[Effect of voltage-dependent calcium channel α1F subunit deficiency on the structure and function of the murine retina].

OBJECTIVE: To investigate the distribution and biological roles of voltage-dependent calcium channel (VDCC) α1F subunit in murine retina. METHODS: Experimental study.α1F(-/-) (homozygous mutant) mice (n = 35) and α1F(+/+) (wild type) mice (n = 35) were used in this study. Immunohistochemistry was performed to determine the expression of VDCC α1F subunit in the mouse retina. Retinae in α1F(-/-) mice and age-matched control mice at 3, 6, 9, 14-day and 3-month after birth were paraffin embedded, sectioned and HE stained, and full-field electroretinogram (ERG) were also recorded at these time points.Statistics were based on independent samples t-test. RESULTS: (1) α1F subunit was absent in α1F(-/-) mice retina. But in α1F(+/+) mice retina, α1F subunit was expressed most strongly in the outer plexiform layer (OPL), less in the inner plexiform layer (IPL) and ganglion cell layer (GCL). (2) OPL thickness in the subunit deficient mice gradually reduced after birth and lost at adult age. (3) In dark-adapted ERGs,standard response showed that the b-wave amplitude of α1F(-/-) mice [(163.8 ± 26.7) µV] significantly decreased compared with that of α1F(+/+) mice [(408.4 ± 54.5) µV] (t = -9.017, P = 0.000), whereas the a-wave amplitude of α1F(-/-) group [(208.2 ± 27.3) µV] was similar to that of control group [(196.0 ± 24.2) µV] (t = 0.748, P = 0.476). CONCLUSION: This study demonstrates that the lack of VDCC α1F subunit affect the structure and function in the OPL of the murine retina.

[Progress on study of achromatopsia and targeted gene therapy].

Achromatopsia is an early onset retinal dystrophy that causes severe visual impairment. To date, four genes have been found to be implicated in achromatopsia-associated mutations: guanine nucleotide-binding protein (GNAT2), cyclic nucleotide-gated channel alpha-3 (CNGA3), cyclic nucleotide-gated channel beta-3 (CNGB3) and phosphodiesterase 6C (PDE6C). Even with early onset, the slow progress and the good responses to gene therapy in animal models render achromatopsia a very attractive candidate for human gene therapy after the successful of the Phase I clinical trials of Leber's congenital amaurosis. With the development of molecular genetics and the therapeutic gene replacement technology, the adeno-associated viral (AAV) vector-mediated gene therapy for achromatopsia in the preclinical animal experiments achieved encouraging progress in the past years. This article briefly reviews the recent research achievements of achromatopsia with gene therapy.

[Relationship between the polymorphism of carboxylic esterases and genetic susceptibility to organophosphates pesticides exposure].

OBJECTIVE: To study the relationship between the polymorphism of butyrylcholinesterase (BChE, EC 3.1.1.8) and paraoxonase (PonE, EC 3.1.8.1), and the individuals' genetic susceptibility to organophosphates pesticides (OPs) exposure. METHODS: 75 OPs exposure workers were selected to determine their BChE-K, PON-192 and PON-55 genotypes using PCR-RFLP. The accumulative symptom scores and the whole blood acetylcholinesterase activity (mmol x h(-1) x ml(-1)) were used as health index. Firstly, the health condition related to single gene site of the three gene loci was analyzed to determine which kinds of genotype were susceptible. Then, used the multiple variance analysis was to see if there existed interactions among these three gene loci. Finally, established the multi-factor linear regression equation, in which considered some other factors that might influence the health situation such as age, gender and the exposure time. According to the equation, could get the accumulative symptom scores of each kind of subpopulation of different genotypes. RESULTS: The mean AChE activities of the exposed workers with BChE-K genotype UU (61 cases), genotype UK (12 cases) and genotype KK (2 cases) were 105.0 +/- 23.0, 84.4 +/- 16.4, 79.0 +/- 9.9, respectively; The accumulative symptom scores were 3.7 +/- 3.8, 9.2 +/- 3.0, 12.5 +/- 0.7, respectively. The AChE activities of the exposed workers with PON-192 genotype BB (37 cases), genotype AB (27 cases) and genotype AA (11 cases) were 116.8 +/- 15.1, 91.2 +/- 15.6, 72.3 +/- 21.4, respectively; The accumulative symptom scores were 2.0 +/- 3.2, 6.7 +/- 3.3, 9.7 +/- 1.8, respectively. Similarly, the AChE activities of the exposed workers with PON-55 genotype LL (70 cases) and genotype LM (5 cases) were 102.4 +/- 23.0, 82.8 +/- 22.0; The accumulative symptom scores were 4.5 +/- 4.2, 9.2 +/- 3.6, respectively. Single variance analysis showed that the accumulative symptom scores of the individuals with abnormal homozygote of these three gene loci were the highest, which indicated that they were most susceptible to OPs. Multiple variance analysis showed there were no interactions among the three gene loci. Age, gender and exposure time had no statistical significance, while genotypes of the three gene loci had statistical significance to health situation. CONCLUSION: Genotypes of BChE-K, PON-192 and PON-55 are related to susceptibility to OPs exposure.

[Protective effect of memantine on N-methyl-D-aspartate receptor in dichlorvos-poisoned rat brain].

OBJECTIVE: To study the protective effect of memantine on the regulation of N-methyl-D-aspartate (NMDA) receptor in dichlorvos-poisoned rat brain, and to understand the mechanism of its role in organophosphate poisoning. METHODS: SD rats were administrated dichlorvos (25 mg/kg, ip) then three groups were treated with memantine at doses of 5, 15 and 45 mg/kg respectively. The activity of acetylcholinesterase (AChE) and binding capacity of NMDA receptor with [(3)H]MK-801 were determined 16 h after dichlorvos injection. RESULTS: The time of onset of toxic symptoms in 15, 45 mg memantine treated groups [(18.40 +/- 1.14) and (21.40 +/- 1.52) min respectively] was higher than that in dichlorvos alone group [(16.75 +/- 1.62) min]; the intensity of muscle fasciculation (1.60 +/- 1.14 and 0.80 +/- 0.84, respectively) was less than that in control group (2.85 +/- 0.37); the total score of poisoning symptoms (8.80 +/- 1.79 and 9.00 +/- 2.24 respectively) was also less than that in dichlorvos group (14.60 +/- 1.70). The AChE activities both in blood and brain of memantine treated groups were not significantly different from those in dichlorvos alone group. The affinity (Kd value) and density (Bmax value) of brain NMDA receptor in dichlorvos exposed rats [(75.55 +/- 7.87) nmol/L, (0.46 +/- 0.06) pmol/mg pro respectively] were higher and lower respectively than those in control group [(37.37 +/- 4.17) nmol/L, (0.62 +/- 0.04) pmol/mg pro respectively]. Lower level of memantine (5 and 25 mg/kg) could antagonize the dichlorvos-evoked down-regulation of [(3)H]MK-801 binding to NMDA receptor in rat brain [Bmax value: (0.55 +/- 0.07) and (0.64 +/- 0.07) pmol/mg pro; Kd value: (38.68 +/- 4.54) and (32.58 +/- 3.90) nmol/L respectively] while higher dose of memantine (45 mg/kg), the Bmax (0.45 +/- 0.06) pmol/mg pro and Kd (22.88 +/- 4.42) nmol/L of NMDA receptor were significantly decreased (P < 0.01). CONCLUSION: Memantine in certain dose range could protect against the down-regulation of NMDA receptor in rat brain, and alleviate organophosphorus poisoning symptoms to some extent. The recovery of AChE activity inhibition wasn't involved in the treatment with memantine on dichlorvos poisoning, therefore, atropine and a proper AChE reactivator (an oxime) should be used clinically.