Tsuyoshi Kudo

The effect of ketamine on clinical endpoints of hypnosis and EEG variables during propofol infusion

Background: We studied the effect of variable doses of ketamine on the endpoints of hypnosis, e.g., unresponsiveness to verbal commands (UVC), loss of eyelash reflex (LER), and inhibition of body movement response with or without sneezing to nasal membrane stimulation (INBMR), and processed EEG variables, e.g., bispectral index (BIS), 95% spectral edge frequency (SEF) and median frequency (MF) during propofol infusion.

Orexin A and B evoke noradrenaline release from rat cerebrocortical slices

Orexin A and B, recently identified in the rat hypothalamus are endogenous neuropeptide agonists for the G‐protein coupled orexin‐1 (OX1) and orexin‐2 (OX2) receptors. In the present study, we have examined the effects of orexin A, B and raised extracellular K+ on noradrenaline release from the rat cerebrocortical slice. We have compared this with other sleep – wake‐related (excitatory) neurotransmitters; dopamine, glutamate, serotonin and histamine. Neurotransmitter release studies were performed in rat cerebrocortical slices incubated in modified Krebs buffer (with and without Ca2++EGTA 1 mM) with various concentrations of orexin A, B and K+ for various times. Orexin A and B‐evoked (10−7 M) noradrenaline release was time‐dependent reaching a maximum some 10 min after stimulation. K+ (40 mM) evoked release was also time dependent but reached a maximum after 6 min. Orexin A, B and K+ stimulation of release was concentration dependent with pEC50 and Emax (% of basal) values of 8.74±0.32 (1.8 nM) and 263±14% and 8.61±0.38 (2.4 nM) and 173±7% and 1.43±0.02 (37 mM) and 1430±70%, respectively. Orexin‐evoked release was partially extracellular Ca2+ dependent. Of the other transmitters studied there was a weak orexin A and B stimulation of glutamate release. In contrast K+ evoked dopamine, glutamate, histamine and serotonin release with pEC50 and Emax (% of basal) values of 1.47±0.05 (34 mM) and 3430±410%, 1.38±0.04 (42 mM) and 1240±50%, 1.47±0.02 (34 mM) and 480±10% and 1.40±0.05 (40 mM) and 560±60% respectively. We conclude that the neuropeptides orexin A and B evoke noradrenaline release from rat cerebrocortical slices.

Effects of central hypocretin-1 administration on hemodynamic responses in young-adult and middle-aged rats.

The prevalence of hypertension in middle age correlates with impaired autonomic regulation and as norepinephrinergic neurons decline with increasing age, and this reduction may contribute to this impairment. Central hypocretin-activated norepinephrinergic neurons contribute to sympathetic regulation. In the present study we compared sympathoadrenal effects of intracerebroventricular (i.c.v.) hypocretin-1(5 nmol) between young-adult (12-14 weeks) and middle-aged (12-14 months) rats. Arterial blood pressure, heart rate and plasma catecholamines were assessed under pentobarbital anesthesia. In addition, we compared hypocretin-1 and K(+)-evoked norepinephrine release from the cerebrocortical slices prepared from young-adult and middle-aged rats. We also examined whether the novel hypocretin receptor-1 antagonist (SB-334867) could reverse these hypocretin-1 effects both in vivo and in vitro. I.c.v. hypocretin-1 significantly increased blood pressure by some 7%, heart rate by 9% and plasma norepinephrine concentrations by 100% in young-adult rats. In middle-aged rats these parameters did not change. Plasma epinephrine did not increase in either group. There was a significant correlation between changes in mean arterial pressure and plasma norepinephrine. Similarly, hypocretin-1 evoked norepinephrine release from cerebrocortical slices prepared from young-adult rats was significantly higher than that of middle-aged rats whilst K(+)-evoked release did not differ between the groups. SB-334867 significantly attenuated hypocretin-1-increased blood pressure and both in vivo and in vitro norepinephrine release. The present data suggest that hypocretinergic neurons may contribute to the regulation of central but not adrenal sympathetic activity. Moreover, sympathetic regulation by hypocretinergic neurones may disappear in middle-age in rats.

Effect of 6-Hydroxydopamine on Host Resistance against Listeria monocytogenes Infection

ABSTRACT Recent studies have shown that immunocompetent cells bear receptors of neuropeptides and neurotransmitters and that these ligands play roles in the immune response. In this study, the role of the sympathetic nervous system in host resistance against Listeria monocytogenes infection was investigated in mice pretreated with 6-hydroxydopamine (6-OHDA), which destroys sympathetic nerve termini. The norepinephrine contents of the plasma and spleens were significantly lower in 6-OHDA-treated mice than in vehicle-treated mice. The 50% lethal dose of L. monocytogenes was about 20 times higher for 6-OHDA-treated mice than for vehicle-treated mice. Chemical sympathectomy by 6-OHDA upregulated interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNF-α) production in enriched dendritic cell cultures and gamma interferon (IFN-γ) and TNF-α production in spleen cell cultures, whereas chemical sympathectomy had no apparent effect on phagocytic activities, listericidal activities, and nitric oxide production in peritoneal exudate cells and splenic macrophages. Augmentation of host resistance against L. monocytogenesinfection by 6-OHDA was abrogated in IFN-γ−/− or TNF-α−/− mice, suggesting that upregulation of IFN-γ, IL-12, and TNF-α production may be involved in 6-OHDA-mediated augmentation of antilisterial resistance. Furthermore, adoptive transfer of spleen cells immune to L. monocytogenes from 6-OHDA-treated mice resulted in untreated naive recipients that had a high level of resistance against L. monocytogenesinfection. These results suggest that the sympathetic nervous system may modulate host resistance against L. monocytogenesinfection through regulation of production of IFN-γ, IL-12, and TNF-α, which are critical in antilisterial resistance.

Effects of general anaesthesia and surgery on renal function and plasma adh levels

SummaryPlasma levels of antidiuretic hormone (ADH) were evaluated in 40 adult patients during and after various types of anaesthesia and surgery. The plasma level of ADH increased significantly 30 minutes after the start of anaesthesia with diethyl-ether (3.7 times) and after thiopentone (1.5 times), but it increased insignificantly in neuroleptanaesthesia (2.4 times) and with halothane (1.3 times). The surgical stress evoked marked increases in plasma ADH levels especially at ten minutes after the skin incision. A slight increase in plasma ADH level still continued into the early post-operative days.The effects of halothane anaesthesia on plasma levels of ADH and on both cortical and medullary renal blood flow (RBF) were investigated in dogs. RBF was measured by means of a heated thermocouple in two groups of eight dogs each. One group was given a high fluid load of 30 ml/kg/hr and the other a low load of 10 ml/kg/hr. The plasma level of ADH increased significantly with deepening halothane anaesthesia in the low fluid load group. However, in the high fluid load dogs it remained unchanged in spite of an increasing inspired halothane concentration. Both cortical and medullary RBF fell significantly as compared with the control values in the low fluid load group. However, in the high fluid load dogs no significant decrease was observed. These results would indicate that the anaesthetic agents investigated in the present study caused increases in plasma ADH levels, but that these antidiuretic effects of anaesthesia might be modified by the volume of fluid infused during anaesthesia and operation.RésuméPendant et après la chirurgie sous différents agents anesthésiques, on a déterminé la concentration plasmatique de ľhormone antidiurétique (ADH) chez 40 patients adultes opérés pour des pathologies abdominales variées. Une augmentation significative de ľADH a été notée après 30 minutes ďanesthésie à ľéther diéthylique (3.7 fois le contrôle) et le thiopentone (1.5 fois). Cette augmentation n’a pas été jugée significative après la neuroleptanesthésie (2.4 fois) et ľanesthésie à ľhalothane (1.3 fois). Le stress chirurgical a provoqué une augmentation importante, surtout à ta dixième minute après ľincision. Le niveau sanguin est demeuré légèrement élevé dans la période post-opératoire immédiate.Les effets de ľanesthésie à ľhalothane sur la concentration plasmatique de ľADH et sur le flux sanguin rénal cortical et médullaire ont aussi fait ľobjet ďune étude chez le chien. Dans deux groupes de huit chiens, on a mesuré au thermocouple le flux sanguin rénal. Le premier groupe a reçu une surcharge liquidienne de 30 ml/kg/hre alors que ľapport n’a été que de 10 ml/kg/hre pour le deuxième groupe. La concentration plasmatique ďADH s’est élevée de façon significative dans le deuxième groupe. Toutefois, dans le premier groupe qui avait reçu le plus grand volume liquidien, le niveau plasmatique ďADH n’a pas changé malgré les augmentations de concentration de ľhalothane. Dans le groupe où ľapport liquidien a été le moins élevé, le flux sanguin cortical et le flux médullaire ont diminué de façon significative par comparaison aux valeurs de contrôle de ce groupe. Cette diminution n’a pas été notée pour le groupe surchargé. Ces résultats suggèrent que les agents anesthésiques utilisés dans cette étude augmentent le niveau ďADH, mais que les effets antidiurétiques de ľanesthésie peuvent ïtre modifiés par la quantité de liquide perfusée pendant ľanesthésie et ľopération.

Depressed Pituitary-Adrenal Response to Surgical Stress in Chronic Schizophrenic Patients

We evaluated whether pituitary-adrenal response to surgical stress is modified in chronic schizophrenic patients. Twenty-two schizophrenic patients on chronic antipsychotic therapy of phenothiazine derivatives over 10 years underwent orthopedic surgery of the extremities under general anesthesia by isoflurane and nitrous oxide. In chronic schizophrenic patients, responses of plasma epinephrine, norepinephrine, ACTH and cortisol levels during surgical stress were significantly lower than those of control patients. The attenuated response to surgical stress in these patients may be associated with their autonomic dysfunction and decreased pituitary-adrenal activity due to chronic administration of antipsychotic agents.

Role of coerulean noradrenergic neurones in general anaesthesia in rats

BACKGROUND Central noradrenergic neurones have a role in alertness, analgesia, and thermoregulation; these neurones are also involved in the mechanism of anaesthesia. Locus coeruleus neurones innervate various central nervous regions including the cerebral cortex and hippocampus, and are responsible for wakefulness and analgesia. We hypothesized that these neurones are also involved in both activation of the γ-aminobutyric acid type A (GABA(A)) receptor and inhibition of N-methyl-d-aspartate (NMDA) receptor-mediated anaesthesia. METHODS Forty-seven male rats were used to compare duration of anaesthesia before and 10 days after noradrenergic neurone depletion after intraperitoneal (i.p.) administration of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4; 0, 5, and 50 mg kg(-1)). The animals received i.p. thiopental (GABA anaesthetic, 45 mg kg(-1)) or ketamine (NMDA anaesthetic, 100 mg kg(-1)). We also tested the effects of coerulean noradrenergic neurone depletion on i.p. ketamine analgesia (15 mg kg(-1)) using the hot-plate test in a further 21 male rats. At the end of each experiment, norepinephrine contents in the cerebral cortex and hippocampus were measured. RESULTS I.P. DSP-4 5 and 50 mg kg(-1) significantly decreased ketamine anaesthesia duration by 12.7% and 22.4%, increased thiopental anaesthesia duration by 10.8% and 24.5%, and reduced ketamine-increased hot-plate latency by 55.2% and 68.1%, respectively. In addition, i.p. DSP-4 5 and 50 mg kg(-1) significantly reduced norepinephrine contents in coerulean brain regions by ∼20% and ∼75%, respectively. There were significant correlations between norepinephrine contents in coerulean brain regions and anaesthesia durations and ketamine analgesia. CONCLUSIONS The present data indicate that coerulean noradrenergic neurones may be responsible for both GABA- and NMDA-mediated anaesthetic actions.

Decreased glucose utilization during prolonged anaesthesia and surgery

We studied the influence of prolonged anaesthesia and surgery on glucose metabolism by means of the euglycaemic insulin clamp method in eight patients who underwent prolonged surgery. Eleven patients who underwent surgery of short duration served as a control group. Plasma concentrations of catabolic hormones were measured simultaneously. Glucose utilization during prolonged anaesthesia, (PA) group, was lower than that in the control group (P < 0.01) (glucose utilization 7.59 ± 0.73 mg · kg−1 · hr−1 in the control group vs 4.03 ± 0.71 mg · kg−1 hr−1 in PA group respectively). There were no significant differences in plasma catecholamine and glucagon concentrations between the PA and control groups. Plasma-free fatty acid levels increased significantly in the PA group before the euglycaemic insulin clamp (free fatty acid level: 0.496 ± 0.053 mmol·L−1 in the control group, vs 0.834 ± 0.103 mmol·L−1 in the PA group at the pre-clamp period, P < 0.01). Tissue resistance to exogenous insulin increased during prolonged anaesthesia and surgery although there were no significant changes in plasma catabolic hormone levels.RésuméOn a étudié l’influence de l’anesthésie prolongée et la chirurgie sur le métabolisme du glucose en utilisant le lest «Euglycaemic insulin clamp method» chez huit patients devant subir une chirurgie prolongée. Onze patients devant subir une chirurgie de courte durée ont servi comme groupe contrôle. Les concentrations plasmatiques des hormones de catabolisme ont été mesurées simultanément. l’utilisation du glucose durant l’anesthésie prolongée (PA), dans le groupe PA, était plus basse que celle du groupe contrôle (P < 0.01) (l’utilisation du glucose 7,59 ± 0,73 mg · kg−1 · hre−1 pour le groupe contrôle versus 4,03 ± 0,71 mg · kg−1 · hre−1 dans le groupe PA). Il n’y avail aucune différence significative dans les catécholamines plasmatiques et les contractions de glucagon entre le groupe PA et le groupe contrôle. Le taux d’acide gras plasmatique libre a augmenté significativement dans le groupe PA avant le test de «Eu glycaemic insulin clamp» (taux d’acide gras libre: 0,496 ± 0,053 mmol · L−1 pour le groupe contrôle versus 0,834 ± 0.103 mmol · L−1 dans le groupe PA pour la période pré-clampage, P < 0,01). La résistance tissulaire à l’insuline exogène a augmenté durant l’anesthésie prolongée et la chirurgie même s’il n’y avait aucun changement significatif dans le niveau des hormones de catabolisme.

EFFECTS OF HALOTHANE ANAESTHESIA AND SURGERY ON ADRENOCORTICAL FUNCTION IN MAN

Summary and ConclusionsThe present study was undertaken to investigate whether or not preanaesthetic medication and halothane anaesthesia affect adrenal cortical function in man as judged by their influence on the plasma levels of free 17-hydroxycorticosteroids. The blood samples were taken in the morning between 8:15 and 8.45 A.M. before induction of anaesthesia, during anaesthesia alone, during surgery, and in the recovery room. The determination of free 17-OHCS in plasma was made by Peterson’s modification of the Porter-Silber method. Twenty patients were given halothane anaesthesia and another eleven patients received premedication alone without anaesthesia.The mean plasma level of 17-OHCS in the preanaesthetic period was in the range of 10.0-10.8 µg. per 100 ml., which was significantly lower than for the non-premedicated patients. Although halothane anaesthesia for 15 minutes after induction with thiopental evoked slight but insignificant increase of 17-OHCS level, halothane anaesthesia for 30 minutes without employing thiopental significantly increased the plasma 17-OHCS levels above the preinduction levels, from 10.8 ± 1.4 to 17.5 ± 1.6 μg. (± = standard error) per 100 ml. The surgical stress increased plasma 17-OHCS levels markedly. These findings indicate that halothane anaesthesia has a stimulating effect on adrenal cortical function in man.RésuméLe présent travail a été entrepris pour chercher si oui ou non la prémédication et l’anesthésie à l’halothane affectent la fonction du cortex surrénalien chez l’homme, autant qu’on peut en juger par leur influence sur les niveaux plasma-tiques des 17-hydroxycorticostéroides en liberté. Les échantillons de sang ont été prélevés le matin entre 8:15 et 8:45 heures, avant l’induction de l’anesthésie, durant l’anesthésie seule, durant l’opération et dans la salle de réveil. Le dosage des 17-OHCS libres dans le plasma a été fait par la méthode de Porter-Silber, modifiée par Peterson. Vingt malades ont reçu une anesthésie à Thalothane et onze autres malades n’ont reçu que la prémédication sans anesthésie. Le niveau plasmatique moyen des 17-OHCS dans la période pré-anesthésique se tenait entre 10.0 et 10.8 mg. par 100 c.c, ce qui était sensiblement inférieur à ce qu’on trouve chez les non-prémédiqués. Bien que l’anesthésie à l’halothane durant 15 minutes après l’induction au pentothal n’ait produit qu’une augmentation sans importance du niveau des 17-OHCS, l’anesthésie à l’halothane durant 30 minutes (sans utiliser de pentothal) a sensiblement augmenté les niveaux plasmatiques des 17-OHCS au dessus des niveaux antérieurs à l’induction, de 10.8 ± 1.4 à 17.5 ± 1.6 mg. par 100 c.c. Le stress chirurgical a augmenté de façon marquée les niveaux plasmatiques des 17-OHCS. Ces résultats indiquent que l’anesthésie à l’halothane a un effet stimulant sur la fonction du cortex surrénalien chez l’homme.

Antinociceptive effects of neurotropin in a rat model of central neuropathic pain: DSP-4 induced noradrenergic lesion

Neurotropin is a nonprotein extract isolated from inflamed skin of rabbits inoculated with vaccinia virus, and used for treatment of neuropathic pain. In the present study, we have determined whether neurotropin could exert antinociceptive action using the central neuropathic pain model that we recently established. Rats were randomly allocated to 3 groups: Sham group (n=20), DSP-4 [N-(-2-chloroethyl)-N-ethyl-2-bromobenzylamine] group (50mg/kg ip, n=18), and DSP-4+5,7-DHT [5,7-dihydroxytryptamine] group (ip DSP-4 50mg/kg+icv 5,7-DHT 200μg, n=18). In Sham, DSP-4 and DSP-4+5,7-DHT groups, the effects of ip neurotropin (100NU/Kg) on hot-plate latency in rats with no lesion, noradrenergic neuron depletion and both noradrenergic and serotonergic neuronal depletion were studied, respectively. Rats in each group were subdivided equally to 2 subgroups: saline and neurotropin. After completion of the hot-plate tests, each rat was decapitated, the cerebral cortex was dissected from its internal structure for measurement of norepinephrine contents. Hot-plate latency significantly decreased by ∼40% 10 days after ip DSP-4 or after ip DSP-4 and 5,7-DHT. Norepinephrine contents in DSP-4 treated rats (55.6±6.3ng/ng tissue) and DSP-4+5,7-DHT treated rats (35.3±6.3ng/ng tissue) were significantly lower than those in intact rats (131.6±5.7ng/ng tissue, p<0.01). Neurotropin significantly increased the area under the curve (AUC) of the hot-plate latency in the DSP-4 and DSP-4+5,7-DHT groups but not in the Sham group. There was a significant correlation between AUC and norepinephrine contents in saline subgroup (p<0.01, r=0.597) but not in neurotropin subgroup in DSP-4 group. Neurotropin exerted an antinociceptive effect in DSP-4 induced central neuropathic pain. The present data suggest neuronal pathways other than descending inhibitory noradrenergic and serotonergic systems may be involved in neurotropin mediated antinociception.