Olfactory cues can exert priming effects on many mammalian species. Paternally experienced marmosets, Callithrix jacchus, exposed to direct isolated olfactory contact with their own infant's scent show rapid decreases in testosterone levels within 20 minutes, whereas paternally inexperienced males do not. The following study tests whether there is a differential steroid response to exposure of infant scent from dependent infants (own and novel) and independent infants (own and novel). We examined the serum levels of estradiol, estrone, testosterone, dihydrotestosterone (DHT), and combined estrogens and androgens in eight male marmosets 20 minutes after exposure to isolated infant scent. Testosterone and androgen levels combined were significantly lower with exposure to own infant scent than a novel infant scent when the infants were at a dependent age but not at an independent age. Estrogen levels elevated significantly in response to own infant scent when the infants were at a dependent age but not at an independent age. These results suggest that marmoset fathers are more responsive to priming cues from related infants and hormonal responses from fathers are greatest when the infant is at a dependent age.

Pregnancy and lactation produce a plethora of hormonal changes in females that promote maternal care of offspring. Males in the biparental marmoset species, (Callithrix jacchus), demonstrate high levels of parenting behaviour and express enhanced circulating reproductive hormones. Furthermore, these hormonal changes are influenced by paternal experience. In order to determine if the paternally experienced male marmoset has altered neurocrine hypothalamic release, as the maternal females does, we examined the release of several reproductive neurocrines, dopamine (DA), oxytocin (OT) and vasopressin (AVP) and prolactin (PRL), in cultured explants of the hypothalamus of paternally experienced male marmosets compared with naïve, paternally inexperienced males. DA levels secreted from the isolated hypothalamus were significantly lower in the experienced males while OT and PRL levels were significantly higher than levels found in inexperienced males. PRL levels decreased rapidly in the hypothalamic media suggesting PRL production occurs elsewhere. AVP levels did not change. Stimulation of the cultured explants with oestradiol significantly decreased DA levels in the inexperienced males but did not alter the other neurocrines suggesting a direct effect of oestradiol on DA suppression in the hypothalamus. While other factors such as age and rearing experience with siblings may play a role in hypothalamic neurocrine levels, these results demonstrate that paternal experience may impact the secretion of neurocrines in a male biparental primate.

Parental experience and hormones play a large role in the common marmoset (Callitrhix jacchus) father’s care of their offspring. We tested the effect of exogenous estradiol or testosterone on the responsiveness of common marmosets to respond to infant distress vocalizations and whether males who haven’t become fathers yet (paired males) would have increased responsiveness to infant distress calls with either steroid or whether parental experience is the most important component for the onset of paternal care. Sixteen male marmosets (8 fathers, 8 paired males) received a vehicle, low dose or high dose of estradiol and additional 16 males were tested with testosterone at three doses for their response either to a vocal control or a recording of an infant distress call for 10 minutes. Without steroid stimulation fathers were significantly more likely to respond to the infant distress stimulus than paired males. Low dose estradiol stimulation resulted in a significant increase in father’s behavioral response toward the infant distress stimulus but not in paired males. Fathers also showed a significant increase in infant responsiveness from the vehicle dose to the estradiol low dose treatment, but not to the estradiol high dose treatment. Testosterone treatment did not show significant differences between infant responsiveness at either dose and between fathers and paired males. We suggest that neither steroid is involved in the onset of paternal care behaviors in the marmoset but that estradiol may be involved in facilitating paternal motivation in experienced fathers.

Background A survey was developed to characterize disease incidence, common pathology lesions, environmental characteristics, and nutrition programs within captive research marmoset colonies. Methods Seventeen research facilities completed the electronic survey. Results Nutritional management programs varied amongst research institutions housing marmosets; eight primary base diets were reported. The most common clinical syndromes reported were gastrointestinal disease (i.e. inflammatory bowel disease like disease, chronic lymphocytic enteritis, chronic malabsorption, chronic diarrhea), metabolic bone disease or fracture, infectious diarrhea, and oral disease (tooth root abscesses, gingivitis, tooth root resorption). The five most common pathology morphologic diagnoses were colitis, nephropathy/nephritis, enteritis, chronic lymphoplasmacytic enteritis, and cholecystitis. Obesity was more common (average 20% of a reporting institution's population) than thin body condition (average 5%). Conclusions Through review of current practices, we aim to inspire development of evidence‐based practices to standardize husbandry and nutrition practices for marmoset research colonies.

Metabolic assessment of a nonhuman primate model of metabolic syndrome and obesity requires the necessary biomarkers specific to the species. While the rhesus monkey has a number of specific assays for assessing metabolic syndrome, the marmoset does not. Furthermore, the common marmoset (Callithrix jacchus) has a small blood volume that necessitates using a single blood volume for multiple analyses. The common marmoset holds a great potential as an alternative primate model for the study of human disease but assay methods need to be developed and validated for the biomarkers of metabolic syndrome. Here we report on the adaptation, development and validation of commercially available immunoassays for common marmoset samples in small volumes. We have performed biological validations for insulin, adiponectin, leptin, and ghrelin to demonstrate the use of these biomarkers in examining metabolic syndrome and other related diseases in the common marmoset.