升级攻击行为、未能建立配偶关系、产生较少的精子栓以及相对较早的死亡年龄有关。鉴于这些潜在的适应性代价，我们进行了两项研究，旨在阐明脑脊液5-HIAA对生殖的影响。研究1回顾性评估了为期四年的时间里，生活在社会群体中且脑脊液5-HIAA浓度不同的成年雄性恒河猴对（n = 15）的相对生殖结果。研究2考察了脑脊液5-HIAA与精子活力和密度之间的关系（n = 12），作为维持脑脊液5-HIAA变异性的一种潜在机制。对于研究1，计算了在最有可能受孕的时间（后代出生日期-165±14天）出现的两只雄性的两个脑脊液5-HIAA样本的平均测量值。对研究中的72只后代，分别对父亲和未成功的雄性之间的脑脊液5-HIAA浓度进行配对比较。我们发现，虽然父亲通常是配对中脑脊液5-HIAA相对较高的雄性，但至少育有一个后代的雄性（父亲）和未能繁殖的雄性（非父亲）之间的脑脊液5-HIAA没有绝对差异。此外，虽然绝对年龄不能预测生殖结果，但脑脊液5-HIAA相对较高的父亲也往往比他们的竞争对手年龄更大。相比之下，对于繁殖的脑脊液5-HIAA相对较低的雄性，父亲比非父亲相对年轻。脑脊液5-HIAA不同的雄性在生殖结果上的这些差异，无法用精子数量或质量的变异性来解释，因为我们没有发现脑脊液5-HIAA与任何一种精子指标之间存在关系的证据。这项研究的结果表明，由于血清素能功能影响行为和生存的许多方面，它也可能与生殖结果以及脑脊液5-HIAA浓度不同的雄性的不同生活史策略有关。
