A gain-of-function mutation in the acid-sensing ion channel 2a induces marked cerebellar maldevelopment in rats.

Specific amino acid substitutions in degenerin mechano-gated channels (DEGs) of C. elegans convert these channels into constitutively active mutants that induce the degeneration of neurons where DEGs are expressed. Acid-sensing ion channel-2a (ASIC2a), a proton-gated cation channel predominantly expressed in central neurons, is a mammalian ortholog of DEGs, and it can remain unclosed to be cytotoxic once the same mutations as the DEG mutants are introduced into its gene. Here we show that heterozygous transgenic (Tg) rats expressing ASIC2a-G430F (ASIC2aG430F), the most active form of the gain-of-function mutants, under the control of the intrinsic ASIC2a promoter exhibited marked cerebellar maldevelopment with mild whole-brain atrophy. The Tg rats were small and developed an early-onset ataxic gait, as evidenced by rotarod and footprint tests. The overall gross-anatomy of the Tg brain was normal just after birth, but a reduction in brain volume, especially cerebellar volume, gradually emerged with age. Histological examination of the adult Tg brain revealed that the cell-densities of cerebellar Purkinje and granule cells were markedly reduced, while the cytoarchitecture of other brain regions was not significantly altered. RT-PCR and immunoblot analyses demonstrated that ASIC2aG430F transcripts and proteins were already present in various regions of the neonatal Tg brain before the deforming cerebellum became apparent. These results suggest that, according to the spatiotemporal pattern of the wild-type (WT) ASIC2a gene expression, the ASIC2aG430F channel induced lethal degeneration in Tg brain neurons expressing both ASIC2aG430F and ASIC2a channels.

SGK1 in Schwann cells is a potential molecular switch involved in axonal and glial regeneration during peripheral nerve injury.

Schwann cells play an important role in peripheral myelination, and dysfunction of these cells leads to axonal damage. Schwann cells degenerate following peripheral nerve injury. Immature Schwann cells proliferate, differentiate, and support axonal regeneration and extension during recovery. There are a lot of intracellular signals involved in the myelination process. Although serum- and glucocorticoid-inducible kinase (SGK1) in Schwann cells is supposedly involved in developmental myelination, its significance during peripheral nerve injury and repair remains unknown. In this study, we examined the dynamics of SGK1 during peripheral nerve repair and the potential role of SGK in the process. Axonal crush injury was first generated in the right sciatic nerve under anesthesia in mice, which exhibited apparent paralysis and subsequent recovery of the injured hindlimbs. Immunohistochemical analysis revealed the appearance of glial fibrillary acidic protein (GFAP)-positive immature Schwann cells around injured nerves, and SGK1 was present in these cells. Next, we employed S16 cells, a Schwann cell line, to explore the impact of SGK1 on Schwann cells. Administration of the SGK inhibitor gsk650394 decreased cell proliferation and increased cell size. SGK inhibition did not cause cellular injury, suggesting that it suppresses proliferation and enlarges Schwann cells without causing cell death. Furthermore, quantitative PCR and immunoblotting revealed that SGK inhibition upregulated the gene expression of BDNF, MBP, and Krox20, which are facilitating factors for myelination and neural regeneration, and downregulated that of Sox10. Taken together, these findings indicate that SGK1 inactivation in Schwann cells diverts cell fate from proliferation to differentiation.

Sex- and Age-related Differences in Spinal Degeneration: An Anatomical and Magnetic Resonance Imaging Study of the Human Spine.

Objectives: A precise anatomical understanding of the morphology of the spine is indispensable for neck and low back pain therapy including rehabilitation. However, few studies have directly addressed spinal morphology with a focus on the height of the vertebral body and discs. The aim of the current study was to analyze sex- and age-related changes in the spine by measuring the distance between adjacent centers of the intervertebral disc spaces from the posterior aspect in cadavers and by using magnetic resonance imaging (MRI) measurements at the cervical and lumbar vertebral levels. Methods: In the cadaveric study, the posterior distance between the adjacent centers of the disc spaces was measured for 58 spinal canals. The equivalent distances were examined using MRI in 370 and 660 subjects who presented with neck pain and back pain, respectively. Results: The distance between the adjacent centers of the intervertebral disc spaces in male cadavers was larger than that in female cadavers from C3 to L5/S1. The MRI results showed that the distance between the adjacent centers of the intervertebral disc spaces decreased with age in all spinal areas in men and women. Cadaveric values were significantly lower than the MRI values in men, whereas in women, no significant differences were observed. Conclusions: These results suggest that age-related changes in the cervical and lumbar spine are associated with differences between men and women in the degrees of progressive vertebral body and disc degeneration.

Differences in postural stability and dynamic visual acuity among healthy young adults in relation to sports activity: a cross sectional study.

[Purpose] Sports activity has been shown to improve postural stability and vestibular function in healthy older adults. The hypothesis was that healthy young adults undertaking sports activity will also have better postural stability and vestibular function compared with healthy young adults who do not undertake sports activity. The purpose of this study was to investigate the differences in postural stability and vestibular function between healthy young adults who undertake sports activity and those who do not undertake such activity. [Participants and Methods] Thirty-nine healthy young adults were recruited and divided into sports and non-sports groups on the basis of their response to a questionnaire concerning regular participation in sports activities over the past 12 months. In both groups, postural stability was measured during quiet standing and standing during head rotation, and dynamic visual acuity was assessed during head rotation. [Results] The results showed significant differences in postural stability during head rotation and dynamic visual acuity between the two groups, whereas no significant differences were found in postural stability during quiet standing. [Conclusion] The results suggest that healthy young adults who undertake sports activity have better postural stability during head rotation and better dynamic visual acuity. The causal effect of these differences is not clear and further investigation is warranted.

Pathology and management of flexible flat foot in children.

We describe the pathology and treatment of flexible flat foot in children. The flexible flat foot is seen in the overly flexible foot and usually involves hypermobility of the subtalar joint. It typically occurs in childhood and may continue to adulthood. The arch develops spontaneously during the first decade of life in most children and comes within the normal range observed in adult feet. We prescribed orthoses for the treatment of flexible flat foot patients. Lateral weight-bearing radiographs and ultrasonography were helpful for the evaluation of the flat foot. Bleck recommended the UCBL shoe insert in cases of flexible flat foot if the standing or lateral rentgenogram demonstrates a talar plantar flexion angle (TPF) of 45° or greater. Bordelon suggested that cases of flexible flat foot should be treated if the standing or lateral roentgenogram demonstrates a Meary's talo-1st metatarsal angle (T1-MTA) of -15°or greater. However, the radiograph of a young child's foot poses some difficulties in making an accurate evaluation, because of the radiolucent cartilage zone. In this situation, a sagittal image obtained by ultrasonography has proved to be a powerful aid to evaluate the type of the flat foot. We classified the flat foot into three types: talo-navicular sag (T-N sag), naviculo-cuneiform sag (NC sag) and talo-navicular and naviculo-cuneiform sag (Mixed sag) following the criteria of Tachdjian. We recommended the NC sag and Mixed sag groups to be treated by using orthoses, while we kept a status of watchful waiting for the T-N sag group. However, we should consider the increasing complaints of children and their parents during the orthotic treatment. A through discussion between the parents of patients and the pediatric orthopedic doctors is necessary before orthotic treatment is started.

Preoperative radiologic predictors of successful soft tissue release surgery for hip subluxation among cerebral palsy patients: A STROBE compliant study.

Paralytic hip subluxation is a common problem in children with cerebral palsy. Although surgical procedures such as soft tissue release and osteotomy have been advocated for its prevention, the exact indications of such procedures remain unclear. We attempted to evaluate preoperative radiographic parameters and identify prognostic factors in children with cerebral palsy. We retrospectively investigated 43 hips in 27 children with cerebral palsy who had undergone soft tissue release surgery for hip subluxation. We evaluated the age at the time of surgery and the radiographic parameters such as the center-edge angle (CEA), the migration percentage (MP), and the acetabular index (AI) at 3 time points: preoperation, 1 year after surgery, and at final follow-up. The outcome measure was determined by the MP value at final follow-up. Student t test was used to compare the quantitative variables between 2 groups (good vs poor outcome). Then the multiple regression analysis was applied to determine the prognostic factors upon soft tissue release surgery. Children with good outcome exhibited higher CEA (average value of -1.43° vs -13.2° in those with poor outcome), lower MP (53.9% vs 71.3%), and lower AI (28.1° vs 35.3°). Upon multiple regression analysis, we found that the age at the time of surgery, preoperative CEA, and preoperative MP did not appear to be independent prognostic factors. The only independent factor that affected prognosis after soft tissue release surgery was the preoperative AI. The preoperative AI values <34° were associated with the good outcome with specificity of 87% and sensitivity of 60% according to the receiver operating characteristic curve analysis. These findings indicate that the outcome of soft tissue release surgery can be predicted by the preoperative AI value.

Potential implication of SGK1-dependent activity change in BV-2 microglial cells.

It has recently been established that microglial activation is involved in the pathophysiology of various neurological and psychiatric disorders such as amyotrophic lateral sclerosis and schizophrenia. The pathological molecular machineries underlying microglial activation and its accelerating molecules have been precisely described in the diseased central nervous system (CNS). However, to date, the details of physiological mechanism, which represses microglial activation, are still to be elucidated. Our latest report demonstrated that serum- and glucocorticoid-inducible kinases (SGK1 and SGK3) were expressed in multiple microglial cell lines, and their inhibitor enhanced the toxic effect of lipopolysaccharide on microglial production of inflammatory substances such as TNFα and iNOS. In the present report, we prepared SGK1-lacked microglial cell line (BV-2) and demonstrated that deficiency of SGK1 in microglia induced its toxic conversion, in which it took amoeboid morphology characteristic of reactive microglia, increased CD68 expression, quickened its proliferation, and showed higher susceptibility to ATP and subsequent cell death. Our data indicate that SGK1 plays pivotal roles in inhibiting its pathological activation, and suggest its potential function as a therapeutic target for the treatment of various disorders related to the inflammation in the CNS.

Serum- and glucocorticoid-inducible kinases in microglia.

Microglia are derived from myelogenous cells and contribute to immunological and inflammatory responses in central nervous system. They play important roles not only in infectious diseases and inflammation after stroke, but also in psychiatric diseases such as schizophrenia. While recent studies suggest the significances of serum- and glucocorticoid-inducible kinases (SGKs) in other immune cells such as macrophages, T cells and dendritic cells, their role in microglia remains unknown. Here we, for the first time, report that SGK1 and SGK3 are expressed in multiple microglial cell lines. An SGK inhibitor, gsk650394, inhibits cell viability. In addition, lipopolysaccharide-induced expression of inflammatory regulators iNOS and TNFα was enhanced by gsk650394. Furthermore, translocation of NF-κB was enhanced by gsk650394. Taken together, these findings suggest that SGKs may play an important role in regulating microglial viability and inflammatory responses.

Morphometric analysis of the peroneal tubercle using a three-dimensional computed tomography model.

BACKGROUND: The peroneal tubercle is a small bony ridge located on the lateral wall on the calcaneus immediately inferior to the lateral malleolus and separates the peroneus brevis and peroneus longus tendons. The size and configuration of the peroneal tubercle has been implicated in the pathogenesis of peroneal tendon tears and tenosynovitis and is the increasing object of clinical interest. However, the morphology of the tubercle is difficult to assess with precision. METHODS: We utilized a new method to evaluate the three-dimensional (3D) geometry of 46 calcanei from 34 consecutive patients; average patient age was 48.0 years who underwent lower extremity computed tomography (CT) for clinical treatment of non-peroneal tubercle-related conditions. The 3D geometries of calcanei were reconstructed by using the computer software to calculate the surface 3D models. To measure the size of the peroneal tubercle, we virtually excised it from the 3D calcaneus model and made a precise measurement of the height. RESULTS: Peroneal tubercles with measured heights of 1mm or more were detected in 65% of the feet, with an average tubercle height of 2.59mm. Peroneal tubercles were larger and more frequent in middle-aged or older than younger patients.

The changes of gap junctions between pituitary folliculo-stellate cells during the postnatal development of Zucker fatty and lean rats.

We investigated the effect of leptin on the postnatal development of gap junctions between folliculo-stellate cells by using Zucker fatty (fa/fa) rats that have defects of the functional leptin receptor. Male Zucker fatty rats (fa/fa) and male Zucker lean rats (+/+) were used at each of the following postnatal ages: 20, 30, 40, 50, 60, 70, 80, 90 days, and 1 year. On one of the aforementioned dates, the anterior pituitary glands were prepared for observation by transmission electron microscopy. We quantified the number of follicles and gap junctions, and calculated the rate of occurrence as the ratio of the number of gap junctions existing between folliculo-stellate cells per intersected follicular profile. In Zucker lean male rats, the number of gap junctions remained relatively constant from days 50 to 90 (0.44 ± 0.02 to 0.49 ± 0.03), and was similar in 1 year old rats (0.47 ± 0.03). These data were statistically higher compared to Zucker fatty male rats. In Zucker fatty male rats, very few gap junctions were observed in 30-day-old rats (0.04 ± 0.01: mean ± SE). This disruption of gap junction formation persisted, and the number of gap junctions remained constant and showed a low level from days 40 to 90 (0.11 ± 0.02 to 0.17 ± 0.02); this finding was similar in 1-year-old rats (0.17 ± 0.02). These observations indicate that the effect of leptin over the gap junction formation within the anterior pituitary glands was directly mediated by interaction with the functional leptin receptor present on the folliculo-stellate cells.

Intercellular communications within the rat anterior pituitary. XVI: postnatal changes of distribution of S-100 protein positive cells, connexin 43 and LH-RH positive sites in the pars tuberalis of the rat pituitary gland. An immunohistochemical and electron microscopic study.

The architecture of luteinizing hormone-releasing hormone (LH-RH) nerve ends and the S-100 protein containing folliculo-stellate cells forming gap junctions in the pars tuberalis is basically important in understanding the regulation of the hormone producing mechanism of anterior pituitary glands. In this study, intact male rats 5-60 days old were prepared for immunohistochemistry and electron microscopy. From immunostained sections, the S-100 containing cells in pars tuberalis were first detected on day 30 and increased in number to day 60; this was parallel to the immunohistochemical staining of gap junction protein, connexin 43. LH-RH positive sites were clearly observed on just behind the optic chiasm and on the root of pituitary stalk on day 30. On day 60, the width of layer increased, while follicles and gap junctions were frequently observed between agranular cells in 10 or more layers of pars tuberalis. In the present study, we investigated the sexual maturation of the anterior pituitary glands through the postnatal development of S-100 positive cells, connexin 43 and LH-RH nerves. It is suggested that the folliculo-stellate cell system including the LH-RH neurons in the pars tuberalis participates in the control of LH secretion along with the portal vein system.

The Pavlik harness in the treatment of developmentally dislocated hips: results of Japanese multicenter studies in 1994 and 2008.

BACKGROUND: It has already been more than 50 years since the Pavlik harness was introduced in Japan, and today the Pavlik harness is widely recognized as the standard initial treatment modality for developmental dysplasia of the hip. We performed a multicenter nationwide questionnaire study concerning the results of Pavlik harness treatment twice in 1994 and 2008. METHODS: In 1994 and in 2008, we sent questionnaires to 12 institutes in Japan specializing mainly in pediatric orthopedics. We compare the results of these two studies and discuss differences in reduction rates, incidence of avascular necrosis in the femoral epiphysis and the percentage of joints with acceptable morphology (Severin grade I + II/total) at skeletal maturity. We statistically assessed these results to see whether there were changes in the treatment outcomes over this 14-year period. RESULTS: Reduction of the dislocated hips was obtained by the Pavlik harness in 80.2% (1990/2481 hips; 1994) and 81.9% (1248/1523 hips; 2008). The incidences of avascular necrosis of the proximal femoral epiphysis in the dysplastic hips were 14.3% (119/835 hips; 1994) and 11.5% (76/663 hips; 2008). The type of avascular necrosis in hips from the 2008 study was determined according to the classification of Kalamchi and MacEwen: 24/69 hips (34.8%) were classified as group I; 20/69 hips (29.0%) as group II; 11/69 hips (15.9%) as group Ill; 14/69 hips (20.3%) as group IV. The percentages of hips with acceptable outcomes at skeletal maturity discerned from Severin X-ray changes (grade I + II/total) were 72.3% (604/835 hips; 1994) and 77.7% (488/628 hips; 2008). CONCLUSION: Reduction rates and the incidence of avascular necrosis in 2008 were statistically similar to the results in 1994. The rate of acceptable outcome (Severin grade I + II/total) in 2008 was statistically higher than that of 1994.

Involvement of the adrenal glands and testis in gap junction formation via testosterone within the male rat anterior pituitary gland.

We investigated the influence of testicular and adrenal androgens on the presence of gap junctions between folliculo-stellate cells in the anterior pituitary glands of 60-day-old Wistar-Imamichi strain male rats. The animals were separated into six groups: Group A served as the controls and had free access to a normal diet and water, Group B was given a normal diet and 0.9% NaCl for their drinking water as the controls of adrenalectomized groups, Group C was castrated, Group D was adrenalectomized, Group E was both castrated and adrenalectomized, and Group F was also both castrated and adrenalectomized. In addition, the animals of Group F were administered a dose of testosterone that is known to produce high physiological levels of the hormones in plasma. Five rats from each group were sacrificed 1, 2, 3, 4, 5, 6, and 7 days after their respective operation, and the anterior pituitary glands were removed and prepared for observation by transmission electron microscopy. We quantified the number of follicles and gap junctions and calculated the rate of occurrence as the ratio of the number of gap junctions existing between folliculo-stellate cells per intersected follicle profile. Simultaneous removal of adrenal glands with castration resulted in a significantly decrease in the number of gap junctions, whereas the administration of testosterone to these rats compensated for this change. These observations indicate that the preservation of gap junctions between folliculo-stellate cells is mainly dependent on androgens from both the testes and adrenal glands in adult male rats.

Ultrastructural changes at the myotendinous junction induced by exercise.

BACKGROUND: Although exercise is believed to reduce the risk of rupture of the myotendinous junction, exercise-induced structural changes in this region have not been studied. We examined exercise-induced ultrastructural changes in the myotendinous junction of the lower legs in rats. METHODS: Ten adult male LETO rats were used. Five rats were randomly placed in the Exercise group; the remaining five were used as controls and placed in the non-Exercise group. Running exercise was performed every day for 4 weeks. The tibialis anterior and gastrocnemius muscles were then removed from both legs from each animal in the two groups. The specimens were subsequently examined by transmission electron microscopy (TEM). Numerous finger-like processes were observed at the myotendinous junction. The changes in frequency of branching of the finger-like process (the number of times one finger-like process branched) and the direction of the processes (the angle of the major axis of a finger-like process to the longitudinal direction of the muscle fiber) were studied. To evaluate the two indicators above, each 10 fingerlike process was randomly and separately selected from the tibialis anterior and gastrocnemius muscles of rats, providing 50 finger-like processes of both muscles for evaluation per group. RESULTS: In terms of the frequency of branching of the fingerlike processes, the mean values obtained in the non-Exercise group were 0.04 and 0.18 times, respectively, in the tibialis anterior and gastrocnemius muscles and were 0.38 and 1.16 times, respectively, in these two muscles in the Exercise group. Regarding the direction of the finger-like processes, the values were 4.1 degrees and 3.6 degrees, respectively in the non-Exercise group and 10.4 degrees and 14.5 degrees , respectively in the Exercise group. The differences between the two animal groups were significant. CONCLUSIONS: Morphological changes in the myotendinous junction occurred as an adaptation to tension increased by exercise.

Electron microscopic observations of the anterior pituitary gland. Part I. The neurons in the "transitional zone" of the anterior pituitary gland.

Since [Westlud, K.N., Chils, G.V., 1982. Localization of serotonin fibers in the rat adenohypophysis. Endocrinology 111, 1761-1763] initially identified the serotonin nerve fibers in the anterior pituitary gland, attention has been paid to the rostral zone of the anterior lobe into which nerve fibers enter and subsequently spread to deeper regions of the lobe. The rostral zone is the trifurcated junction of the partes tuberalis, intermedia and distalis, and has the important role(s) for hormone secretion via the "transitional zone" [Sato, G, Shirasawa, N, Sakuma, E, Sato, Y, Asai, Y, Wada, I, Horiuchi, O, Sakamoto, A, Herbert, DC, Soji, T, 2005a. Intercellular communications within the rat anterior pituitary. XI: An immunohistochemical study of distributions of S-100 positive cells in the anterior pituitary of the rat. Tissue and Cell 37, 269-280.]. The objective of this study was to focus on the ultrastructure of this "zone." All of the animals studied were fixed by perfusion with glutaraldehyde via the left ventricle of the heart and examined by electron microscopy. In the "transitional zone," a cluster of neuronal elements was observed between the folliculo-stellate cell-rich area and the anterior lobe. This cluster consisted of myelinated fibers, unmyelinated fibers, neuroendocrine fibers, large cells, and supporting cells. The large cells were perikarya of neurons which made a "ganglion-like" structure with associated satellite cells. Agranular, folliculo-stellate cells were intermingled among the elements. This is the first report that neuronal elements form clusters in the "transitional zone." A relationship of the unmyelinated and neuroendocrine fibers in the basal layer and in the "transitional zone" is discussed.

Bilaterally existing sternoclavicularis anticus muscles.

A 92-year-old Japanese woman was found to have the sternoclavicularis anticus muscles existing bilaterally during the course of educational dissection at Nagoya City University Medical School. It was confirmed that these muscles received the nerve supply from small branches of the lateral pectoral nerves from the brachial plexus. Herein is documented the precise gross anatomical findings with some morphometric measurements. Moreover, the morphology of this muscle is discussed in relation to previously described variations of the pectoral sheet of muscles.

Intercellular communication within the rat anterior pituitary: XIV electron microscopic and immunohistochemical study on the relationship between the agranular cells and GnRH neurons in the dorsal pars tuberalis of the pituitary gland.

Although numerous investigators in 1970s to 1980s have reported the distribution of LH-RH nerve fibers in the median eminence, a few LH-RH fibers have been shown to be present in the pars tuberalis. The significance of the finding remains to be elucidated, and there are few studies on the distribution of LH-RH neurons in the pars tuberalis, especially in the dorsal pars tuberalis (DPT). Adult male Wistar-Imamichi rats were separated into two groups: one for electron microscopy and the other for immunohistochemistry to observe LH-RH and neurofilaments. Pituitary glands attached to the brain were fixed by perfusion, and the sections were prepared parallel to the sagittal plane. The typical glandular structure of the pars tuberalis was evident beneath the bottom floor of the third ventricle, and the thick glandular structure was present in the foremost region. Closer to the anterior lobe, the glandular structure changed to be a thin layer, and it was again observed at the posterior portion. Then the pituitary stalk was surrounded with the dorsal, lateral, and ventral pars tuberalis. LH-RH and neurofilaments fibers were noted in the bottom floor, and some of them vertically descended to the gland. Adjacent to the glandular folliculostellate cells in the pars tuberalis, Herring bodies with numerous dense granules invading into the gland were present between the pituitary stalk and DPT. It was postulated that the "message" carried by LH-RH might have been transmitted to the cells in the DPT to aid in the modulation of LH release.

Compound class specific 14C analysis of polycyclic aromatic hydrocarbons associated with PM10 and PM1.1 aerosols from residential areas of suburban Tokyo.

Compound class specific radiocarbon analysis (CCSRA) was performed for polycyclic aromatic hydrocarbons (PAHs) associated with airborne particulate matter (APM) with diameter <10 microm (PM10) and <1.1 microm (PM1.1) collected from a residential area of suburban Tokyo, Japan, and seasonal and particle-size radiocarbon variations were investigated. Source diagnostic isomer pair ratios indicated mixed contributions from petroleum combustion and from biomass and coal combustion to the PAHs in APM. The delta14C- PAHs in APM, ranging from -787 to -514 per thousand, indicated dominance of fossil fuel combustion. The delta14C of 5-6 rings (HMW) PAHs were higher than the 3-4 rings (LMW) species in both PM10 and PM1.1 samples. The delta14C of HMW-PAHs indicated greater biomass-burning contributions in summer than in winter and no apparent particle-size variation. Conversely, the delta14C of LMW species showed a greater contribution from fossil sources in summer and in larger particles (PM10). This finding could be tentatively attributed to the recondensation of fossil-PAHs vaporized from petroleum sources. A 14C isotopic mass balance approach estimated that biomass burning contributes 17-45% of the PAH burden in suburban Tokyo, and that the increase in the biomass-PAH accounts for approximately 27% and 22% of winter-time elevation of LMW- and HMW-PAHs, respectively. These are far exceeding what is expected from the emission statistics for CO2 and combusted materials in Japan and emphasizing the importance of biomass-burning as a source of PAHs; which, in turn, demonstrates the utility and the significance of field-based source assessment by using CCSRA for an effective regulation of atmospheric pollution by PAHs.

Intercellular communications within the rat anterior pituitary XII: immunohistochemical and physiological evidences for the gap junctional coupling of the folliculo-stellate cells in the rat anterior pituitary.

Since Farquhar [1957. "Corticotrophs" of the rat adenohypophysis as revealed by electron microscopy. Anat. Rec. 127, 291] was the first to report the presence of agranular folliculo-stellate cells as corticotrophs in the anterior pituitary gland, there were no reports about electro-physiological characteristics of the folliculo-stellate cells because of its no hormonal activity and the chaotic distribution of the parenchyma cells. Male Wistar rats, aged 7 weeks with weighing 250--300 g, were separated into two groups. One group was used for immunohistochemical and light microscopical studies to detect S-100 protein and connexin 43. The other group was used for the electro-physiological study and then for the electron microscopical study to know the fine structural character of folliculo-stellate cells after the electro-physiological experiment. Clusters of S-100 protein cells (agranulated folliculo-stellate cells) and numerous connexin 43 positive sites on S-100 protein cells were clear in the "transitional zone" at which the pituitary tissue made the transition from the pars tuberalis to the proximal part of the anterior lobe. Penetration of electrodes to the cells distributed in the transitional zone showed stable membrane potential ranged between--27 and--67mV with no spontaneous activity. Random penetration of electrode showed that larger populations of cell ( approximately 80%) had membrane potentials with -55.6+/-5.1 mV, and less than 20% of cells had the resting membrane potential with -36.0+/-4.4 mV. There were two types of cell couplings; one major group for the recordings from cells with similar deep resting membrane potentials and the other for the recordings from cells with different resting membrane potentials. The former indicated that two cells were electrically coupled while the latter no electrical couples were observed. Carbenoxolone depolarized the membrane by 12.3+/-5.5 mV and reduced the amplitude of electrotonic potentials, and the response recovered by removal of carbenoxolone by the superfusate. The transitional zones of the pituitary glands examined the electrical coupling were observed by an electron microscopy. Almost cytological profiles were observed as intact. The results clearly indicated that the folliculo-stellate cell system deeply participated in the regulation of the anterior pituitary parallel with the portal vessel system, which was the main regulatory system for pituitary hormone secretion.