Effect of topical ophthalmic instillation of rocuronium bromide on the intraocular pressure of kestrels (Falco tinnunculus) and little owls (Athene noctuae).

OBJECTIVE: To assess the effect of rocuronium bromide-induced mydriasis on the intraocular pressure (IOP) of kestrels (Falco tinnunculus) and little owls (Athene noctuae). ANIMALS: 13 adult kestrels and 13 adult little owls. PROCEDURES: All birds were ophthalmologically normal. During the first of 2 treatment periods, a 1% rocuronium bromide solution was topically instilled in both eyes of all birds at a dose of 0.12 mg (12 µL) for kestrels and 0.20 mg (20 µL) for little owls. No ophthalmic treatments were administered during the second (control) treatment period, which was conducted 1 week after the first. During both treatment periods, rebound tonometry was used to measure IOP before rocuronium bromide instillation or at the beginning of the control period (baseline) and at predetermined times after baseline or until the pupillary light reflex returned to normal. All IOP measurements were obtained between 8 am and 5 pm. RESULTS: The mean IOP did not differ significantly from baseline for either species during the control treatment period. During the rocuronium bromide treatment period, complete mydriasis was achieved in all birds. The mean IOP was significantly decreased from baseline and from the corresponding mean IOP for the control period beginning 60 and 30 minutes after drug instillation for kestrels and owls, respectively, and reached its nadir at 60 minutes after drug instillation for both species. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that topical instillation of rocuronium bromide in the eyes successfully induced mydriasis and decreased the IOP of common kestrels and little owls.

Substance P and the neurokinin-1 receptor expression in dog ileum with and without inflammation.

In the gastrointestinal tract, the tachykinin Substance P (SP) is involved in motility, fluid and electrolyte secretion, and blood flow and regulation of immunoinflammatory response. SP exerts its biological activity on target cells by interacting mainly with the neurokinin-1 receptor (NK1R). The present study aims to quantify the percentage of SP-immunoreactive (SP-IR) enteric neurons and the density of SP-IR nerve fibers in the ileum of control dogs (CTRL-dogs; n=7) vs dogs with spontaneous ileal inflammation (INF-dogs; n=8). In addition, the percentage of enteric neurons bearing NK1R, and nitrergic neurons (nNOS-IR) expressing NK1R immunoreactivity were evaluated in both groups. The percentages of SP-IR neurons were similar in CTRL- and INF-dogs, in either the myenteric (MP) (15±8% vs. 16±7%, respectively) and submucosal plexus (SMP) (26±7% vs. 24±14%, respectively). In INF-dogs, the density of SP-IR mucosal nerve fibers showed a trend to decrease (P=0.07). Myenteric neurons of CTRL- and INF-dogs expressed similar percentages of NK1R-immunoreactivity (39±5% vs. 38±20%, respectively). Submucosal NK1R-IR neurons were occasionally observed in a CTRL-dog. MP nitrergic neurons bearing NK1R showed a trend to decrease in INF-dogs vs. CTRL- dogs (41±22% vs. 65±10%, respectively; P=0.11). In INF-dogs, muscle cells and immune cells overexpressed NK1R immunoreactivity. These findings should be taken as a warning for possible intestinal motility disorders, which might occur during administration of NK1R-antagonist drugs. Conversely, the strong expression of NK1R immunoreactivity observed in muscle and mucosal immune cells of inflamed tissues may provide a rationale for the use of NK1R antagonist drugs in the treatment of intestinal inflammation.

The KIT gene is associated with the english spotting coat color locus and congenital megacolon in Checkered Giant rabbits (Oryctolagus cuniculus).

The English spotting coat color locus in rabbits, also known as Dominant white spotting locus, is determined by an incompletely dominant allele (En). Rabbits homozygous for the recessive wild-type allele (en/en) are self-colored, heterozygous En/en rabbits are normally spotted, and homozygous En/En animals are almost completely white. Compared to vital en/en and En/en rabbits, En/En animals are subvital because of a dilated ("mega") cecum and ascending colon. In this study, we investigated the role of the KIT gene as a candidate for the English spotting locus in Checkered Giant rabbits and characterized the abnormalities affecting enteric neurons and c-kit positive interstitial cells of Cajal (ICC) in the megacolon of En/En rabbits. Twenty-one litters were obtained by crossing three Checkered Giant bucks (En/en) with nine Checkered Giant (En/en) and two en/en does, producing a total of 138 F1 and backcrossed rabbits. Resequencing all coding exons and portions of non-coding regions of the KIT gene in 28 rabbits of different breeds identified 98 polymorphisms. A single nucleotide polymorphism genotyped in all F1 families showed complete cosegregation with the English spotting coat color phenotype (θ=0.00 LOD  =75.56). KIT gene expression in cecum and colon specimens of En/En (pathological) rabbits was 5-10% of that of en/en (control) rabbits. En/En rabbits showed reduced and altered c-kit immunolabelled ICC compared to en/en controls. Morphometric data on whole mounts of the ascending colon showed a significant decrease of HuC/D (P<0.05) and substance P (P<0.01) immunoreactive neurons in En/En vs. en/en. Electron microscopy analysis showed neuronal and ICC abnormalities in En/En tissues. The En/En rabbit model shows neuro-ICC changes reminiscent of the human non-aganglionic megacolon. This rabbit model may provide a better understanding of the molecular abnormalities underlying conditions associated with non-aganglionic megacolon.