Biomedical subjects

E Kishi

Publications and source records attributed to E Kishi.

At least 19 recordsLinked to original sources

PubMed2001

Hypothalamic cholinergic regulation of body temperature and water intake in rats.

Without disturbing the behavior of unanesthetized rats, the perfusion of neostigmine through microdialysis probe into the anterior hypothalamus (AH), paraventricular nucleus (PVN) and lateral ventricle (LV) decreased body temperature and increased water intake. On the other hand, the perfusion into the supraoptic nucleus (SON) increased the body temperature. The perfusion of neostigmine increased the extracellular concentration of acetylcholine in the perfusion sites except LV. Changes, both decrease and increase, in body temperature and increase in water intake were correlated with increases in c-fos-like immunoreactivity (Fos-IR) in the hypothalamus, pons and medulla. Distinct Fos-IR was found in the PVN, SON, median preoptic nucleus (MnPO), locus coeruleus (LC), area postrema and nucleus of the solitary tract (NTS). Co-administration of atropine with neostigmine completely suppressed the changes in the body temperature, water intake and Fos-IR, all of which were induced by the neostigmine perfusion into AH, PVN and SON. In the LV-perfused rats, on the other hand, co-administration of atropine and neostigmine only partially prevented body temperature reduction and still induced significant hypothermia. These results suggest that muscarinic receptor activation in specific regions of the hypothalamus and the activation of LC and NTS are implicated in the regulation of body temperature and water intake. Other receptor processes are involved in the LV-induced changes.

Animals↗

PubMed2001

Development of obesity and neurochemical backing in aurothioglucose-treated mice.

To clarify the neurochemical backing of aurothioglucose (ATG)-induced obesity in mice, we investigated lesion sites, hypothalamic neurotransmitters and c-Fos-like immunoreactivity (Fos-IR). At day 2 after ATG, tissue loss or cells death was observed in several parts of the ventral area of the ventromedial hypothalamic nucleus (VMH), and the dorsal area of arcuate nucleus and in the nucleus of the solitary tract (NTS). However, the greater part of the VMH was retained. Body weight began to increase in week 1. Hypothalamic serotonin (5-HT) and the metabolites were increased at day 2. The contents of acetylcholine, norepinephrine and dopamine in the hypothalamus showed no significant change. In week 1, the area shown tissue loss was compacted and plugged up. In the control group, most obvious c-Fos-like immunoreactive region was paraventricular nucleus (PVN). At day 2, Fos-IR was observed around destroyed regions in the hypothalamus and NTS, but few Fos-IR was found in the other regions including PVN. The Fos-IR around destroyed regions diminished after week 1. In week 3, Fos-IR in the PVN increased. These results suggest that the development of ATG-induced obesity cannot be attributed to solely VMH destruction. The restoration processes of the neuronal dysfunction involving PVN seem to play an important role in the development of obesity. NTS lesion and 5-HT system might contribute to decrease in food intake for several days after ATG.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

Opposite regulation of body temperature by cholinergic input to the paraventricular nucleus and supraoptic nucleus in rats.

Hypothalamic cholinergic system plays an important role in the regulation of body temperature and fluid balance. We have previously shown that cholinergic stimulation of the anterior hypothalamus and preoptic area was accompanied by a fall in body temperature, increased water intake, and increased Fos protein in the paraventricular nucleus (PVN) and supraoptic nucleus (SON). In the present study, to estimate the role played by cholinergic input to the PVN and SON in thermoregulation and water intake, we used microdialysis for cholinergic stimulation with neostigmine and analysis of the nucleus, and also investigated immunoreactivity for c-Fos protein in the brain. This stimulation increased extracellular concentration of acetylcholine in these nuclei. Stimulation of the PVN decreased body temperature and increased water intake. On the other hand, stimulation of the SON increased body temperature. Both in PVN-stimulated and SON-stimulated rats, c-Fos-like immunoreactivity (Fos-IR) was evident in the PVN, SON and certain regions including locus coeruleus (LC), area postrema and nucleus of the solitary tract (NTS). Addition of atropine to the dialysis medium attenuated the increase of Fos-IR and suppressed the cholinergic stimulation-induced responses in body temperature and water intake. These results suggest that cholinergic muscarinic mechanisms in PVN and SON play an opposite function in the regulation of body temperature. The same neuronal pathway including LC and NTS may participate in an advance both in hypothermia and in hyperthermia.

Acetylcholine↗

PubMed2001

Role of preoptic and anterior hypothalamic cholinergic input on water intake and body temperature.

To elucidate the role played by cholinergic mechanism in the preoptic area (POA) and anterior hypothalamus (AH) in the control of body temperature and water intake of rats, we used microdialysis without disturbing the behavior of unanesthetized animals. After microdialysis, we also investigated immunoreactivity for c-Fos protein in the hypothalamus. Stimulation with neostigmine, an acetylcholine esterase inhibitor, through microdialysis probe increased extracellular concentration of acetylcholine (ACh) in the POA and AH, and was accompanied by a dose-dependent fall in body temperature and increased water intake. Addition of atropine, a muscarinic receptor antagonist, to the dialysis medium containing neostigmine suppressed the neostigmine-induced changes in rectal temperature and water intake. Neostignime markedly increased c-Fos-like immunoreactivity (Fos-IR) in certain hypothalamic areas, including the paraventricular nucleus, supraoptic nucleus and median preoptic nucleus. This increase was also attenuated by atropine. These results suggest that cholinergic inputs and activation of muscarinic processes in POA and AH induced a decline in body temperature and increased water intake.

Acetylcholine↗

PubMed2001

Cholinergic input to the supraoptic nucleus increases Fos expression and body temperature in rats.

To examine the role played by cholinergic input and processes in the supraoptic nucleus (SON) in the control of body temperature and water intake in rats, we used microdialysis to stimulate and analyze SON without disturbing the behavior of unanesthetized rats. After microdialysis, we also investigated immunoreactivity for c-Fos protein in the brain as an index of neuronal activation. Stimulation with neostigmine, an acetylcholine esterase inhibitor, through the microdialysis probe increased the extracellular concentration of acetylcholine in the SON. This cholinergic stimulation dose-dependently increased body temperature but did not significantly change the water intake. The stimulation markedly increased c-Fos-like immunoreactivity (Fos-IR) in the SON and certain hypothalamic areas, including the paraventricular nucleus (PVN) and median preoptic nucleus (MnPO). Fos-IR was also evident in certain regions of the pons and brainstem, including the locus ceruleus (LC), area postrema (AP), and nucleus of the solitary tract (NTS). Addition of atropine, a muscarinic receptor antagonist, to the dialysis medium containing neostigmine attenuated the increase of Fos-IR and suppressed the neostigmine-induced responses in body temperature. These results suggest that cholinergic input and activation of the muscarinic cholinoceptive neurons in the SON contribute to the regulation of body temperature. Activation of noradrenergic pathways in the brainstem including LC and NTS may be involved in the thermoregulation mechanism.

Animals↗

PubMed2001

Hypothalamic neuroactivity in specific processes and central regulation of body temperature and water intake.

The method described was designed to elucidate the role of a particular neuronal system or specific nucleus in the central nervous system (CNS) in controlling physiological and biological functions. The neurochemical aspects of the CNS regulatory mechanism and related networks remain to be further investigated. There is little information available about the relationship between neuroactivity in the specific brain nuclei and physiological or biological responses in mammals. An adequate analysis of this relationship provides valuable insight to clarify which nucleus and what types of neurons are truly involved in the excitation of physiological events and its regulation. In the present study, we used microdialysis for stimulation of the anterior hypothalamus (AH) and simultaneous analysis of cholinergic activity, and we investigated c-Fos-like immunoreactivity (Fos-IR) in the brain in the same animal following microdialysis. The nuclear protein c-Fos, the product of c-fos oncogene, has been used as a marker of neuronal activity at the cellular level in the brain. Various physiological and pharmacological stimuli have been shown to induce Fos-IR in specific neuronal populations located in various regions of the brain. However, there are few studies investigating the responses produced by c-Fos expression in specific regions in same animals. We showed the involvement of hypothalamic cholinergic mechanisms in the thermoregulatory and water regulatory processes using the above procedures.

Acetylcholine↗

PubMed2001

Confirmation of the anxiolytic-like effect of dihydrohonokiol following behavioural and biochemical assessments.

Previous studies in this laboratory revealed that dihydrohonokiol-B (DHH-B; 3'-(2 propenyl)-5-propyl-(1,1'-biphenyl)-2,4'-diol), a partially reduced derivative of honokiol, was an effective anxiolytic-like agent in mice at an oral dose of 0.04 mg kg(-1), and at higher doses, when evaluated by the elevated plus-maze test. The aim of this study was to further confirm the anxiolytic-like effect of DHH-B using an additional behavioural procedure (Vogel's conflict test in mice) and a biochemical assessment (in-vitro determination of muscimol-stimulated 36Cl- uptake into mouse cortical synaptoneurosomes). As in earlier experiments, DHH-B (0.04-1 mg kg(-1), p.o.) was shown to prolong the time spent in the open-sided arms of the elevated plus-maze in a dose-dependent manner. Moreover, in the Vogel's conflict test, DHH-B (5 mg kg(-1), p.o.) significantly increased punished water intake. In tests with mouse cerebral cortical synaptoneurosomes, 10 and 30 microM of DHH-B significantly increased 36Cl- influx in the absence of muscimol. In the presence of 25 microM muscimol, the addition of 1 microM DHH-B led to significant enhancement of 36Cl- uptake, while 30 microM DHH-B was required to further stimulate the 36Cl- uptake induced by 250 microM muscimol. The results of these studies confirm that DHH-B is a potent anxiolytic-like agent and that GABA(A) receptor-gated Cl(-)-channel complex is involved in the anxiolytic-like efficacy of DHH-B.

Administration, Oral↗

PubMed2000

Different cardiovascular neuron groups in the ventral reticular formation of the rostral medulla in rabbits: single neurone studies.

To examine whether the cardiovascular neurons of the ventral medulla consist of functionally different kinds of neurons, single neuronal activity of the ventral medulla, activity of the renal sympathetic nerves (RSNA), blood flow of the ear (EarBF) and arterial pressure (AP) were recorded in urethane-anesthetized, vagotomized and immobilized rabbits during electrical stimulation of the aortic nerve (AN, baroreceptor afferent fibers) and electrical stimulation of the dorsomedial hypothalamus (DMH) that reduced EarBF but less affected on AP and RSNA. The dorsolateral funiculus of the second cervical cord was stimulated to evoke antidromic spikes of medullary neurons. Two kinds of reticulo-spinal neurons were identified. Activities of one kind of neurons were facilitated by stimulation of DMH (latency 48.6+/-27.6 ms, n=11) but they did not respond to stimulation of the AN. Therefore, it was presumed that these neurons controlled vasomotion of the ear through the vasoconstrictor neurons in the spinal cord but did not participate in regulation of systemic AP. Activities of the other neurons were inhibited by stimulation of the AN (latency 47.8+/-8 4 ms, n=16) but they did not respond to the DMH stimulation. These neurons were identical to those reported previously as the RVLM neurons, and they contributed to regulate systemic AP but might not participate in control of cutaneous vascular movement. The former neurons were located medially to the latter in the reticular formation of the rostral ventral medulla. These results provided evidence at the single neuronal level that the cardiovascular neurons in the ventral medulla were consisted of functionally different sympatho-excitatory neurons and they were located at the different sites in the rostral ventral medulla.

Animals↗

PubMed2000

Comparative assessment of the anxiolytic-like activities of honokiol and derivatives.

Honokiol has previously been shown to be an effective anxiolytic-like agent in mice when administered for 7 days at 0.2 mg/kg/day prior to evaluation in an elevated plus-maze, while 20 mg/kg is required for efficacy as a single oral dose. The aim of this study was to find analogs of honokiol that are more effective for acute administration. Among the eight analogs evaluated, one partially reduced derivative of honokiol [3'-(2-propenyl)-5-propyl-(1,1'-biphenyl)-2,4'-diol] exhibited significant anxiolytic-like activity at 0.04 mg/kg. Following oral administration of 1 mg/kg of this analog, anxiolytic-like activity was clearly evident at 1 h, peaked at 3 h, and remained significant for longer than 4 h after treatment. Combined administration of the derivative with diazepam led to enhanced anxiolytic-like efficacy. Moreover, as with diazepam, the anxiolytic-like effect of the analog was reduced by flumazenil. In contrast, bicuculline, a GABA(A) antagonist, had no effect on the activity of the derivative. Taken together, these results suggest that this analog of honokiol acts at the benzodiazepine recognition site of the GABA(A)-benzodiazepine receptor complex.

Animals↗

PubMed2000

Does dihydrohonokiol, a potent anxiolytic compound, result in the development of benzodiazepine-like side effects?

The aims of this study were to assess whether dihydrohonokiol, 3'-(2-propenyl)-5-propyl-(1,1'-biphenyl)-2,4'-diol (DHH-B), a potent anxiolytic compound, developed benzodiazepine-like side effects. A 1 mg kg(-1) dose of diazepam, almost equivalent to the minimum dose for the anxiolytic effect, disrupted the traction performance, potentiated hexobarbital-induced sleeping and impaired learning and memory performance. DHH-B, even at a dose of 1 mg kg(-1) (i.e. five times higher than the minimum dose for significant anxiolytic effect) neither developed diazepam-like side effects nor enhanced the side effects of diazepam. Rather, the potentiation by diazepam of hexobarbital-induced sleeping was reduced by 1 mg kg(-1) DHH-B. Furthermore, mice treated with 10 daily administrations of 1 and 5 mg kg(-1) diazepam, but not 0.2-5 mg kg(-1) DHH-B, showed precipitated withdrawal symptoms characterized by hyper-reactivity, tremor and tail-flick reaction when they were challenged with flumazenil (10 mg kg(-1) i.p.). These results suggest that, unlike the benzodiazepine anxiolytic diazepam, DHH-B is less likely to induce motor dysfunction, central depression, amnesia or physical dependence at the effective dose required for the anxiolytic effect.

Analysis of Variance↗

PubMed2000

The anxiolytic effect of two oriental herbal drugs in Japan attributed to honokiol from magnolia bark.

An improved elevated plus-maze test in mice revealed that seven daily treatments with two different traditional Chinese medicines, known as Kampo medicines in Japan, Hange-koboku-to (composed of extracts of 5 plants) and Saiboku-to (composed of extracts of 10 plants), produced an anxiolytic effect, and the effect was mainly due to the presence of honokiol derived from magnolia. This study was carried out to evaluate the anxiolytic potential of honokiol, Hange-koboku-to and Saiboku-to, which were prescribed with two different magnolia samples: Kara-koboku (Magnoliae officinalis) (KA) or Wa-koboku (Magnoliae obovata) (WA). The doses of test samples were adjusted to ensure a constant dose of honokiol at 0.2 mg kg(-1). Although the doses of magnolol (an isomer of honokiol), as well as those of undetermined chemicals, varied among samples, the seven daily treatments with 9 out of 10 test samples produced an anxiolytic effect almost equivalent to that produced by 0.2 mg kg(-1) honokiol. The only exception was the sample containing the lowest amount of honokiol. Magnolia-free preparations of Hange-koboku-to or Saiboku-to did not have any anxiolytic effect. These results confirm that honokiol derived from magnolia is the causal chemical of the anxiolytic effect of Hange-koboku-to and Saiboku-to.

Animals↗

PubMed1999

Application of the elevated plus-maze test in mice for evaluation of the content of honokiol in water extracts of magnolia.

In our previous study using an improved elevated plus-maze in mice, the oriental herbal medicine Saiboku-to prolonged the time spent in open arms, showing an anxiolytic effect, and the effect was mainly caused by honokiol derived from magnolia. This study was carried out to compare the anxiolytic potentials of honokiol and water extracts of three magnolia samples; two being Kara-koboku (Magnolia officinalis) (KA: from Zhejiang-sheng, China; honokiol 0.25% and magnolol 1.16%, and KB: from Sichuan-sheng, China; honokiol 1.72% and magnolol 1.71%), and one being Wa-koboku (Magnolia obovata) (WA: from Iwate-ken, Japan; honokiol 0.32% and magnolol 0.81%). Seven daily treatments with 0.1-1 mg/kg honokiol, but not 0.2 and 1 mg/kg magnolol, revealed an anxiolytic effect with the peak potential at 0. 2 mg/kg. The anxiolytic potentials of 40 and 80 mg/kg KA, which contained the highest amount of magnolol, were almost equivalent to those of 0.1 and 0.2 mg/kg honokiol, respectively. KB, at 11.6 mg/kg, and 62.5 mg/kg WA resulted in almost the same anxiolytic potential as that of 0.2 mg/kg honokiol. No significant change in the ambulatory activity was produced by any drug treatment. These results suggest that honokiol is the chemical responsible for the anxiolytic effect of the water extract of magnolia and that the other chemicals including magnolol in magnolia scarcely influence the effect of honokiol. It is also considered that the elevated plus-maze test is applicable for evaluation of the content of honokiol in magnolia.

Animals↗

PubMed1998

Functional significance of the 10 Hz rhythmic discharges in sympathetic nerves.

1. By measuring renal vascular conductance in anaesthetized and immobilized rabbits, the functional significance of the 10 Hz rhythmic discharges in the sympathetic nerves was assessed by electrical stimulation of the renal nerve. This stimulation mimicked the intermittently occurring 10 Hz rhythmic discharges. 2. Comparison of high-frequency (10-20 Hz) intermittent electrical stimulation with continuous low-frequency (5 Hz) stimulation showed that the intermittent high-frequency stimulation evoked faster (smaller time constant) and larger responses of the renal vascular conductance if the total number of stimulus pulses was the same. 3. Therefore, the intermittently occurring 10 Hz rhythmic discharges in the sympathetic nerve produces faster and larger effects on peripheral organs than effects produced by continuous discharges if the number of spikes is equal.

Animals↗

PubMed1998

Stimulation of rat hypothalamus by microdialysis with K+: increase of ACh release elevates plasma glucose.

The effects of stimulation of the ventromedial hypothalamus (VMH) or lateral hypothalamus (LH) with potassium chloride through a microdialysis probe were studied. The concentrations of ACh and norepinephrine (NE) in the dialysate obtained from the hypothalamic nuclei and plasma glucose concentration were measured. Stimulation of the hypothalamic nuclei, VMH and LH, with potassium increased the plasma glucose level as well as the extracellular concentrations of ACh and choline. Addition of atropine, a muscarinic ACh receptor antagonist, into the potassium solution reduced the increase in the level of plasma glucose. Cholinergic stimulation of these nuclei with neostigmine increased the extracellular concentrations of ACh and plasma glucose. Stimulation of the nuclei with potassium also increased the release of NE. However, stimulation of the VMH or LH with NE and/or pargyline, a monoamine oxidase inhibitor, through the dialysis probe membrane did not significantly increase the plasma glucose concentration. These results suggest that activation of the muscarinic cholinergic or ACh-receptive neurons in the hypothalamic nuclei, VMH and LH, contribute to the elevation of plasma glucose level.

Acetylcholine↗

PubMed1997

Effects of ventromedial hypothalamus stimulation on glycogenolysis in rat liver using in vivo microdialysis.

In vivo microdialysis was applied to study the effects of ventromedial hypothalamus (VMH) stimulation on liver glycogenolysis under anesthesia. We examined glucose output and norepinephrine (NE) outflow from the liver through analysis of glucose and NE in the liver dialyzate. Stimulation of the VMH increased glucose output and NE outflow from the liver and increased the plasma glucose level. Similar results were obtained on hepatic nerve stimulation. Bilateral adrenalectomy did not abolish the glycogenolysis induced by VMH stimulation. NE outflow increased to a much greater extent in adrenalectomized rats. These data show that VMH stimulation causes glycogenolysis and glucose output from the liver mainly via the hepatic nerves, and that microdialysis is a simple and useful method for the study of liver metabolism in vivo.

Adrenalectomy↗

PubMed1997

Hypothalamic cholinergic activity and 2-deoxyglucose-induced hyperglycemia.

To clarify the role of the hypothalamic cholinergic system in the regulation of peripheral glucose metabolism, we investigated hypothalamic cholinergic activities after administration of 2-deoxyglucose (2-DG). Intravenous administration of 2-DG (500 mg/kg) caused neuroglycopenia and marked hyperglycemia; the level of plasma glucose increased to 210% of the initial levels of 20 min. For evaluation of the cholinergic activity, we employed a microwave device and subsequently analyzed the contents of acetylcholine (ACh) and choline after microdissection of the hypothalamic nuclei, ventromedial hypothalamic nucleus (VMH), lateral hypothalamus (LH), and paraventricular nucleus (PVN). In addition, we analyzed fluctuation of extracellular levels of ACh using in vivo brain microdialysis. A decrease in the ACh content, and a corresponding increase in the choline content, was observed in those hypothalamic nuclei min after administration of 2-DG. In the microdialysis perfusate, on the other hand, extracellular level of ACh was increased by 2-DG administration. These data show that ACh release, which is cholinergic activity, was increased after 2-DG administration. Our results suggest the involvement and importance of the hypothalamic cholinergic system in 2-DG-induced hyperglycemia.

Acetylcholine↗

PubMed1997

Comprehensive analysis of neurotransmitters and their metabolites including acetylcholine and choline in rat brain nuclei.

We have designed this method for the comprehensive and adequate analysis of neurotransmitters and metabolites including acetylcholine (ACh) and choline in specific brain nuclei. In physiological and pharmacological studies, the role of specific neurotransmitters in the central nervous system (CNS) has often been studied by microinjection of their agonist and antagonist into the target regions, with the action and role of the transmitter in question being deduced in a relatively straightforward manner from the results. However, none of these studies have investigated fluctuation in neurotransmitter and metabolite contents in response to a variety of stimuli in vivo. No comprehensive analysis of neurotransmitters in small specific area in the CNS has been undertaken due to the difficulties of proper analysis of ACh and choline. Different types of neuronal systems in the CNS affect each other. Thus, it is not necessarily clear that different types of neurons do in fact respond to an administered agonist and antagonist. For example, dopaminergic neuron mediated control of cholinergic interneuron in the striatum and dopaminergic regulation of cortical ACh release have been documented. Similarly, the cholinergic system affects dopaminergic and noradrenergic neurons. Intraventricular administration of an ACh esterase inhibitor, neostigmine, increases dopamine and noradrenaline release in the hypothalamus. So, an adequate comprehensive analysis of the transmitters and the metabolites in the same tissue sample provides valuable aid to clarify what types of neurons truly respond to the administered drugs and the excitation of physiological events. For an appropriate analysis we employed a microwave device, which made the estimation of ACh and choline possible. In addition to this, we employed a punch technique for the microdissection of the specific nuclei and area from the brain slice.

Acetylcholine↗

PubMed1996

Effects of hepatic nerve stimulation on blood glucose and glycogenolysis in rat liver: studies with in vivo microdialysis.

In vivo microdialysis was applied to investigate the effects of hepatic nerve stimulation on glycogenolysis in rat liver under anesthesia. We analyzed the norepinephrine (NE) outflow and glucose output from the liver through the measurement of NE and glucose in the microdialysis dialyzate, as well as the plasma glucose level. Stimulation of the hepatic nerves (10 Hz, 20 V, 2 ms, 20 s every minute) increased NE outflow and glucose output from the liver. The blood glucose level increased by 1.5-1.6 times over the basal level at the end of the 10 min intermittent stimulation. Bilateral adrenalectomy and pancreatectomy did not abolish the glycogenolysis that was induced by the nerve stimulation. Phentolamine an alpha-antagonist, reduced the effects of nerve stimulation on the glucose output and the plasma glucose level. Phentolamine caused an increase in the NE outflow. Quinacline, an inhibitor of phospholipase A2, inhibited the glycogenolytic nerve effects without any inhibition of the NE outflow. These data show that hepatic nerve stimulation produces glycogenolysis via alpha-adrenergic mechanism and partly mediated by eicosanoids, and that microdialysis is a useful and simple method for the study of liver metabolism in physiological conditions.

Adrenalectomy↗