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 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.

Neural control of sweat secretion: a review.

BACKGROUND: Humans have 4 million exocrine sweat glands, which can be classified into two types: eccrine and apocrine glands. Sweat secretion, a constitutive feature, is directly involved in thermoregulation and metabolism, and is regulated by both the central nervous system (CNS) and autonomic nervous system (ANS). OBJECTIVES: To explore how sweat secretion is controlled by both the CNS and the ANS and the mechanisms behind the neural control of sweat secretion. METHODS: We conducted a literature search on PubMed for reports in English from 1 January 1950 to 31 December 2016. RESULTS AND CONCLUSIONS: Acetylcholine acts as a potent stimulator for sweat secretion, which is released by sympathetic nerves. ß-adrenoceptors are found in adipocytes as well as apocrine glands, and these receptors may mediate lipid secretion from apocrine glands for sweat secretion. The activation of ß-adrenoceptors could increase sweat secretion through opening of Ca2+ channels to elevate intracellular Ca2+ concentration. Ca2+ and cyclic adenosine monophosphate play a part in the secretion of lipids and proteins from apocrine glands for sweat secretion. The translocation of aquaporin 5 plays an important role in sweat secretion from eccrine glands. Dysfunction of the ANS, especially the sympathetic nervous system, may cause sweating disorders, such as hypohidrosis and hyperhidrosis.

Rapid stress system drives chemical transfer of fear from sender to receiver.

Humans can register another person's fear not only with their eyes and ears, but also with their nose. Previous research has demonstrated that exposure to body odors from fearful individuals elicited implicit fear in others. The odor of fearful individuals appears to have a distinctive signature that can be produced relatively rapidly, driven by a physiological mechanism that has remained unexplored in earlier research. The apocrine sweat glands in the armpit that are responsible for chemosignal production contain receptors for adrenalin. We therefore expected that the release of adrenalin through activation of the rapid stress response system (i.e., the sympathetic-adrenal medullary system) is what drives the release of fear sweat, as opposed to activation of the slower stress response system (i.e., hypothalamus-pituitary-adrenal axis). To test this assumption, sweat was sampled while eight participants prepared for a speech. Participants had higher heart rates and produced more armpit sweat in the fast stress condition, compared to baseline and the slow stress condition. Importantly, exposure to sweat from participants in the fast stress condition induced in receivers (N = 31) a simulacrum of the state of the sender, evidenced by the emergence of a fearful facial expression (facial electromyography) and vigilant behavior (i.e., faster classification of emotional facial expressions).

Innervation and receptor profiles of the human apocrine (epitrichial) sweat gland: routes for intervention in bromhidrosis.

BACKGROUND: Human apocrine (epitrichial) sweat glands secrete in response to local or systemic administration of catecholamines and cholinergic agonists. As the process of secretion in human apocrine glands is not fully understood and no literature detailing the expression of adrenergic, cholinergic and purinergic receptors is available, there is a need to know the receptor types. Such data could provide new approaches for the treatment of axillary bromhidrosis. OBJECTIVES: To investigate the localization of nerve fibres, adrenergic, cholinergic and purinergic receptors in human axillary apocrine sweat glands by immunohistochemistry. METHODS: Human axillary apocrine sweat glands were investigated by serial sectioning of paraffin wax-embedded skin samples from volunteers. Sections were examined by light microscopy and immunohistochemistry, using antibodies against neurofilament, alpha- and beta-adrenoceptors, P2Y(1), P2Y(2) and P2Y(4) purinoceptors, and M(3) cholinoceptors. RESULTS: Neurofilaments were found near the eccrine but not the apocrine gland. Apocrine glands demonstrated the presence of beta-2 and beta-3 adrenoceptors in the secretory coil of the gland, but not alpha-1, beta-1 or M(3) receptors. Glandular purinergic staining (P2Y(1), P2Y(2) and P2Y(4)) was found in what looked like myoepithelial cells, while P2Y(1) and P2Y(2) staining was found on apical membranes and diffusely throughout secretory cells. Eccrine gland staining acted as internal positive controls. CONCLUSIONS: No nerve fibres were found near the apocrine gland, suggesting that any catecholamine influence is through humoral effects and that glands could be influenced by beta-adrenoceptor subtypes and purinoceptors. Blockage of both these types of receptors offers a route to controlling apocrine secretion from axillary glands and reducing the opportunity for the development of bromhidrosis.

Infraorbital glands of a male Formosan serow (Capricornis crispus swinhoei).

The morphology of the infraorbital glands of a male Formosan serow was examined. The glands consisted of an inner sebaceous portion and an outer apocrine portion. The inner sebaceous portion was much larger than that of the male Japanese serow. The sebaceous portion of the gland consisted of the ordinary and modified types of tissue that are present in the infraorbital gland of the female Japanese serow, and the modified tissue contained some melanin granules and melanocytes. The apocrine portion of the glands was composed of tubules in which the myoepithelial cells stained intensely to very weakly upon immunohistochemical staining with antibody against a smooth muscle actin. Nerve fibers that contained calcitonin gene-related peptide were scattered in the apocrine portion. These findings indicate that the sebaceous gland of the male Formosan serow is different from that of the male Japanese serow but rather similar to that of the female Japanese serow. Moreover, the apocrine gland is innervated by peptide-containing nerve fibers.

Myoepithelial cells and innervation in the infraorbital gland of the Japanese serow (Capricornis crispus).

Both the apocrine and the sebaceous portions of the infraorbital gland of the Japanese serow were examined to obtain morphological evidence related to the mechanism of secretion. The examination was carried out by an immunohistochemical method using antibodies against alpha-smooth muscle actin for myoepithelial cells and protein gene product 9.5 for nerve fibers. Immunostaining for alpha-smooth muscle actin was apparent in the myoepithelial cells of apocrine tubules and varied within the same glands and among individual glands. Immunostaining for protein gene product 9.5 revealed the presence of nerve fibers around apocrine tubules. The immunoreactive nerve fibers were fine or varicose. In the sebaceous glands of the ordinary type and of the modified type, no immunoreactivity specific for alpha-smooth muscle actin or protein gene product 9.5 was observed. These results suggest that apocrine tubular activity of the infraorbital gland occurs independently in each tubule and that secretion by the apocrine tubules is controlled by the myoepithelial cells via nerve fibers.

Innervation of the apocrine sweat glands.

The apocrine glands of the oral angle of the squirrel, and of the hairy skin of the body and the anal sacs of the cat possess cholinergic and adrenergic innervation. Their secretory tubules are enlaced by cholinergic nerves containing chiefly non-specific cholinesterase; the acetylcholinesterase concentration in them is very low in the squirrel and i the glands of the skin of the cat's body, and higher in the glands of the anal sac of the cat. The adrenergic nerve fibers of the apocrine glands possess a very low monoamine oxidase concentration; however, their nonmyelinated terminals, lying on the secretory cells and reaching the lumen of the secretory division, are rich in monoamine oxidase. The innervation of the apocrine and eccrine sweat glands is very similar; in the nerves of the apocrine glands, the acetylcholinesterase and monoamine oxidase concentrations are lower in comparison with the nerves of the eccrine glands; the monoamine oxidase concentration is also lower in cells of the apocrine glands. The question of the essential similarity of the innervation of both types of skin glands - skin and sebaceous - is discussed.

Morphological evidence for the innervation of apocrine sweat glands in the general hairy skin of the goat.

A histomorphological and histochemical study was made on the nerve supply to the apocrine sweat glands in the general hairy skin of the goat. In harmony with the previous report that the sweat glands in the goat are functionally under the control of sympathetic nervous system, the present study clearly demonstrates cholinesterase-reactive nerve fibers that closely surround the secretory portion of these glands in most of the hairy skin area, though the nerve network is fairly coarse. Analysis with cholinesterase inhibitors indicated that the sudomotor nerves in the goat contain both specific and non-specific cholinesterase.