The motor, modulatory, and sensory neurotransmitters that mediate the peristaltic reflex in the mouse colon were identified by direct measurement, and their involvement in various pathways was determined by selective receptor antagonists. Mucosal stimulation in the central compartment of a three-compartment flat sheet preparation of mouse colon elicited ascending contraction and descending relaxation in the orad and caudad compartments, respectively. Ascending contraction was accompanied by substance P release, a marker for excitatory neurotransmitter release, into the orad compartment and was partly inhibited by atropine and spantide, and abolished by a combination of the two antagonists. Descending relaxation was accompanied by vasoactive intestinal peptide (VIP) release, a marker for inhibitory neurotransmitter release, into the caudad compartment, and was partly inhibited by VIP10-28 and NG-nitro-L-arginine, and abolished by a combination of the two agents. Somatostatin release increased during descending relaxation: immunoneutralization of somatostatin or blockade of its effect with a selective somatostatin type 2 receptor antagonist inhibited descending relaxation. The delta-opioid receptor antagonist naltrindole augmented descending relaxation and ascending contraction. Calcitonin gene-related peptide (CGRP) release increased in the central compartment and was mediated by concurrent release of 5-hydroxytryptamine (5-HT) because its release was blocked by a 5-HT4 receptor antagonist. Both the latter and the CGRP antagonist CGRP8-37, inhibited ascending contraction and descending relaxation. Thus, the reflex in mouse like that in rat and human intestine is initiated by mucosal release of 5-HT and activation of 5-HT4 receptors on CGRP sensory neurons and is relayed via somatostatin and opioid interneurons to VIP/nitric-oxide synthase inhibitory motor neurons and via cholinergic interneurons to acetylcholine/tachykinin excitatory motor neurons.

Kokumi taste substances exemplified by γ-glutamyl peptides and Maillard Peptides modulate salt and umami tastes. However, the underlying mechanism for their action has not been delineated. Here, we investigated the effects of a kokumi taste active and inactive peptide fraction (500–10,000 Da) isolated from mature (FII_m) and immature (FII_im) Ganjang, a typical Korean soy sauce, on salt and umami taste responses in humans and rodents. Only FII_m (0.1–1.0%) produced a biphasic effect in rat chorda tympani (CT) taste nerve responses to lingual stimulation with 100 mM NaCl + 5 μM benzamil, a specific epithelial Na⁺ channel blocker. Both elevated temperature (42 °C) and FII_m produced synergistic effects on the NaCl + benzamil CT response. At 0.5% FII_m produced the maximum increase in rat CT response to NaCl + benzamil, and enhanced salt taste intensity in human subjects. At 2.5% FII_m enhanced rat CT response to glutamate that was equivalent to the enhancement observed with 1 mM IMP. In human subjects, 0.3% FII_m produced enhancement of umami taste. These results suggest that FII_m modulates amiloride-insensitive salt taste and umami taste at different concentration ranges in rats and humans.

Coexpression of Y₁, Y₂, and Y₄ receptors on smooth muscle cells was determined by reverse transcription-polymerase chain reaction, and the receptors were characterized by radioligand binding, selective receptor protection, and functional analysis of signaling pathways. ¹²⁵I-peptide YY (PYY) binding was completely inhibited by neuropeptide Y (NPY) and PYY, and partially inhibited by the Y₁ agonist [Leu³¹, Pro³⁴]NPY or the Y₂ agonist NPY_13–36. In cells where Y₁ receptors were preserved by selective receptor protection, ¹²⁵I-PYY binding was selectively inhibited by the Y₁ agonist or antagonist BIBP 3226 [(R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl)methyl]-d-arginine-amide]. Conversely, in cells where Y₂ receptors were preserved, ¹²⁵I-PYY binding was selectively inhibited by the Y₂ agonist or antagonist BIIE 0246 [(S)N²-[1-[2-[4-[(R,S)-5,11-dihydro-6(66H)-oxodibenz[b,e]azepin-11-y]-1piperazinyl]-2-oxoethyl]cyclopentyl]acetyl]-N-[2-[1,2-dihydro-35(4H)-dioxo-1,2-diphenyl-3H-1,2,4-triazol-4-yl]ethyl]-argininamide]. All Y receptors activated preferentially G_i2, but only Y₂ and Y₄ receptors activated G_q. Consequently, Y₂ agonists (NPY, PYY, and NPY_13–36) and the Y₄ agonist (pancreatic polypeptide) induced concentration-dependent contraction, inositol 1,4,5-trisphosphate (IP₃) formation, and increase in cytosolic free Ca²⁺. Contraction induced by Y₂ and Y₄ agonists was not affected by 0 Ca²⁺, Ca²⁺ channel blockers, or pertussis toxin (PTx), but it was abolished by thapsigargin, U73122 [1-(6-(17β-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-25-dione], or the myosin light chain kinase inhibitor ML-9 [1-(5-chloronaphthalene-1-sulfonyl)homopiperazine, HCl]. Y₂-mediated contraction was inhibited by the selective Y₂ antagonist BIIE 0246. Insensitivity to PTx implied that the coupling to G_i did not initiate (Y₁) or contribute (Y₂ and Y₄) to contraction. All Y receptor agonists inhibited cAMP formation in a PTx-sensitive manner. The patterns of contraction and inhibition of cAMP by various Y receptors were corroborated by selective receptor protection. The study demonstrates coexpression of Y₁, Y₂, and Y₄ receptors on smooth muscle negatively coupled to adenylyl cyclase via G_i2. Coupling of Y₂ and Y₄ receptors to G_q determines their ability to induce IP₃-dependent Ca²⁺ release and initiate contraction.

Across the entire distribution of a species, populations may have variable responses to environmental perturbations. Many bat species experience mortality in large portions of their range during hibernation and along migratory paths to and from wintering grounds, from White-nose syndrome (WNS) and wind energy development, respectively. In some areas, warm temperatures may allow bats to remain active through winter, thus decreasing their susceptibility to WNS and/or mortality associated with migration to wintering grounds. These areas could act as a refugia and be important for the persistence of local populations. To determine if warmer temperatures affect bat activity, we compared year-round activity of bat populations in the Coastal Plain and Piedmont of North Carolina, USA, two regions that differ in winter temperature. We established six recording stations, four along a 295-kilometer north-south transect in the Coastal Plain, and two in the Piedmont of North Carolina. We recorded bat activity over two years. We supplemented our recordings with mist-net data. Although bat activity was lower during winter at all sites, the odds of recording a bat during winter were higher at Coastal Plain sites when compared with Piedmont sites. Further, bats in the Piedmont had a lower level of winter activity compared to summer activity than bats in the Coastal Plain that had more similar levels of activity in the winter and summer. We found high bat species richness on the Coastal Plain in winter, with winter-active species including those known to hibernate throughout most of their range and others known to be long distance migrants. In particular, two species impacted by WNS, the northern long-eared bat (Myotis septentrionalis) and tricolored bat (Perimyotis subflavus), were present year round in the Coastal Plain. The tricolored bat was also present year-round in the Piedmont. In the Coastal Plain, the long distance migratory hoary bat (Lasiurus cinereus) was active in the winter but not present during the other seasons, and the long distance migratory silver-haired bat (Lasionycteris noctivagans) was active primarily in the winter, suggesting the Coastal Plain may be an overwintering ground for these two species. We suggest that the winter activity exhibited by populations of bats on the North Carolina Coastal Plain has important conservation implications and these populations should be carefully monitored and afforded protection.

A two-compartment, flat-sheet preparation of rat colon was devised, which enabled exclusive measurement of longitudinal muscle activity during the ascending and descending phases of the peristaltic reflex. A previous study using longitudinal muscle strips revealed the operation of an integrated neuronal circuit consisting of somatostatin, opioid, and VIP/pituitary adenylate cyclase-activating peptide (PACAP)/nitric oxide synthase (NOS) interneurons coupled to cholinergic/tachykinin motor neurons innervating longitudinal muscle strips that could lead to descending contraction and ascending relaxation of this muscle layer. Previous studies in peristaltic preparations have also shown that an increase in somatostatin release during the descending phase causes a decrease in Met-enkephalin release and suppression of the inhibitory effect of Met-enkephalin on VIP/PACAP/NOS motor neurons innervating circular muscle and a distinct set of VIP/PACAP/NOS interneurons. The present study showed that in contrast to circular muscle, longitudinal muscle contracted during the descending phase and relaxed during the ascending phase. Somatostatin antiserum inhibited descending contraction and augmented ascending relaxation of longitudinal muscle, whereas naloxone had the opposite effect. VIP and PACAP antagonists inhibited descending contraction of longitudinal muscle and augmented ascending relaxation. Atropine and tachykinin antagonists inhibited descending contraction of longitudinal muscle. As shown in earlier studies, the same antagonists and antisera produced opposite effects on circular muscle. We conclude that longitudinal muscle contracts and relaxes in reverse fashion to circular muscle during the peristaltic reflex. Longitudinal muscle activity is regulated by excitatory VIP/PACAP/NOS interneurons coupled to cholinergic/tachykinin motor neurons innervating longitudinal muscle.