Junghye Kim

The difference between electroacupuncture only and electroacupuncture with manipulation on analgesia in rats

Plain acupuncture uses manipulation (rotation or varying the depth of insertion of the needle) to increase its effect. However, in commonly used electroacupunture (EA), variable manipulations have not been used. This study was performed to investigate the possibility of an increase in analgesic effect by adding manipulation to EA. The pain index used was the Tail-Flick latency (TFL) of the rat, which was lightly anesthetized with thiopental sodium (intraperitoneally). Four types of manipulation were used. Rotation and varying the depth of the needle (RN and VN) was employed using two different types of manipulation during each 20 min stimulation of EA. Each manipulation persisted for 1 min out of every 5 min (long - duration and long - interval: LDLI) or 12 s every 1 min (short - duration and short interval: SDSI). EA produced an increase in TFL; peak value was 49.7+/-12.2% of the pre - EA and occurred immediately after cessation of 20 min of EA stimulation. Performing RN or VN combined with EA also increased TFL more than just EA and a greater peak increase in TFL was observed with a SDSI - RN and SDSI - VN as compared to a LDLI - RN and LDLI - VN (77.5+/-13.8, 79.2+/-19.8 and 67.3+/-14.0%, 65.6+/-23.7% of the pre - EA, respectively). These results indicate that manipulation combined with EA produces a more potent antinociception than when only EA is applied.

Age-related change in the neuropeptide Y and NADPH-diaphorase-positive neurons in the cerebral cortex and striatum of aged rats

Age-related changes of neuropeptide Y (NPY) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) were examined in the rat cerebral cortex and striatum by immunohistochemical and histochemical methods. Double labeling for NPY and NADPH-d showed that about 30-70% of NPY-immunoreactive (NPY-IR) neurons in the cerebral cortex of the control (4-month-old) rats contained NADPH-d and that 50-75% in the aged (24-month-old) rats. The aged rats showed a significant increase in percentage of colocalization of NPY and NADPH-d in comparison with the control rats in the temporal cortex, occipital cortex, cingulate cortex, insular cortex, retrosplenial cortex and caudatoputamen. However, colocalization percentage between control and aged rats in the frontal cortex, parietal cortex, perirhinal cortex, entorhinal cortex and nucleus accumbens were practically identical. In the aged group, the number of NPY-IR/NADPH-d-positive neurons was not significantly decreased in the cerebral cortex and striatum compared to the control group. However, the number of NPY-IR/NADPH-d-negative neurons was significantly decreased in all cerebral cortical areas and caudatoputamen in the aged group except in the nucleus accumbens. Major loss of NPY-IR/NADPH-d-negative neurons in the aged group were observed in the neurons of layer II/III and V/VI. These results demonstrate that the NADPH-d containing NPY-IR neurons are less influenced by aging than the control group in the cerebral cortex and striatum of rats.

The chronic inhibition of nitric oxide synthase enhances cell proliferation in the adult rat hippocampus

We investigated the effect of chronic blocking nitric oxide synthase (NOS), an enzyme producing NO from L-arginine, on granule cell proliferation in the dentate gyrus of adult rats under normal conditions. We treated 7-nitroindazole (7-NI) for 5, 15, and 25 days or N-nitro-L-arginine-methyl ester (L-NAME) for 25 days to block NOS activity and subsequently injected 5-bromo-2-deoxyuridine (BrdU) to detect proliferating cells. The BrdU-immunoreactive (IR) cell number was significantly increased in the 7-NI 15 and 25 day treated group, but not in the control or in the 7-NI 5 day treated group. L-NAME treatment for 25 days significantly increased BrdU-IR cells versus the control and 7-NI 25 day treated group. In addition, nissl staining showed no cell death occurred in the dentate gyrus after 7-NI or L-NAME 25 day treatments. Our results demonstrate that chronic inhibition of NOS increases cell proliferation and has no effect on cell death in the dentate gyrus of the rat hippocampus, which suggests that NO may regulate cell proliferation in the dentate gyrus.

The inhibition of nitric oxide synthase enhances PSA-NCAM expression and CREB phosphorylation in the rat hippocampus.

It is well known that nitric oxide (NO) acts downstream of NMDA receptor activation, which regulates the neural plasticity in the brain. In the present study, the effect of L-NAME, a non-selective nitric oxide synthase (NOS) inhibitor, on neural plasticity in the hippocampus was investigated. L-NAME increased the expression of PSA-NCAM and pCREB in the adult rat hippocampus. The co-localization of PSA-NCAM and pCREB indicates a possible relationship between the two in the granule cell layer in the dentate gyrus. Our results demonstrate that NO, as a subsignal of NMDA receptors, could be involved in the structural plasticity of the granule cell layer in the dentate gyrus by regulating the expression of PSA-NCAM and pCREB in the hippocampus.

Inhibition of neuronal nitric oxide synthase increases adrenalectomy-induced granule cell death in the rat dentate gyrus

Recent studies have shown that the expression of neuronal nitric oxide synthase (NOS) mRNA is increased after adrenalectomy (ADX). However, the role of increased NO production after ADX in the dentate gyrus is unknown. In this study, the relationship between NO inhibition and apoptosis in the dentate gyrus after ADX was examined. 7-Nitroindazole (7-NI; 30 mg/kg, i.p.), a selective inhibitor of neuronal NOS, was injected 1 day before ADX and subsequently once every 24 h. Then 4 days after ADX, dentate granule cell death was evaluated using silver impregnation and Nissl staining methods. Inhibition of neuronal NOS by 7-NI increased the number of dying granule cells approximately 4-fold in the dentate gyrus of the ADX rats, compared to vehicle-injected ADX controls. These results suggest that increased NO production after ADX may play an endogenous neuroprotective role in the dentate gyrus.

Differential effects of aging on NADPH-diaphorase and VIP neurons in cerebral cortex of rats.

AGE-RELATED changes of NADPH-diaphorase (NADPH-d) and vasoactive intestinal polypeptide (VIP) were examined in the rat brain. Aged (24 months) rats showed a significant decrease in the number of VIP-immunoreactive (IR) neurons in the cerebral cortex when compared with control (4 months) rats. However, the number of NADPH-d-positive neurons was not significantly different in the two groups. Quantitative analysis of cell areas revealed a significant shrinkage of VIP-IR neurons in the aged group, whereas no further cell shrinkage was noted for NADPH-d-positive neurons compared with the control group. These morphometric results demonstrate that NADPH-d-containing neurons are more resistant to aging than the VIP-IR neurons in the cerebral cortex of rats.

Differential changes in neuropeptide Y and nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in rat hippocampus after kainic acid-induced seizure

Changes in neuropeptide Y (NPY) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d)-positive neurons in the hippocampus were investigated 5, 10 and 20 days after kainic acid (KA) administration using a double labeling method. The numbers of NADPH-d-positive-only and NPY/NADPH-d-positive neurons decreased in the CA1/2-CA3 regions of the hippocampus, 5, 10 and 20 days after KA administration, however, the number of NPY-positive-only neurons increased in the same regions 5 and 10 days after KA administration. In the dentate gyrus (DG) region of the hippocampus, the numbers of NPY-positive-only, NADPH-d-positive-only and NPY/NADPH-d-positive neurons increased 5 days after KA administration, and 20 days after KA administration, the number of NADPH-d-positive-only neurons decreased to levels similar to or lower than the level of the controls. However, the numbers of NPY/NADPH-d-positive and NPY-positive-only neurons in the DG region 20 days after KA administration remained at control levels. These results indicate that, NADPH-d-positive-only neurons are vulnerable to, and NPY-positive-only neurons are resistant to KA-induced seizures in the whole hippocampus, but that NPY/NADPH-d-positive neurons have different sensitivities in subregions of the hippocampus to KA-induced seizures. In addition, the present findings provide the first statistical and morphological evidence, which demonstrates that NPY-positive-only, NADPH-d-positive-only and NPY/NADPH-d-positive neurons in the hippocampus have different sensitivities to KA-induced seizures.

7-Nitroindazole upregulates phosphorylated cAMP response element binding protein, polysialylated-neural cell adhesion molecule and tryptophan hydroxylase expression in the adult rat hippocampus

We examined the effect of nitric oxide (NO) on the expression of phosphorylated cAMP response element binding (pCREB) protein and on the polysialylated form of the neural cell adhesion molecule (PSA-NCAM), in the hippocampus of the adult rat, by administering 7-nitroindazole (7-NI) for 5 days, to block neuronal nitric oxide synthase (nNOS) activity. It was found that PSA-NCAM and pCREB immunoreactive cells were increased two-fold in the dentate gyrus by this treatment. In addition, the immunoreactivities of serotonin (5-HT, 5-hydroxytryptamine), known to be involved in neural plasticity, and of tryptophan hydroxylase immunoreactive-fibers in the dentate gyrus were both upregulated by 7-NI. Our results indicate that nNOS inhibition upregulates neural plasticity and increases 5-HT in the rat hippocampus, and suggest the existence of regulatory relationships between NO, neural plasticity and 5-HT.

Analgesic effect of the acupuncture using the method of quick insertion and withdrawal of the needle in rats

The method of quick insertion and withdrawal of the needle (QIW) in acupuncture is a technique of stimulation not retaining the needle in the acupuncture point. We examined the analgesic effects of five different types of QIW along with the changes of stimulation quantity, time, and depth, and then compared the analgesic effect of the most effective QIW to that of plain acupuncture (PA). When tail-flick latency values between the strongest QIW-I group and PA group were compared, there was no significant difference (analyzed by t-test). These results indicate that QIW technique has an analgesic effect similar to PA technique and that the conditions, which for the QIW-I was shown the most effective analgesia, are a duration of 5 s at intervals of 1 s and at the depth of 3 mm.