Satoshi Obayashi

Accumulation of endogenous inhibitors for nitric oxide synthesis and decreased content of L-arginine in regenerated endothelial cells.

1 We examined regeneration of endothelial cells (ECs), neointima formation, decreased endothelium‐dependent relaxation (EDR) and changes in the contents of L‐arginine, NG–monomethyl‐L‐arginine (l‐NMMA), asymmetrical NG, NG–dimethylarginine (ADMA) and symmetrical NG, NG–dimethylarginine (SDMA) in the regnerated ECs, 6 weeks after balloon denudation of the rabbit carotid artery. 2 Regeneration of ECs was completed in 6 weeks and a significant neointima formation accompanied by the decreased EDR was observed. 3 L‐NMMA and ADMA contents in the regenerated ECs (23.5 ± 4.3 and 21.2 ± 2.0 pmol mg−1 DNA, respectively) were significantly (P<0.05 and P<0.01) higher than those in the control ECs (8.8 ± 3.0 and 7.4plusmn;1.9 pmol mg−1 DNA, respectively), whereas L‐arginine was significantly (P< 0.005) decreased in the regenerated ECs (31,470±1,050 pmol mg−1 DNA) as compared to that in the control ECs (47,870±1,890 pmol mg−1 DNA). SDMA content was below the assay limits. 4 L‐NMMA and ADMA, but not SDMA, inhibited the EDR induced by acetylcholine in a concentration‐dependent manner. The inhibition with L‐NMMA and ADMA was prevented by an addition of L‐arginine, but not by D‐arginine. 5 These results suggest that the accumulation of endogenous inhibitors for nitric oxide synthesis and decreased L‐arginine content are associated with decreased NO production/release from regenerated ECs and neointima formation.

Effect of nicotine on the intimal hyperplasia after endothelial removal of the rabbit carotid artery

1. The present experiments were designed to investigate the effect of long-term oral nicotine (10 mg/200 ml/kg/day for 7 weeks) on the intimal hyperplasia after endothelial removal of the rabbit carotid artery. 2. The plasma concentrations of nicotine were determined to be 11.7-12.5 ng/ml during the term of administration and corresponded to the plasma levels in human smokers. 3. Six weeks after the endothelial removal, light microscopy revealed a marked intimal hyperplasia. Administration of nicotine tended to accelerate the intimal hyperplasia, which was estimated by comparing the histological findings, DNA content and wet weight of the vessel wall. 4. Acetylcholine- and A23187-induced endothelium-dependent relaxations were greatly impaired in the hyperplastic artery strips. The impairment of relaxations tended to be accelerated in the nicotine group. Sodium nitroprusside-induced relaxation was not different between the control and the hyperplastic artery strips and remained unaffected in the nicotine group. 5. The concentrations of endogenous nitric oxide (NO) synthesis inhibitors, NG-monomethyl-L-arginine (L-NMMA) and asymmetrical NG,NG-dimethyl-L-arginine (ADMA) were significantly more increased in the regenerated endothelial cells compared with those in the control endothelial cells. The concentrations of L-NMMA and ADMA in the regenerated endothelial cells were significantly increased by as much as 1.3 x 10(-6) and 5.6 x 10(-7) M, respectively, in the nicotine group. 6. Immunoreactive endothelin-1 was significantly increased in the hyperplastic vessel wall (2.4 times that of the control) in 6 weeks. Administration of nicotine tended to increase the level. 7. It seems possible to assume from these results that, although, under the present experimental conditions, nicotine exhibited a tendency to accelerate the intimal hyperplasia after endothelial removal, the longer exposure to nicotine or a higher dose of the agent or both would significantly accelerate the intimal hyperplasia through the enhanced impairment of endothelium-derived relaxing factor/ NO production, which might be brought about by the enhanced increases in L-NMMA and ADMA concentrations, and the enhanced increase in endothelin-1 in the vessel wall.

Associations between anxiety, depression and insomnia in peri- and post-menopausal women

OBJECTIVES To determine the correlation between somatic and psychological symptoms and insomnia and the contribution of depression and anxiety to insomnia in a sample of peri- and post-menopausal women in a clinical setting. STUDY DESIGN The responses of 237 peri- and post-menopausal women enrolled in the Systematic Health and Nutrition Education Program (SHNEP) at the Menopause Clinic of the Tokyo Medical and Dental University Hospital between November 2007 and December 2010 to the Menopausal Health-Related Quality of Life (MHR-QOL) and Hospital Anxiety and Depression Scale (HADS) questionnaires were subjected to Spearmans rank correlation and logistic regression analyses. RESULTS The analysis revealed that (1) insomnia is highly prevalent, (2) the symptoms of difficulty in initiating sleep (DIS) and experiencing non-restorative sleep (NRS) are more strongly correlated with psychological than somatic symptoms, and (3) DIS is strongly associated with anxiety while NRS is strongly associated with depression in the population studied. CONCLUSIONS Insomnia is highly prevalent among peri- and post-menopausal female patients in a clinical setting and more closely associated with psychological than somatic symptoms. DIS is strongly correlated with anxiety while NRS is strongly correlated with depression.

Linalyl acetate as a major ingredient of lavender essential oil relaxes the rabbit vascular smooth muscle through dephosphorylation of myosin light chain

In a preliminary experiment, we found that lavender essential oil relaxes vascular smooth muscle. Thus, the present experiments were designed to investigate the relaxation mechanism of linalyl acetate as the major ingredient of lavender essential oil in rabbit carotid artery specimens. Linalyl acetate produced sustained and progressive relaxation during the contraction caused by phenylephrine. The relaxation effect of linalyl acetate at a concentration near the EC50 was partially but significantly attenuated by nitroarginine as an inhibitor of nitric oxide synthase, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one as an inhibitor of guanylyl cyclase, or by the denudation of endothelial cells. In specimens without endothelium, the phenylephrine-induced contraction and phosphorylation of myosin light chain (MLC) were significantly attenuated after the pretreatment with linalyl acetate. The relaxation caused by linalyl acetate in the endothelium-denuded specimens was clearly inhibited by calyculin A as an inhibitor of MLC phosphatase, although not by ML-9 as an inhibitor of MLC kinase. Furthermore, suppression of the phenylephrine-induced contraction and MLC phosphorylation with linalyl acetate was canceled by the pretreatment with calyculin A. These results suggest that linalyl acetate relaxes the vascular smooth muscle through partially activation of nitric oxide/cyclic guanosine monophosphate pathway, and partially MLC dephosphorylation via activating MLC phosphatase.

Different localization of ETA and ETB receptors in the hyperplastic vascular wall.

We investigated which subtypes of endothelin-1 (ET-1) receptors are involved in the pathogenesis of angioplasty-induced lesion formation in the rabbit carotid artery. Four weeks after removing endothelial cells (EC), we noted a marked intimal hyperplasia. The Bmax values for [125I]ET-1 and [125I]IRL1620 (an agonist for the ETB receptors) bindings were greater in the hyperplastic artery, without changes in Kd values. [125I]ET-1 binding was completely inhibited by unlabeled ET-1 and Ro 462005, a mixed-type antagonist for the ETA and ETB receptors, but partially by BQ123, a selective antagonist for ETA receptors, and IRL1620. The [125I]ET-1 binding sites not inhibited with BQ123 were significantly increased in the hyperplastic artery. The binding study suggested the presence of non-ETA/non-ETB receptors. The rank order of the increasing ratio in the density of receptors was ETB > putative non-ETA/non-ETB > total ET-1 receptors > ETA. The histochemical experiments with biotinylated ET-1 at lysine-9 side chain alone or in combination with unlabeled ET-1, BQ123, Ro 46–2005, or IRL1620, showed the ETA receptors to be localized mainly in the media, whereas the ETB receptors localized mainly in the neointima. These results suggest that the increased ET-1 receptors, especially ETB and/or putative non-ETA/non-ETB, are closely related to the occurrence of the intimal hyperplasia after endothelial removal.

Estrogen Replacement Effectively Improves the Accelerated Intimal Hyperplasia Following Balloon Injury of Carotid Artery in the Ovariectomized Rats

Present experiments were designed to investigate the effects of ovariectomy (OVX) and estrogen replacement (ER) on neointimal formation after balloon injury of the rat carotid artery. Young adult female rats were divided into 3 groups of sham operation (control), ovariectomy, and ovariectomy plus estrogen replacement. Estrogen replacement was initiated by implanting a sustained release pellet containing water-soluble 17β-estradiol 1 week after the ovariectomy. Carotid arteries were harvested 2 weeks after the balloon injury for determinations. The balloon injury caused intimal hyperplasia, which was accompanied by the impaired endothelium-dependent relaxation and cyclic GMP production, and accumulation of asymmetric dimethylarginine (ADMA) as an endogenous NOS inhibitor. Bilateral ovariectomy accelerated the intimal hyperplasia. The acceleration was accompanied by the enhanced impairment of NO production, attenuated reendothelialization, and enhanced accumulation of ADMA. The estrogen replacement improved the accelerated intimal hyperplasia with concomitant improvement of the impaired NO production and accumulated asymmetric dimethylarginine, and facilitated reendothelialization. These results suggests that the enhanced impairment of NO production, which possibly results from the accumulated asymmetric dimethylarginine and lack of reendothelialization, may contribute to the acceleration of intimal hyperplasia by ovariectomy and that estrogen replacement effectively improves the intimal hyperplasia by restoring the impaired NO production through reducing endogenous NOS inhibitor and facilitating reendothelialization.

Endogenous Nitric Oxide Synthase Inhibitors in Endothelial Cells, Endothelin-1 Within the Vessel Wall, and Intimal Hyperplasia in Perimenopausal Human Uterine Arteries

The present experiments were designed to investigate the ability to produce nitric oxide, concentrations of N G -monomethyl- l -arginine ( l -NMMA), and asymmetric N G, N G -dimethyl- l -arginine (ADMA) in endothelial cells, endothelin-1 within the vessel wall, and the degree of intimal hyperplasia (intima/media ratio) in perimenopausal human uterine arteries. According to the tentative classification based on basal cyclic GMP levels, 16 arteries could be grouped into groups I and II consisting of eight each. Net production of the nucleotide was significantly higher in group I than that in group II. Concentration of l -NMMA plus ADMA and endothelin-1 content were significantly higher in group II. All specimens from group I were histologically normal, whereas mild to severe intimal hyperplasia was observed in group II specimens. Although considerable individual variations were detectable in the intima/media ratio, l -NMMA plus ADMA and endothelin-1 (n = 35 each), there were significant and positive correlations between three parameters, indicating that intimal hyperplasia became greater as l -NMMA plus ADMA and endothelin-1 were increased. These results suggest that endogenous nitric oxide synthase inhibitors in endothelial cells and endothelin-1 within the vessel wall are important markers of intimal hyperplasia.

Associations among depression, anxiety and somatic symptoms in peri‐ and postmenopausal women

The aim of this study was to investigate the associations among depression, anxiety and physical symptoms in peri‐ and postmenopausal women in a clinical setting.

Role of endothelium in the human uterine arteries during normal menstrual cycle.

1 The present experiments were designed to investigate the role of endothelium in the human uterine arteries during the normal menstrual cycle. 2 Acetylcholine (ACh) produced a concentration‐dependent relaxation response during the higher level of plasma 17β‐oestradiol (E2) (follicular and luteal phases, E2 = 131.9 ± 15.9 pg ml−1, n = 13; group I). However, the agent did not produce a definite relaxation, but produced a slight contraction during the ovulatory and menstruation phases (E2 = 19.8 ± 2.9 pg mg−1, n = 5; group II). During the follicular and luteal phases (E2 = 181.1 ± 9.0 pg ml−1, n = 6), ACh produced a slight contraction, but not relaxation in 6 cases (group III). Relaxation in response to A23187 in group II was not different from that in group I, while it was significantly (P<0.05 and P <0.005) reduced in group III. Sodium nitroprusside (SNP)‐induced relaxation was similar in the three groups. 3 Correlation between the maximum response to ACh and the plasma E2 was highly significant (γ = 0.8142, P <0.001) in 18 cases of groups I and II, but not in all 24 cases including group III (γ = 0.1183, NS). 4 Relaxations in response to ACh in group I or A23187 in all groups were abolished after removal of the endothelium. In group I, ACh‐ and A23187–induced relaxations were greatly inhibited by methylene blue or NG‐nitro‐l‐arginine (l‐NOARG) and partially inhibited by indomethacin. None of these treatments except for methylene blue modified the SNP‐induced relaxation, which was significantly inhibited by methylene blue. 5 The A23187‐induced relaxation was hardly affected by methylene blue or l‐NOARG in group III, but was partially inhibited by these agents in group II. The effect of indomethacin in inhibiting the A23187 induced‐relaxation was most potent (58.9%) in group III and least (16.9%) in group I. 6 There were no histological changes in 14 cases out of 18 (groups I and II), but very slight intimal thickening was observed in 4 cases in group I. On the other hand, severe intimal thickening was observed in all 6 cases in group III. 7 These results indicate that, in human uterine artery strips, ACh and A23187 cause endothelium‐dependent relaxations, which are mediated mainly through EDRF/NO in group I, mainly prostacyclin (PGI2) in group III, or both in group II. It is suggested that lack of the production/release of EDRF/NO and/or of interaction between EDRF/NO and PGI2 might play a role in the formation of intimal thickening in human uterine arteries.

Effects of oral estrogen and hypnotics on Japanese peri- and postmenopausal women with sleep disturbance.

Aim:  To assess the effects of estrogen and hypnotics on Japanese peri‐ and postmenopausal women with sleep disturbance.