Comparison of the efficacy of salmeterol/fluticasone propionate combination in Japanese and Caucasian asthmatics

INTRODUCTION

The effect of ethnicity on the efficacy of salmeterol (S)+fluticasone propionate (FP) has not been examined in Japanese and Caucasian asthmatics. In this study, the efficacy of combination treatment with S and FP from a single inhaler (SFC) was compared with concurrent treatment with S and FP administration from separate inhalers (S+FP) in Japanese and Caucasian asthmatics.

METHODS

This was a randomised, double-blind, crossover study in male and female Japanese (n=18) and Caucasian (n=17) asthmatics (50-100% predicted FEV(1); >35% reversibility in sGaw). Subjects received SFC (S 50 mcg/FP 250 mcg b.i.d.) and S+FP (S 50 mcg b.i.d.+FP 250 mcg b.i.d.) for 14 days. sGaw and FEV(1) were determined 0-12h after the first and last doses.

RESULTS

Treatment with both SFC and S+FP produced marked bronchodilation, which was maintained 0-12h after the first dose. Baseline sGaw and FEV(1) increased up to 51% and 180 mL, respectively, in Japanese subjects over 2 weeks of treatment, with similar improvements in Caucasian subjects. On Day 14 the 0-12h S+FP:SFC treatment ratios (90% CI) for sGaw AUC and peak were 1.05 (0.98, 1.12) and 1.05 (0.97, 1.14), respectively, in Japanese subjects, and 0.99 (0.92, 1.07) and 0.98 (0.89, 1.07), respectively, in Caucasian subjects, with no difference between the two ethnic groups.

CONCLUSIONS

The finding of a similar significant bronchodilator response in Japanese and Caucasian asthmatics following concurrent and combination treatment with salmeterol and FP suggests that the therapeutic response to these agents is comparable and independent of ethnicity in Japanese and Caucasian asthma patients.

Pharmacodynamic study of procaterol hydrochloride dry powder inhaler: evaluation of pharmacodynamic equivalence between procaterol hydrochloride dry powder inhaler and procaterol hydrochloride metered-dose inhaler in asthma patients in a randomized, double-dummy, double-blind crossover manner

Therapeutic equivalence between procaterol hydrochloride dry powder inhaler (Meptin DPI) and procaterol hydrochloride metered-dose inhaler (Meptin MDI), the currently marketed formulation, was assessed in 16 patients with bronchial asthma. The study was conducted in a randomized, double-dummy, double-blind crossover manner, using forced expiratory volume in the first second (FEV1) as an index of bronchodilatory effect. In Period I, the patients received 20 mcg of either Meptin DPI or Meptin MDI, and then crossed over in Period II after a washout interval of 3--28 days. Pharmacodynamic equivalence was accessed using AUC (FEV1)/h and peak FEV1 as indices, and the data were analyzed by analysis of variance (ANOVA). Factors used for the analysis were the treatment group and/or carryover effect, patients within each group, period, and treatment. The 90% confidence intervals for the differences between the two treatments were --0.0995 to --0.0204 (L) for mean AUC (FEV1)/h and --0.102 to --0.022 (L) for mean peak FEV1, both within the acceptance criteria of --0.15 to 0.15 (L). Meptin DPI was therefore assessed as being equivalent to the current Meptin MDI.

Pharmacodynamic equivalence study of CFC-free and CFC-containing procaterol hydrochloride metered-dose inhalers

Equivalence between a CFC-free procaterol hydrochloride metered-dose inhaler using HFA-227 as a propellant (Meptin [HFA]) and a CFC-containing procaterol hydrochloride metered-dose inhaler (Meptin [CFC]) was assessed in 28 patients with bronchial asthma. The study was conducted in a randomized, double-dummy, double-blind crossover manner, using forced expiratory volume in the first second (FEV1) as an index of bronchodilatory effect. In Period I, the patients received 20 microg of either Meptin [HFA] or Meptin [CFC] and then crossed over in Period II after a washout interval of 3-28 days. Pharmacodynamic equivalence was assessed using AUC (FEV1)/h and peak FEV1 as indices, and the data was analyzed by analysis of variance. Factors used for the analysis were the treatment group and/or carryover effect, patients within each group, period, and treatment. The 90% confidence intervals for the differences between the two treatments were -0.0507 to 0.0039 (L) for mean AUC (FEV1)/h and -0.056 to 0.026 (L) for mean peak FEV1, both within the acceptance criteria of -0.15 to 0.15 (L). Meptin [HFA] was therefore assessed as being equivalent to the current Meptin [CFC].

Improvement of accessory symptoms of hypertension by TSUMURA Orengedokuto Extract, a four herbal drugs containing Kampo-Medicine Granules for ethical use: a double-blind, placebo-controlled study

A double-blind, placebo-controlled study was conducted to evaluate the efficacy, safety, and utility of TSUMURA Orengedokuto Extract Granules for Ethical Use (TJ-15) as a treatment for the accessory symptoms of hypertension. Two capsules of the study drug were administered orally 3 times daily (i.e., before meals) for 8 weeks. Among 265 patients enrolled in the study, 134 were assigned to the TJ-15 group and 131 were assigned to the placebo group, of whom 204 patients (103 in the TJ-15 group and 101 in the placebo group) were included in the efficacy and utility analyze and 251 patients (128 in the TJ-15 group and 123 in the placebo group) were included in the safety analysis. Efficacy was significantly higher in the TJ-15 group based on the total score for the accessory symptoms of hypertensions which was the primary efficacy endpoint (Wilcoxon's rank sum test, p=0.013). When each accessory symptom of hypertension was assessed separately, efficacy was higher for hot flushes and facial suffusion in the TJ-15 group (Wilcoxon's rank sum test, p=0.034, and 0.022, respectively). There were no significant differences between the TJ-15 and the placebo groups with respect to the decrease of blood pressure or the antihypertensive effect. There was also no significant difference between the two groups with regard to the overall safety rating. The utility rating was significantly higher in the TJ-15 group than in the placebo group (Wilcoxon's rank sum test, p=0.016). In conclusion, TJ-15 was superior to placebo with respect to efficacy, safety, and utility for the treatment of accessory symptoms of hypertension.

Serum contents of the free forms of alpha(1)-microglobulin and ulinastatin: relation to diseased states in patients with mood disorders

We have found previously that the relationship between the urinary contents of alpha(1)-microglobulin (alpha(1)M) and ulinastatin (UT) in patients with mood disorder differs from that of age-matched healthy subjects. However, it has yet to be determined whether or not the difference in the relation correlates with the contents of the free forms of alpha(1)M and UT in serum and whether changes in the existing forms of alpha(1)M and UT in serum reflect the actual disease states. The relation between serum contents of the free forms of alpha(1)M and UT in 10 patients with mood disorders was different from that of 17 age-matched healthy subjects. The regression plot between scores of the Hamilton Rating Scale for Depression and ratios of the free form content to total content (F/T ratio) of UT was more informative on the depressive state than that of alpha(1)M. The F/T ratios of UT may afford a useful objective index in monitoring the diseased state of a patient with mood disorder.

Elevation of striatal interleukin-6 and serum corticosterone contents in MPTP-treated mice

1. Changes in the content of striatal interleukins (IL-1 beta and IL-6) and serum corticosterone in relation to deterioration of the dopaminergic system induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; a dopaminergic neurotoxin; 20 mg/kg i.p., four administrations/12 h) in C57BL/6J mice were investigated. 2. Striatal dopamine, IL-1 beta, IL-6 and serum corticosterone were measured on days 1 and 7 post-MPTP. 3. Dopamine depletion was more severe on day 7 than on day 1 post-treatment. 4. Increases in IL-6 were observed on days 1 and 7 post-MPTP. The increase in striatal IL-6 content varied with the extent of dopamine depletion, although the IL-1 beta concentration remained unchanged compared with control values on days 1 and 7 post-treatment. 5. Serum corticosterone was not different from control on day 1 post-MPTP. However, marked increases in the serum corticosterone were observed on day 7 post-treatment. 6. These results suggest that changes in striatal IL-6 and serum corticosterone are closely associated with the severity of MPTP-induced dopaminergic degeneration.

Sex- and age-related changes in urinary contents of alpha 1-microglobulin and ulinastatin in mice

1. Using two murine strains, ICR/Jcl and senescence-accelerated-prone inbred mouse 1 (SAMP1), age-associated changes in urine indices (e.g. urine volume, creatinine contents, contents of alpha 1-microglobulin (alpha 1M) and ulinastatin (UT) and the relation of urinary contents of alpha 1M and UT were investigated. 2. Sex-related differences in the indices were not observed in ICR nor in SAMP1 mice. 3. Urine indices per 24 h of ICR mice at 6 and 14 months of age were higher than those at 3 months of age, although indices of SAMP1 mice did not change with ageing. Urinary contents of alpha 1M and UT in ICR mice at 6 and 14 months of age were higher than those in SAMP1 mice. However, contents of alpha 1M and UT expressed as the contents per creatinine did not differ between these two strains. 4. In the relation between urinary contents of alpha 1M and UT, a positive correlation was displayed both in ICR and SAMP1 mice, and the regression slope did not significantly differ with ageing in these two strains. 5. These results suggest that ageing per se is not a factor which affects the relation of urinary contents of alpha 1M and UT.

Impairment of the correlation between urinary contents of alpha-1-microglobulin and ulinastatin is induced by intracerebroventricularly administered interleukin-6 in mice

We have found previously that the correlation between urinary contents of alpha-1-microglobulin (alpha1M) and ulinastatin (UT) depends on the type of neuropsychiatric disease. Since interleukin (IL)-1beta and IL-6 are closely involved in pathophysiological aspects of various neuropsychiatric diseases, effects of intracerebroventricularly (i.c.v.) administered IL-1beta and IL-6 on the correlation between urinary contents of these two glycoproteins were examined in mice, a species in which alpha1M and UT and also the correlation between the urinary contents thereof are expressed similarly to humans. Indices (volume, contents of creatinine, alpha1M and UT, and alpha1M/UT ratio) in urine collected after i.c.v. administrations of 2 and 20 ng of either IL-1beta or IL-6 were not statistically different from those of the vehicle-treated (control) groups. Neither IL-1beta (2 and 20 ng) nor the lower dose of IL-6 (2 ng) affected the positive correlation between urinary contents of alpha1M and UT. However, a higher dose of IL-6 (20 ng) nullified the positive correlation for 2 days after administration. Recovery to a positive correlation was thereafter displayed. These findings suggest that central IL-6 plays an important role in correlating urinary contents of alpha1M and UT without affecting the renal functions.

Ethanol reduces spontaneous firing and potentiates GABA-induced currents in acutely dissociated rat medial vestibular nucleus neurons

Effects of ethanol on acutely dissociated medial vestibular nucleus (MVN) neurons were examined using whole-cell patch clamp technique to elucidate the mechanism underling the inhibitory effects of this drug on the neurons observed in in vivo studies. Dissociated MVN neurons obtained from male Wistar rats were superfused with extracellular solution continuously at a flow rate of 1-3 ml/min. Whole-cell patch clamp recording was performed according to standard procedures. GABA was applied by pressure from a pipette placed near the neuron recorded. Ethanol was applied via pipette by pressure or through bath perfusion. Acutely dissociated MVN neurons regularly showed spontaneous firing. Under current-clamp conditions, bath application of ethanol at 0.1% caused hyperpolarization and reduced spontaneous firing in MVN neurons, while 0.1% ethanol did not affect spontaneous firing. Pulse application of higher concentrations of ethanol (0.1-1%) caused similar hyperpolarization. Under voltage-clamp conditions at a holding potential of -30 mV, GABA induced outward currents in a concentration-dependent manner. GABA-induced currents were potentiated in the presence of 0.01% ethanol. These results indicate that high concentrations of ethanol (0.1-1%) directly induce inhibition of spontaneous firing and low concentrations (0.01%) enhance GABA-induced inhibition in the MVN neurons.

Nullification of a positive correlation between urinary contents of alpha1-microglobulin and ulinastatin with intracerebroventricularly administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (MPP+) in mice

Striatal dopamine contents in C57BL/6J mice were reduced at 24 h after intracerebroventricular (ICV) administration of 1-methyl-4-phenyl-1,2, 3,6-tetrahydropyridine (MPTP) or 1-methyl-4-phenylpyridinium (MPP+) in a dose-dependent manner. A dose of 1.8 microg MPP+ significantly (P < 0.05) suppressed the dopamine contents, whereas a similar dose of MPTP did not. A definite positive correlation between urinary contents of alpha1-microglobulin (alpha1M) and ulinastatin (UT) existed in normal mice. However, this correlation was nullified by ICV administration of 18 and 36 microg MPTP or 1.8 and 18 microg MPP+. With 1.8 microg MPTP, a positive correlation between urinary contents of alpha1M and UT was displayed. The urine volume, creatinine content, glomerular filtration rate, alpha1M and UT contents, and alpha1M/UT ratio of urine collected for 24 h post-ICV administration of MPTP or MPP+, were not statistically different from those of control mice. Our findings suggest that the central effects of MPP+, a neurotoxic metabolite of MPTP, nullify the positive correlation between urinary contents of alpha1M and UT without affecting renal functions.

Ischemia induces a reduction in the content of ulinastatin-like substance in the murine hippocampus

Effects of ischemia on the content of a ulinastatin (UT)-like substance in the murine cerebral cortex and hippocampus were studied. At 24 h post-ischemia, a significant (p < 0.05) decrease in the content of UT-like substance in the hippocampus but not the cerebral cortex and a concurrent increase in the activity of micro-calpain were observed. In in vitro experiments, a decrease was registered in the content of UT-like substance in the hippocampus in the presence of calcium. This decrease was inhibited by both EDTA and calpastatin treatments. These results implicate the destruction of UT-like substance by micro-calpain in the ischemic hippocampus.

Nullification of a positive correlation between urinary levels of alpha 1-microglobulin and ulinastatin by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice

The relationships between urinary levels of alpha 1-microglobulin (alpha 1M) and ulinastatin (UT) were investigated in C57BL/6J mice, a species which reportedly possesses the gene similar to that of humans for synthesizing the precursor protein of alpha 1M and UT. A positive correlation was established in normal mice. However, repetitive administrations (20 mg/kg, IP, four administrations/12 h) of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) nullified the positive correlation. A similar phenomenon was induced by ICV-administered MPTP (18 and 36 micrograms) in the animals. Furthermore, L-dopa administration (50 mg/kg, IV) in MPTP-treated (1 week after the final IP administration of MPTP) mice reversed the tendency of MPTP, although the agent alone did not affect the positive correlation in normal mice. These results suggest that nullification of the positive correlation probably was induced by the central effects of MPTP. We have found previously that the lack of a positive correlation between urinary levels of alpha 1M and UT distinguishes Parkinson's disease from other neuropsychiatric diseases such as dementia (Alzheimer-type and vascular dementia), schizophrenia and mood disorders. Our present results displayed a phenomenon that the lack of correlation between urinary levels of alpha 1M and UT in patients with Parkinson's disease is reproducible in MPTP-treated mice.

Significant decreases of ulinastatin-like immunoreactive substance in the cerebrospinal fluid of patients with dementia

Studies to elucidate changes in the contents of ulinastatin-like immunoreactive substance (UTIRS) and alpha 1-microglobulin-like immunoreactive substance (alpha 1 MIRS) in cerebrospinal fluid (CSF) of patients with dementia were performed. Levels of UTIRS in the dementia group were significantly (p < 0.01) lower than those in dementia-free subjects. In addition, lower levels of UTIRS were registered in subjects afflicted with a higher severity of dementia. However, the levels of alpha 1 MIRS were not affected in the dementia group compared with dementia-free subjects. Neither UTIRS nor alpha 1 MIRS contents were related to the existence and stages of Parkinson's disease. These results suggest that UTIRS levels in the CSF are associated with the severity of dementia.

Non-existence of a positive correlation between urinary levels of alpha 1-microglobulin and ulinastatin in patients with Parkinson's disease

Urinary levels of alpha 1-microglobulin (alpha 1M) and of ulinastatin (UT) and the alpha 1M/UT ratio did not differ significantly between age-matched controls and patients with Parkinson's disease, and among subdivided groups based on Yahr's stages in Parkinson's disease. Furthermore, these indexes did not correlate with Yahr's stages. Although alpha 1M and UT levels did not correlate in patients with Parkinson's disease, a positive correlation was observed in the control group. The non-existence of a positive correlation between alpha 1M and UT levels distinguishes Parkinson's disease from other neuropsychiatric diseases such as dementia (Alzheimer-type and vascular dementia), schizophrenia and mood disorder.

Changes in the ratio of urinary alpha 1-microglobulin to ulinastatin levels in patients with Alzheimer-type dementia and vascular dementia

Relationships between urinary levels of alpha 1-microglobulin (alpha 1M) and ulinastatin (UT) in patients with dementia were investigated. There were no significant differences in alpha 1M and UT levels and alpha 1M: UT ratios among three groups: age-matched control subjects, patients with either Alzheimer-type senile dementia (ATD) or vascular dementia (VD). Although a positive correlation was established between alpha 1M and UT levels in these groups, the regression of the demented patients differed significantly from that of controls (P < 0.05). A tendency towards a negative correlation between alpha 1M: UT ratios and the levels of severity or duration of the disease was displayed in the ATD group, whereas a tendency toward a positive correlation between alpha 1M: UT ratios and the levels of severity was observed in the VD group. These results suggest that changes in the relationships between urinary levels of alpha 1M and UT may provide a useful biochemical index for diagnoses of ATD and VD.

Prospective, randomized, placebo-controlled, double-blind, multicenter study of exercise with enoxaparin pretreatment for stable-effort angina

In this double-blind, placebo-controlled, multicenter trial, we examined the combined effects of repeated exercise and intravenous enoxaparin (low-molecular-weight heparin) on treadmill exercise capacity and angiographic collateral growth and compared them with the effect of repeated exercise with placebo. Fifty-two patients with stable-effort angina were randomly assigned to receive one of two doses of enoxaparin (40 or 60 mg) or placebo. In each patient, 20 treadmill exercise sessions were performed with the pretreatment of enoxaparin or placebo for 2 to 3 weeks. Before and after treatment, coronary cineangiography was repeated to evaluate the changes in coronary and collateral circulation. Improvement of rate-pressure product (RPP) at the onset of angina was taken as an index of enhanced collateral flow reserve. Although the mean differences in the magnitude of increase in RPP were not significantly different between the 3 groups, a heterogeneous response was observed: 1620 beats/min.mm Hg in 40 mg (p = 0.12), 3060 beats/min.mm Hg in 60 mg (p = 0.02), and 1090 beats/min.mm Hg in placebo (p = 0.44). The end-points of the exercise test were changed from chest discomfort to leg fatigue or dyspnea in 10 (28%) of 36 enoxaparin-treated patients but in only 1 (6%) of 16 placebo patients (p = value not significant (NS)). Similarly, the extent of coronary and collateral circulation to the completely obstructed coronary artery was increased in 17 (47%) of 36 enoxaparin-treated patients but only in 4 (25%) of 16 placebo patients (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of D2 receptor agonist-induced inhibition by D1 receptor agonist in the ventral tegmental area

1. A microiontophoretic study was performed on chloral hydrate-anaesthetized rats to examine the role of D1 receptors in the ventral tegmental area (VTA) neurones, which are inhibited by autoreceptor and D2 receptor agonists. 2. Inhibition by microiontophoretic application of quinpirole (a D2 agonist) of antidromic spikes elicited by stimulation of the nucleus accumbens in dopaminergic neurones of the VTA, was significantly enhanced by simultaneous application of SKF 38393 (D1 agonist), although SKF 38393 alone had little effect on the neurones. 3. In addition, quinpirole-induced inhibition was antagonized by iontophoretic application of domperidone (D2 antagonist), but was not affected by SCH 23390 (D1 antagonist). 4. Furthermore, SKF 38393-induced enhancement of inhibition by quinpirole was antagonized by simultaneous application of SCH 23390. 5. These results suggest that activation of D1 receptors located on the VTA dopaminergic neurones or on non-dopaminergic nerve terminals is not essential for inducing inhibition of the dopaminergic neurones, but enhances D2 receptor-mediated inhibition directly or indirectly via inhibitory neurones.

Demonstration of a human urinary trypsin inhibitor (urinastatin)-like substance in the murine brain

A human urinary trypsin inhibitor (urinastatin)-like immunoreactive substance with trypsin-inhibitory activities was found in the murine brain. Regional levels of this urinastatin (UT)-like substance in the brain were within 5 ng/mg protein and were expressed in a descending order as follows: cerebral cortex not equal to hippocampus > hypothalamus > mesencephalon not equal to corpus striatum >> medulla oblongata > cerebellum. Mechanical lesioning of the cerebral cortex or hippocampus with a needle induced a rapid and intense appearance of a UT-like immunoreactive substance in the neuronal cells of injured sites. Conditioned fear-stress induction incited a reversible increase in the level of UT-like immunoreactive substance in the hippocampus. These results suggest that the UT-like immunoreactive substance is produced by neurons in response to brain injury and fear-stress stimuli.

Effects of heparin on the inhibitory activities of human urinary trypsin inhibitor (ulinastatin) on trypsin, chymotrypsin and leukocyte elastase

Effects of heparin on the inhibitory activities of human urinary trypsin inhibitor (ulinastatin) on trypsin, chymotrypsin and leukocyte elastase were studied. Heparin per se neither influenced the enzymatic activities nor changed the mode of inhibition of ulinastatin on the enzymes. In the presence of heparin, inhibitory effects of ulinastatin on trypsin were enhanced, whereas its effects on chymotrypsin and elastase were attenuated. These results suggest that the two functional domains in ulinastatin are differently affected by heparin.

Ifenprodil prevents glutamate cytotoxicity via polyamine modulatory sites of N-methyl-D-aspartate receptors in cultured cortical neurons

Neuroprotective effects of ifenprodil, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, against glutamate cytotoxicity were examined in cultured rat cortical neurons. The viability of the cultures was markedly reduced by a 10-min exposure to glutamate followed by incubation with glutamate-free medium for 60 min. Ifenprodil and its derivative SL 82.0715 dose-dependently prevented cell death induced by glutamate. The NMDA antagonists MK-801 and 3-[(+/-)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid also prevented glutamate cytotoxicity with a potency similar to that of ifenprodil. Ifenprodil as well as MK-801 prevented NMDA-induced cytotoxicity, but did not affect kainate-induced cytotoxicity. Glutamate cytotoxicity was inhibited by removing extracellular Ca++ during and immediately after glutamate exposure. Ifenprodil and MK-801 reduced NMDA-induced Ca++ influx measured with rhod-2. Either spermidine, a polyamine modulatory site agonist, or glycine, a strychnine-insensitive glycine site agonist, potentiated NMDA- and glutamate-induced cytotoxicity. The protective effects of ifenprodil against NMDA- and glutamate-induced cytotoxicity were significantly reduced by spermidine, but not by glycine. These findings indicate that ifenprodil protects cortical neurons against glutamate cytotoxicity by selective antagonism of the polyamine modulatory site of the NMDA receptor complex.

Decreased dopamine and increased norepinephrine levels in the spontaneously epileptic rat, a double mutant rat

Dopamine (DA) and norepinephrine (NE) brain levels and turnover rate were examined in the spontaneously epileptic rat (SER: zi/zi, tm/tm), a double mutant rat obtained by mating tremor heterozygotes (tm/+) with zitter homozygotes associated with epileptic seizures composed of spontaneously occurring tonic convulsion and absence-like seizure. DA and NE levels were also determined in age-matched male zitter, tremor and Kyo: Wistar rats. DA levels in caudate nucleus were significantly lower in adult age (10-12 weeks) SER, which showed epileptic seizures, and zitter rats than in adult Kyo: Wistar and tremor rats. DA levels in other areas such as thalamus-hypothalamus, midbrain, and pons medulla were not different among SER, zitter, tremor, and Kyo: Wistar rats at age 10-12 weeks. Except in cerebral cortex and hippocampus, there were no differences in brain DA levels between young seizure-free SER (age 5 weeks) and young Kyo: Wistar rats. Furthermore, the turnover rate of DA was significantly lower in caudate nucleus of adult SER than of Kyo: Wistar rat, whereas in pons-medulla there was no difference between the two strains. In contrast, NE levels in the thalamus-hypothalamus, midbrain, cerebellum and pons-medulla were higher in SER and zitter rats at age 10-12 weeks than in age-matched tremor and Kyo: Wistar rats. Higher NE levels were also observed in midbrain, cerebellum, and pons-medulla of young SER as compared with young Kyo: Wistar rats. Turnover rates of NE were significantly lower in pons-medulla and cerebellum of the adult SER than in those of Kyo: Wistar rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of protein kinase C on the muscarinic excitation of rat adrenal chromaffin cells

The role of protein kinase C (PKC) in the muscarinic excitation of chromaffin cells freshly isolated from rat adrenal medullae was examined by the patch-clamp recording method. Acetylcholine and McN-A-343, a M1-receptor agonist, depolarized the cell and induced action potentials. Phorbol 12,13-dibutyrate (PDBu), an activator of PKC, increased acetylcholine-induced firing concomitant with a persistent depolarization. Under voltage-clamp recording, both McN-A-343 and PDBu decreased the cesium-sensitive K+ current, which was induced by shifting the membrane potential between -140 mV and -40 mV. These results suggested that the stimulation of muscarinic M1-receptors by cholinergic drugs activated phospholipase C to degrade phosphoinositide, consequently producing diacylglycerol, and diacylglycerol activates PKC to induce excitation of adrenal chromaffin cells.

Abnormal excitability of hippocampal CA3 pyramidal neurons of spontaneously epileptic rats (SER), a double mutant

The spontaneously epileptic rat (SER:zi/zi, tm/tm), a double mutant, shows both tonic convulsions and absence-like seizures characterized by low-voltage fast waves and by 5-7 Hz spike and wave-like complexes in the cerebral cortical and hippocampal EEG, respectively. Characteristics of hippocampal CA3 pyramidal neurons were examined to determine whether these neurons are abnormally excitable. When a single stimulus was given to the mossy fiber, there was repetitive firing and a depolarization shift in neurons of mature SER (over 12 weeks old), in which epileptic seizures had fully developed. However, in young SER (7-8 weeks old) and littermates (zi/zi, tm/+), which did not show any seizures, only a single spike was elicited with each single stimulation of the mossy fiber. Intracellular recording showed that the resting membrane potential was not significantly different among young and mature SER and littermates, but a long-lasting (100-200 ms) depolarizing shift accompanied by repetitive firing was observed following a single stimulation of the mossy fiber in half of the CA3 neurons of mature SER. Furthermore, the input impedance of the CA3 neurons in mature SER was lower than that in young SER and in littermates. These results indicate that SER hippocampal CA3 neurons become abnormally excitable in conjunction with the development of epileptic seizures.

Antiepileptic effects of CNK-602A, a novel thyrotropin-releasing hormone analog, on absence-like and tonic seizures of spontaneously epileptic rats

The effects of CNK-602A (N-[(6-methyl-5-oxo-3-thiomorpholinyl) carbonyl]-L-histidyl-L-prolinamide), a novel thyrotropin-releasing hormone related analog, were investigated on absence-like seizure and tonic convulsion in the spontaneously epileptic rat (SER), which is a genetically defined double-mutant. When CNK-602A of 0.2-1 mg/kg was given intravenously to the animal, there were no changes in the background EEG except for an increase in low-voltage fast waves concomitant with behavioral alertness. However, CNK-602A suppressed absence-like seizure and tonic convulsion in a dose-dependent manner for over 1 h. These antiepileptic effects of CNK-602A on both seizures were antagonized by pretreatment with haloperidol (1 mg/kg, i.p.). It was found, using a brain in vivo microdialysis method, that CNK-602A at a dose of 1 mg/kg, which inhibits the seizures, increased the release of dopamine in the caudate nucleus. These results suggest that CNK-602A inhibits the seizures of SER in a similar manner to thyrotropin-releasing hormone (TRH), probably by increasing the release of dopamine in the central nervous system. In addition, the antiepileptic effects of CNK-602A were more potent and lasted longer than those of TRH.

Existence of a human urinary trypsin inhibitor (urinastatin)-like substance in the rat brain

A human urinary trypsin inhibitor, urinastatin (UT)-like immunoreactive substance with trypsin inhibitory activity, was demonstrated in certain brain regions in rats, especially the cerebral cortex, hippocampus and hypothalamus. Although this UT-like substance in the rat brain displayed an N-terminal amino acid sequence similar to that of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), it did not show any GAPDH activity. These results indicate that the UT-like substance in the rat brain is a protein different from GAPDH and indicates a localized distribution within certain brain regions partly related to learning and memory.

Human urinary trypsin inhibitor (urinastatin)-like substance in mouse liver

Mouse liver contains a human urinary trypsin inhibitor (urinastatin, UT)-like immunoreactive substance with trypsin inhibitory activity. Northern blot analysis demonstrates the presence of the appropriate 1.3 kb mRNA band in liver tissue but not in kidney or other tissues examined. Administration of hydrocortisone, which is known to increase the urinary excretion of the UT-like substance, increased the levels of UT-like substance in serum and in the liver tissue. In contrast, deoxycorticosterone acetate did not have such an effect. These results suggest that the gene encoding UT-like substance is primarily expressed in the liver of the mouse, and that glucocorticoids play an important role in regulating the hepatic synthesis of UT-like substance. Furthermore, these findings indicate that the mouse is a suitable species for research on the biological function of UT or UT-like substances.

Effects of L-threo-DOPS, a noradrenaline precursor, on the long-term potentiation in the rat hippocampal mossy fiber-CA3 region

The effects of L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS), a synthetic precursor of norepinephrine (NE), on the long-term potentiation (LTP) in the hippocampal mossy fiber-CA3 system was examined in urethane-anesthetized rats, the objective being to determine whether or not this drug acts as NE on the LTP. L-threo-DOPS may be effective for treating some type of mental disorders, including dementia. The LTP, induced in CA3 by tetanic stimulation (100 Hz for 1 s) applied to the mossy fiber persisted for more than 4 h. When L-threo-DOPS (50 and 150 micrograms) was injected into the lateral ventricle 30 min prior to the tetanic stimulation, there were no significant alterations in the LTP. However, in animals treated with reserpine (5 mg/kg i.p.) 24 h before the experiment, LTP was not induced with tetanic stimulation alone yet was obtained when tetanic stimulation was preceded by L-threo-DOPS (50 and 150 micrograms) applied to the ventricle. The LTP obtained by L-threo-DOPS in the reserpine-treated animal was inhibited by pretreatment with benserazide and was completely blocked by the simultaneous administration of sotalol. These results suggest that NE converted from L-threo-DOPS plays an important role in inducing LTP in the mossy fiber-CA3 system in the animals deficient in catecholamines.

Characteristics of muscarinic cholinergic, gamma-aminobutyric acid(A) and phencyclidine receptors in spontaneously epileptic rats; in vitro quantitative autoradiographic analysis

Characteristics of muscarinic cholinergic (mACh), gamma-aminobutyric acid(A) (GABAA) and phencyclidine (PCP) receptors in the spontaneously epileptic rats (SER), which exhibit both absence-like seizures and tonic convulsion, were examined using in vitro quantitative autoradiography. Computer analysis using autoradiographic technique revealed that the amount of the specific binding of [3H]quinuclidinyl benzilate (QNB) to mACh receptors in the striatum of SER was more than that of zitter rats, not exhibiting both seizures and convulsion. However, the specific bindings of [3H]muscimol and [3H]N-(1-[2-thienyl]cyclohexyl)3,4-piperidine (TCP) to GABAA and PCP receptors, respectively, of SER were not different from those of zitter rats in various regions tested. These results suggest that hyperfunction of mACh receptors in the striatum is involved in the appearance of absence-like seizures and tonic convulsion of SER.

Effects of thyrotropin-releasing hormone and a related analog, CNK-602A, on long-term potentiation in the mossy fiber-CA3 pathway of guinea pig hippocampal slices

The effects of thyrotropin-releasing hormone (TRH) and a related analog, CNK-602A, that induces the release of catecholamines, on long-term potentiation (LTP) of the population spike in mossy fiber-CA3 pathways were investigated in guinea pig hippocampal slices. TRH augmented LTP of the population spike at concentrations of 10(-6)-10(-5) M. CNK-602A also augmented LTP at concentrations of 10(-6)-10(-5) M in a dose-dependent manner. LTP in slices of the hippocampus obtained from animals given 6-hydroxydopamine (6-OHDA) intraventricularly was significantly lower than that in non-treated animals. However, both TRH and CNK-602A (10(-6) M) augmented LTP in slices from 6-OHDA-treated animals. These findings suggest that TRH and CNK-602A augment LTP in the mossy fiber-CA3 pathway without activating noradrenergic and/or dopaminergic fibers.

Inhibition of lateral vestibular nucleus neurons by 5-hydroxytryptamine derived from the dorsal raphe nucleus

Electrophysiological studies were performed to elucidate the effect of 5-hydroxytryptamine (5-HT) originating in the dorsal raphe nucleus (DR) on neuronal activity in the lateral vestibular nucleus (LVN) neurons, using cats anesthetized with alpha-chloralose. LVN neurons were classified into monosynaptic and polysynaptic neurons according to their responses to vestibular nerve stimulation. Conditioning stimuli applied to the DR inhibited orthodromic spikes elicited by vestibular nerve stimulation predominantly in polysynaptic neurons of the LVN. The iontophoretic application of 5-HT also inhibited orthodromic spikes of the LVN neurons. A close correlation was observed between the effects of DR conditioning stimulation and iontophoretically applied 5-HT in the same neurons. These inhibitions with both treatments were antagonized during the application of methysergide, a 5-HT antagonist. In the majority of LVN polysynaptic neurons that responded to antidromic stimulation of the ipsilateral or contralateral abducens nucleus, orthodromic spikes elicited by vestibular nerve stimulation were inhibited by DR conditioning stimulation and the iontophoretic application of 5-HT. In contrast, LVN neurons that responded to antidromic stimulation of the vestibulospinal tract were rarely affected by these treatments. These results indicate that 5-HT derived from the DR inhibits the synaptic transmission of LVN polysynaptic neurons ascending to the abducens nucleus, and suggest that 5-HT derived from the DR is involved in the regulation of the vestibulo-ocular reflex.

Ontogeny of absence-like and tonic seizures in the spontaneously epileptic rat

The ontogeny of epileptic seizures in spontaneously epileptic rats (SER; zi/zi, tm/tm) was studied by examining behaviour and electroencephalogram (EEG) simultaneously. Weight gain and survival time were also studied. Compared with the control Kyo:Wistar rats, SER showed a much smaller increase in body weight. All male and female SER died before 20 and 18 weeks of age, respectively. Body tremor was observed at 2 weeks of age but disappeared after 11 weeks. Staggering gait appeared after 7 weeks of age, and intensified with age. Absence-like seizures characterized by paroxysmal appearance of 5-7 Hz spike-wave-like complexes were observed in the cortical or hippocampal EEG after 5 weeks of age, and tonic seizures with low voltage fast waves were observed after 6 weeks of age. All SER exhibited both absence-like and tonic seizures with high frequencies from 12 weeks of age. Differences with other spontaneous rat models of epilepsy and application methods for estimating seizure-inhibitory effects of anti-epileptic drugs are discussed.

Inhibition by thyrotropin-releasing hormone of epileptic seizures in spontaneously epileptic rats

The effects of thyrotropin-releasing hormone (TRH) were investigated on absence-like seizures, which are characterized by the sudden appearance of 5-7 Hz spike-wave-like complexes in the cortical and hippocampal EEG, and on tonic convulsions of spontaneously epileptic rats (SER; zi/zi, tm/tm), a double mutant obtained by mating zitter homozygote (zi/zi) with tremor heterozygote rats (tm/+). TRH (5 and 10 mg/kg i.v.) inhibited the appearance of both absence-like seizures and tonic convulsions of SER without inducing obvious changes in the background EEG. The inhibitory effects were seen 5-20 min after injection of 10 mg/kg TRH and were antagonized by pretreatment with haloperidol (0.5 and 1.0/kg i.p.), although haloperidol alone did not affect the seizures. These results suggest that TRH has an antiepileptic effect in the genetically defined animal model, SER, and that the effect is mediated by the central dopaminergic system.

Effects of anti-vertigo drugs on medial vestibular nucleus neurons activated by horizontal rotation

The effects of anti-vertigo drugs on medial vestibular nucleus (MVN) neurons were examined to assess the site and mode of action using cats anesthetized with alpha-chloralose. Single neuron activity in the MVN was extracellularly recorded using a silver wire microelectrode attached along a seven-barreled micropipette, each of which was filled with diphenhydramine, diphenidol, betahistine, glutamate or NaCl. Type I of the MVN neurons were identified according to the responses obtained when the animal placed on a turn-table was rotated sinusoidally. The effects of the drugs were examined on type I neurons which received impulses primarily from the labyrinth and sent them to the oculomotor nuclei. The microiontophoretic application of diphenhydramine, diphenidol and betahistine inhibited rotation-induced firing of type I MVN neurons. Diphenhydramine and diphenidol were more potent than betahistine. These results suggest that these drugs directly act on MVN neurons to reduce the responsiveness to rotatory stimulation.

Inhibition by talipexole, a thiazolo-azepine derivative, of dopaminergic neurons in the ventral tegmental area

A microiontophoretic study using rats anesthetized with chloral hydrate and immobilized with gallamine triethiodide was carried out to compare the effect of talipexole (B-HT 920 CL2:2-amino-6-allyl-5,6,7,8-tetrahydro-4H-thiazolo [4,5-d]-azepine-dihydrochloride), a dopamine autoreceptor agonist, on dopaminergic neurons in the ventral tegmental area (VTA) to non-dopaminergic neurons in the VTA. VTA neurons were classified into two types according to the responses to antidromic stimulation of the nucleus accumbens (Acc): type I neurons with a long spike latency (8.69 +/- 0.24 msec) upon Acc stimulation and low spontaneous firing rate (6.80 +/- 1.34/sec), and type II neurons with a short latency (2.76 +/- 0.20 msec) and high spontaneous firing rate (26.77 +/- 7.05/sec), probably corresponding to dopaminergic and non-dopaminergic neurons, respectively. In type I neurons, microiontophoretic application of talipexole and dopamine inhibited antidromic spike generation elicited by Acc stimulation, and talipexole-induced inhibition was antagonized by domperidone (dopamine D-2 antagonist). In type II neurons, however, the antidromic spikes were not affected by either talipexole or dopamine. Furthermore, spontaneous firing was also inhibited by iontophoretically applied talipexole and dopamine in most type I neurons, but rarely affected by either drug. Inhibitory effects of talipexole were antagonized by domperidone. These results suggest that talipexole acts on dopamine D-2 receptors, thereby inhibiting the dopaminergic neurons in the VTA.

Dopamine D-1 receptor-mediated inhibition of nucleus accumbens neurons from the ventral tegmental area

1. Spike generation by stimulation of the parafascicular nucleus of thalamus was extracellularly recorded in the nucleus accumbens of chloral hydrate-anesthetized adult Wistar rats using a silver-wire microelectrode attached along a seven-barreled micropipette, each of which was filled with dopamine, SKF 38393 (D-1 agonist), bromocriptine (D-2 agonist), haloperidol, SCH 23390 (D-1 antagonist) and domperidone (D-2 antagonist). The drugs were microiontophoretically applied to the target neurons recorded. 2. Effects of dopamine receptor antagonists on the inhibition of the spike generation by conditioning stimuli applied to the ventral tegmental area preceding the test stimulus to the parafascicular nucleus and those of dopamine agonists on the test stimulus-induced spikes were examined. 3. The parafascicular nucleus stimulation-induced spikes were inhibited by dopamine as well as D-1 and D-2 agonists and by the conditioning stimulation of the ventral tegmental area. The conditioning stimulation-induced inhibition was antagonized by haloperidol and SCH 23390, but not by domperidone. 4. Activation of D-1 receptors, which make probably synaptic contact with dopaminergic nerve terminals from the ventral tegmental area, is considered to result in inhibition of the neuronal activity of the nucleus accumbens neurons receiving input from the parafascicular nucleus of the thalamus. In addition, D-2 receptors located extrajunctionally may be involved in the inhibition of the same neurons in the nucleus accumbens.

Inhibition by intravenously administered sodium bicarbonate of neuronal activity in medial vestibular nucleus neurons

The effects of 7% sodium bicarbonate on medial vestibular nucleus (MVN) neurons were examined to elucidate the mechanism underlying its anti-vertigo action, using alpha-chloralose-anesthetized cats. Intravenous injection of the drug at 1, 2 and 4 ml/kg every 10 min dose-dependently inhibited rotation- and glutamate-induced firing of type 1 neurons, although a low dose of the drug enhanced firing in a few neurons. However, microiontophoretic application of bicarbonate ions did not inhibit rotation- or glutamate-induced firing. After injection of the drug, the Po2 level in arterial blood did not differ from previous levels, but the bicarbonate ion levels dose-dependently increased concomitantly with an increase in pH, as compared with previous levels. These results suggest that the intravenous injection of 7% sodium bicarbonate directly inhibits the neuronal activity of the MVN, although the lower dose may enhance neuronal activity by acting on the peripheral vestibule.

A patch clamp study of muscarinic excitation of the rat adrenal chromaffin cells

A patch clamp study was performed to determine the ionic mechanisms underlying the muscarinic excitation of rat adrenal chromaffin cells. Burst-like, single-channel currents with brief openings were recorded during cell-attached or cell-free patch recording when the pipette solution contained high K+ media (70-140 mM), and the currents were recorded at potentials near the resting membrane potential. The amplitude and frequency of channel openings were dependent on the membrane potential and the K+ concentration of the external medium. Moreover, the single-channel currents observed with high K+ outside the membrane during inside-out recording were suppressed by the addition of a K+ channel blocker, tetraethylammonium, inside the membrane. These results suggest that the single K+ currents recorded in the present study had properties similar to those of the resting or muscarine-activated K+ currents in atrioventricular cells of the rabbit heart. During cell-attached patch recording with the high K+ medium in the recording pipette, muscarine at concentrations of 10(-5) to 10(-4) M dose dependently decreased the frequency of the channel openings but did not affect the current-voltage relationship or the time constants of open and close time histograms. These results indicate that muscarinic-induced suppression of K+ currents is caused by a decrease in the number of active K+ channels at the resting membrane potential.

Voltage and current clamp studies of muscarinic and nicotinic excitation of the rat adrenal chromaffin cells

Characteristics of the muscarinic and nicotinic excitation of chromaffin cells that had been freshly isolated from the rat adrenal medullae were analyzed using voltage and current clamp techniques. A dose-dependent increase in the extracellularly recorded firing of cells was observed when 10(-6) to 10(-4) M acetylcholine (ACh) were locally applied to the cells in the vicinity of the target cell being recorded using a microinflow method. During voltage clamp recording at the resting membrane potential, ACh induced two different sequential inward currents: a transient current with a rapid rising phase (fast response) and an apparent inward current with a slow rising phase (slow response). The membrane conductance increased during the ACh-induced fast response, and it subsequently decreased during the slow response. The amplitude of the fast response decreased when the holding potential was shifted to depolarized levels, whereas the amplitude of the slow response increased with depolarization. Nicotine produced fast depolarization and a transient inward current that was reduced by the membrane depolarization. In contrast, muscarine induced a slow depolarization and an apparent inward current that increased with depolarization. Muscarine also reduced the inward K+ current that had been induced by the application of a high K+ medium to the outside of the cell at the resting membrane potential. It is suggested that muscarinic excitation is triggered by the suppression of K+ channels that are open at potentials near the resting membrane potential. The present results indicate that ACh-induced excitation of adrenal chromaffin cells involves two separate mechanisms mediated by nicotinic and muscarinic receptors.

Mediation of micturition reflex by central norepinephrine from the locus coeruleus in the cat

We examined whether norepinephrine originating in the locus coeruleus mediates the micturition reflex in anesthetized cats. 6-Hydroxydopamine, a catecholamine neurotoxin, injected bilaterally into the locus coeruleus markedly decreased catecholamine fluorescence in the lesioned area and induced urinary retention after 72 to 84 hr. At this time, there was no or only slight contraction of the urinary bladder induced by its distension, while the contraction was noted before the treatment. However, phenylephrine, an alpha 1-receptor agonist, applied intrathecally in 6-hydroxydopamine-treated animals induced moderate bladder contraction. In sham-operated animals, the bladder contraction on its distension was inhibited by intrathecally applied prazosin, an alpha 1-receptor antagonist. Thus, in the micturition reflex, norepinephrine derived from the locus coeruleus acts on the alpha 1-adrenergic receptors in the sacral cord, and induces urinary bladder contraction via activation of the sacral parasympathetic preganglionic neurons.

Inhibition of hippocampal CA1 neurons by 5-hydroxytryptamine, derived from the dorsal raphe nucleus and the 5-hydroxytryptamine1A agonist SM-3997

Electrophysiological studies, using chloral hydrate-anesthetized rats, were undertaken to determine whether hippocampal pyramidal neurons, receiving input from the medial septal nucleus, were affected by 5-hydroxytryptamine (5-HT) derived from the dorsal raphe nucleus. The pyramidal neurons in the CA1 region of the hippocampus were classified into short- and long-latency neurons, based on their response to stimulation of the medial septal nucleus. Microiontophoretically applied atropine inhibited the generation of spikes upon stimulation of the medial septal nucleus in short-latency neurons, but had no effect on long-latency neurons. In the short-latency neurons, the stimulation-induced spikes of the medial septal nucleus were inhibited by conditioning stimuli applied to the dorsal raphe nucleus and iontophoretic application of 5-HT and the 5-HT1A agonists, SM-3997 (3 a alpha,4 beta,7 beta,7a alpha-hexahydro-2-(4-(4-(2-pyrimidinyl)-1- piperazinyl)-butyl)-4,7-methano-1H-isoindole-1,3(2H)-dione dihydrogen citrate) and 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin). The conditioning effect of the dorsal raphe nucleus was antagonized by methysergide. However, in the long-latency neurons, the spikes elicited by stimulation of the medial septal nucleus were not affected by the conditioning stimulation of the dorsal raphe nucleus, or iontophoretically applied 5-HT. These results indicate that 5-HT, originating in the dorsal raphe nucleus inhibited hippocampal pyramidal neurons receiving cholinergic input from the medial septal nucleus, but not those receiving non-cholinergic input from the medial septal nucleus. The drug SM-3997 inhibited the activity of hippocampal pyramidal neurons, that receive excitatory cholinergic input from the medial septal nucleus by acting on 5-HT1A receptors.

Long-term effects of continual intake of phenobarbital on the spontaneously epileptic rat

Spontaneously epileptic rats (SER) are a double mutant (zi/zi, tm/tm) spontaneously exhibiting both tonic and absence-like seizures. We examined the long-term effects of continual intake of phenobarbital (PB) on SER as a method of assessing long-term evaluation of antiepileptic drugs (AEDs). Food pellets containing 0.1% PB were given ad libitum from 7 weeks of age. Plasma PB level was maintained at 30-70 micrograms/ml after age 11 weeks. Tonic seizures were inhibited markedly in rats that received PB until age 15-16 weeks, but thereafter the inhibitory effects of PB gradually decreased. An increase of body weight and prolongation of survival were also noted in SER that received PB. Cortical and hippocampal EEG of SER were recorded with chronically implanted electrodes from 11 weeks of age pre-PB and 3, 7, and 14 days post-PB intake. These animals exhibit absence-like seizures characterized by sudden appearance of 5-7-Hz spike-wave-like complexes on EEG concomitant with immobility and staring. The seizures were not affected until age 13 weeks (2 weeks after intake of PB), although tonic seizures were inhibited. SER are considered a useful model for evaluating the long-term effects of AEDs.

Inhibition by enkephalin of medial vestibular nucleus neurons responding to horizontal pendular rotation

Electrophysiological studies were performed to determine whether or not enkephalin modulates the activities of medial vestibular nucleus (MVN) neurons responding to horizontal pendular rotation using alpha-chloralose anesthetized cats. The effects of microiontophoretically applied drugs were examined in type I and type II neurons identified according to responses to horizontal, sinusoidal rotation; type I and type II neurons showed an increase and decrease in firing with rotation ipsilateral to the recording site and vice versa with contralateral rotation, respectively. Iontophoretic application of enkephalin suppressed spike firing induced by rotation of the animals in type I neuron, but not in type II neuron. The spike firing induced by iontophoretically applied glutamate was also inhibited during the application of enkephalin. The inhibition by enkephalin of both rotation- and glutamate-induced firing was antagonized by naloxone which was given simultaneously. These results suggest that enkephalin acts on MVN type I neuron to inhibit transmission from the vestibule, thereby controlling vestibulo-ocular reflex.