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Proc Natl Acad Sci U S A. 2018 Sep 11;115(37):9264-9269. doi: 10.1073/pnas.1720530115. Epub 2018 Aug 27.

Responses to pup vocalizations in subordinate naked mole-rats are induced by estradiol ingested through coprophagy of queen's feces.

Author information

1
Companion Animal Research, School of Veterinary Medicine, Azabu University, 252-5201 Sagamihara, Japan.
2
Department of Physiology, Keio University School of Medicine, 160-8582 Tokyo, Japan.
3
Biomedical Animal Research Laboratory, Institute for Genetic Medicine, Hokkaido University, 060-0815 Hokkaido, Japan.
4
Department of Aging and Longevity Researches, Kumamoto University, 860-0811 Kumamoto, Japan.
5
Center for Metabolic Regulation of Healthy Aging, Kumamoto University, 860-8556 Kumamoto, Japan.
6
Companion Animal Research, School of Veterinary Medicine, Azabu University, 252-5201 Sagamihara, Japan; mogik@azabu-u.ac.jp.

Abstract

Naked mole-rats form eusocial colonies consisting of a single breeding female (the queen), several breeding males, and sexually immature adults (subordinates). Subordinates are cooperative and provide alloparental care by huddling and retrieving pups to the nest. However, the physiological mechanism(s) underlying alloparental behavior of nonbreeders remains undetermined. Here, we examined the response of subordinates to pup voice and the fecal estradiol concentrations of subordinates during the three reproductive periods of the queen, including gestation, postpartum, and nonlactating. Subordinate response to pup voice was observed only during the queen's postpartum and was preceded by an incremental rise in subordinates' fecal estradiol concentrations during the queen's gestation period, which coincided with physiological changes in the queen. We hypothesized that the increased estradiol in the queen's feces was disseminated to subordinates through coprophagy, which stimulated subordinates' responses to pup vocalizations. To test this hypothesis, we fed subordinates either fecal pellets from pregnant queens or pellets from nonpregnant queens amended with estradiol for 9 days and examined their response to recorded pup voice. In both treatments, the subordinates exhibited a constant level of response to pup voice during the feeding period but became more responsive 4 days after the feeding period. Thus, we believe that we have identified a previously unknown system of communication in naked mole-rats, in which a hormone released by one individual controls the behavior of another individual and influences the level of responsiveness among subordinate adults to pup vocal signals, thereby contributing to the alloparental pup care by subordinates.

KEYWORDS:

alloparental behavior; coprophagy; estradiol; naked mole-rats

PMID:
30150390
PMCID:
PMC6140523
[Available on 2019-03-11]
DOI:
10.1073/pnas.1720530115
[Indexed for MEDLINE]

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