Nitric Oxide Increases the Expression of Aquaporin-4 Protein in Rat Optic Nerve Astrocytes through the Cyclic Guanosine Monophosphate/Protein Kinase G Pathway

2015 ◽  
Vol 54 (4) ◽  
pp. 212-221 ◽  
Author(s):  
Hidehiro Oku ◽  
Seita Morishita ◽  
Taeko Horie ◽  
Teruyo Kida ◽  
Masashi Mimura ◽  
...  
2001 ◽  
Vol 18 (6) ◽  
pp. 849-856 ◽  
Author(s):  
WILLIAM H. BALDRIDGE ◽  
ANDY J. FISCHER

Nitric oxide (NO) activates soluble guanylyl cyclase (sGC) and the resulting increase in cyclic guanosine monophosphate (cGMP) is an important intracellular signalling pathway in the vertebrate retina. Immunocytochemical detection of cGMP following exposure to NO donors has proven an effective method of identifying cells that express sGC. While such an approach has proven useful for the study of several vertebrate retinas, it has not been applied to the well-characterized teleost retina. Therefore, in the present study, we have applied this approach to the retina of the goldfish (Carassius auratus). In the presence of the phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX), incubation of goldfish eyecups in Ringer's solution containing (±)-S-nitroso-N-acetylpenicillamine (SNAP) increased cGMP-like immunoreactivity (cG-ir) in bipolar, horizontal, amacrine, and ganglion cells and in ganglion cell axons and optic nerve. Weak labeling was observed in horizontal cells but no change in cG-ir was noted within photoreceptors. The NO donor-stimulated increases of cG-ir in horizontal, bipolar, amacrine, and ganglion cells are consistent with known physiological effects of NO on these neurons. The physiological significance of NO action at the level of optic nerve is not known. The lack of an effect of SNAP on cG-ir in photoreceptors was unexpected, as there are known physiological actions of NO, mediated by cGMP, on these neurons. Although this may be due to insufficient sensitivity of immunolabeling, this result may indicate a difference between isoforms of sGC or cGMP PDE in these neurons, compared to neurons where exogenous NO increased cG-ir.


Hypertension ◽  
2020 ◽  
Vol 76 (4) ◽  
pp. 1055-1068
Author(s):  
Ehsan Ataei Ataabadi ◽  
Keivan Golshiri ◽  
Annika Jüttner ◽  
Guido Krenning ◽  
A.H. Jan Danser ◽  
...  

For the treatment of systemic hypertension, pharmacological intervention in nitric oxide-cyclic guanosine monophosphate signaling is a well-explored but unexploited option. In this review, we present the identified drug targets, including oxidases, mitochondria, soluble guanylyl cyclase, phosphodiesterase 1 and 5, and protein kinase G, important compounds that modulate them, and the current status of (pre)clinical development. The mode of action of these compounds is discussed, and based upon this, the clinical opportunities. We conclude that drugs that directly target the enzymes of the nitric oxide-cyclic guanosine monophosphate cascade are currently the most promising compounds, but that none of these compounds is under investigation as a treatment option for systemic hypertension.


2011 ◽  
Vol 108 (6) ◽  
pp. 400-405 ◽  
Author(s):  
Azam Shah Mohamad ◽  
Muhammad Nadeem Akhtar ◽  
Shaik Ibrahim Khalivulla ◽  
Enoch Kumar Perimal ◽  
Mohamed Hanief Khalid ◽  
...  

2011 ◽  
Vol 286 (12) ◽  
pp. 10712-10724 ◽  
Author(s):  
Esperanza Jiménez ◽  
Francisco Zafra ◽  
Raquel Pérez-Sen ◽  
Esmerilda G. Delicado ◽  
Maria Teresa Miras-Portugal ◽  
...  

The sodium- and chloride-coupled glycine neurotransmitter transporters (GLYTs) control the availability of glycine at glycine-mediated synapses. The mainly glial GLYT1 is the key regulator of the glycine levels in glycinergic and glutamatergic pathways, whereas the neuronal GLYT2 is involved in the recycling of synaptic glycine from the inhibitory synaptic cleft. In this study, we report that stimulation of P2Y purinergic receptors with 2-methylthioadenosine 5′-diphosphate in rat brainstem/spinal cord primary neuronal cultures and adult rat synaptosomes leads to the inhibition of GLYT2 and the stimulation of GLYT1 by a paracrine regulation. These effects are mainly mediated by the ADP-preferring subtypes P2Y1 and P2Y13 because the effects are partially reversed by the specific antagonists N6-methyl-2′-deoxyadenosine-3′,5′-bisphosphate and pyridoxal-5′-phosphate-6-azo(2-chloro-5-nitrophenyl)-2,4-disulfonate and are totally blocked by suramin. P2Y12 receptor is additionally involved in GLYT1 stimulation. Using pharmacological approaches and siRNA-mediated protein knockdown methodology, we elucidate the molecular mechanisms of GLYT regulation. Modulation takes place through a signaling cascade involving phospholipase C activation, inositol 1,4,5-trisphosphate production, intracellular Ca2+ mobilization, protein kinase C stimulation, nitric oxide formation, cyclic guanosine monophosphate production, and protein kinase G-I (PKG-I) activation. GLYT1 and GLYT2 are differentially sensitive to NO/cGMP/PKG-I both in brain-derived preparations and in heterologous systems expressing the recombinant transporters and P2Y1 receptor. Sensitivity to 2-methylthioadenosine 5′-diphosphate by GLYT1 and GLYT2 was abolished by small interfering RNA (siRNA)-mediated knockdown of nitric-oxide synthase. Our data may help define the role of GLYTs in nociception and pain sensitization.


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