A nationwide survey of factors influencing adherence to ocular hypotensive eyedrops in Japan.

INTRODUCTION: Few reports have investigated the status of adherence in Japan on a large scale. We aimed to investigate the status of adherence to topical glaucoma treatment and its associated factors. METHODS: A nationwide survey was conducted as a prospective fashion. Participants in this survey were subjects with primary open-angle glaucoma, normal-tension glaucoma, or ocular hypertension or pseudoexfoliation glaucoma who had been prescribed anti-glaucoma ophthalmic eyedrops and whose ophthalmologist considered prescribing any fixed combination of ocular hypotensive eyedrops for the first time between 2011 and 2012. Subjects and their attending ophthalmologists independently completed a questionnaire by utilizing a fixed combination of ocular hypotensive eyedrops. RESULTS: A total of 1358 ophthalmologists from 1071 medical institutions participated in this survey. We registered 4430 subjects (2049 males and 2381 females). In total, data from 3853 subjects (87.6%) were analyzed after inclusion of subjects based on inclusion and exclusion criteria. Good adherence was defined as not forgetting instillation during the past week. Rates of good adherence reported by subjects and ophthalmologists were 72.4 and 78.5%, respectively (P < 0.0001). The consistency of adherence evaluation between subjects and ophthalmologists was moderate [kappa score 0.5025 (95% confidence interval 0.4740-0.5309)]. Significant factors associated with adherence were size of clinic, age, gender, number of types of ocular hypotensive eyedrops, ease of instillation, preferred number of eyedrops, preferred frequency of instillation of eyedrops, and knowledge of glaucoma. CONCLUSION: Adherence to ocular hypotensive eyedrops among Japanese subjects was relatively good. Concordance of adherence between subjects' reports and ophthalmologists' responses was moderate. Size of clinic, number of types of ocular hypotensive eyedrops, ease of instillation, preferred number of eyedrops, preferred frequency of instillation of eyedrops, and knowledge of glaucoma were associated with adherence among Japanese glaucoma subjects.

Comparison of the Effect of Bromfenac versus Betamethasone Ophthalmic Solutions in Patients with Diabetic Macular Edema.

PURPOSE: To examine the effect of 0.1% bromfenac (BF) ophthalmic solution and 0.1% betamethasone (BM) ophthalmic solution on diabetic macular edema (DME). METHODS: This was a prospective trial. Nineteen patients (mean age of 66.6 ± 10.1 years) with DME and mean retinal thickness within a diameter of 1 mm from the fovea (central subfield thickness: CST) of 250-500 µm were randomized and instilled with BF or BM. CST, best-corrected visual acuity (BCVA), and intraocular pressure (IOP) were measured at 4, 8, and 12 weeks after administration. RESULTS: CST at baseline (p = .128) and that at 4, 8, and 12 weeks of administration was not significantly different between the BF (10 patients) and BM groups (9 patients). In patients with glycated hemoglobin (HbA1c) <8.0%, CST, compared with baseline, was significantly decreased in the BF group (seven patients) at 8 (p = .025) and 12 weeks (p = .043) of administration. When compared with the baseline, no significant changes in BCVA were observed at any point in time in either group. Baseline IOP was comparable between the groups. In the BM group, the values of change in IOP from baseline significantly increased at 8 (p = .025) and 12 weeks (p = .044) of administration, with no significant changes in IOP over the 12 weeks of administration in the BF group. CONCLUSIONS: BF did not affect IOP even after 12 weeks of administration, suggesting its effect in reducing CST in DME with good glycemic control. TRIAL REGISTRATION: University Hospital Medical Information Network (UMIN-CTR); UMIN000026201, February 18, 2017; Japan Registry of Clinical Trials; jRCTs031180308, March 15, 2019.

Effects of Astaxanthin, Lutein, and Zeaxanthin on Eye-Hand Coordination and Smooth-Pursuit Eye Movement after Visual Display Terminal Operation in Healthy Subjects: A Randomized, Double-Blind Placebo-Controlled Intergroup Trial.

(1) Background: The impairment of eye-hand coordination and smooth-pursuit eye movement caused by visual display terminal (VDT) operation is thought to impair daily living activities, for which no effective methods are currently known. On the other hand, various food ingredients, including astaxanthin, lutein, and zeaxanthin, are known to help improve the eye health of VDT operators. This study aimed to test the hypothesis that the combination of astaxanthin, lutein, and zeaxanthin can prevent the impairment of eye-hand coordination and smooth-pursuit eye movement caused by VDT operation. (2) Methods: We conducted a randomized, placebo-controlled, parallel-group clinical trial. Healthy subjects who regularly worked with VDTs were randomly assigned to the active and placebo groups. All of the subjects took soft capsules containing 6 mg of astaxanthin, 10 mg of lutein, and 2 mg of zeaxanthin or placebo soft capsules once daily for eight weeks. We evaluated the eye-hand coordination, smooth-pursuit eye movements, and macular pigment optical density (MPOD) at 0, two, four, and eight weeks after soft-capsule intake. (3) Results: The active group showed significantly improved eye-hand coordination after VDT operation at eight weeks. However, there was no clear improvement in the effect of the supplementation on smooth-pursuit eye movements. The active group also showed a significant increase in MPOD levels. (4) Conclusions: Consumption of a supplement containing astaxanthin, lutein, and zeaxanthin mitigates the decline of eye-hand coordination after VDT operation.

Topical bromfenac reduces multiple inflammatory cytokines in the aqueous humour of pseudophakic patients.

Intraocular surgery is associated with increased ocular inflammation. If maintained for a prolonged period after surgery, this inflammation can cause various complications, including subconjunctival fibrosis and bleb scarring. This clinical trial was a prospective, randomised, single-blind, interventional study comparing the efficacy and safety of 0.1% bromfenac sodium ophthalmic solution and 0.02% fluorometholone ophthalmic suspension in the inhibition of multiple inflammatory cytokines in the aqueous humour of 26 patients with pseudophakic eyes who had undergone phacoemulsification and intraocular lens implantation. The patients were randomly assigned to one of the trial drugs, and aqueous humour samples were collected before and after drug administration. Platelet-derived growth factor-AA levels significantly decreased in both drug groups, but they were significantly higher in the fluorometholone group than in the bromfenac group (P = 0.034). Bromfenac also significantly decreased vascular endothelial growth factor level (P = 0.0077), as well as monocyte chemoattractant protein-1 level (P = 0.013), which was elevated for a prolonged period after phacoemulsification. These data suggest that bromfenac is useful to alleviate prolonged microenvironmental alterations in the aqueous humour of pseudophakic eyes.

Stratification-Based Investigation of Adjunctive Brimonidine or Timolol to a Prostaglandin Analogue in Japanese Patients with Normal-Tension Glaucoma.

PURPOSE: We previously investigated the efficacy and safety of adding 0.1% brimonidine (Brim) or 0.5% timolol (Tim) to prostaglandin analogue (PGA) monotherapy to treat patients with normal-tension glaucoma (NTG) with intraocular pressure (IOP) of ≤16 mmHg. Herein, we describe an additional post-hoc stratifying analysis of the possible differences in the effect of IOP-lowering and pulse rate (PR) after adjunctive Brim or Tim to PGA. PATIENTS AND METHODS: This study included 128 subjects. Patients with NTG treated with PGA were stratified based on their baseline IOP. The changes in IOP from baseline and the effect of patient factors on IOP changes were investigated. Patients were stratified by age for investigation of their PR and blood pressure (BP). The change and the effect of patient factors on PR and BP were investigated. RESULTS: After stratification analysis, in 52 eyes treated with Brim and 61 eyes with Tim with baseline IOP 12 ≤ IOP ≤ 16 mmHg, both eye drops lowered IOP significantly (P < 0.0001), and the IOP-lowering efficacy of Brim was non-inferior to that of Tim. However, in 9 Brim- and 6 Tim-treated eyes with baseline IOP of <12 mmHg, no statistically significant decrease in IOP was evident with either eye drop. In the Tim group, PR decreased significantly (P < 0.05) after stratification by age. CONCLUSION: The IOP-lowering efficacy of Brim was non-inferior to that of Tim after stratification by baseline IOP (12 ≤ IOP ≤ 16 mmHg). The discrepancy in the IOP-lowering effects of Brim and Tim observed in the previous study was thought to be related to enrolled subjects with low baseline IOP. PR decreased significantly in the Tim group even after age stratification. PR should be considered when selecting ß-blockers for glaucoma treatment.

Lactobacillus helveticus SBT2171 Alleviates Perennial Allergic Rhinitis in Japanese Adults by Suppressing Eosinophils: A Randomized, Double-Blind, Placebo-Controlled Study.

This article examines the effects of fermented milk (FM) containing Lactobacillus helveticus SBT2171 (LH2171) on the subjective symptoms of individuals with mild and moderate perennial allergy. Two hundred subjects were divided into two groups and consumed FM containing LH2171 or placebo FM once per day for 16 weeks. The primary endpoints were defined as per the degree of nasal and ocular symptoms and difficulty in daily life as determined by the Japanese guidelines for allergy rhinitis and the Japanese allergic rhinitis standard quality of life questionnaire, respectively. The secondary endpoints included parameters related to allergic symptoms in the blood and nasal fluids, as well as the mental status. The severity of allergic rhinitis significantly improved in the LH2171 group compared to that in the placebo group. Additionally, the LH2171 group showed a significantly lower degree of "stuffy nose" (as per the diary survey) than the placebo group. Eosinophil counts in the nasal fluids and in the blood were significantly lower in the LH2171 group compared to the placebo group. Thus, the oral administration of FM containing LH2171 cells alleviated perennial allergic rhinitis in individuals with mild and moderate symptoms, possibly via suppression of eosinophils in both the blood and nasal fluids.

The Effect of Brimonidine 0.1% on Disc Hemorrhage in Primary Open-Angle Glaucoma Patients.

BACKGROUND: This retrospective study evaluated the effect of adjunctive administration of brimonidine 0.1% on disc hemorrhage (DH) in patients with primary open-angle glaucoma or normal-tension glaucoma who were already treated with other anti-glaucoma drugs. METHODS: Patients with DH, before adjunctive therapy with brimonidine, were enrolled. Subjects were excluded if their treatment regimen was changed within 1 year after initiation of adjunctive therapy with brimonidine. We investigated the frequency of DH and intraocular pressure (IOP). Both parameters were compared before and after adjunctive administration of brimonidine. RESULTS: The frequency of DH before and after brimonidine administration was 0.67±0.68 and 0.31±0.72 times/year, respectively, with a significant decrease (P=0.01), and the mean IOP before and after brimonidine administration was 12.5±1.9 and 11.2±2.2 mmHg, respectively, (P=0.0006) with a significant reduction after adjunctive administration. CONCLUSION: The results of this study supported the hypothesis that the frequency of DH is reduced by brimonidine alongside lowering of IOP.

Effects of high magnesium intake on bone mineral status and lipid metabolism in rats.

Effects of magnesium (Mg)-intake on mineral levels in bone, blood and various tissues, bone density and plasma lipids were examined in 4-wk-old, female Wistar rats fed diets of five different Mg-contents of 1/10, 1 (standard diet (Mg 47 mg/100 g diet): control group), 2, 5 and 10-fold of the standard content for 4 wk. In rats fed the 1/10-fold Mg diet, the body weight gain declined with a statistical significance compared to control rats, while no significant differences were observed in rats fed on the 2-, 5-, and 10-fold Mg diets. The imbalance of mineral concentrations in the rats fed 1/10 Mg diet was induced, but in the rats fed high Mg diets were not induced except in tibia. Mg concentration in tibia of rats fed the 10-fold Mg diet significantly increased compared to the control group. All groups (1/10-fold, 2-, 5-, and 10-fold Mg groups) showed no significant changes in tibial mineral levels, except Mg in the 10-fold group, compared to the control group. With increase in Mg-intake, decline of plasma lipid parameters such as cholesterol, triglycerides and phospholipids are induced. Based on these results, it was suggested that a higher Mg-intake (around 5-fold of the standard Mg-content) might have a prophylactic potential against the onset of hyperlipidemia and cardiovascular disease by reducing lipid indices, and Mg decline in bone.

Effect of crocetin on quality of sleep: A randomized, double-blind, placebo-controlled, crossover study.

OBJECTIVES: The aim of the present study was to investigate the effect of crocetin on sleep architecture and subjective sleep parameters in healthy adult participants with mild sleep complaints. DESIGN: A randomized, double-blind, placebo-controlled, crossover study with two intervention periods of 14 days each, separated by a 14-day wash-out period. INTERVENTIONS: Thirty participants were randomly assigned to one of two sequence groups. Each group was given crocetin at 7.5 mg/day, or placebo. We measured objective sleep parameters using single-channel electroencephalography and assessed subjective sleep parameters using the Oguri-Shirakawa-Azumi Sleep Inventory, Middle-age and Aged version (OSA-MA). MAIN OUTCOME MEASURES: Differences between crocetin and placebo in an objective sleep parameter (delta power), and OSA-MA scores. RESULTS: Delta power was significantly increased with crocetin compared with placebo. There were no significant differences in the other sleep parameters, including sleep latency, sleep efficiency, total sleep time, and wake after sleep onset. Subjective scores for sleepiness on rising and feeling refreshed were significantly improved with crocetin compared with placebo. CONCLUSIONS: The findings of the present study suggest that crocetin supplementation contributes to sleep maintenance, leading to improved subjective sleep quality.

Safety Evaluation and Plasma Carotenoid Accumulation in Healthy Adult Subjects after 12 Weeks of Paprika Oleoresin Supplementation.

Paprika oleoresin is obtained by solvent extraction from Capsicum annuum L. fruits and contains multiple carotenoids, such as capsanthin, ß-carotene, zeaxanthin, and ß-cryptoxanthin, which are considered protective against various diseases. Herein, we investigated the effect of paprika oleoresin supplementation on plasma carotenoid accumulation and evaluated the safety of the oleoresin. We used a double-blinded, placebo-controlled comparative clinical study design and tested the effects of varying doses in healthy adult subjects. In total, 33 subjects were randomly divided into three groups to take capsules containing 0, 20, or 100 mg of paprika oleoresin daily for 12 consecutive weeks. Plasma carotenoid concentrations were measured at 0, 4, 8, and 12 weeks, and the safety of paprika oleoresin capsules was investigated using analyses of blood biochemistry, hematology, and urine contents. In these experiments, ß-cryptoxanthin and zeaxanthin dose-dependently accumulated in plasma within the dose range of the study over 12 consecutive weeks of paprika oleoresin supplementation. Moreover, ß-cryptoxanthin accumulated to higher levels than the other paprika oleoresin carotenoids. In contrast, capsanthin was not detected in plasma before or during the 12-week treatment period. Finally, no adverse events were associated with intake of paprika oleoresin (20 and 100 mg/day) in safety evaluations. Paprika oleoresin is a suitable source of carotenoids, especially ß-cryptoxanthin.

Changes in adherence and associated factors among patients on newly introduced prostaglandin analog and timolol fixed-combination therapy.

PURPOSE: We investigated patient adherence and factors related to a newly introduced prostaglandin analog and timolol fixed-combination eye drops (PGTFC). PATIENTS AND METHODS: The Glaucoma Research on Adherence to fixed-Combination Eye drops in Japan (GRACE) study group performed a nationwide prospective questionnaire survey. Participants in this study were patients with glaucoma who were scheduled to receive any type of PGTFC for the first time. The participants answered a questionnaire on the day of PGTFC introduction and again at a return visit 4-6 weeks after PGTFC introduction. The physicians in charge were asked to complete a separate questionnaire on the day of PGTFC introduction. One of two leaflets was randomly delivered to each participant before the description of the PGTFC. One leaflet explained how to correctly instill the eye drops, and the other explained the clinical meaning of intraocular pressure reduction in addition to explaining how to correctly instill the eye drops. Nonadherence was defined as forgetting to instill the eye drops one or more times during the week before the return visit. RESULTS: In total, 3,597 patients (age, 68.4±12.2 years) met the study protocol requirements. PGTFC introduction significantly reduced the number of antiglaucoma eye drops from 1.93±0.78 to 1.34±0.54 (P<0.0001) and significantly improved adherence (P<0.00001). Factors significantly associated with nonadherence at the return visit included a history of nonadherence as reported by either the patient or their physician before introduction, acceptable instillation times as reported by the patient, and burdensome eye drop instillation as reported by the patient. No significant difference was observed between the two leaflets in terms of their effects on adherence. CONCLUSION: PGTFC significantly improved adherence and some of the factors that were significantly associated with adherence. REGISTRATION NUMBER: UMIN000013696.

Multicenter, Randomized, Investigator-Masked Study Comparing Brimonidine Tartrate 0.1% and Timolol Maleate 0.5% as Adjunctive Therapies to Prostaglandin Analogues in Normal-Tension Glaucoma.

INTRODUCTION: This study compared the efficacy and safety of adjunctive brimonidine tartrate 0.1% ophthalmic solution (brimonidine) and timolol maleate 0.5% ophthalmic solution (timolol) in prostaglandin analogue (PGA)-treated normal-tension glaucoma (NTG), assessing the non-inferiority of brimonidine in terms of intraocular pressure (IOP) reduction. METHODS: In this multicenter, randomized, investigator-masked, parallel-group, clinical study, adjunctive brimonidine or timolol was administered twice daily for 12 weeks in eyes with NTG that had been treated with PGA for at least 90 days and required additional treatment despite an IOP of 16 mmHg or less. IOP was measured on at least three visits before add-on therapy (mean baseline IOP), and at weeks 4, 8, and 12 after adjunctive administration. Systolic/diastolic blood pressure, pulse rate, and adverse events (AEs) were recorded at each visit. RESULTS: A total of 152 individuals were enrolled and 128 (84.2%) were eligible for efficacy analyses. IOP in both groups at each visit decreased significantly from baseline (P < 0.001). However, the difference in the change from baseline IOP at week 12 between the brimonidine (-1.05 ± 1.81 mmHg) and timolol (-1.41 ± 1.40 mmHg) groups was 0.36 mmHg (95% confidence interval [CI] [-0.21, 0.92]), which exceeded the value of the non-inferiority margin (0.75 mmHg). Baseline systolic/diastolic blood pressure decreased significantly in both groups at certain visits (P < 0.05), while baseline pulse rates decreased significantly in the timolol group (P < 0.001), with no significant differences in the brimonidine group. AE-related treatment discontinuation occurred in 2/71 (2.8%) and 2/75 (2.7%) patients in the brimonidine and timolol groups, respectively. CONCLUSION: This study demonstrated an add-on effect of brimonidine to PGAs, although non-inferiority of brimonidine to timolol as adjunctive therapy in PGA-treated NTG in terms of IOP reduction was not observed. Brimonidine was associated with no adverse effects on pulse rate. FUNDING: Senju Pharmaceutical Co., Ltd. TRIAL REGISTRATION: UMIN Clinical Trials Registry identifier, UMIN000014810.

Functional and morphological organization of the nucleus tractus solitarius in the fictive cough reflex of guinea pigs.

Projection of the superior laryngeal nerve (SLN) afferent fibers into the nucleus tractus solitarius (NTS) was investigated using a fluorescent tracer in guinea pigs. High density of fluorescence was detected in the ipsilateral NTS extending from 0.5 mm caudal to 1.2 mm rostral to the obex. At coronal slices, the fluorescent granules, lines and patches were located in the interstitial, medial and dorsal regions of NTS. Fluorescence was also found in the dorsal region of contralateral commissural NTS. Microstimulation of the rostral NTS, which corresponded to the region showing the strong fluorescence, induced an increase in the inspiratory discharge of phrenic nerve that was immediately followed by a large burst discharge of the iliohypogastric nerve in decerebrate, paralyzed and artificially ventilated guinea pigs. This serial response of the two nerves was identical to that induced by electrical stimulation of the SLN. Intravenous injection of codeine suppressed both NTS and SLN-induced responses. The SLN-induced response was inhibited by microinjection of codeine into the ipsilateral NTS and abolished by lesion of the ipsilateral NTS. These results suggest that the NTS has an integrative function in production of cough reflex and is possible sites of action of central antitussive agents.

Effects of progesterone on apneic events during behaviorally defined sleep in male rats.

Drug therapy with progesterone has been applied to the patients with sleep apnea syndrome, but its clinical efficacy is equivocal. In the present study, we examined the effects of progesterone (1 and 30 mg/kg, i.p.) on the apneic events during behaviorally defined sleep in male rats at 4, 14 and 26 weeks of age by using a whole body plethysmographic measurement. The number of events of spontaneous apnea (SA) and post-sigh apnea (PSA) increased with aging. The duration of SA or PSA was also prolonged in old rats. A low dose (1 mg/kg) of progesterone significantly decreased the number of both SA and PSA, and this effect increased in an age-dependent manner. However, progesterone had no effect on the duration of SA and PSA. Neither the basal respiratory rate nor the total sleep time was changed. On the other hand, a higher dose (30 mg/kg) of progesterone had no effect on the number of SA and PSA, while it prolonged the duration of PSA. It also prolonged the total sleep time without affecting the basal respiratory rate. Pretreatment with mifepristone (5 mg /kg, i.p.), an antagonist of progesterone receptors, inhibited the effects of the low dose of progesterone, but did not show any antagonistic effect on the high dose-induced changes. These results suggest that the progesterone-mediated mechanisms are involved, at least partly, in respiratory function during sleep and the progesterone therapy is possibly effective within an appropriate dose range for the sleep apnea syndrome.

Relationship between consecutive deterioration of mean deviation value and progression of visual field defect in open-angle glaucoma.

PURPOSE: To analyze the relationship between consecutive deterioration of mean deviation (MD) value and glaucomatous visual field (VF) progression in open-angle glaucoma (OAG), including primary OAG and normal tension glaucoma. PATIENTS AND METHODS: The subjects of the study were patients undergoing treatment for OAG who had performed VF tests at least 10 times with a Humphrey field analyzer (SITA standard, C30-2 program). The VF progression was defined by a significantly negative MD slope (MD slope worsening) at the final VF test during the follow-up period. The relationship between the MD slope worsening and the consecutive deterioration of MD value were retrospectively analyzed. RESULTS: A total of 165 eyes of 165 patients were included in the analysis. Significant progression of VF defects was observed in 72 eyes of 72 patients (43.6%), while no significant progression was evident in 93 eyes of 93 patients (56.4%). There was significant relationship between the frequency of consecutive deterioration of MD value and MD slope worsening (P<0.0001, Cochran-Armitage trend test). A significant association was observed for MD slope worsening in the eyes with three (odds ratio: 2.1, P=0.0224) and four (odds ratio: 3.6, P=0.0008) consecutive deterioration of MD value in multiple logistic regression analysis, but no significant association in the eyes with two consecutive deterioration (odds ratio: 1.1, P=0.8282). The eyes with VF progression had significantly lower intraocular pressure reduction rate (P<0.01). CONCLUSION: This retrospective study has shown that three or more consecutive deterioration of MD value might be a predictor to future significant MD slope worsening in OAG.

Biphasic effects of morphine on bulbar respiratory neuronal activities in decerebrate cats.

To understand neuronal mechanisms underlying respiratory depression induced by morphine, membrane potential, input resistance and burst discharge in different types of respiratory neurons were recorded in decerebrate and vagotomized cats. Intravenous morphine (0.3-3.0 mg/kg) dose-dependently decreased the respiratory discharge in the phrenic and iliohypogastric nerves. The drug changed the respiratory frequency in a biphasic fashion, a transient increase (early phase) followed by a long-lasting decrease (late phase). During the early phase, the membrane was hyperpolarized throughout the respiratory cycle and the burst discharge was decreased in all types of respiratory neurons. During the late phase, the active phase depolarization and the inactive phase hyperpolarization were decreased, resulting in a decline of membrane potential fluctuations. Input resistance was decreased during the early phase and increased during the late phase. Iontophoresed (50-100 nA) morphine produced hyperpolarization of the membrane and a decrease in input resistance in respiratory neurons. This hyperpolarization remained unaltered after iontophoresed tetrodotoxin depressed the synaptic transmission. These effects of morphine were completely blocked by naloxone and beta-funaltrexamine, but not by naltrindole. The present results suggest that morphine depresses the respiratory neuronal activity through two different mechanisms, both of which are mediated by mu receptors.

Synaptic mechanisms of inspiratory off-switching evoked by pontine pneumotaxic stimulation in cats.

To elucidate synaptic mechanisms and the involvement of N-methyl-D-aspartate (NMDA) receptors in inspiratory off-switching (IOS) evoked by the stimulation of the nucleus parabrachialis medialis (NPBM), excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) were recorded from bulbar augmenting inspiratory (aug-I) and postinspiratory (PI) neurons in vagotomized cats. Stimulation of NPBM produced either transient inhibition or premature termination of inspiration (reversible or irreversible IOS), depending on the stimulus intensity. Each neuron displayed four-phasic postsynaptic responses during the reversible IOS, i.e. Phase 1 EPSPs, Phase 2 IPSPs, Phase 3 EPSPs and Phase 4 IPSPs in aug-I neurons, and Phase 1 plus 2 EPSPs, Phase 3 IPSPs and Phase 4 EPSPs in PI neurons. During the irreversible IOS, Phase 4 responses were replaced by sustained hyperpolarization in aug-I neurons and decrementing depolarization in PI neurons. Blockade of NMDA receptors by dizocilpine (0.3 mg kg(-1) i.v.) selectively increased Phase 4 potentials in both types of neurons and decreased the thresholds for evoking the irreversible IOS. The NPBM-induced responses had a pattern and time-course similar to those induced by vagal stimulation. The present results suggest that pneumotaxic and vagal inputs converge on the common IOS circuit, and the effectiveness of both inputs is modulated by NMDA receptors.

Phrenic and iliohypogastric nerve discharges during tussigenic stimulation in paralyzed and decerebrate guinea pigs and rats.

Although effects of antitussive drugs have been examined in inbred small animals using a whole body plethysmography, neuronal mechanisms underlying the cough reflex are not fully understood. The present study analyzed the reflex discharge patterns of the phrenic (PN) and iliohypogastric nerves (IHN) evoked in decerebrate and paralyzed guinea pigs and rats. In guinea pigs, electrical stimulation of the superior laryngeal nerve, chemical stimulation with capsaicin and mechanical stimulation to the intratracheal mucosa equally produced a serial PN-IHN response. This response was characterized by an increased PN discharge and following spindle-shaped burst of the IHN. The evoked discharges overlapped for 20 ms. In rats, by contrast, mechanical stimulation was without effect while capsaicin and electrical stimulation produced two types of responses, both of which differed from that observed in guinea pigs. The first type consisted of an augmented burst of the IHN that was immediately followed by an increased PN discharge. The second type was a large spindle-shaped burst of the IHN that occurred 80 ms after the end of the preceding PN discharge. Codeine (3 mg/kg i.v.) depressed all types of responses evoked in guinea pigs and rats. The present study demonstrated that the fictive cough comparable with those induced in other experimental animals was produced consistently in guinea pigs, but not in rats. Therefore, guinea pigs are suitable for investigation of the neuronal mechanisms underlying the cough reflex and assessment of antitussive drugs.

Distribution of mu receptors in the ventral respiratory group neurons; immunohistochemical and pharmacological studies in decerebrate cats.

Immunoreactivity for mu receptors was investigated in 21 bulbar respiratory neurons, individually identified by intracellular recording and labeling with neurobiotin. In 14 of these neurons, effects of iontophoresed morphine were examined. Morphine hyperpolarized the membrane and decreased spike discharges in 4/6 augmenting inspiratory (aug-I), 4/5 postinspiratory (post-I) and 3/3 augmenting expiratory (aug-E) neurons. It had no effect on two aug-I and one post-I neurons. Strong immunoreactivity for mu receptor was detected in the soma and dendrites of 5/8 aug-I, 5/7 post-I and 6/6 aug-E neurons. In the remaining three aug-I and two post-I neurons that included cells unresponsive to morphine, weak immunoreactivity was detected only in the dendrites. These results demonstrated wide, but uneven, distribution of mu receptors in bulbar respiratory neurons and suggest their contribution to respiratory depression by opioids.

Hypercapnic and hypoxic ventilatory responses in long-term streptozotocin-diabetic rats during conscious and pentobarbital-induced anesthetic states.

To clarify the diabetes mellitus (DM)-associated changes in the respiratory neuronal control system, acute ventilatory responses to progressively increasing hypercapnia (6%) and hypoxia (10%) were compared between normal (N) and streptozotocin (60 mg/kg, i.v.) -DM rats for a long period up to 28 weeks. The same comparison was conducted during the anesthetic state induced with pentobarbital (35 mg/kg, i.p.). During the conscious state, basic ventilatory parameters, such as respiratory rate, tidal volume and minute ventilation, were not impaired in DM rats, but ventilatory responses to hypercapnia and hypoxia were reduced significantly at 16 weeks and later after streptozotocin injection. The reduced responses in DM rats were not recovered by insulin treatment (5-6 U/body, s.c., daily). During the anesthetic state, both hypoxic and hypercapnic responses were depressed more intensely in N rats than in DM rats, resulting in an equivalent level of the response in the two groups. The present study demonstrated that ventilatory responses to hypercapnia and hypoxia were reduced in a long-term DM condition. This may be derived from the impairment of the peripheral and central chemosensitivity. The reduction in ventilatory responses was exaggerated during the anesthetic state.