Testicular regulation of seasonal change in apocrine glands in the back skin of the brown bear (Ursus arctos)

Brown bears communicate with other individuals using marking behavior. Bipedal back rubbing has been identified as a common marking posture. Oily substances are secreted via enlarged sebaceous glands in the back skin of male bears during the breeding season. However, whether apocrine gland secretion...

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Bibliographic Details
Published in:Journal of Veterinary Medical Science 2018, Vol.80(6), pp.1034-1040
Main Authors: TOMIYASU, Jumpei, KONDOH, Daisuke, YANAGAWA, Yojiro, SATO, Yoshikazu, SAKAMOTO, Hideyuki, MATSUMOTO, Naoya, SASAKI, Kazuyoshi, HANEDA, Shingo, MATSUI, Motozumi
Format: Article
Language:English
Subjects:
Animals
Apocrine Glands - innervation
Apocrine Glands - metabolism
Behavior, Animal
Communication
glycocomposition
Japan
Male
olfactory communication
Seasons
Skin
skin gland
tree-rubbing
Ursidae
Ursus arctos
Volatile Organic Compounds - analysis
Wildlife Science
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Summary:Brown bears communicate with other individuals using marking behavior. Bipedal back rubbing has been identified as a common marking posture. Oily substances are secreted via enlarged sebaceous glands in the back skin of male bears during the breeding season. However, whether apocrine gland secretions are associated with seasonal changes remains unknown. The present study aimed to identify histological and histochemical changes in the secretory status and the glycocomposition of the apocrine glands in the back skin of male bears in response to changes in seasons and/or reproductive status. The apocrine glands of intact males during the breeding season were significantly larger and more active than those of castrated males during the breeding season and those of intact males during the non-breeding season. Lectin histochemical analyses revealed a more intense reaction to Vicia villosa agglutinin (VVA) in the cytoplasm, mainly Golgi zones of apocrine cells during the breeding season among castrated, compared with intact males. Positive staining for VVA was quite intense and weak in intact males during the non-breeding and breeding seasons, respectively. Ultrastructural analysis revealed VVA positivity in the Golgi zone, especially around secretory granules in apocrine cells. Changes in lectin binding might reflect a change in the secretory system in the apocrine cells. The present histological and histochemical findings of changes in the secretory status and glycocomposition of the apocrine glands according to the season and reproductive status suggest that these glands are important for chemical communication.
ISSN:0916-7250
1347-7439
DOI:10.1292/jvms.17-0689