Substance P and calcitonin gene-related peptide intrinsic choroidal neurons in human choroidal whole-mounts

The choroidal nervous system: a link between mineralocorticoid receptor and pachychoroid

Central serous chorioretinopathy (CSCR) belongs to the pachychoroid spectrum, a pathological phenotype of the choroidal vasculature, in which blood flow is under the choroidal nervous system (ChNS) regulation. The pathogenesis of CSCR is multifactorial, with the most recognised risk factor being intake of glucocorticoids, which activate both the gluco- and the mineralocorticoid (MR) receptors. As MR over-activation is pathogenic in the retina and choroid, it could mediate the pathogenic effects of glucocorticoids in CSCR. But the role of MR signalling in pachychoroid is unknown and whether it affects the ChNS has not been explored. Using anatomo-neurochemical characterisation of the ChNS in rodents and humans, we discovered that beside innervation of arteries, choroidal veins and choriocapillaris are also innervated, suggesting that the entire choroidal vasculature is under neural control. The numerous synapses together with calcitonin gene-related peptide (CGRP) vesicles juxtaposed to choroidal macrophages indicate a neuro-immune crosstalk. Using ultrastructural approaches, we show that transgenic mice overexpressing human MR, display a pachychoroid-like phenotype, with signs of choroidal neuropathy including myelin abnormalities, accumulation and enlargement of mitochondria and nerves vacuolization. Transcriptomic analysis of the RPE/choroid complex in the transgenic mice reveals regulation of corticoids target genes, known to intervene in nerve pathophysiology, such as Lcn2, rdas1/dexras1, S100a8 and S100a9, rabphilin 3a (Rph3a), secretogranin (Scg2) and Kinesin Family Member 5A (Kif5a). Genes belonging to pathways related to vasculature development, hypoxia, epithelial cell apoptosis, epithelial mesenchymal transition, and inflammation, support the pachychoroid phenotype and highlight downstream molecular targets. Hypotheses on the imaging phenotype of pachychoroid in humans are put forward in the light of these new data. Our results provide evidence that MR overactivation causes a choroidal neuropathy that could explain the pachychoroid phenotype found in transgenic mice overexpressing human MR. In patients with pachychoroid and CSCR in which systemic dysautonomia has been demonstrated, MR-induced choroidal neuropathy could be the missing link between corticoids and pachychoroid.

Can the long term using of pregabalin in fibromyalgia affect the choroid and retinal nerve fiber layer?

BACKGROUND

In this study, the effects of long-term pregabalin use on the choroid and retinal nerve fiber layer were investigated in the fibromyalgia disease.

METHODS

The patient group consisted of 41 fibromyalgia patients using pregabalin. The control group consisted of 41 newly diagnosed fibromyalgia patients who had not received any treatment yet. Choroidal and retinal nerve fiber layer thickness measurements were performed with Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA, USA) 30 minutes after pupil dilation with 1% tropicamide.

RESULTS

There was no difference in subfoveal choroidal thickness, nasal choroidal thickness and temporal choroidal thickness between the patient and control groups (p > 0.05). Increasing the duration of drug use within the patient group was found to thin the retinal nerve fiber layer (p < 0.05).

CONCLUSION

We found that pregabalin had no effect on the choroid, while it had a thinning effect for retinal nerve fiber layer. It is recommended not to be preferred pregabalin in fibromyalgia patients with retinal nerve fiber layer damage such as diabetic retinopathy and glaucoma. Patients treated with pregabalin should have regular control in the ophthalmology clinic.

Ocular Autonomic Nervous System: An Update from Anatomy to Physiological Functions

The autonomic nervous system (ANS) confers neural control of the entire body, mainly through the sympathetic and parasympathetic nerves. Several studies have observed that the physiological functions of the eye (pupil size, lens accommodation, ocular circulation, and intraocular pressure regulation) are precisely regulated by the ANS. Almost all parts of the eye have autonomic innervation for the regulation of local homeostasis through synergy and antagonism. With the advent of new research methods, novel anatomical characteristics and numerous physiological processes have been elucidated. Herein, we summarize the anatomical and physiological functions of the ANS in the eye within the context of its intrinsic connections. This review provides novel insights into ocular studies.

Evaluation of choroidal thickness via enhanced depth-imaging optical coherence tomography in patients with systemic hypertension

Purpose:

The purpose was to evaluate choroidal thickness via spectral domain optical coherence tomography (SD-OCT) and to compare the data with those of 24-h blood pressure monitoring, elastic features of the aorta, and left ventricle systolic functions, in patients with systemic hypertension.

Materials and Methods:

This was a case-control, cross-sectional prospective study. A total of 116 patients with systemic hypertension, and 116 healthy controls over 45 years of age, were included. Subfoveal choroidal thickness (SFCT) was measured using a Heidelberg SD-OCT platform operating in the enhanced depth imaging mode. Patients were also subjected to 24-h ambulatory blood pressure monitoring (ABPM) and standard transthoracic echocardiography (STTE). Patients were divided into dippers and nondippers using ABPM data and those with or without left ventricular hypertrophy (LVH+ and LVH-) based on STTE data. The elastic parameters of the aorta, thus aortic strain (AoS), the beta index (BI), aortic distensibility (AoD), and the left ventricular mass index (LVMI), were calculated from STTE data.

Results:

No significant difference in SFCT was evident between patients and controls (P ≤ 0.611). However, a significant negative correlation was evident between age and SFCT in both groups (r = −0.66/−0.56, P ≤ 0.00). No significant SFCT difference was evident between the dipper and nondipper groups (P ≤ 0.67), or the LVH (+) and LVH (-) groups (P ≤ 0.84). No significant correlation was evident between SFCT and any of AoS, BI, AoD, or LVMI.

Discussion:

The choroid is affected by atrophic changes associated with aging. Even in the presence of comorbid risk factors including LVH and arterial stiffness, systemic hypertension did not affect SFCT.

Distribution of substance P and the calcitonin gene-related peptide in the human tensor tympani muscle

Substance P-immunoreactive nerve fiber (SP-IR NF) and calcitonin gene-related peptide-immunoreactive nerve fiber (CGRP-IR NF) are important mediators of neurogenic inflammation and blood supply. SP-IR and CGRP-IR NFs in the tensor tympani muscle (TTM) of the human middle ear have yet to be described. In this study, the TTM, tympanic membrane, malleus in the middle ear and tensor veli palatini muscle (TVPM) were examined by whole-mount immunohistochemistry in tissue from Japanese subjects. Thirteen human cadavers (ranging in age from 46 to 90 years) were used in this study. SP-IR and CGRP-IR NFs were primarily found on vessels at the origin, insertion and belly of the surface of the TTM and on the internal surface of the tympanic membrane. These neural factors were also detected on the surface of the malleus and the insertion of the TVPM. Therefore, our results indicate that existence of the SP-IR and CGRP-IR NFs of the TTM and the TVPM may reflect muscle properties involved in pain or inflammation of the middle ear.

Cellular and physiological mechanisms underlying blood flow regulation in the retina and choroid in health and disease

We review the cellular and physiological mechanisms responsible for the regulation of blood flow in the retina and choroid in health and disease. Due to the intrinsic light sensitivity of the retina and the direct visual accessibility of fundus blood vessels, the eye offers unique opportunities for the non-invasive investigation of mechanisms of blood flow regulation. The ability of the retinal vasculature to regulate its blood flow is contrasted with the far more restricted ability of the choroidal circulation to regulate its blood flow by virtue of the absence of glial cells, the markedly reduced pericyte ensheathment of the choroidal vasculature, and the lack of intermediate filaments in choroidal pericytes. We review the cellular and molecular components of the neurovascular unit in the retina and choroid, techniques for monitoring retinal and choroidal blood flow, responses of the retinal and choroidal circulation to light stimulation, the role of capillaries, astrocytes and pericytes in regulating blood flow, putative signaling mechanisms mediating neurovascular coupling in the retina, and changes that occur in the retinal and choroidal circulation during diabetic retinopathy, age-related macular degeneration, glaucoma, and Alzheimer's disease. We close by discussing issues that remain to be explored.