Natural variation in early parental care may contribute to long-term changes in behavior in the offspring. Here we investigate the role of variable early care in biparental prairie voles (Microtus ochrogaster). Total amounts of parental care were initially quantified for 24 breeder pairs and pairs were ranked in relation to one another based on total contact. Consistency in key components of care suggested a trait-like quality to parental care. Based on this ranking, breeder pairs from the top (high-contact) and bottom (low-contact) quartiles were selected to produce high- and low-contact offspring to investigate adolescent behavior after varying early care. Parental care of subject offspring was again observed postnatally. Offspring of high-contact parents spent more time passively nursing and received more paternal non-huddling contact while low-contact offspring spent more time actively nursing and received more paternal huddling and pseudohuddling in the first postnatal days (PNDs). Low-contact offspring also displayed faster rates of development on a number of physical markers. Post-weaning, offspring were evaluated on anxiety-like behavior, social behavior and pre-pulse inhibition (PPI) to a tactile and an acoustic startle. High-contact offspring spent more time sniffing a juvenile and less time autogrooming. With an infant, high-contact offspring spent more time in non-huddling contact and less time autogrooming and retrieving than did low-contact offspring. Considering sexes separately, high-contact females spent more time sniffing a novel juvenile than low-contact females. High-contact males spent more time in non-huddling contact with an infant than low-contact males; while low-contact females retrieved infants more than high-contact females. In both measures of social behavior, high-contact males spent less time autogrooming than low-contact males. These results suggest a relationship between early-life care and differences in social behavior in adolescence.

Various hypotheses have been proposed to explain the function of alloparental behavior in cooperatively breeding species. We examined whether alloparental experience as juveniles enhanced later parental care and reproductive success in the prairie vole (Microtus ochrogaster), a cooperatively breeding rodent. Juveniles cared for one litter of siblings (1EX), two litters of siblings (2EX) or no siblings (0EX). As adults, these individuals were mated to other 0EX, 1EX or 2EX voles, yielding seven different pair combinations, and we recorded measures of parental behaviors, reproductive success, and pup development. As juveniles, individuals caring for siblings for the first time were more alloparental; and as adults, 0EX females paired with 0EX males spent more time in the nest with their pups. Taken together, these results suggest that inexperienced animals spend more time in infant care. As parents, 1EX males spent more time licking their pups than 2EX and 0EX males. Pups with either a 1EX or 2EX parent gained weight faster than pups with 0EX parents during certain developmental periods. While inexperienced animals may spend more time in pup care, longterm benefits of alloparenting may become apparent in the display of certain, particularly important parental behaviors such as licking pups, and in faster weight gain of offspring.

Mate-guarding and territorial aggression (both intra- and inter-sexual) are behavioral components of social monogamy seen in male coppery titi monkeys (Callicebus cupreus) both in the field and in the laboratory. Methodology for studying these behaviors in captivity facilitates the translation of questions between field and lab. In this study, we tested whether exposure to a mirror would stimulate mate-guarding behavior in male titi monkeys, and whether this exposure was accompanied by hormonal changes. Eight males were exposed to a mirror condition (treatment) or the back of the mirror (control) for five sessions, and behavioral responses were filmed. Blood samples were taken to measure levels of cortisol, oxytocin, and vasopressin. Lipsmacks (p< 0.0001), arching (p< 0.0001), tail-lashing (p= 0.009), restraining (p= 0.015), and approaches to the female (p= 0.0002) were all higher during the mirror condition, while tail-twining tended to decline during the mirror condition (p = 0.076). Hormones did not vary by experimental treatment, but were correlated with certain behaviors during the presentation of the mirror. While social behaviors changed with mirror exposure, self-directed and mirror-guided behaviors did not, indicating a lack of self-recognition. Use of a mirror was a safe and effective means of investigating mate-guarding behavior in response to a simulated intrusion, with the added benefit of not needing another animal to serve as an intruder; and thus may be of use in providing a laboratory model for natural behavior. Especially as it eliminates the need for a stimulus animal, it would also be of possible use in investigating responses to a simulated intruder in wild populations of titis and other pithecines.

Background: 5-HT 4 receptor (5-HT 4 R) agonists exert prokinetic actions in the GI tract, but non-selective actions and potential for stimulation of non-target 5-HT 4 Rs have limited their use. Since 5-HT 4 Rs are expressed in the colonic epithelium and their stimulation accelerates colonic propulsion in vitro, we tested whether luminally acting 5-HT 4 R agonists promote intestinal motility. Methods: Non-absorbed 5-HT 4 R agonists, based on prucalopride and naronapride, were assessed for potency at the 5-HT 4 R in vitro, and for tissue and serum distribution in vivo in mice. In vivo assessment of prokinetic potential included whole gut transit, colonic motility, fecal output, and fecal water content. Colonic motility was also studied ex vivo in mice treated in vivo. Immunofluorescence was used to evaluate receptor distribution in human intestinal mucosa. Key Results: Pharmacological screening demonstrated selectivity and potency of test agonists for 5-HT 4 R. Bioavailability studies showed negligible serum detection. Gavage of agonists caused faster whole gut transit and colonic motility, increased fecal output, and elevated fecal water content. Prokinetic actions were blocked by a 5-HT 4 R antagonist and were not detected in 5-HT 4 R knockout mice. Agonist administration promoted motility in models of constipation. Evaluation of motility patterns ex vivo revealed enhanced contractility in the middle and distal colon. Immunoreactivity for 5-HT 4 R is present in the epithelial layer of the human small and large intestines. Conclusions and Inferences: These findings demonstrated that stimulation of epithelial 5-HT 4 Rs can potentiate propulsive motility and support the concept that mucosal 5-HT 4 Rs could represent a safe and effective therapeutic target for the treatment of constipation.

Prairie voles (Microtus ochrogaster) are monogamous rodents that display high levels of affiliative behaviors, including pair-bonding, biparental care, and cooperative breeding. Species differences in basal cocaine- and amphetamine-regulated transcript (CART) mRNA and peptide expression have been found between prairie voles and polygamous meadow voles. Therefore, we hypothesized that the CART system may play a role in the regulation of social behavior in this species. Male and female adult prairie voles were placed in a cage either alone, or with a novel social partner of the same or opposite sex. After 45 minutes, subjects were sacrificed and CART peptide expression was examined using immunohistochemistry. We examined fifteen hypothalamic, limbic, and hindbrain regions of interest, focusing on areas that show species-specific patterns of expression. We found that subjects paired with a novel conspecific had lower levels of peptide in the bed nucleus of the stria terminalis (BNST) than isolated animals. This may reflect increased peptide release following increased dopaminergic activity in animals exposed to a novel conspecific. Additionally, CART peptide was higher in the nucleus accumbens (NAc) of subjects paired with an opposite sex partner compared to those paired with a same-sex conspecific, although there was no difference between isolated subjects and either socially housed group. These findings suggest that CART in the NAc is differentially responsive to the sex of adult conspecifics and that the social environment influences CART expression in the prairie vole in a region- and stimulus-specific manner.