Diet, Digestion and Energy Intake in Captive Common Marmosets (Callithrix jacchus): Research and Management Implications

Common marmosets (Callithrix jacchus) are susceptible to intestinal inflammation which leads to chronic diarrhea, weight loss, and vitamin D deficiency. We examined food intake and digestion in three mixed-sex groups of adult marmosets maintained on three commercial base diets. Animals underwent two consecutive 4-day digestion trials. Body mass stayed constant. Feces and diet were assayed for Mn, fat, and gross energy (GE). Apparent digestibility of dry matter (ADDM) was calculated by the total collection method and from dietary and fecal Mn; the methods produced correlated results (r = 0.658, p \u3c 0.001). Apparent digestibility of energy (ADE) was calculated from ADDM and the GE of feces and diet; apparent digestibility of fat (ADfat) was calculated from ADDM and fecal fat. ADDM and ADE varied by diet (p \u3c 0.001). We found poor digesters on all three diets. The concentration of fecal fat was inversely related to ADE (r = −0.729, p \u3c 0.001). High fecal fat (\u3e10%) was associated with ADfat of zero, consistent with lipid malabsorption. Mean digestible energy intake (DEI) was equal to 1.5 the estimated metabolic rate, but varied widely between individuals. The diet with the fewest animals with high fecal fat had the highest mean DEI and most animals above 450 g, suggesting it may be obesogenic

Prospects and Perspectives in Primate Aging Research

As improvements in standard of living and advances in medicine have resulted in greater life expectancy, the relative proportion of elderly has continued to increase in human populations across the globe. The primary goal of aging research is to gain a better understanding of the series of events that lead to increased frailty and disease vulnerability with age. The direct study of human aging is an active area of research; however, the opportunity to conduct mechanistic studies and gain insights into the underlying biology is limited. In this special forum issue of Antioxidant & Redox Signaling, we present a selection of articles and reviews that illustrate some of the recent advances in primate aging research. The overarching goal of this work is to underscore the potential for mechanistic discovery that is presented by nonhuman primate models, and to promote studies that validate novel approaches and techniques in nonhuman primates before their adaptation for human health care. Antioxid. Redox Signal. 14, 203–205

Fathering style influences health outcome in common marmoset (Callithrix jacchus) offspring.

In the cooperative breeding common marmoset monkey, Callithrix jacchus, fathers share the care responsibility and energetic load with their mate from the time their infants are born. However, not all fathers show the same level of participation in direct infant care. Here we present the first results demonstrating that fathering style can improve both survival and growth trajectory of a male's offspring during the first 30 weeks of life and that these infant outcomes are consistent within a father throughout successive births. Twenty-four marmoset fathers were tested for their responsiveness to an infant distress call when their infants were approximately two weeks old. These fathers were categorized as either responsive (RS) or nonresponsive (NRS) based on their response to the calls. Survival past 1 month was then determined and bi-monthly weights of current infants through 30 weeks of age were taken. Infant survival to the first month was significantly higher with RS fathers than with NRS fathers during this critical time period. Infants from RS fathers also had a higher growth trajectory with significant differences in body weight in the 28th and 30th week after birth. Only the RS fathers showed a significant increase in serum testosterone in response to infant cries suggesting a physiological role of testosterone in the motivation to search for the infant. Furthermore, all offspring born to RS fathers from subsequent births also showed a significantly higher survival rate and higher growth trajectory than for offspring of NRS fathers. These results suggest that fathering style is a consistent trait and responsive fathers improve infant survival rate and growth during the first 30 weeks. Such fathering style traits may be passed on to the male offspring due to environmental or genetic factors

Maintenance of bone mass despite estrogen depletion in female common marmoset monkeys (Callithrix jacchus).

Estrogen depletion leads to bone loss in almost all mammals with frequent regular ovarian cycles. However, subordinate adult female common marmosets (Callithrix jacchus) undergo socially induced anovulation and hypoestrogenism without clinically apparent adverse skeletal consequences. Thus, we speculated that this non human primate might have evolved a mechanism to avoid estrogen-depletion bone loss. To test this possibility, we performed three experiments in which lumbar-spine (L5-L6) bone mineral content (BMC) and density (BMD) were assessed using dual-energy X-ray absorptiometry: (i) cross-sectionally in 13 long-term ovariectomized animals and 12 age- and weight-matched controls undergoing ovulatory cycles; (ii) longitudinally in 12 animals prior to, 3-4 and 6-7 months following ovariectomy (ovx), and six controls; and (iii) cross-sectionally in nine anovulatory subordinate and nine dominant females. In Experiments 1 and 3, plasma estradiol and estrone concentrations were measured and uterine dimensions were obtained by ultrasound in a subset of animals as a marker of functional estrogen depletion. Estrogen levels, uterine trans-fundus width, and uterine dorso-ventral diameter were lower in ovariectomized and subordinate females than in those undergoing ovulatory cycles. However, no differences were found in L5-L6 BMC or BMD. These results indicate that estrogen depletion, whether surgically or socially induced, is not associated with lower bone mass in female common marmosets. Thus, this species may possess unique adaptations to avoid bone loss associated with estrogen depletion

Growth hormone therapy during neonatal hypoxia in rats: body composition, bone mineral density, and insulin-like growth factor-1 expression

Hypoxia from birth results in a decrease in body weight gain, body size, and bone mineral density (BMD). The purpose of the present study was to determine whether short-term administration of growth hormone (GH) (rat GH; 100 microg/d) could attenuate some of these effects of neonatal hypoxia. Rat pups (with their lactating dams) were exposed to hypoxia (vs normoxic control) from birth. Hypoxia was continued until 14 d of age, with rat GH (vs vehicle control) administered daily. Hypoxia significantly inhibited body weight gain; GH therapy did not reverse this effect. GH therapy did reverse the inhibitory effect of hypoxia on tail length but not on body length. Hypoxia decreased BMD analyzed by dual X-ray absorptiometry (DXA); this effect was not reversed by GH therapy. Both GH therapy and hypoxia decreased the percentage of body fat analyzed by DXA, the effects of which were additive when combined. There were minimal effects of hypoxia and GH therapy on plasma insulin-like growth factor-1 (IGF-1), IGF-binding protein-3, and hepatic IGF-1 mRNA expression. We conclude that some of the effects of hypoxia on body habitus are reversed by GH therapy, but that short-term GH therapy did not prevent a loss of BMD. GH therapy for more than 14 days may be necessary to appreciate fully its potential in the treatment of the sequelae of neonatal hypoxia

Ketamine-induced neuromuscular reactivity is associated with aging in female rhesus macaques.

Rhesus macaques represent an important species for translational and pre-clinical research studies across a multitude of disease and injury models, including aging. Ketamine anesthesia is used in humans and non-human primates but may be associated with adverse effects, including neuromuscular reactions. The effects of aging on ketamine adverse effects is not well characterized. Urodynamic recordings and electromyography (EMG) studies were performed in aged (>20 years old) and adult (3.9-14.9 years old) female rhesus macaques under an equal and light plane of sedation by constant rate infusion (CRI) of ketamine. A total of 4 of 41 adult subjects (9.7%) showed clinical signs of ketamine-induced abnormal neuromuscular reactivity, whereas a larger portion of 14 of 26 aged subjects showed similar ketamine-induced neuromuscular reactivity (53.8%; P< 0.001). The ketamine CRI rate was 19.8±0.9 mg/kg/h in adults and lower in aged subjects at 16.5±1.4 mg/kg/h (P<0.05). The ketamine CRI rate was negatively correlated with age (r = -0.30, P<0.05, n = 64). The incidence of ketamine reactivity or CRI rate was not different between aged pre-and post-menopausal females. EMG recordings during neuromuscular reactivity showed coordinated activation of multiple muscles, suggesting a central nervous system (CNS) mechanism for ketamine-associated neuromuscular reactivity. The incidence of ketamine-induced neuromuscular reactivity is age related but not affected by the estrous cycle in female rhesus macaques. A coordinated activation of multiple muscles, innervated by different peripheral nerves, suggests that ketamine-induced neuromuscular reactivity originates in the CNS

Caloric Restriction Impacts Plasma Micrornas In Rhesus Monkeys

Caloric restriction (CR) is one of the most robust interventions shown to delay aging in diverse species, including rhesus monkeys (Macaca mulatta). Identification of factors involved in CR brings a promise of translatability to human health and aging. Here, we show that CR induced a profound change in abundance of circulating microRNAs (miRNAs) linked to growth and insulin signaling pathway, suggesting that miRNAs are involved in CR\u27s mechanisms of action in primates. Deep sequencing of plasma RNA extracts enriched for short species revealed a total of 243 unique species of miRNAs including 47 novel species. Approximately 70% of the plasma miRNAs detected were conserved between rhesus monkeys and humans. CR induced or repressed 24 known and 10 novel miRNA species. Regression analysis revealed correlations between bodyweight, adiposity, and insulin sensitivity for 10 of the CR-regulated known miRNAs. Sequence alignment and target identification for these 10 miRNAs identify a role in signaling downstream of the insulin receptor. The highly abundant miR-125a-5p correlated positively with adiposity and negatively with insulin sensitivity and was negatively regulated by CR. Putative target pathways of CR-associated miRNAs were highly enriched for growth and insulin signaling that have previously been implicated in delayed aging. Clustering analysis further pointed to CR-induced miRNA regulation of ribosomal, mitochondrial, and spliceosomal pathways. These data are consistent with a model where CR recruits miRNA-based homeostatic mechanisms to coordinate a program of delayed aging

Experiment 1.

<p>Testosterone percent change from control vocal to infant distress cries. RS fathers showed a significant change (p = 0.03) in their testosterone levels after searching for the source of the infant cries while NRS fathers did not show any testosterone change.</p