Contraction Of Myoepithelial Cells Research Articles

Hemal sinus basal laminae contact sites: a possible route between gonadal lumen and myoepithelial cells in the gonad of the sea star Patiria pectinifera.

Sea stars are a group of marine invertebrates suitable for studying the hormonal regulation of reproduction and spawning. In spite of substantial progress in understanding how various substances such as 1-methyladenine act in their gonads, there are still many gaps concerning the fine details of their action. One such gap is how the gonadal wall contraction is induced. Recent literature data suggest that, upon 1-methyladenine stimulation, some cells within the gonadal lumen produce non-neuronal acetylcholine that, upon contact with the gonadal wall, induces contraction of myoepithelial cells. Our ultrastructural study of the gonads in the sea star Patiria pectinifera has shown, for the first time, that there are sites where the basal laminae bordering the hemal sinus directly contact one another and appear at this contact site as a single entity. These contact sites are often associated with hemidesmosome-like junctions that anchor male accessory cells or female follicle cells on one side of the site and myoepithelial cells on the opposite. We suggest that contraction-inducing substance is secreted from an accessory or follicle cell, passes through a basal lamina contact site, and on the opposite side of the contact site acts on a myoepithelial cell to induce its contraction.

Gap junction-mediated contraction of myoepithelial cells induces the peristaltic transport of sweat in human eccrine glands

Eccrine sweat glands play an essential role in regulating body temperature. Sweat is produced in the coiled secretory portion of the gland, which is surrounded by obliquely aligned myoepithelial cells; the sweat is then peristaltically transported to the skin surface. Myoepithelial cells are contractile and have been implicated in sweat transport, but how myoepithelial cells contract and transport sweat remains unexplored. Here, we perform ex vivo live imaging of an isolated human eccrine gland and demonstrate that cholinergic stimulation induces dynamic contractile motion of the coiled secretory duct that is driven by gap junction-mediated contraction of myoepithelial cells. The contraction of the secretory duct occurs segmentally, and it is most prominent in the region surrounded by nerve fibers, followed by distension-contraction sequences of the excretory duct. Overall, our ex vivo live imaging approach provides evidence of the contractile function of myoepithelial cells in peristaltic sweat secretion from human eccrine glands.

Role of the adenylate cyclase/cyclic AMP pathway in oxytocin-induced lacrimal gland myoepithelial cells contraction

The aim of these studies was to investigate the involvement of the second messenger 3′,5′-cyclic adenosine monophosphate (cAMP) and its downstream effectors in oxytocin (OXT)-mediated lacrimal gland myoepithelial cell (MEC) contraction. Lacrimal gland MEC were isolated and propagated from alpha-smooth muscle actin (SMA)-GFP mice. RNA and protein samples were prepared to analyze G protein expression by RT-PCR and western blotting; respectively. Changes in intracellular cAMP concentration were measured using a competitive ELISA kit. To increase intracellular cAMP concentration, the following agents were used: forskolin (FKN, a direct activator of adenylate cyclase), 3-isobutyl-1-methylxanthine (IBMX, an inhibitor of the phosphodiesterase that hydrolyzes cAMP), or a cell permeant cAMP analog, dibutyryl (db)-cAMP. In addition, inhibitors and selective agonists were used to investigate the role of cAMP effector molecules, protein kinase A (PKA) and exchange protein activated by cAMP (EPAC) in OXT-induced MEC contraction. MEC contraction was monitored in real time and changes in cell size were quantified using ImageJ software. The adenylate cyclase coupling G proteins, Gαs, Gαo, and Gαi, are expressed in lacrimal gland MEC at both the mRNA and protein levels. OXT increased intracellular cAMP in a concentration-dependent manner. FKN, IBMX and db-cAMP significantly stimulated MEC contraction. Preincubation of cells with either Myr-PKI, a specific PKA inhibitor or ESI09, an EPAC inhibitor, resulted in almost complete inhibition of both FKN- as well as OXT-stimulated MEC contraction. Finally, direct activation of PKA or EPAC using selective agonists triggered MEC contraction. We conclude that cAMP agonists modulate lacrimal gland MEC contraction via PKA and EPAC activation which also play a major role in OXT induced MEC contraction.

The Matricellular Protein SPARC Decreases in the Lacrimal Gland At Adulthood and During Inflammation.

Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein abundantly expressed in basement membranes and capsules surrounding a variety of organs and tissues. It mediates extracellular matrix organization and has been implicated in cell contraction. Here, we evaluated the expression of SPARC in the murine lacrimal gland at adulthood and during inflammation. Lacrimal glands of young mice (4-6 weeks old) and adult mice (32-40 weeks old) were used for extraction of DNA, RNA, and protein. The presence of SPARC was assessed by quantitative PCR, ELISA, and immunofluorescence microscopy. 5-Methylcytosine and DNA methylation were evaluated using ELISA and bisulfite genomic sequencing, respectively. The effects of cytokines and inflammation in Sparc expression were evaluated in vitro and in the non-obese diabetic (NOD) mouse model of Sjögren's syndrome. The mRNA and protein levels of SPARC were downregulated in lacrimal glands of mature adult mice presenting age-related histological alterations such as increased deposition of lipofuscin and lipids. Epigenetic analyses indicated that glands in adult mice contain higher levels of global DNA methylation and show increased hypermethylation of specific CpG sites within the Sparc gene promoter. Analysis of smooth muscle actin (SMA)-green fluorescent protein (GFP) transgenic mice revealed that SPARC localizes primarily to myoepithelial cells within the gland. Treatment of myoepithelial cells with IL-1β or TNF-α and the development of inflammation in the NOD mice led to decreased transcription of Sparc. SPARC is a novel matricellular glycoprotein expressed by myoepithelial cells in the lacrimal gland. Loss of SPARC during adulthood and chronic inflammation might have detrimental consequences on myoepithelial cell contraction and the secretion of tear fluid.

Pulmonary neuroendocrine cells sense succinate to stimulate myoepithelial cell contraction.

Pulmonary neuroendocrine cells (PNECs) are rare airway cells with potential sensory capacity linked to vagal neurons and immune cells. How PNECs sense and respond to external stimuli remains poorly understood. We discovered PNECs located within pig and human submucosal glands, a tissue that produces much of the mucus that defends the lung. These PNECs sense succinate, an inflammatory molecule in liquid lining the airway surface. The results indicate that succinate migrates down the submucosal gland duct to the acinus, where it triggers apical succinate receptors, causing PNECs to release ATP. The short-range ATP signal stimulates the contraction of myoepithelial cells wrapped tightly around the submucosal glands. Succinate-triggered gland contraction may complement the action of neurotransmitters that induce mucus release but not gland contraction to promote mucus ejection onto the airway surface. These findings identify a local circuit in which rare PNECs within submucosal glands sense an environmental cue to orchestrate the function of airway glands.

Role of the Phospholipase C Pathway and Calcium Mobilization in Oxytocin-Induced Contraction of Lacrimal Gland Myoepithelial Cells.

PurposeWe reported that oxytocin (OXT), added to freshly prepared lacrimal gland lobules, induced myoepithelial cell (MEC) contraction. In other systems, OXT activates phospholipase C (PLC) generating Inositol 1,4,5-trisphosphate (IP3) which increases intracellular calcium concentration ([Ca2+]i) causing contraction. The aim of the current study was to investigate the role of this pathway in OXT-induced contraction of MEC.MethodsTear volume was measured using the cotton thread method. Lacrimal gland MEC were isolated and propagated from α-smooth muscle actin (SMA)-green fluorescent protein (GFP) mice, in which MEC express GFP making them easily identifiable. RNA and protein samples were prepared for RT-PCR and Western blotting for G protein expression. Changes in [Ca2+]i were measured in Fura-2 loaded MEC using a ratio imaging system. MEC contraction was monitored in real time and changes in cell size were quantified using ImageJ software.ResultsOXT applied either topically to surgically exposed lacrimal glands or delivered subcutaneously resulted in increased tear volume. OXT stimulated lacrimal gland MEC contraction in a dose-dependent manner, with a maximum response at 10−7 M. MEC express the PLC coupling G proteins, Gαq and Gα11, and their activation by OXT resulted in a concentration-dependent increase in [Ca2+]i with a maximum response at 10−6 M. Furthermore, the activation of the IP3 receptor to increase [Ca2+]i is crucial for OXT-induced MEC contraction since blocking the IP3 receptor with 2-APB completely abrogated this response.ConclusionsWe conclude that OXT uses the PLC/Ca2+ pathway to stimulate MEC contraction and increase lacrimal gland secretion.

Lacrimal Gland Myoepithelial Cells Are Altered in a Mouse Model of Dry Eye Disease

The purpose of this study was to determine the pathogenic changes that occur in myoepithelial cells (MECs) from lacrimal glands of a mouse model of Sjögren syndrome. MECs were cultured from lacrimal glands of C57BL/6J [wild type (WT)] and thrombospondin 1 null (TSP1-/-, alias Thbs1-/-) mice and from mice expressing α-smooth muscle actin-green fluorescent protein that labels MECs. MECs were stimulated with cholinergic and α1-adrenergic agonists, vasoactive intestinal peptide (VIP), and the purinergic agonists ATP and UTP. Then intracellular [Ca2+] was measured using fura-2, and contraction was observed using live cell imaging. Expression of purinergic receptors was determined by Western blot analysis, and mRNA expression was analyzed by microarray. The increase in intracellular [Ca2+]I with VIP and UTP was significantly smaller in MECs from TSP1-/- compared with WT mice. Cholinergic agonists, ATP, and UTP stimulated contraction in MECs, although contraction of MECs from TSP1-/- mice was reduced compared with WT mice. The amount of purinergic receptors P2Y1, P2Y11, and P2Y13 was significantly decreased in MECs from TSP1-/- compared with WT mice, whereas several extracellular matrix and inflammation genes were up-regulated in MECs from TSP1-/- mice. We conclude that lacrimal gland MEC function is altered by inflammation because the functions regulated by cholinergic agonists, VIP, andpurinergic receptors are decreased in TSP1-/- compared with WT mice.

Organellar Contacts of Milk Lipid Droplets.

Milk-secreting epithelial cells of the mammary gland are functionally specialized for the synthesis and secretion of large quantities of neutral lipids, a major macronutrient in milk from most mammals. Milk lipid synthesis and secretion are hormonally regulated and secretion occurs by a unique apocrine mechanism. Neutral lipids are synthesized and packaged into perilipin-2 (PLIN2) coated cytoplasmic lipid droplets within specialized cisternal domains of rough endoplasmic reticulum (ER). Continued lipid synthesis by ER membrane enzymes and lipid droplet fusion contribute to the large size of these cytoplasmic lipid droplets (5–15 μm in diameter). Lipid droplets are directionally trafficked within the epithelial cell to the apical plasma membrane. Upon contact, a molecular docking complex assembles to tether the droplet to the plasma membrane and facilitate its membrane envelopment. This docking complex consists of the transmembrane protein, butyrophilin, the cytoplasmic housekeeping protein, xanthine dehydrogenase/oxidoreductase, the lipid droplet coat proteins, PLIN2, and cell death-inducing DFFA-like effector A. Interactions of mitochondria, Golgi, and secretory vesicles with docked lipid droplets have also been reported and may supply membrane phospholipids, energy, or scaffold cytoskeleton for apocrine secretion of the lipid droplet. Final secretion of lipid droplets into the milk occurs in response to oxytocin-stimulated contraction of myoepithelial cells that surround milk-secreting epithelial cells. The mechanistic details of lipid droplet release are unknown at this time. The final secreted milk fat globule consists of a triglyceride core coated with a phospholipid monolayer and various coat proteins, fully encased in a membrane bilayer.

867 Contraction of myoepithelial cells in human eccrine sweat glands, revealed by 3D live imaging

Sweat glands are single tubular organs subdivided into two parts: excretory and secretory ducts, both of which form a complicated coiled structure in the deep dermis. Secretory ducts are surrounded by contractile myoepithelial cells. Contraction of these myoepithelial cells is thought to contribute to the secretion of sweat. However, it remains unknown whether sweat gland myoepithelial cells contract. We previously revealed that myoepithelial cells were aligned in a well-oriented manner, enabling efficient contraction of secretory ducts, which likely facilitates sweat excretion. Human sweat gland dynamics were captured using a live-imaging system with actin, nuclear, and cell membrane markers. The contraction of myoepithelial cells was induced by pilocarpine, an acetylcholine analogue. Live-imaging data revealed that a portion of the secretory duct began to contract in the direction of narrowing tube diameter, immediately after pilocarpine addition; this was followed by gradual distention of two distal excretory ducts. The contractile motion of the coiled tubular components of the sweat gland showed sequential contraction, enabling transportation of sweat. Moreover, this contraction was inhibited by the sweating antagonist, atropine. These results suggest that myoepithelial cell contraction may be necessary to generate the driving force for transporting the sweat. We plan to further analyze the kinetics of myoepithelial contracting motion, in combination with pharmacological intervention, to identify the specific regulatory mechanisms involved.

Oxytocin Induces Mammary Epithelium Disruption and Could Stimulate Epithelial Cell Exfoliation.

Mammary epithelial cells (MEC) are exfoliated from the epithelium into milk, influencing the number of MEC present in the udder. This process is associated with epithelium integrity. The release of oxytocin (OT) induced by milking causes myoepithelial cell contraction, which, in turn, may stimulate MEC exfoliation through mechanical forces. To investigate the role of OT in MEC exfoliation, we inhibited or induced myoepithelial cell contraction by injecting the OT receptor antagonist atosiban (Ato) or a supraphysiological dose of OT, respectively. Eight cows were assigned to 2 treatments during 2 milkings according to a crossover experimental design: Control+OT (cows were first milked to collect standard milk and then received 5IU of OT to collect residual milk through a second milking) and Ato + OT (cows were injected with Ato (50μg/kg of body weight) and milked to collect cisternal milk, then received 5IU of OT to collect alveolar milk through a second milking). Milk MEC were purified to determine their concentration and number in milk. Mammary epithelium integrity was assessed by measuring the kinetics of plasma lactose concentration. Inhibiting myoepithelial cell contraction by Ato injection decreased the number of exfoliated MEC in milk. In contrast, OT injection increased the concentration of MEC in the residual milk and the number of MEC in the alveolar milk. Ato injection reduced plasma lactose concentration, whereas, in both treatments, OT injections increased it. Our results suggested that myoepithelial cell contraction caused by OT could stimulate MEC exfoliation into milk and was associated with epithelium disruption.

Odorous secretions in anurans: morphological and functional assessment of serous glands as a source ofvolatile compounds in the skin of the treefrog Hypsiboas pulchellus (Amphibia: Anura: Hylidae).

Serous (granular or venom) glands occur in the skin of almost all species of adult amphibians, and are thought to be the source of a great diversity of chemical compounds. Despite recent advances in their chemistry, odorous volatile substances are compounds that have received less attention, and until now no study has attempted to associate histological data with the presence of these molecules in amphibians, or in any other vertebrate. Given the recent identification of 40 different volatile compounds from the skin secretions of H. pulchellus (a treefrog species that releases a strong odour when handled), we examined the structure, ultrastructure, histochemistry, and distribution of skin glands of this species. Histological analysis from six body regions reveals the presence of two types of glands that differ in their distribution. Mucous glands are homogeneously distributed, whereas serous glands are more numerous in the scapular region. Ultrastructural results indicate that electron-translucent vesicles observed within granules of serous glands are similar to those found in volatile-producing glands from insects and also with lipid vesicles from different organisms. Association among lipids and volatiles is also evidenced from chemical results, which indicate that at least some of the volatile components in H. pulchellus probably originate within the metabolism of fatty acids or the mevalonate pathway. As odorous secretions are often considered to be secreted under stress situations, the release of glandular content was assessed after pharmacological treatments, epinephrine administrated invivo and on skin explants, and through surface electrical stimulation. Serous glands responded to all treatments, generally through an obvious contraction of myoepithelial cells that surround their secretory portion. No response was observed in mucous glands. Considering these morpho-functional results, along with previous identification of volatiles from H. pulchellus and H. riojanus after electrical stimulation, we suggest that the electron-translucent inclusions found within the granules of serous glands likely are the store sites of volatile compounds and/or their precursors. Histochemical and glandular distribution analyses in five other species of frogs of the hylid tribe Cophomantini, revealed a high lipid content in all the species, whereas a heterogeneous distribution of serous glands is only observed in species of the H. pulchellus group. The distribution pattern of serous glands in members of this species group, and the odorous volatile secretions are probably related to defensive functions.

Pengaruh Pijat Panggung terhadap Produksi ASI Ibu Post Partum di Ruang Cempaka Room Ngudi Waluyo Wlingi Hospital

Breast milk is an emulsion of fat in the protein solution, laktosa, and inorganic salts secreted by the mamary glands of the mother. The oxytocin hormone is a hormone that affects of lactation process. Oxytocin is up to the alveoli of the mammry myoepithelial cell contraction causes surrounding the mammary alveoli and lactiferous ducts. Back massage on cervical 5-6 until the bottom of the shoulder blade stimulate endorphins and oxytocin secretion and improves blood circulation breast area. The purpose of research to determine the effect of back massage on milk production an mothers post partum in cempaka’s room Ngudi Waluyo Wlingi Hospital November 2014. Design Quasi Experimental research with the design of the Control Group Pre-Test Post-Test Design with Non Random data retrieval with Consecutive Sampling (1 week) with total 24 population and total sample 20 respondents. Analysis data with two different Test Mean (T Test) Independent by using Paired Sample Test with H1 is accepted when the value of p < 0,05 and Independent Sample Test H1 is accepted when the value of p < 0,05. And research result Paired Sample Test the showed significant values (p) of 0,000 smaller than alpha 0,05. And there is influence of back massage on milk production before and after treatment. From the reserch result suggested all post partum mothers to do a back massage.

Invertebrate specific D1‐like dopamine receptor in control of salivary glands in the black‐legged tick Ixodes scapularis

The control of tick salivary secretion, which plays a crucial role in compromising the host immune system, involves complex neural mechanisms. Dopamine is known to be the most potent activator of salivary secretion, as a paracrine/autocrine factor. We describe the invertebrate-specific D1-like dopamine receptor (InvD1L), which is highly expressed in tick salivary glands. The InvD1L phylogenic clade was found only in invertebrates, suggesting that this receptor was lost in vertebrates during evolution. InvD1L expressed in Chinese hamster ovary (CHO)-K1 cells was activated by dopamine with a median effective dose (EC50 ) of 1.34 μM. Immunohistochemistry using the antibody raised against InvD1L revealed two different types of immunoreactivities: basally located axon terminals that are colocalized with myoinhibitory peptide (MIP) and SIFamide neuropeptides, and longer axon-like processes that are positive only for the InvD1L antibody and extended to the apical parts of the acini. Both structures were closely associated with the myoepithelial cell, as visualized by beta-tubulin antibody, lining the acinar lumen in a web-like fashion. Subcellular localizations of InvD1L in the salivary gland suggest that InvD1L modulates the neuronal activities including MIP/SIFamide varicosities, and leads the contraction of myoepithelial cells and/or of the acinar valve to control the efflux of the luminal content. Combining the previously described D1 receptor with its putative function for activating an influx of fluid through the epithelial cells of acini, we propose that complex control of the tick salivary glands is mediated through two different dopamine receptors, D1 and InvD1L, for different downstream responses of the acinar cells.

Use of Wood's model to analyze the effects of milking methods on lactation curve in sheep

One hundred and sixty-six lactating Makui breed sheeps (2–6 years old) were used to investigate the effects of two milking methods (milking with oxytocin (OT) and milking without oxytocin (HT)), ewes age and stage of lactation on milk yield and composition during 168 days of lactation and to estimate shape of lactation curve using Wood's model. Oxytocin treatment (OT) had a significant effect on the average daily milk yield (ADMY) and total milk yield (TMY) (P<0.0001). TMY for OT ewes was 45.61% (P<0.01) greater than that in HT ewes. OT ewes had significantly (P<0.01) longer lactation period (LL) than HT ewes. The effects of ewes age on ADMY, TMY and LL were significant (P<0.01). In both milking methods, 4-, 5- and 6-year-old ewes produced significantly (P<0.01) greater ADMY and TMY than 2 years old ones. Stages of lactation had a highly significant (P<0.0001) effect on milk yield. Except (b) parameter, (a) and (c) parameters of Wood's model were significantly (P<0.05) affected by milk measurement methods. In addition, effects of ewes age on the model's parameters were significant (P<0.05). TMY obtained by Wood's model was not affected (P>0.05) whereas peak time (PT), peak yield (PY) and persistency (P) were significant (P<0.05) as compared with Fleischmann method for two milking methods. OT ewes reached PT (day) earlier than HT ewes. OT method had a significant effect on fat and SNF percent (P<0.05) whereas percent of protein and lactose unaffected by OT and HT methods (P>0.05). In both methods, stages of lactation had a highly significant effect on milk fat, protein and SNF percentage (P<0.05). The results of this experiment showed that oxytocin has galactopoietic effect due to the contraction of myoepithelial cells maybe limiting the effects of milk-borne negative feed-back mechanism on milk secretion and Wood's model overestimated TMY and PY whereas underpredicted PT and P.

Lactogenic activity of rats stimulated by Gunnera perpensa L. (Gunneraceae) from South Africa.

Gunnera perpensa L. (Gunneraceae) is a medicinal plant used by Zulu traditional healers to stimulate milk production. The effect of an aqueous extract of the rhizome of the plant on milk production in rats was investigated. Female lactating rats that received oral doses of the extract of G.perpensa significantly (p<0.05) produced more milk than controls. The plant extract did not however, significantly influence the levels of prolactin, growth hormone, progesterone, cortisol, ALT, AST and albumin in the blood. The mammary glands of rats treated with the extract showed lobuloalveolar development. The extract (0.8 µg/ml) was also found to stimulate the contraction of the uterus and inhibit (23%) acetylcholinesterase activity. The cytotoxicity of the extract (LC₅₀) to two human cell lines (HEK293 and HepG2) was 279.43 µg/ml and 222.33µg/ml, respectively. It is inferred that the plant extract exerts its activity on milk production and secretion by stimulating lobuloalveolar cell development and the contraction of myoepithelial cells in the alveoli. It is concluded that Gunnera perpensa contains constituents with lactogenic activity that apparently contribute to its effectiveness in folk medicine.

Smooth muscle α actin is specifically required for the maintenance of lactation

Smooth muscle α-actin (Acta2) is one of six highly conserved mammalian actin isoforms that appear to exhibit functional redundancy. Nonetheless, we have postulated a specific functional role for the smooth muscle specific isoform. Here, we show that Acta2 deficient mice have a remarkable mammary phenotype such that dams lacking Acta2 are unable to nurse their offspring effectively. The phenotype was rescued in cross fostering experiments with wild type mice, excluding a developmental defect in Acta2 null pups. The mechanism for the underlying phenotype is due to myoepithelial dysfunction postpartum resulting in precocious involution. Further, we demonstrate a specific defect in myoepithelial cell contractility in Acta2 null mammary glands, despite normal expression of cytoplasmic actins. We conclude that Acta2 specifically mediates myoepithelial cell contraction during lactation and that this actin isoform therefore exhibits functional specificity.

Confocal microscopy with double immunofluorescence staining reveals the functional transient receptor potential vanilloid subtype 1 expressed in myoepithelial cells of human submandibular glands

Myoepithelial cells (MECs) mainly surround acini and intercalated ducts in the human salivary glands. The contraction of MECs provides the expulsive force to promote salivation. We previously found functional transient receptor potential vanilloid subtype 1 (TRPV1) was expressed in rabbit and human submandibular glands and increased saliva secretion. However, it was unknown whether TRPV1 was expressed in MECs of submandibular glands. In this study, we observed the immunoflourescence of TRPV1 was not only located in serous acini and ducts but also surround the basal layer of the acinus and intercalated ducts of human submandibular glands. Double immunofluorescence staining revealed colocalization of TRPV1 with calponin, vimentin, and α-smooth muscle actin, which indicated the myoepithelial expression of TRPV1. Treating submandibular gland tissues with capsaicin, an agonist of TRPV1, substantially increased the phosphorylation of the 20-kDa regulatory light-chain subunit of myosin (MLC(20) ), a crucial molecule for contraction of smooth muscle cells, in MECs. Pretreatment with capsazepine, a specific TRPV1 inhibitor, blocked capsaicin-induced MLC(20) phosphorylation. These results suggest that TRPV1 is expressed in MECs of the human submandibular gland and mediates myoepithelial contraction via a mechanism involving MLC(20) phosphorylation.

Differential polymorphism in cutaneous glands of archaic Leiopelma species

Endemic New Zealand frogs of the genus Leiopelma are from a basal lineage of extant anurans that release defensive secretions onto their skin when disturbed. Here, we characterize the gross anatomy and microscopic structure of the skin of L. archeyi, L. hochstetteri, and L. pakeka using stereoscopic, light and transmission electron microscopy. The terrestrial L. archeyi and L. pakeka possess dimorphic granular glands, categorized as type I and II, based on their frequency and morphological traits, whereas the semi-aquatic L. hochstetteri lacks type I glands. This is the first report of differential dimorphism in anurans of the same genus. This dimorphism could be interpreted as an adaptation to different physiological or ecological needs of these species. However, species within this ancient genus share similar general gland morphology with other anurans, namely, a secretory unit containing storage granules ensheathed by myoepithelial cells. Type I glands are ellipsoid, large and contain a homogeneous mass of electron-dense granules (1.8 ± 0.08 μm in diameter). Type II glands are round and contain larger heterogeneous granules (4.06 ± 0.16 μm) of varying densities. Exposure to noradrenaline causes the contraction of myoepithelial cells, resulting in bulk discharge of type I glands through the epidermal duct onto the skin surface. Differential release of secretions from dimorphic glands may be indicative of their functional specialisation in antipredatory or regulative roles. Mass spectrometric techniques were used to de novo sequence peptides present in the skin secretions of Leiopelma species. A total of 30 previously undescribed peptides from Leiopelma species were fully or partially sequenced. These peptides exhibited no similarity to any known compounds.

Myoepithelial Cell Contraction and Milk Ejection Are Impaired in Mammary Glands of Mice Lacking Smooth Muscle Alpha-Actin1

Mammary myoepithelial cells are specialized smooth musclelike epithelial cells that express the smooth muscle actin isoform: smooth muscle alpha-actin (ACTA2). These cells contract in response to oxytocin to generate the contractile force required for milk ejection during lactation. It is believed that ACTA2 contributes to myoepithelial contractile force generation; however, this hypothesis has not been directly tested. To evaluate the contribution of ACTA2 to mammary myoepithelial cell contraction, Acta2 null mice were utilized and milk ejection and myoepithelial cell contractile force generation were evaluated. Pups suckling on Acta2 null dams had a significant reduction in weight gain starting immediately postbirth. Cross-fostering demonstrated the lactation defect is with the Acta2 null dams. Carmine alum whole mounts and conventional histology revealed no underlying structural defects in Acta2 null mammary glands that could account for the lactation defect. In addition, myoepithelial cell formation and organization appeared normal in Acta2 null lactating mammary glands as evaluated using an Acta2 promoter-GFP transgene or phalloidin staining to visualize myoepithelial cells. However, mammary myoepithelial cell contraction in response to oxytocin was significantly reduced in isolated Acta2 null lactating mammary glands and in in vivo studies using Acta2 null lactating dams. These results demonstrate that lack of ACTA2 expression impairs mammary myoepithelial cell contraction and milk ejection and suggests that ACTA2 expression in mammary myoepithelial cells has the functional consequence of enhancing contractile force generation required for milk ejection.

Properties of substance P-stimulated mucus secretion from porcine tracheal submucosal glands

Human and pig airway submucosal glands secrete mucus in response to substance P (SubP), but in pig tracheal glands the response to SubP is >10-fold greater than in humans and shares features with cholinergically produced secretion. CFTR-deficient pigs provide a model for human cystic fibrosis (CF), and in newborn CF pigs the response of tracheal glands to SubP is significantly reduced (Joo et al. J Clin Invest 120: 3161-3166, 2010). To further define features of SubP-mediated gland secretion, we optically measured secretion rates from individual adult porcine glands in isolated tracheal tissues in response to mucosal capsaicin and serosal SubP. Mucosal capsaicin (EC(50) = 19 μM) stimulated low rates of secretion that were partially inhibited by tetrodotoxin and by inhibitors for muscarinic, VIP, and SubP receptors, suggesting reflex stimulation of secretion by multiple transmitters. Secretion in response to mucosal capsaicin was inhibited by CFTR(inh)-172, but not by niflumic acid. Serosal SubP (EC(50) = 230 nM) stimulated 10-fold more secretion than mucosal capsaicin, with a V(max) similar to that of carbachol. Secretion rates peaked within 5 min and then declined to a lower sustained rate. SubP-stimulated secretion was inhibited 75% by bumetanide, 53% by removal of HCO(3)(-), and 85% by bumetanide + removal of HCO(3)(-); it was not inhibited by atropine but was inhibited by niflumic acid, clotrimazole, BAPTA-AM, nominally Ca(2+)-free bath solution, and the adenylate cyclase inhibitor MDL-12330A. Ratiometric measurements of fura 2 fluorescence in dissociated gland cells showed that SubP and carbachol increased intracellular Ca(2+) concentration by similar amounts. SubP produced rapid volume loss by serous and mucous cells, expansion of gland lumina, mucus flow, and exocytosis but little or no contraction of myoepithelial cells. These and prior results suggest that SubP stimulates pig gland secretion via CFTR- and Ca(2+)-activated Cl(-) channels.