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Marmoset wasting syndrome (MWS) is clinically characterized by progressive weight loss. Although morbidity and mortality of MWS are relatively high in captive marmosets, its causes remain unknown. Lipid mediators are bioactive metabolites which are produced from polyunsaturated fatty acids, such as arachidonic acid (AA) and eicosapentaenoic acid. These lipid metabolites regulate a wide range of inflammatory responses and they are excreted into the urine. As urinary lipid profiles reflect systemic inflammatory conditions, we comprehensively measured the levels of 141 types of lipid metabolites in the urines obtained from healthy common marmoset (Callithrix jacchus) (N = 7) or marmosets with MWS (N = 7). We found that 41 types of metabolites were detected in all urine samples of both groups. Among them, AA-derived metabolites accounted for 63% (26/41 types) of all detected metabolites. Notably, the levels of AA-derived prostaglandin (PG) E2, PGF2α, thromboxane (TX) B2 and F2-isoprostanes significantly increased in the urine samples of marmosets with MWS. In this study, we found some urinary lipid metabolites which may be involved in the development of MWS. Although the cause of MWS remains unclear, our findings may provide some insight into understanding the mechanisms of development of MWS.

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Cooperatively breeding, group-living common marmosets show differentiated relationships, where more strongly bonded dyads within a group engage more in affiliative interactions than less strongly bonded ones. Intriguingly, recent results suggest that strong bonds do not only occur between breeding partners but between individuals from any sex or status, and that strong-bond partners exhibit correlated oxytocin fluctuations (dyadic oxytocin synchrony, OTS) over a period of six weeks. To date, it is unclear whether such relationships are stable over time and whether they are also reflected in higher partner-specific proactive prosociality. To assess the long-term stability of the relationship structure of common marmoset family groups, we investigated whether hormonal and behavioral markers of group structure (dyadic OTS, dyadic affiliation, and individual group integration) in common marmoset families remained stable over a period of six months. We collected baseline urinary OT and social behavior of 36 dyads from three family groups in a non-reproductive period (period A), and again six months later, around the birth of new infants (period B). Patterns of dyadic OTS, dyadic affiliation, and individual group integration were consistent between the two study periods. Oxytocin data from a fourth group (10 dyads), collected in two non-reproductive periods separated by a period of more than five years, could replicate this finding. Furthermore, OTS was also correlated with proactive prosociality that was assessed experimentally for 38 dyads during an earlier study. These results suggest that differentiated relationships are stable over time, even between group members other than the breeding pair, and that more strongly bonded partners also show higher levels of proactive prosociality. Future studies are necessary to identify whether these relationships have an adaptive function, perhaps with regard to positive consequences on cooperativeness.

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Oxytocin is a key regulator of social bonding and is positively linked to affiliation and prosocial behavior in several mammal species. In chimpanzees, this link is dyad-specific as affiliative interactions only elicit high oxytocin release if they involve strongly bonded individuals. These studies involved isolated dyads and sampling events. Little is known about the role of oxytocin in affiliation and social bonding, and about potential long-term patterns of bonding-related and dyad-specific oxytocin effects within highly affiliative and cooperative social groups. Our aim was to investigate whether bonding-related oxytocin signatures linked to dyadic affiliation are present in family groups of cooperatively breeding marmoset monkeys (Callithrix jacchus) that show high levels of cohesion and cooperation. In 30 dyads from four family groups and one pair, we measured urinary baseline oxytocin over six weeks and analyzed the link to bond strength (mean dyadic affiliation). Strongly bonded dyads showed synchronized longitudinal fluctuations of oxytocin, indicating that dyad-specific oxytocin effects can also be traced in the group context and in an interdependent species. We discuss these results in light of the potential function of differentiated relationships between marmoset dyads other than the breeding pair, and the role of oxytocin as a mediator for social bonding.

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Exposure to androgens during prenatal development shapes both physiological and behavioral developmental trajectories. Notably, in rhesus macaques, prenatal androgen exposure has been shown to increase rough-and-tumble play, a prominent behavioral feature in males during the juvenile period in primates. While macaques are an Old World, polygamous species with marked sexually dimorphic behavior, New World callitrichine primates (marmosets and tamarins) live in cooperative breeding groups and are considered to be socially monogamous and exhibit minimal sexual dimorphism in social play, which suggests that androgen may affect this species in different ways compared to macaques. In addition, we previously described considerable variation in maternal androgen production during gestation in marmosets. Here we tested the association between this variation and variation in offspring rough-and-tumble play patterns in both males and females. We measured testosterone and androstenedione levels in urine samples collected from pregnant marmoset mothers and then observed their offspring's play behavior as juveniles (5-10 months of age). In contrast to findings in rhesus macaques, hierarchical regression analyses showed that higher gestational testosterone levels, primarily in the second semester, were associated with decreased rough-and-tumble play in juveniles, and this relationship appears to be driven more so by males than females. We found no reliable associations between gestational androstenedione and juvenile play behavior. Our findings provide evidence to suggest that normative variation in levels of maternal androgen during gestation may influence developmental behavioral trajectories in marmosets in a way that contradicts previous findings in Old World primates.

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Callitrichine primates (marmosets and tamarins) often remain in their natal groups beyond the time of sexual maturity. Although studies have characterized the development of female reproductive function in callitrichine offspring, less is known about the male reproductive development. To document reproductive development in male marmosets, we monitored urinary androgen (uA) excretion in males housed in a captive colony of white-faced marmosets (Callithrix geoffroyi). Young male marmosets showed relatively low and stable rates of uA excretion early in life, with elevated production at the end of the juvenile period (9-10 months) and again at the onset of adulthood (16 months). uA levels of adult breeding males were also measured to compare to adult-aged sons. Although breeding males did have higher uA levels than their adult-aged sons, these differences did not reach conventional levels of significance. Evidence from some other reports has suggested that androgen levels of males in other species are influenced by social factors, such as the presence of a sexually receptive female or of dependent offspring. In this study, however, uA levels did not vary, based on their mothers' pregnancy status or the presence of younger siblings in the natal group. Patterns of androgen excretion in the white-faced marmoset roughly reflect those of other callitrichine species. Furthermore, unlike callitrichine daughters, gonadal activity in sons does not seem to be sensitive to within-group social cues.

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Fetal development is a critical period of physical development, and factors in the intrauterine environment can cause lasting effects on the growth and development of offspring. There is little research evaluating organizational effects of early androgen exposure of endogenous maternal origins on the prenatal and postnatal growth of offspring. We evaluated the association between maternal androgen levels during gestation and pre- and postnatal growth of offspring. Maternal androgen levels in marmoset females were measured using enzyme immunoassays of urine samples acquired during 18 pregnancies. Somatic measurements of the resulting 25 viable offspring were taken on postnatal days (PND) 2, 30, 60, 120, 180, 240, and 300. Maternal androgen levels during the first trimester were negatively associated with weight, body length, and several girth measurements (i.e., torso, head, chest, and arm circumference) of offspring on PND 2. First trimester maternal androgen was also negatively associated with physical growth during early and late infancy but seemed to be positively associated with a rebound in juvenile growth. Exposure to maternal androgen during early gestation led to both a reduction in birth weight and postnatal catch-up for both males and females, equally. Fetal growth retardation and the reprogramming of metabolic tissues by exposure to prenatal androgen could be mediating factors of suppressed postnatal growth.

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The fate of [35S]-phenothiazine, a veterinary anthelmintic, has been investigated in the adult male marmoset (Callithrix jacchus) following oral administration. A near complete recovery of radioactivity (c. 95%) was achieved in 0-3 days, with just over one-third of the dose (c. 37%) being present in the urine and the remainder (c. 58%) being accounted for in the faeces. The majority of the urinary radioactivity (c. 91%) was present as conjugates, tentatively identified as phenothiazine N-glucuronide and leucophenothiazone sulphate. Smaller amounts of phenothiazone, thionol, phenothiazine sulphoxide and unchanged phenothiazine were also identified. The only compound identified in the faeces was unchanged phenothiazine.

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Corticotropin-releasing hormone (CRH), a potent neuropeptide, is produced by the placenta of anthropoid primates. No other mammals, including prosimian primates, are known to produce placental CRH. In humans, placental CRH appears to play an important role in the progression of pregnancy to parturition. Maternal circulating CRH begins to rise early in pregnancy and increases until parturition. Gorillas and chimpanzees share this pattern of increasing maternal CRH during pregnancy with humans. In humans, chimpanzees, and gorillas, maternal CRH and estradiol concentrations are correlated, consistent with the hypothesis that CRH is involved in the biosynthetic pathway for placental estrogen production. In contrast, in baboons, maternal circulating CRH rises precipitously early in pregnancy and then declines, though CRH is detectable until birth. This research was designed to investigate the pattern of maternal circulating CRH in the common marmoset during pregnancy. Blood samples were taken across gestation from nine subjects over 11 pregnancies, and the plasma was assayed for CRH. The pattern of maternal circulating CRH in the common marmoset was similar to that of the baboon, with a rapid rise starting at about 50 days postconception and a peak at approximately 70 days postconception. By 110 days postconception, CRH concentration had plateaued at a significantly lower value. The peak and mean values for CRH were associated with fetal number (e.g., females gestating triplets had higher values than females gestating twins). Urinary estradiol showed no association with plasma CRH concentration. Marmosets appear to differ from the great apes in this regard, and to share a pattern of maternal CRH during pregnancy with the baboon, indicating that the baboon and marmoset pattern may be ancestral. The function of the early rapid rise of CRH in baboons and marmosets, and the significance of this difference between monkeys and apes, are not known.

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The proximate mechanisms that regulate transitions in mammalian female reproductive effort have not been widely studied. However, variation in circulating levels of the androgenic steroid hormone testosterone (T) appears to mediate a trade-off between investment in current and future offspring in males [Ketterson, E.D., Nolan, V., Jr., 1992. Hormones and life histories: an integrative approach. Am. Nat. 140, S33-S62; Ketterson, E.D., Nolan, V., Jr., 1994. Hormones and life histories: an integrative approach. In: L.A. Real (Ed.), Behavioral Mechanisms in Evolutionary Ecology, University of Chicago Press, Chicago, pp. 327-353; Ketterson, E. D., Nolan, V., Jr., 1999. Adaptation, exaptation, and constraint: A hormonal perspective. Am. Nat. 154S, S4-S25]. The purpose of this study was to investigate the possibility that T is also associated with transitions in the reproductive effort of females, by examining the relationship between urinary T excretion, maternal caregiving behavior, and the timing of the postpartum conception in female Wied's black tufted-ear marmosets (Callithrix kuhlii). We examined the maternal carrying effort and peripartum T profiles of six females across two conditions: (1) when they conceived during the period of infant dependence (DPID), such that gestation was coupled with lactation; and (2) when the same females conceived after the period of infant dependence (APID). We also assessed the relationship between postpartum T levels and caregiving effort. When female marmosets conceived DPID, they dramatically reduced their caregiving effort, and had higher levels of urinary T, relative to when they conceived APID. Further, the litter-to-litter changes in maternal caregiving effort that we observed were related to variation in urinary T excretion; as weekly levels of urinary T excretion increased, concurrent caregiving effort declined. Our results suggest that variation in T secretion may regulate transitions in female reproductive behavior, and that the regulation of male and female parental behavior may be mediated by homologous neuroendocrine mechanisms.

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Previous studies have found a clear relationship between prolactin (prl) and paternal care in various vertebrate taxa. In New World monkeys, it has been demonstrated in several species that fathers have high prolactin levels even during periods without infant rearing. In this study, we followed the reproductive careers of common marmoset males as they transitioned from being an adult son within their native family to fathering their own offspring for the first time. Specifically, we examined the first experience of elevated prolactin levels in marmoset males. Additionally, we investigated the effects of the total number of experienced births as well as of age on prolactin levels. Our results show that common marmoset males did not experience an increase in prolactin secretion after pairing or shortly before birth of their first infants. However, prolactin levels rose more than twofold after the birth of their first infants and had lowered again 2.5 months after this event. We found no correlation between prolactin levels and the number of previous births experienced or age. Our study demonstrates that further work about a possible enhancing effect of prolactin on paternal care, by means of experimentally reducing hormonal levels, should be conducted in common marmosets using first-time fathers before males experience the first paternal increase in prolactin levels.

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BACKGROUND: Early environment is a major determinant of long-term mental health, evidenced by the relationship between early-life neglect or abuse and chronically increased vulnerability to developmental psychopathology, including major depressive disorder (MDD). Animal studies can increase understanding of environmentally mediated causal risk processes. We describe how daily deprivation of biological parenting in primate infants disrupts development of homeostatic and reward systems central to MDD. METHODS: Nine breeding pairs of marmoset monkeys provided control twins (CON) and early-deprived twins (ED); the latter were socially isolated for 30-120 min/day on days 2-28. During the first year of life, basal urinary norepinephrine (NE) titers and cardiophysiologic activity were measured. At the end of year 1 (adolescence), automated neuropsychologic tests were conducted to measure responsiveness to changes in stimulus-reward association (simple/reversed visual discrimination learning) and to reward per se (progressive ratio [PR] reinforcement schedule). RESULTS: The ED monkeys exhibited increased basal urinary NE titers and increased systolic blood pressure relative to CON siblings. The ED monkeys required more sessions to reinstate stimulus-oriented behavior following reversal, suggesting increased vulnerability to perceived loss of environmental control; ED monkeys also performed less PR operant responses, indicating that reward was less of an incentive and that they were mildly anhedonic relative to CON. CONCLUSIONS: In marmoset monkeys, neglect-like manipulation of ED leads to chronic changes in homeostatic systems, similar to those in children and adolescents exposed to early-life adversity and in MDD, and to responses to environmental stimuli similar to those that characterize MDD.

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The first author trained 12 laboratory-housed common marmosets (Callithrix jacchus) in pairs to assess the practicality of positive reinforcement training as a technique in the management of these nonhuman animals. Behaviors taught were (a) target training to allow in homecage weighing and (b) providing urine samples. Between 2 to 13, 10-minute training sessions established desired behaviors. Training aggressive animals only after they had been fed eliminated aggression during training. Trained animals proved extremely reliable, and data collection using trained animals was considerably faster than collection using current laboratory techniques. The results suggest that positive reinforcement training is a practical option in the management of laboratory-housed marmosets.

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Using positive reinforcement, J. McKinley trained 12 common marmosets (Callithrix jacchus) to provide urine samples on request. The study then exposed the marmosets to mildly stressful, routine husbandry procedures (i.e., capture and weighing). The nonhuman animals spent less time inactive poststressor as opposed to prestressor. L. Bassett collected matched behavioral data from 12 nontrained marmosets who were less accustomed to human interaction. These animals spent significantly more time self-scratching and locomoting as well as less time inactive, poststressor. Collapsed data from the 2 populations showed increased scent marking, poststressor. These results suggest that locomotion, self-scratching, and scent marking are useful, noninvasive behavioral measures of stress and, thus, reduced welfare in the common marmoset. Overall, nontrained animals showed more self-scratching than did their trained counterparts. It was not possible to collect urine from nontrained marmosets. In response to the stressor, however, trained animals showed no significant change in excreted urinary cortisol. These results suggest that training marmosets may allow them to cope better with routine laboratory procedures.

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The authors explored whether prolactin is associated with paternal care in 3 monkey species: titi monkey (Callicebus cupreus), common marmoset (Callithrix jacchus), and Goeldi's monkey (Callimico goeldii). They compared prolactin levels in fathers before and after infant birth as well as between fathers and nonfathers. C. cupreus fathers carry infants almost exclusively, have higher prolactin levels than nonfathers, but show no prolactin increase after infant birth. C. goeldii fathers carry infants only after 3 weeks, show an increase in prolactin levels during the precarrying period, but do not have higher levels than nonfathers. C jacchus fathers are the primary carriers, have higher prolactin levels than nonfathers, and show a trend for a prolactin increase after the birth of infants. In conclusion, species differences in the patterns of prolactin secretion were evident and reflect the different paternal roles.

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1. The diurnal pattern of urinary estradiol and creatinine excretion was investigated in order to evaluate the relationship between total estradiol excretion per day and the estradiol concentration or the estradiol-to-creatinine ratio from single urine samples in female common marmosets (Callithrix j. jacchus). 2. During a 36-day period, urine was collected from five adult female marmosets in 3-hr intervals during the light time of an LD 12:12 (400:0.1 lx) which corresponded to the animals' activity time. 3. Estradiol concentration was determined by radioimmunoassay after glucuronidase treatment and creatinine concentration was measured photometrically. 4. Concentration and amount of excreted estradiol, and the creatinine concentration showed a distinct diurnal pattern with significantly higher levels at the beginning of the activity time compared to later sampling times. 5. No diurnal pattern was present in the estradiol-to-creatinine ratio, but the difference between lower follicular and higher luteal phase levels of estradiol excretion remained significant in the 36-day period. 6. Correlation analyses revealed significantly positive correlations between the total estrogen mass excreted per day and the estradiol-to-creatinine ratio in "morning urine" samples. 7. Thus the estradiol-to-creatinine ratio of single urine samples collected at the beginning of the activity time provides a reliable estimate of total estrogenic output in this species. 8. Studies of the circadian pattern of urinary hormone excretion, however, require total urine sampling.

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Two systems are described for the collection of 24 h urine samples from the common marmoset (Callithrix jacchus). Using 84 adult animals, 1210 24-h samples were collected. Mean urinary excretion was 14.4 +/- 7.5 ml/24 h (n = 1210, mean +/- SD). No differences were observed between sexes (for 52 females, 24 h volume = 15.1 +/- 8.0 ml; for 32 males, 24 h volume = 12.5 +/- 6.0 ml). No significant differences were observed between pregnant and non-pregnant females with respect to 24 h urine volume, and bilateral gonadectomy did not influence subsequent urinary excretion in either sex. For 161 pairs of observations, the intake of drinking water (11.7 +/- 10.2 ml/24 h) and the volume of urine excreted (12.6 +/- 7.1 ml/24 h) showed a positive correlation (r = 0.406 d.f. 159, P less than 0.001: y = 0.558x + 4.247).

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Hydroxypregnanolone is the most abundant progesterone metabolite in the urine of marmoset monkeys (Callithrix jacchus). The substance is excreted as conjugate. The concentration of this steroid may be monitored by high performance, thin layer chromatography and postchromatographic derivatization. Hydroxypregnanolone was purified and subsequently identified by NMR spectroscopy and gas chromatography/mass spectroscopy. The exact chemical structure is 5 alpha-pregnane-3 alpha, 7 alpha-diol-20-one.

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In Callithrix jacchus the urinary excretion of hydroxypregnanolone (5 alpha-pregnane-3 alpha, 7 alpha-diol-20-one) shows a luteal rise during the ovulatory cycle. This progesterone metabolite can therefore be used as an indication of ovulation, implantation, and subsequently for the persistence of the pregnancy. The excretion can be monitored by high performance thin-layer chromatography (HPTLC) and postchromatographic derivatization after enzymatic hydrolysis of the conjugate. Profiles of urinary hydroxypregnanolone levels are presented and correlated with luteinizing hormone excretion. The method is noninvasive and therefore suited for long-term studies in these monkeys.

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