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T Osaka

Publications and source records attributed to T Osaka.

At least 19 recordsLinked to original sources
PubMed1995

A novel apparatus that permits multiple routes for infusions and body-fluid collections in a freely-moving animal.

A novel apparatus is described for simultaneous performance of multi-channel infusions/body-fluid collections and multichannel electrical recordings/stimulations in a freely behaving animals. This apparatus consists of a cylindrical cage and other devices described below. Electrical contacts are achieved via a slip-ring commutator. A rotation detector detects the turning of the animal in the cage, and a controller rotates the floor under the animal in the opposite direction by means of a stepping motor. Thus, excessive twisting of the fluid tubing between the animal and experimental equipment is released by rotation of the floor. Floor rotation starts when the animal turns in either direction and exceeds a present number of rotations. When the turning exceeds certain rates, the floor is rotated with higher angular velocities. This floor rotation little affected sleep-wake activities, brain temperature, food and water intake, and general behavior of the rat. Thus, multi-channel fluid routes have been realized; and by excluding the swivel apparatus from the fluid lines, advantages such as no fluid leakage at the swivel, no extra dead volume, and low torque to rotate the device have been gained.

Animals↗
PubMed1995

Noradrenaline inhibits preoptic sleep-active neurons through alpha 2-receptors in the rat.

Effects of noradrenaline (NA) on the activity of sleep-related neurons in the preoptic area (POA) and the neighboring basal forebrain were examined in the rat. Of 36 sleep-active neurons tested, 19 were inhibited and the other 17 were unaffected by NA applied through a multibarrel pipette. The alpha 2-agonist clonidine inhibited 11 of 14 sleep-active neurons and did not affect the other 3 neurons, whereas the alpha 1-agonist methoxamine (n = 13) and the beta-agonist isoproterenol (n = 11) had no effect on any of the sleep-active neurons tested. Thus, alpha 2-receptors mediated the NA-induced inhibition. Of 22 waking-active neurons tested, NA excited 10, inhibited 1, and had no effect on the remaining 11. Methoxamine excited 4 of 13 waking-active neurons tested, whereas isoproterenol (n = 9) and clonidine (n = 4) were without effect on any of the waking-active neurons tested. Accordingly, alpha 1-receptors probably mediated the NA-induced excitation. Seventy-seven state-indifferent neurons, which lacked activity related to the sleep-waking state, and 20 paradoxical sleep-active neurons were mostly (65%-70%) insensitive to NA. These results suggest that NA promotes wakefulness by inhibiting sleep-active neurons and by exciting waking-active neurons.

Animals↗
PubMed1995

Prostaglandin D2 modulates sleep-related and noradrenaline-induced activity of preoptic and basal forebrain neurons in the rat.

Prostaglandin D2 (PGD2) was applied by pressure through a multibarrel micropipette to sleep-related neurons in the preoptic and neighboring basal forebrain area in head-restrained unanesthetized rats. During wakefulness, PGD2 excited six of 13 sleep-active neurons, inhibited seven of 13 waking-active neurons, and did not affect the remaining neurons. During slow-wave sleep (SWS), however, PGD2 excited only three of 17 sleep-active neurons and inhibited two of 13 waking-active neurons. State-indifferent neurons, which lacked activity related to the sleep-waking state, were insensitive to PGD2 irrespective of wakefulness (n = 24) and SWS (n = 40). These results suggest that PGD2 promotes sleep by exciting sleep-active neurons and by inhibiting waking-active neurons. Furthermore, continuous administration of PGD2 attenuated activity changes associated with wakefulness of five sleep-active and three waking-active neurons tested. Because we had suggested the involvement of preoptic noradrenaline (NA) in arousal, we examined possible modulatory effects of PGD2 on NA-induced neuron responses. PGD2 attenuated NA-induced inhibitory responses in four of six sleep-active neurons and in one of 10 state-indifferent neurons. PGD2 also attenuated NA-induced excitation in four waking-active neurons tested. Accordingly, the modulatory action of PGD2 on sleep-related neurons is important in the mechanism of sleep.

Animals↗
PubMed1995

Activity of neurons in the lateral preoptic area during drinking behavior by the rat.

Rats were trained to drink water, sucrose solution, and saline while their heads were painlessly held in a stereotaxic apparatus with an attachment fixed to the skull. A total of 286 neurons in the lateral preoptic area (LPO) were recorded during the drinking behavior. During water intake, 40% of the neurons tested were either excited or inhibited. Sucrose elicited responses in 25% of the neurons, and saline in 34%. Of the 52 neurons recorded while rats drank all test solutions, 8 specifically responded to water, 3 were sucrose specific, 4 were saline specific, 12 responded to all solutions, and the remaining 25 did not respond to any solutions. Artificial cerebrospinal fluids (ACSFs) with physiologically hypertonic (+30 mOsm/kg, by NaCl or mannitol) and hypotonic (-30 mOsm/kg) osmotic pressure were applied to 88 neurons through a multibarrel micropipette. Of these neurons, 15 (17%) were hypotonic-sensitive; they were excited by hypotonic ACSF and/or inhibited by hypertonic ACSFs. There were 4 (5%) that were hypertonic-sensitive; they were excited by hypertonic ACSFs and/or inhibited by hypotonic ACSF. Of six hypotonic-sensitive neurons examined, three were water specific, and none were sucrose nor saline specific. Of four hypertonic-sensitive neurons, one was water specific, and another was saline specific. These results showed activity of some LPO neurons specifically related to water intake. Osmosensitive neurons in the LPO may regulate water intake.

Action Potentials↗
PubMed1995

Osmosensitive hypothalamic neurons and their responses to cardiovascular receptor activation.

Neurons in the rostral hypothalamic areas were examined with physiologically hypertonic (+30 mOsm/kg, by NaCl or mannitol) and hypotonic (-30 mOsm/kg) artificial cerebrospinal fluids (ACSFs) applied by pressure through a multibarrel micropipette in urethane-anesthetized rats. Of 304 neurons tested, 39 were excited by the hypertonic ACSFs and/or inhibited by the hypotonic ACSF, and 35 were inhibited by the hypertonic ACSFs and/or excited by the hypotonic ACSF. The former cells were designated hypertonic-sensitive and the latter hypotonic-sensitive. Both types of osmosensitive neurons were diffusely scattered in the examined areas, but neurons in the lateral preoptic area and the bed nucleus of the stria terminalis responded more frequently (30-40%) to the osmotic stimuli. Osmosensitive and insensitive neurons were recorded during activation of the baro- and volume receptors of the cardiovascular system. Of seven neurons that were excited during temporal hypotension induced by intravenous administration of nitroprusside, five were hypertonic-sensitive and two were osmotically insensitive. Hypertonic-sensitive neurons may be activated during dehydration, which increases the osmotic pressure and decreases the volume of body fluids. Of six neurons that were excited during temporal hypertension induced by intravenous administration of phenylephrine, four were hypotonic-sensitive and two were osmotically insensitive. Hypotonic-sensitive neurons may be activated during rehydration or overhydration. Osmosensitive neurons probably integrate cardiovascular and osmotic information that is important for the central regulation of body fluids.

Action Potentials↗
PubMed1995

Adjuvant-induced persistent photosensitivity models in guinea pigs. II. Characterization of immunological mechanisms.

The immunological characteristics of our adjuvant-induced persistent photosensitivity (AIPP) guinea pig model were examined. The sensitivity to long-wavelength ultraviolet light (UVA) was transferred with peritoneal exudate cells. Proliferative response was observed in peritoneal exudate cells and lymph node cells concomitantly cultured in the presence of sera that had previously been irradiated with UVA. Cervical lymph nodes of AIPP animals were found to be hypertrophic, and the ratio of major histocompatibility complex (MHC) class II positive cells was increased as compared to that of intact guinea pigs. These results suggest that persistent photosensitivity elicited with UVA is based on cellular autoimmunity. Thus, the AIPP guinea pig model should be useful to study the mechanism of persistent photosensitivity disease in humans.

Adjuvants, Immunologic↗
PubMed1994

Prostaglandin D2-sensitive, sleep-promoting zone defined in the ventral surface of the rostral basal forebrain.

The site of action for the sleep-promoting effect of prostaglandin (PG) D2 was extensively examined in the brain of adult male rats (n = 231). PGD2 was administered at 100 pmol/0.2 microliter per min for 6 hr (2300-0500 hr) through chronically implanted microdialysis probes or infusion cannulae. Among the administrations of PDG2 by dialysis probes (n = 176), only those (n = 8) to a ventro-rostral part of the basal forebrain by the probes implanted on the midline consistently increased slow-wave sleep (SWS), by 51 +/- 6 min (mean +/- SEM) above the baseline value (111 +/- 11 min). Since this area is separated by a cleft into right and left regions, the results were interpreted to mean that, through this cleft, PGD2 diffused in the subarachnoid space over the adjacent ventral surface, where it had the effect of promoting sleep. When PGD2 was directly infused into the subarachnoid space (n = 55), extraordinary increases exceeding 90 min were consistently attained for the SWS at sites located between 0.5 and 2 mm rostral to the bregma and between 0 and 1.2 mm lateral to the midline defined according to the stereotaxic coordinates adopted from the brain atlas of Paxinos and Watson [Paxinos, G. & Watson, C. (1986) The Rat Brain in Stereotaxic Coordinates (Academic, San Diego)]. Thus, we demarcated a "PGD2-sensitive, sleep-promoting zone" within this region in the ventral surface of the rostral basal forebrain. During the bilateral infusion of PGD2 into the subarachnoid space of this zone, the hourly mean SWS level of the nocturnal animals (n = 6) in the night reached the maximum at the second hour of the infusion period; this maximum hourly SWS level, corresponding to the daytime level of the same animals, lasted until the end of PGD2 infusion.

Animals↗
PubMed1994

Noradrenergic inputs to sleep-related neurons in the preoptic area from the locus coeruleus and the ventrolateral medulla in the rat.

Responses of sleep-related neurons in the preoptic area (POA) to stimulation of the locus coeruleus (LC) and the ventrolateral medulla (VLM), components of the reticular activating system, were recorded in the unanesthetized, head-restrained rat. Single-pulse stimulation of the LC and the VLM, respectively, inhibited 50% and 54% of 30 sleep-active neurons and excited 47% and 67% of 34 waking-active neurons. The remaining neurons were mostly unaffected. Seventy-three neurons that were not related to a sleep-wake state were mostly (i.e., 73-80%) unresponsive to stimulation. The high incidence of responses by sleep-related neurons suggests that neural inputs from the LC and VLM regulate the hypnogenic mechanisms in the POA. Stimulation of the LC antidromically activated 15% of sleep-active neurons and 11% of waking-active neurons. Thus, some of the sleep-related neurons in the POA may regulate LC neurons. In a later stage of the experiment, we used isoflurane-anesthetized rats that had been used for recording sleep-related neurons. Antagonists for adrenoceptors at a concentration of 10 microM were applied to neurons through a multibarrel micropipette to examine the involvement of noradrenaline in the responses as a neurotransmitter. Application of the alpha 2-blocker, yohimbine, attenuated the inhibitory responses in all 7 neurons tested. The beta-blocker, timolol, and the alpha 1-blocker, prazosin, did not alter any of the inhibitory responses. On the other hand, timolol attenuated the excitatory responses in 4 of 7 neurons, and prazosin attenuated the excitatory responses in 5 of 12 neurons. Yohimbine did not affect the excitatory responses. Thus, the LC and the VLM probably inhibit sleep-active neurons through alpha 2-adrenoceptors and excite waking-active neurons through either beta- or alpha 1-adrenoceptors.

Animals↗
PubMed1994

The healing process of chronic colitis in rats, induced by 2,4,6-trinitrobenzene sulfonic acid, with special reference to the role of fibronectin.

BACKGROUND: The healing process of rat chronic colitis was investigated to evaluate the role of fibronectin produced by fibroblasts in the healing tissue. METHODS: Chronic colitis was produced by intrarectal instillation of 2,4,6-trinitrobenzene sulfonic acid. The healing process was observed by light and electron microscopy and immunocytochemistry. Time course of fibronectin mRNA expression was measured by Northern blot hybridization. RESULTS: By light and electron microscopy, an abundance of young fibroblasts had gathered at the healing tissue and were involved in incorporation into the endothelium of the preexisting vessels, as vasoformative cells, and in transformation to new muscle cells in muscular regeneration. Such processes became pronounced from day 3 and persisted for 6 weeks. Immunocytochemical data showed that fibronectin, produced in the rough endoplasmic reticulum of the fibroblasts and released to the extracellular surface, played inductive roles in the movement and aggregation of such cells and in their contacts with neighboring endothelial cells of the preexisting capillaries. Northern hybridization showed that mRNA coding for fibronectin rapidly reached maximum on day 3 and gradually decreased almost to the control level at 6 weeks. CONCLUSIONS: These observations elucidate the role of young fibroblasts, as multipotent cells, and of fibronectin in acceleration of the healing process in this model of chronic colitis.

Animals↗
PubMed1993

Lateral preoptic neurons inhibit thirst in the rat.

Kainic acid (KA) and muscimol were injected into the lateral preoptic area (LPO) of the rat to study their effects on drinking behavior. A low dose (5 ng) of KA, which stimulates neurons, decreased the amount of water intake induced by hypertonic saline (IP) and angiotensin II (SC). Injection of 2 ng muscimol, a potent GABAA receptor agonist that suppresses neurons, facilitated drinking responses induced by hypertonic saline, but did not affect angiotensin II-induced drinking. Rats injected with a high dose (150 ng) of KA, which destroys neurons, showed marked polydipsia accompanied by increased urination. One week after the KA lesion, drinking and urine output recovered to normal. During the polydipsia, a small volume of concentrated urine could be excreted if water intake was restricted. After recovery, excessive drinking responses followed water deprivation and hypertonic saline load. The rats normally drank water in response to angiotensin II and to polyethylene glycol solution. The results show that activation of LPO neurons inhibits water intake, and that suppression of LPO neurons facilitates osmotically induced water intake. Therefore, LPO neurons are probably involved in the inhibition of thirst.

Animals↗
PubMed1993

Postnatal decrease in muscarinic cholinergic influence on Ca2+ currents of rabbit ventricular cells.

We have studied developmental changes in the muscarinic cholinergic modulation of L-type Ca2+ current (ICa) in enzymatically isolated adult and newborn (1-4 days old) rabbit ventricular cells using the whole-cell patch-clamp method. Carbachol (10 microM) caused a 2.8-fold increase in the half-maximal concentration (EC50) for isoproterenol to stimulate ICa for adult cells compared with the control with little effect on the maximal ICa density (Imax), whereas the stimulatory effect of isoproterenol on newborn ICa was completely eliminated by 10 microM of carbachol and was decreased by 40% at 0.1 microM carbachol. Carbachol increased the EC50 for forskolin to stimulate ICa 2.9-fold for adult cells and 7.3-fold for newborn cells with little effect on the Imax for either group. 5'-Guanylyl imidodiphosphate [Gpp(NH)p; 100 microM] reduced the stimulatory effect of 0.1 microM isoproterenol on adult ICa (percent increase over predrug level) by a factor of 1.8 compared with the control (400 microM guanosine triphosphate), whereas the isoproterenol effect on newborn ICa was completely eliminated by Gpp(NH)p. The isoproterenol effect on adult ICa persisted after the washout of isoproterenol in the presence of Gpp(NH)p. Gpp(NH)p also reduced the stimulatory effect of 1 microM of forskolin by a factor of 2.0 and 8.2 for adult and newborn cells, respectively, in comparison to the control. Carbachol caused no additional effect on forskolin-stimulated ICa for either adult or newborn ICa in the presence of Gpp(NH)p. Pretreatment with pertussis toxin completely eliminated the inhibitory effect of carbachol on forskolin-stimulated ICa for both groups. In addition, the effect of forskolin on ICa was markedly enhanced by the pertussis toxin pretreatment in newborn cells, whereas the enhancement was relatively small for adult cells. We conclude that the muscarinic cholinergic influence on L-type ICa decreases after birth in rabbit ventricular cells, presumably through a diminishing influence of an inhibitory G protein on regulating adenylyl cyclase during the postnatal period.

Adenylate Cyclase Toxin↗
PubMed1993

Relationship between total serum cholesterol level and nutritional and physical status in Nepalese rural people.

To investigate the nutritional condition in a hilly village (Kotyang) and a suburban village (Bhadrakali) in Nepal and to clarify the possible cause of the difference in total serum cholesterol level between the two groups of villagers habitually eating low fat diets, we carried out a nutrition survey using the 24-h recall method and blood sampling in 403 subjects (204 men and 199 women) in the hilly village and 466 (244 men and 222 women) in the suburban village. Total serum cholesterol was statistically significantly lower in the hilly villagers than in the suburban villagers for both sexes, but HDL-cholesterol was not. In both villages, 82% of the total energy was taken from carbohydrate, 7-8% from fat and 10% from protein. Energy, protein, fiber, potassium, magnesium, monounsaturated fatty acid, polyunsaturated fatty acid, and vitamin A in the hilly villagers were significantly higher than those in the suburban villagers. Total serum cholesterol was significantly associated with age and body fat percentage, suggesting that total serum cholesterol level was not directly associated with total fat intake in these Nepalese people.

Adult↗
PubMed1993

Investigation of high salt intake in a Nepalese population with low blood pressure.

The relation between BP and the factors influencing an increase in BP with age were investigated in the inhabitants of two representative hilly (Kotyang: 206 men and 212 women) and suburban (Bhadrakali: 265 and 244) villages in Nepal. BP for both sexes was statistically significantly higher in Bhadrakali than in Kotyang. Neither hypertension nor elevation of BP with age for men and very few women (1.4%) with hypertension were observed in Kotyang, while 10.9% of men and 4.9% of women were found to be hypertensive in Bhadrakali. Average urinary Na excretion was 183-221 mEq/day in both villages. Urinary Na/K ratio, percentage body fat (%Fat), total protein, total cholesterol and serum Ca were statistically significantly higher in Bhadrakali than in Kotyang, and maximal oxygen uptake and serum Mg were higher in Kotyang. In spite of high salt consumption, there was no increase in BP with age in Kotyang's males, suggesting that the BP may be influenced by physical activity, fat-free mass and nutrient consumption in addition to the high sodium intake, and that extremely high physical activity and very low %Fat could serve to mute the influence of high sodium intake.

Adult↗
PubMed1992

Intraperitoneal administration of recombinant human interleukin-1 beta inhibits osmotic thirst in the rat.

Decrease in water intake after intraperitoneal injection of interleukin-1 beta (IL-1 beta) was studied in the rat. Administration of IL-1 beta at a dose of 20 micrograms/kg attenuated osmotic thirst induced by intraperitoneal injection of hypertonic saline, but did not affect hypovolemic thirst induced by subcutaneous injection of either polyethylene glycol or angiotensin II. Interleukin-1 beta also decreased spontaneous intake of water but not that of 1.8% saline. The results suggest that the decrease in water intake by IL-1 beta is caused, at least in part, by suppression of osmotic thirst but not by general suppression of behavior. The effects of IL-1 beta were not secondary responses accompanied by feeding behavior, since food supply was removed during the experiments. Pretreatment with indomethacin blocked the decrease in water intake by IL-1 beta, suggesting the involvement of production of prostaglandins.

Angiotensin II↗
PubMed1992

Structural study of cell wall mannan of a Candida albicans (serotype A) strain.

The structure of the mannan of Candida albicans NIH A-207 strain (serotype A) was investigated by adopting mild acetolysis followed by enzymolysis with an Arthrobacter GJM-1 exo-alpha-mannosidase. The resultant oligosaccharides, from pentaose to octaose (where manp = D-mannopyranose), were identified as manp beta (1----2)manp alpha (1----2)manp alpha (1----2)manp alpha (1----2)manp, manp beta (1----2)manp beta (1----2)manp alpha (1----2)manp alpha (1----2)- manp alpha (1----2)manp, manp beta (1----2)manp beta (1----2)manp beta (1----2)manp alpha (1----2)manp alpha (1----2)manp alpha (1----2)manp and manp beta (1----2)manp beta (1----2)manp beta (1----2)manp beta (1----2)manp alpha (1----2)manp alpha (1----2)manp alpha (1----2)manp, respectively. Analyses of alpha-linked oligosaccharides obtained by acetolysis under conventional conditions gave the same oligosaccharides, from biose to heptaose, as those obtained from the mannans of C. albicans NIH B-792 (serotype B) and J-1012 (serotype A, formerly serotype C).

Candida albicans↗
PubMed1992

Excitation of hypothalamic paraventricular neurons by stimulation of the raphe nuclei.

Extracellular recordings were made from 467 anti-dromically identified neurosecretory neurons and 148 non-neurosecretory neurons in the paraventricular nucleus of the hypothalamus of hemispherectomized cats under pentobarbital anesthesia. Stimulation of the dorsal, median, and pontine raphe nuclei excited 31%, 26%, and 12% of neurosecretory neurons tested, respectively, and inhibited 9%, 7%, and 8%. The excitatory responses in 13 of 14 neurons tested were blocked by either of two intravenously administered 5-HT2 antagonists, cyproheptadine or methysergide. The 5-HT1A antagonist, (-)pindolol, partially blocked the excitatory responses elicited by raphe stimulation in three of five neurons tested. The inhibitory responses to raphe stimulation were not affected by application of these antagonists. More non-neurosecretory neurons than neurosecretory neurons were excited in response to raphe stimulation and these excitatory responses were also blocked by these antagonists. We conclude that most electrically stimulated synaptic inputs from the midbrain raphe nuclei to the hypothalamic paraventricular nucleus are excitatory and are mainly mediated by 5-HT2 receptors.

Animals↗