Antagonism of medetomidine sedation by atipamezole in pigs.

The efficacy of atipamezole as a medetomidine antagonist was evaluated in pigs. The atipamezole doses (intramuscularly) were 80, 160, 320 and 480 micrograms/kg of body weight, which were one, two, four and six times higher than the preceding medetomidine dose (80 micrograms/kg, intramuscularly). Atipamezole effectively reversed medetomidine-induced sedation, and the optimal action was seen at doses of 160 and 320 micrograms/kg. Recovery from sedation was quick and smooth, and adverse effects such as hyperactivity or tachycardia were minimal with either dose.     

Suppression of MyoD induces spontaneous adipogenesis in skeletal muscle progenitor cell culture

The degree of intramuscular adipose tissue accumulation is one of the factors affecting meat quality. Accumulation of adipocytes is also observed under the pathological condition of skeletal muscle such as muscular dystrophy and sarcopenia. The origin of adipocytes seen in skeletal muscle is mesenchymal progenitor cells that can give rise to both adipocytes and fibroblasts. In the present study, we demonstrated that siRNA-mediated suppression of MyoD expression in rat skeletal muscle progenitor cell culture, which comprises both myogenic satellite cells and mesenchymal progenitor cells, resulted in diminished myotube formation and an unexpected spontaneous appearance of white adipocytes. Suppressing myomaker expression also resulted in complete absence of myotube formation without reducing MyoD expression, but no adipogenesis was seen in this scenario, indicating that decline in MyoD expression rather than decreased myotube formation is necessary to induce adipogenesis. In addition, spontaneous adipogenesis induced by suppressing MyoD expression in culture was inhibited by the conditioned medium from control culture, indicating that anti-adipogenic factor(s) are secreted from MyoD-positive myogenic cells. These results indicate the presence of regulatory mechanism on adipogenesis by myogenic cells.     

Histocytological specificities of adrenal cortex in the New World Monkeys, Aotus lemurinus and Saimiri boliviensis

The New World monkey Aotus spp. (night monkeys) are expected for use of valuable experimental animal with the close species of Saimiri spp. (squirrel monkeys). Saimiri is known to show spontaneous hypercortisolemia, although few reports in Aotus. We compared basic states of blood steroid hormones and histological structure of the adrenal glands in two monkeys. Serum cortisol and ACTH levels were statistically lower in Aotus than Saimiri. Conversely, Aotus adrenocortical area showed significant enlargement, especially at the zona fasciculata. Electron microscopic observation at Aotus fasciculata cells revealed notable accumulation of large lipid droplets and irregular shapes of the mitochondrial cristae. These results suggest potential differences in cellular activities for steroidogenesis between Aotus and Saimiri and experimental usefulness in adrenocortical physiology and pathological models.     

Quadruple or quintuple conversion of hlb, sak, sea (or sep), scn, and chp genes by bacteriophages in non-beta-hemolysin-producing bovine isolates of Staphylococcus aureus

In 13 of 43 non-beta-hemolysin-producing bovine isolates of Staphylococcus aureus, two truncated beta-hemolysin (hlb) genes were demonstrated by PCR and sequencing, and one truncated hlb gene was located beside the integrase (int) gene of phage origin. The staphylokinase (sak) gene was detected in all 13 isolates in which the truncated hlb genes were detected by PCR. Enterotoxin A (sea) and enterotoxin P (sep) genes were also detected in 5 and 2 of the 13 isolates, respectively. Moreover, the scn and chp genes encoding staphylococcal complement inhibitor (SCIN) and chemotaxis inhibitory protein of S. aureus (CHIPS) were detected in 13 and 4 of the 13 isolates, respectively. The bacteriophage induced by mitomycin C treatment was able to lysogenize one beta-hemolysin-producing isolate of S. aureus, and the sak and scn genes were detected from the lysogenized isolate. These results suggest quadruple or quintuple conversion of hlb, sak, sea (or sep), scn, and chp genes by bacteriophages among non-beta-hemolysin-producing bovine isolates of S. aureus.     

Differences in lectin-binding properties between the common mucosal epithelium and follicle-associated epithelium in the rabbit small intestine

Differences in sugar distribution between the villous epithelium and follicle-associated epithelium (FAE) were compared using lectins in the rabbit small intestine. In every portion, villous columnar epithelial cells primarily exhibited a positive reaction to the GalNAc, GlcNAc, galactose, and oligosaccharide. In the ileal Peyer's patch (PP), whereas microvillous epithelial cells exhibited positive reactions, M cells tended to be negative. The villous epithelial reaction to the fucose group was negative, but M cells and microvillous epithelial cells showed a positive to the fucose. No epithelium had a positive reaction to the mannose and glucose. The variety of lectin-binding properties of villous epithelial cells and M cells may reflect specificity for the recognizing luminal substances such as antigenic molecules and bacterial elements.     

Androgen induces production of male effect pheromone in female goats

Previously we showed that the primer pheromone responsible for the "male effect" was produced in specific skin regions of castrated male goats by androgen treatments. In the present study, we examined whether androgen can also induce production of the male effect pheromone in female goats. Capsules containing dihydrotestosterone (DHT) or testosterone (T) were subcutaneously implanted into six ovariectomized (OVX) goats for 28 days. Small skin samples were collected from the head and rump regions, and the pheromone activity of their ether extracts was examined using a bioassay that monitors the electrophysiological manifestation of the hypothalamic gonadotropin-releasing hormone pulse generator as multiple-unit activity. Behaviors of OVX goats towards ovary-intact estrous goats were also examined before and at the end of DHT or T treatment. Before androgen treatment, neither the head nor rump skin samples in OVX goats showed pheromone activity. DHT treatment induced pheromone activity in the head skin sample of six OVX goats and in the rump skin sample of two OVX goats. Similar results were obtained by T treatment. In addition, OVX goats treated with T showed masculine-type sexual behaviors such as courtship and mounting behaviors towards the estrous goats. These results demonstrate that androgen is capable of inducing primer pheromone activity in the female and suggest that the synthesis pathway of the male effect pheromone exists in both sexes in the goat.     

Effect of ovary lipid of skipjack tuna on rat serum components after stress application

Lipid extracted from the ovary of skipjack tuna by the method that we developed is rich in phospholipid-type docosahexaenoic acid. The ovary lipid of skipjack tuna (OLS) was studied for its anti-stress activity in male Wistar rats, focusing on stress-related blood components: recovery from stress was examined after application of water immersion restraint stress. As a result, serum corticosterone (CORT) secretion was inhibited and decreased rapidly after stress application in rats given OLS compared with control rats. As CORT acts as a glucocorticoid, non-esterified fatty acid (NEFA) is expected to increase by stress application. However, the concentration tended to be lower in rats given OLS than in control rats. With respect to OLS concentration, OLS increased serum dehydroepiandrosterone, secretion concentration-dependently. In addition, as with the recovery study, it tended to inhibit the increase in NEFA. These results indicate that OLS may have an anti-stress activity against acute stress.     

Effects of testosterone on rat placental development

We investigated the morphological effects of testosterone on placental development in a rat model of polycystic ovarian syndrome (PCOS). Testosterone propionate (TP), which was subcutaneously administered to pregnant rats with 5 mg/animal from gestation day (GD) 14 to GD 18, induced a maternal weight reduction without mortality or clinical signs from GD 19 onwards. A decrease in fetal and placental weight, an increase in intrauterine growth retardation (IUGR) rates, and histological changes in the placenta were observed on GD 21 but not on GD15 or 17. Histopathologically, on GD 21, the trophoblast septa thickened, and the maternal sinusoids were narrowed in the labyrinth zone, resulting in a small placenta. Additionally, the placental weight, thickness, and histological morphology in the labyrinth zone on GD 21 in the TP-treated group were nearly identical to those on GD 17 in the control and TP-treated groups. Therefore, it was assumed that the testosterone-induced small placenta was induced in association with the developmental inhibition of the fetal part of the placentas from GD 17 onwards.