Zuoming Zhang

Effects of Hydrogen-rich Saline on Rats with Acute Carbon Monoxide Poisoning

BACKGROUND Studies have shown that inhalation of hydrogen gas, which acts as an antioxidant, can protect the brain against free radicals in rats with ischemia-reperfusion. The neuronal damage caused by acute carbon monoxide (CO) poisoning is partly free radical mediated. We hypothesize that hydrogen may prevent neurological damage from CO poisoning. OBJECTIVES This study is designed to test whether hydrogen (H(2))-rich saline will have a protective effect on rats with acute CO poisoning. METHODS Male Sprague-Dawley rats were subjected to CO poisoning. H(2)-rich saline was administered by peritoneal injection (6 mL/kg/24 h). We used the Morris water maze and the open field test to determine cognitive function. After cognitive function studies, rats were decapitated and the levels of trace elements copper (Cu), zinc (Zn), and iron (Fe) in serum and brain were assessed by flame atomic absorption spectrometry. Necrosis, apoptosis, and autophagy of neurons were assessed by H-E staining and immunohistochemical staining in another group of rats. RESULTS H(2)-rich saline treatment improved the cognitive deficits and reduced the degree of necrosis, apoptosis, and cell autophagy in rats. Additionally, H(2)-rich saline decreased the content of Fe in serum and brain in these rats, and increased the content of serum Cu related to free radical metabolism. CONCLUSIONS H(2)-rich saline may effectively protect the brain from injury after acute CO poisoning. The mechanism of this protection may be related to lessening oxidative damage by affecting trace elements in vivo.

Effects of acute cold exposure on carotid and femoral wave intensity indexes: evidence for reflection coefficient as a measure of distal vascular resistance

Our aim was to investigate the effects of acute cold pressor test (CPT) on augmentation index (AI) and wave intensity (WI) indexes from right common carotid artery (RCCA) and right common femoral artery (RCFA) and to test whether the reflection coefficient (RC) from wave intensity analysis can reflect the distal vascular resistance (DVR) accurately. Forty-three healthy males were randomly selected for measurements at baseline and 1 min after CPT at RCCA or RCFA. CPT induced similar increases of heart rate and blood pressure in RCCA and RCFA groups with their pulse pressures unchanged. The W(2) (the second peak of WI) was too obscure in RCFA to be analyzed. The W(1) (the first peak of WI) of both arteries, W(1)-W(2) (interval between W(1) and W(2)), and NA (negative area between W(1) and W(2), indicating reflected waves) of RCCA and the R-W(1) (interval between the R wave of ECG and W(1)) of RCFA decreased obviously, whereas the W(2) and R-W(1) of RCCA and the RC (calculated as NA/W(1)) of RCFA increased with no changes in the RC of RCCA and the NA of RCFA during CPT compared with baseline. The AIs from both arteries increased significantly after CPT. These results suggested that acute CPT has opposing effects on cerebral and peripheral vascular resistances, with the former decreased and the latter increased. The RCs from RCCA and RCFA are more associated with the changes of cerebral and peripheral vascular resistances, respectively, than the NA and AI, and the RC is of guiding value in assessing DVR.

A potential spontaneous rat model of X-linked congenital stationary night blindness

Purpose: To describe a possible spontaneous rat model of X-linked congenital stationary night blindness (CSNB). Methods: Experimental animals were generated by mating the affected animal to normal rats, and from interbreeding littermates. To define the inheritance pattern, full-field electroretinograms (ERGs) were recorded from all progeny. Results: During the course of other experiments, an affected male rat was identified by a reduced amplitude ERG b-wave. When this rat was mated to normal Sprague–Dawley rats, all of the F1 progeny had normal ERG waveforms. When F1 offspring were interbred, 51% of the male offspring had b-wave reductions while all female offspring had normal ERG waveforms. When F1 females were backcrossed to the original affected male, b-wave reductions were noted in both male and female offspring; overall, 46.8% of the backcross progeny exhibited a b-wave reduction. In affected animals, the b-wave was selectively affected as the a-wave appeared to retain normal amplitude and kinetics at 1–4 months old. Cone ERGs were significantly reduced in amplitude and somewhat delayed. Similar ERG results were also obtained under the same stimulus conditions from human patients with complete CSNB (CSNB1). Conclusions: The inheritance pattern is consistent with an X-linked recessive trait. The electrophysiological results suggest that this mutant rat line may provide another model for CSNB1.

A novel middle-wavelength opsin (M-opsin) null-mutation in the retinal cone dysfunction rat

The disease-causing gene which underlies a naturally occurring X-linked mutant cone dysfunction Sprague-Dawley rat model was investigated. Full-field electroretinogram (ERG) and simple sequence length polymorphism analyses were applied to 441-second filial generation rats that were derived from crossing a mutant rat and a Brown-Norway rat. After identifying a mutation mapping within the telomeric region of chromosome X, a candidate gene related to retinal cone function in this region was further screened using real-time PCR, immunohistochemistry and histological methods. The results showed that a G-to-T substitution at the splice acceptor site of intron 4 was present in the opsin 1, medium-wave sensitive (Opn1mw) gene, thereby causing down-regulated transcription and translation. These changes were consistent with abnormities seen in the ERG response. However, there was no significant histological change in the mutant rat retina. Therefore, we infer from this that the causative gene for the mutation is Opn1mw and consequently term this a middle-wavelength opsin cone dysfunction (MCD) rat model. The deficiency in vision of the MCD rat is similar to the color vision defects that occur in humans with a color vision defect but without recessive retinal degeneration. This rat model may be useful for understanding the mechanism that is responsible for color vision and for developing clinical therapies for several retinal dystrophies caused by cone opsin deficiencies.

Intraocular pressure and ocular perfusion pressure in myopes during 21 min head-down rest.

INTRODUCTION Myopic eyes show structural differences from normal eyes and may respond differently to microgravity, increasing the risk for possible development of ocular hypertension and glaucoma on orbit. In this experiment we used head-down rest (HDR) at an angle of 15 degrees to produce hydrostatic changes similar to acute exposure to microgravity. METHODS There were 65 subjects (129 eyes) who were divided into groups characterized by refraction: emmetropes (N = 46; refraction error between -0.99 D and +0.10 D), low myopes (N = 39; > or = -1.0 D to < -3.0 D), and moderate myopes (N = 44; > or = -3.0 D to < -6.0 D). Each subject was studied resting in a horizontal position and after 1, 6, 11, 16, and 21 min of HDR. Measured variables included systolic and diastolic blood pressure (SBP and DBP, respectively), intraocular pressure (IOP), and ocular perfusion pressure (OPP). RESULTS The mean values of IOP increased significantly in all eyes during HDR, with IOP peaking at 6 min. Compared to emmetropes and low myopes, moderate myopes showed a significantly greater increase in IOP and higher peak values for IOP (18.6, 18.7, and 19.8 mmHg for emmetropes, low, and moderate myopes, respectively). Mean values of OPP in moderate myopes were significantly lower than in emmetropes and low myopes during HDR. Compared with baseline, mean SBP and DBP decreased obviously in emmetropes during HDR, while changes were minimal in the other groups. CONCLUSION Abnormal auto-regulation of ocular blood pressure in myopes of moderate and greater severity may pose a risk factor for developing ocular hypertension and possibly glaucoma when exposed to microgravity. HDR may offer a method of screening candidates for spaceflight for this risk prior to microgravity exposure.

Retinal horizontal cells reduced in a rat model of congenital stationary night blindness

This work was conducted to determine whether congenital stationary night blindness (CSNB), which is caused by a Cacna1f mutation, could affect development of second-order neurons in the retina, such as horizontal cells (HCs). The CSNB rats and age-matched wild type rats were sacrificed at postnatal days (PND) 15, 30 and 60. Morphometric analyses of HCs, which were labeled by a primary antibody to calbindin D-28K, were performed at the light microscopic level on retinal cross sections and whole mount retinas. Calbindin D-28K was measured by western blotting in retinal samples. We found that the average number and density of HCs, Calbindin level and thickness of OPL were all decreased significantly in CSNB group compared to control group. These results indicated that second-order retinal neurons, such as horizontal cells, are affected by retinal degeneration. The relationship between the absence of HCs and the gene defect of CSNB requires further research.

Behavioral phenotypic properties of a natural occurring rat model of congenital stationary night blindness with Cacna1f mutation.

Cacna1f gene mutation could lead to incomplete congenital stationary night blindness (iCSNB) disease. The CSNB-like phenotype rat is a spontaneous rat model caused by Cacna1f gene mutation. The present study explored the phenotypic properties of behavior performance in CSNB rats further. The vision-related behaviors of CSNB rats were assessed with a Morris water maze (MWM), passive avoidance tests, and open-field test. Motor ability was evaluated with a rotarod test and a wire hang test, and mechanical pain and thermalgia were used to evaluate sensory system function. Electroretinograms (ERGs) were recorded to evaluate the function of the retina. The vision-related results showed that longer latencies of escape and reduced probe trial in MWM for CSNB rats. There were more errors in avoidance test; CSNB rats were more active in the open field and presented a different pattern of exploration. The locomotor-related behaviors showed shorter falling latencies in the rotarod test and shorter gripping time in CSNB rats. And mechanical thresholds of pain increased in CSNB rats. The ERGs indicated that both the amplitude and latency of rod and cone systems were impaired in the CSNB rats. In summary, Cacna1f gene mutation changed the performance of various behaviors in the CSNB rat aside from vision-related phenotype. Cacna1f gene might play a role in a wide range of responses in the organism. These results confirm the importance of a comprehensive profile for understanding the behavior phenotype of Cacna1f gene mutation in CSNB rat.

The Success of Cataract Surgery and the Preoperative Measurement of Retinal Function by Electrophysiological Techniques

Purpose. To study the effect of different electrophysiological methods to evaluate retinal function prior to cataract surgery. Methods. Cataract patients who had no significant other eye disease were chosen. VA, pattern visual evoked potential (PVEP), electroretinogram (ERG), and multifocal electroretinogram (mfERG) responses were measured from 150 cataract patients and 20 control subjects. Results. When the preoperative VA was more than 0.3 in cataract patients, the amplitude of PVEP was not significantly different between cataract and control subjects. The amplitude of central point mfERG was significantly lower in cataract patients compared with control group from HM to 0.8 of preoperative VA. The 95% confidence intervals (CIs) of the amplitudes of center point mfERG were calculated for a range of preoperative VA values. Most of the patients within 95% CI of the center point mfERG had a postoperative VA more than 0.5. Conclusions. The amplitude of central point mfERG in cataract patients was the most relevant parameter to the preoperative VA compared with PVEP and ERG. The 95% CI of the amplitude of central point mfERG for each level of VA could help to evaluate preoperative macular function which is used to predict the outcome of cataract surgery.

Sirtuin Type 1 Mediates the Retinal Protective Effect of Hydrogen-Rich Saline Against Light-Induced Damage in Rats

PURPOSE Molecular hydrogen has been used as an antioxidant to treat many diseases in clinical and animal studies. However, the therapeutic mechanism of molecular hydrogen remains unclear. We previously reported mitigation of light-induced damage in the rat retina by intraperitoneal injection of hydrogen-rich saline (HRS). In the present study, we investigated whether Sirtuin Type 1 (Sirt1), a class III histone deacetylase, mediates the retinal protective effect of HRS in rats with light-induced retinal damage. METHODS Rats were treated with HRS for 5 days after intense light exposure, and then ERGs were performed and retinas were collected to evaluate the effect of HRS on Sirt1 expression. The necessity of Sirt1 for the retinal protective effect of HRS was investigated using the Sirt1 activator resveratrol, the Sirt1 inhibitor EX-527, and short interfering RNAs. RESULTS In light-damaged retinas, 5 days of HRS treatment increased Sirt1 expression, mitigated a- and b-wave amplitude reduction, and decreased the reduction of outer nuclear cell layers. The Sirt1 activator resveratrol mimicked the effect of HRS in light-damaged retinas. This result supported our hypothesis that Sirt1 mediates the protective effect of HRS. Additionally, the retinal protective effect of HRS was inhibited by both the Sirt1 inhibitor EX-527 and Sirt1 targeted short interfering RNAs. Hydrogen-rich saline also increased B-cell lymphoma 2 (Bcl-2) expression and the activity of the antioxidant enzyme superoxide dismutase (SOD). Conversely, HRS decreased Bcl2-associated X protein expression, cleaved caspase-3, and oxidant-stress product malondialdehyde (MDA) in a Sirt1-dependent manner. CONCLUSIONS Sirt1 mediates light-induced damage mitigation by HRS through inhibition of apoptosis and oxidant-stress.

Cacna1f gene decreased contractility of skeletal muscle in rat model with congenital stationary night blindness.

The CACNA1F gene encodes a member of the alpha-1F subunit family in the voltage-dependent calcium channel (Cav1.4) complex. Mutations in this gene result in incomplete congenital stationary night blindness (iCSNB2) in humans. And Cav1.4 mutation could affect the functions of the skeletal muscle. This study investigated the role of Cacna1f mutations in alteration of the skeletal muscle functions in a Cacna1f mutation rat model (Cacna1f(CSNB2) rat). We found that the muscle endurance behaviors of Cacna1f(CSNB2) rats were significantly lower than those of the wild-type rats. The high-frequency fatigue resistance of the soleus muscle was decreased in Cacna1f(CSNB2) rats under continuous tetanic stimulation. The expression levels of the syntaxin (SYN) proteins in the soleus of the Cacna1f(CSNB2) rats were lower than those of wild-type rats. SYN was expressed in the soleus muscle, but not in the extensor digitorum longus. The Cav1.4 protein was not detected in the skeletal muscle of Cacna1f(CSNB2) rats. The Cacna1f mRNA level in the soleus of Cacna1f(CSNB2) rats was decreased compared with that in wild-type rats. This study demonstrated for the first time that the Cacna1f mutation reduces the function of slow-twitch skeletal muscle. And it also demonstrated that the Cacna1f gene affects synapse-associated protein expression, which may block the signal transmission in synaptic connectivity of the retina and skeletal muscle in Cacna1f-mutant rats.