Sequence, detection of polymorphisms and radiation hybrid mapping of the equine catechol-o-methyltransferase gene.
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Animals↗
Biomedical subjects
T Kikusui
Publications and source records attributed to T Kikusui.
Alarm pheromone enhances stress-induced hyperthermia in rats.
Behavioral and physiological effects of alarm pheromones emanating from stressed conspecific animals were investigated. Experimentally naive male Wistar rats were exposed to the test chambers containing alarm pheromones, which had been released by other rats receiving foot shocks in the same chamber beforehand. Along with behavioral analysis, the heart rate (HR) and core body temperature (cBT) were measured simultaneously using a biotelemetory system. Exposure to the alarm pheromones increased freezing, sniffing and walking and decreased resting as compared with rats exposed to control odors. In addition, these pheromone-exposed animals showed consistent increases in body temperature, i.e., stress-induced hyperthermia. After exposure to the alarm substances, immunoreactivity to nuclear Fos protein in the mitral cell layer in the accessory olfactory bulb (AOB) also increased compared with the reaction to control odors. These results suggest that an alarm pheromone enhances stress responses of conspecific animals both behaviorally and physiologically, and that these effects are mediated via activation of the AOB.
Animals↗
Induction of primer pheromone production by dihydrotestosterone in the male goat.
Castrated goats were treated with dihydrotestosterone (DHT) for four weeks. Skin samples were collected from the head and the rump regions before and after the DHT treatment. The primer pheromone activities of these samples were assessed neurophysiologically by recording electrophysiological manifestations of the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator activity. Pheromone activity was detected in both the head and rump skin samples following the DHT treatment, although the development of sebaceous glands was limited to the head region. Taken together with our previous finding that testosterone treatment results in the appearance of primer pheromone activity in the skin sample of the head region but not of the rump region. these observations suggests that the regional difference of pheromone production would be ascribed to intrinsic expression levels of 5alpha-reductase, an enzyme converting testosterone to DHT.
Animals↗
Pharmacological manipulations of the extinction process of fear-induced ultrasonic vocalization in rats.
The effects of pharmacological manipulation on the extinction process of fear-induced ultrasonic vocalizations (USVs), which are considered distress calls related to anxiety, were investigated. Male Wistar rats were conditioned to emit USVs by being given repeated electrical foot-shocks while in a chamber. After 10 sessions of conditioning, the animals started to emit USVs upon mere exposure to the shock chamber without being shocked. Using these animals, the extinction process of the USVs was examined. With repeated exposure to the chamber without shocks, the USVs first increased and then gradually decreased. i.e., the extinction burst was observed. Daily intraperitoneal injections of a benzodiazepine-GABA receptor agonist diazepam (DZP; 1.0 mg/kg) or a tricyclic antidepressant clomipramine (CLM; 20 mg/kg) inhibited this extinction burst. Moreover, CLM, but not DZP, shortened the period required for extinction as compared with the vehicle-treated animals. Following the extinction phase, the emission of USVs was enhanced by the cessation of both drug treatments. These results suggest that CLM would be useful for reducing anxiety-related behaviors in the extinction process, as long as withdrawal symptoms after long-term drug treatments are taken into consideration.
Animals↗
The allocentric place discrimination task is selectively and highly dependent on the central muscarinic system in rats.
The allocentric place discrimination task (APDT) is useful in evaluating working memory separately from and simultaneously with motivation, motor and sensory ability. Muscarinic acetylcholine receptor antagonist scopolamine has been shown to selectively impair the accuracy of APDT without changing swimming speed, distance, and still time. For further evaluation of other neurotransmitters' roles in the APDT, pharmacological manipulations were performed. Neither diazepam 3.0 mg/kg, mecamylamine 10 mg/kg, haloperidol 0.5 mg/kg, nor 8-OH DPAT 1.0 mg/kg affected accuracy of place discrimination. Two kinds of responses were observed following the administration of MK-801 0.3 mg/kg: the accuracy of rats for longer swimming distance tended to decrease, and the accuracy of rats for normal swimming distance did not change. Therefore, NM-801 did not seem to affect the working memory selectively. In addition, neither flumazenil 10 mg/kg, ondansetron 0.3 mg/kg nor R(-)-alpha-metylhistamine 10 mg/kg attenuated the scopolamine-induced deficits. These results suggest that the central muscarinic receptors are selectively and highly important in the APDT.
8-Hydroxy-2-(di-n-propylamino)tetralin↗
Testosterone-dependent primer pheromone production in the sebaceous gland of male goat.
To test the hypothesis that the primer pheromone responsible for inducing the "male effect" is produced in the sebaceous gland androgen dependently, we examined the correlation between morphological changes of sebaceous glands and the pheromone activity in skin samples taken from castrated goats that had been treated with testosterone. Five castrated goats were implanted s.c. with testosterone capsules to maintain physiological levels of plasma testosterone for four weeks. Skin samples were obtained from the head region on Day 0 (the day of testosterone implant), Day 7, Day 14, Day 28 (the day of testosterone removal), Day 36, Day 42, and Day 56. Matched blood samples were also collected for measurement of testosterone concentration. The pheromone activity of the ether-extracts of the upper dermal layer containing sebaceous glands was assessed by its stimulatory effect on the hypothalamic GnRH pulse generator, which was monitored for changes of specific multiple unit activity (MUA) in ovariectomized estradiol-primed goats as described previously. The sebaceous gland enlarged during the testosterone treatment but reduced in size after testosterone removal. The pheromone activity first appeared in 2 out of 5 goats on Day 7 and in all the 5 goats by Day 28. Fourteen days after testosterone removal (Day 42), the pheromone activity was no longer detectable in any of the 5 goats. In short, the sebaceous gland size and the pheromone activity shifted almost in parallel. The present results provide strong support for the view that the primer pheromone is produced testosterone dependently in the sebaceous gland of the male goat.
Animals↗
Regional differences of pheromone production in the sebaceous glands of castrated goats treated with testosterone.
The primer pheromone is responsible for the "male effects" in goats and produced in the sebaceous glands testosterone-dependently. In the present study, the responses of sebaceous glands obtained from the head and rump regions of castrated goats were examined by our bioassay system after testosterone treatment to demonstrate the presence of regional differences in the pheromone production in male goats. The testosterone treatment resulted in the marked development of sebaceous glands and the induction of pheromone bioactivity in the head region of the goats. On the contrary, this treatment brought neither development of the sebaceous glands nor induction of pheromone bioactivity in the rump region. The treatment increased immunoreactivities to androgen receptors (AR) and 5alpha-reductase in the sebaceous glands of both regions, although the activities were more apparent in the head region than the rump region. These findings suggest that the primer pheromone of male goats is produced specifically in the sebaceous glands of the head region due partly to regional differences in the expression of AR and 5alpha-reductase mediating testosterone bioactivities.
3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
Sex determination based on fecal DNA analysis of the amelogenin gene in sika deer (Cervus nippon).
A sex determination method using DNA extracted from feces has been developed for sika deer (Cervus nippon). We determined a partial sequence of the amelogenin gene of sika deer, which exists on both X and Y chromosomes with a deletion region on the Y chromosome. Based on the sexually dimorphic sequences, we designed a pair of primers which could amplify DNA fragments the lengths of which are different between males and females. PCR products were detected in 34 out of 37 fecal samples collected from captured deer and the sexes estimated by the present method were perfectly matched with the actual sexes.
Amelogenin↗
Spatial working memory is independent of hippocampal CA1 long-term potentiation in rats.
This study investigated the relationship between spatial working memory and hippocampal long-term potentiation (LTP) using the allocentric place discrimination task (APDT) in rats, in which the selection accuracy is a good index for spatial working memory. Either the selective M1 muscarinic receptor antagonist pirenzepine (50 microg) or the choline uptake inhibitor hemicholinium-3 (5 microg) impaired APDT selection accuracy, but neither affected the induction of LTP in the hippocampal CA1 region in anesthetized rats. In contrast, the selective N-methyl-D-aspartate receptor antagonist D-amino-5-phosphonopentanoate (200 nmol) did not impair APDT selection accuracy but completely blocked hippocampal CA1 LTP. These results suggest that spatial working memory is independent of hippocampal CA1 LTP and that the central cholinergic system is involved in spatial working memory, but not through the modulation of hippocampal CAI LTP.
Animals↗
Simultaneous evaluation of spatial working memory and motivation by the allocentric place discrimination task in the water maze in rats.
In order to evaluate learning and memory deficits separately from and simultaneously with motivational, motor and sensory impairments in identical animals, we developed the allocentric place discrimination task test using a water maze in rats. For this assessment task, two similar, visible platforms, one was fixed and the other was floating, were simultaneously present in a pool, and the working memory of the allocentric place discrimination task was evaluated. After training, the task accuracy was high about 85% correct and animals were used repeatedly. The accuracy decreased significantly when the pool was surrounded with a black curtain. Muscarinic receptor antagonist scopolamine 0.5 mg/kg selectively impaired the accuracy. Muscle relaxant dantrolene 10 mg/kg selectively decreased swimming speed. Under low motivational condition (warm water), still time increased and swimming speed decreased, but the accuracy was not affected. Similar to warm water, opioid receptor agonist morphine 15 mg/kg increased still time and decreased swimming speed. These results suggest that the allocentric place discrimination task is useful in evaluating spatial working memory ability independently of and concurrently with also visual, motor ability and motivation in identical animals.
Analgesics, Opioid↗
Pathophysiological changes evoked by lipopolysaccharide administration in goats.
To establish an adequate experimental model for the study of immuno-neuroendocrine mechanisms underlying the behavioral changes during the acute infection, temporal relationship of various physiological responses to endotoxin administration was examined in ovariectomized goats. Immediately after intravenous injection of 200 ng/kg of lipopolysaccharide, there were an abrupt decrease of white blood cell number and a gradual increase of rectal temperature, which were followed by elevation of plasma levels of adrenocorticotropic hormone, cortisol, glucose, free fatty acids, and then later by an increase of heart rate. The results suggest that the endotoxin administration would evoke a stereotyped cascade of, febrile, neuroendocrine and metabolic as well as autonomic response to the activation of immune systems in the ruminant species.
Acute Disease↗
Immunohistochemical localization of corticotropin-releasing factor, [arginine8]-vasopressin and oxytocin neurons in the goat hypothalamus.
Distribution patterns of corticotropin-releasing factor (CRF), [arginine8]-vasopressin (AVP) and oxytocin (OXY) neurons were examined immunohistochemically in the female goat hypothalamus. The majority of the CRF immunoreactive (-IR) cells were located in the parvocellular part of the paraventricular nucleus (PVN) with smaller population found in the magnocellular part of the PVN. CRF-IR cells were also found in the suprachiasmatic nucleus, the preoptic area and around the fornix in the caudal part of the hypothalamus. AVP- and OXY-IR cells were similarly distributed in the hypothalamus. The majority of AVP- and OXY-IR cells were observed in the magnocellular part of PVN and the supraoptic nucleus. Smaller numbers of AVP- and OXY-IR cells were found in the parvocellular part of the PVN and lateral hypothalamic area. AVP-IR but not OXY-IR cells were located in the suprachiasmatic nucleus. CRF-IR fibers were concentrated in the external palisade zone of the median eminence (ME) with a few fibers found in the internal palisade zone of the ME, whereas AVP- and OXY-IR fibers were concentrated in the internal palisade zone of the ME with a few fibers found in the external zone. These results support the view that not only CRF but also AVP and OXY are released into the hypophysial portal blood and involved in the control of pituitary endocrine function in ruminant species.
Animals↗
Changes in the behavioral parameters following the lipopolysaccharide administration in goats.
The present study was aimed at the establishment of an experimental model for the numerical assessment of sick animal behavior. Four goats were given bolus injections of 200 ng/kg of lipopolysaccharide (LPS) or vehicle (0 hr) under non-restrained conditions, and observed for behavioral changes and clinical symptoms during the period between -1 and 10 hr. The apparent clinical symptoms of miosis and shivering were observed during the period from 39.5 +/- 3.1 to 296.5 +/- 9.9 min and from 46.0 +/- 2.3 to 251.0 +/- 15.5 min after the LPS administration, respectively. As to the general behaviors, the total length for standing and sternum lying during the period from 0 to 5 hr after LPS administration showed no change, however, that for feeding and rumination, and the cumulative number of grooming episode were significantly reduced as compared to the control period. On the other hand, the cumulative numbers of urination, defecation and yawning showed a tendency to increase but not significantly. These results suggest that stereotyped behavioral responses, which are typically seen in acute phase of sickness, can be transiently induced in goats by treating them with LPS.
Animals↗
Involvement of corticotropin-releasing factor in the retrieval process of fear-conditioned ultrasonic vocalization in rats.
The role of the corticotropin-releasing factor (CRF) system in the fear-conditioned ultrasonic vocalizations (USVs) induced by foot shocks in rats was investigated. In the acquisition phase of fear conditioning, the intracerebroventricular administration of CRF receptor antagonist alpha-hCRF attenuated USV responses related to context memory. Even after experiencing eight consecutive days of foot-shock challenges, the alpha-hCRF group emitted similar number of USVs as the control group if they were not given the drug. After the conditioning phase, the groups treated with alpha-hCRF or CRF receptor 1 (CRFR1) antagonist CP-154,526 emitted fewer conditioned USVs than the control group, although there was no difference in the USVs after the shock, which reflected physical stress. These results suggest that the central CRF systems, especially those mediated via CRFR1, are involved in the retrieval process, but not the acquisition or retention processes, of fear-related memory.
Animals↗
Age-related working memory deficits in the allocentric place discrimination task: possible involvement in cholinergic dysfunction.
It is well known that learning and memory ability declines with aging. Age-related long-term changes in learning and memory ability in rats were investigated with the place navigation task and the allocentric place discrimination task (APDT) in a water maze using the same animals for each task. In a working memory place navigation task, aged animals could learn the location of the platform as well as when they were young, although strategy shifts were observed. In contrast, accuracy in the APDT significantly declined from 90% to 65% with aging. This impairment was ameliorated by an acetylcholine esterase inhibitor physostigmine at 22-23 months old. No amelioration was, however, detected in the same animals tested when they further aged to 26-27 months old. These results suggest that the APDT performance is sensitive to age-related memory deficits and that this may be due to the cholinergic dysfunction.
Aging↗