Biomedical subjects

L T Ho

Publications and source records attributed to L T Ho.

At least 19 recordsLinked to original sources

PubMed2002

Neuroprotective effect of intermittent hypoxia on iron-induced oxidative injury in rat brain.

The neuroprotective effect of intermittent hypoxia on ferrous citrate (iron)-induced oxidative stress was investigated in the nigrostriatal dopaminergic system of rat brain. Female Wistar rats were subjected to 380 mm Hg in an altitude chamber for 15 h/day for 7, 14, or 28 days. Iron was locally infused in the substantia nigra of anesthetized rats. Seven days after infusion, lipid peroxidation was elevated in the infused substantia nigra and dopamine content and tyrosine hydroxylase-positive axons were decreased in the ipsilateral striatum in the normoxic rats. Intermittent hypoxic treatment prevented iron-induced oxidative injuries. Induction of the neuroprotection required 2 weeks. Intracerebroventricular infusion of L-buthionine-[S,R]-sulfoximine (L-BSO), which mimicked a reduced antioxidative condition, aggravated iron-induced oxidative injuries. Intermittent hypoxia ameliorated L-BSO-induced augmentation of iron-induced oxidative injuries. Basal GSH (glutathione) content, GSH/GSSG ratio, superoxide dismutase (SOD) and catalase activities in intact substantia nigra were not altered by intermittent hypoxia. Furthermore, intermittent hypoxia attenuated iron-induced reductions in GSH content, GSH/GSSG ratio, and SOD, iron-induced increase in catalase but had no effect on glutathione peroxidase. Our data suggest that intermittent hypoxia may protect the nigrostriatal dopaminergic system from iron-induced oxidative injuries. Moreover, antioxidative defensive systems may partially contribute to the neuroprotection by intermittent hypoxia.

Animals↗

PubMed2002

Exacerbation of insulin resistance and postprandial triglyceride response in newly diagnosed hypertensive patients with hypertriglyceridaemia.

The purpose of the study is to examine the differences in insulin resistance and postprandial triglyceride (TG) response between hypertensive patients with or without hypertriglyceridaemia. The study is a comparative cohort study with matching. Thirty-one newly diagnosed hypertensive patients without any medication were recruited from a health survey. The participants were further divided into two groups: those with fasting TG <2.26 mmol/L, and those with TG between 2.26 and 5.65 mmol/L. Both groups were matched in age, sex, body mass index and waist circumference. Each patient received a 75-g oral glucose tolerance test, an insulin suppression test, and a 1000 kcal high fat mixed meal test. The hypertriglyceridaemic hypertensive patients had significantly higher fasting insulin, 2-h plasma glucose, 2-h insulin, and steady-state plasma glucose (SSPG) (13.16 +/- 1.87 vs 9.76 +/- 3.18 mmol/L). They also had a greater postprandial TG response to the challenge of mixed meal (DeltaAUC 20.76 +/- 10.06 vs 7.97 +/- 3.18 mmol 8 h/L). The postprandial TG response was closely correlated (r = 0.72-0.95, P < 0.0001) with fasting TG in all hypertensive patients. Both fasting TG levels and postprandial TG response were significantly (P < 0.05) correlated with SSPG. In conclusion, the hypertensive patients with hypertriglyceridaemia were more insulin resistant than those without it. Exacerbation of postprandial hypertriglyceridaemia was identified in these patients. The TG response to the challenge of high fat meal was significantly correlated with fasting TG and insulin resistant in them. The results provide a rationale for the alleviation of insulin resistance and hypertriglyceridaemia in these atherosclerosis-prone hypertensive patients.

Adult↗

PubMed2002

Surrogate estimates of insulin sensitivity in Chinese diabetic patients and their offspring.

AIMS: To evaluate the relationship between surrogate measures of insulin sensitivity and results from euglycaemic insulin clamp in Chinese diabetic patients and their offspring. METHODS: The study included 59 volunteers from 20 diabetic families. Each participant completed a 75-g oral glucose tolerance test (OGTT) and a euglycaemic insulin clamp. We tested the correlation of surrogate measures of insulin sensitivity with M-values and M/I ratios (the amount of glucose infused during 90-120 min of the clamp was defined as M, and the mean values of plasma insulin during 90-120 min as I) from the euglycaemic insulin clamp. These measures included fasting insulin (FPI), insulin at 120 min of OGTT, insulin area under the curve of OGTT, fasting glucose-to-insulin ratio, homeostasis model assessment for insulin sensitivity (HOMA-IR and HOMA %S) and the Matsuda-DeFronzo index from OGTT. RESULTS: The Matsuda-DeFronzo index closely correlated to M-value and M/I in 21 diabetic, 38 non-diabetic individuals and the 59 participants overall (with M-value, r = 0.68, 0.84 and 0.84; with M/I, r = 0.71, 0.72 and 0.75, respectively, all P < 0.001). Without OGTT, HOMA %S was a good surrogate index for diabetic (correlated to M-value and M/I, r = 0.71 and 0.68, P = 0.001) and for non-diabetic subjects (to M-value, r = 0.73; to M/I, r = 0.55, both P < 0.001). FPI was as good as HOMA %S and Matsuda-DeFronzo index. CONCLUSIONS: The Matsuda-DeFronzo index, HOMA %S and FPI are good surrogate estimates of insulin sensitivity in Chinese diabetic subjects and their offspring.

Adult↗

PubMed2002

Oral doxercalciferol therapy for secondary hyperparathyroidism in a peritoneal dialysis patient.

Control of hyperphosphatemia and the administration of vitamin D are the primary treatment modalities for the prevention and management of secondary hyperparathyroidism. Vitamin D therapy for secondary hyperparathyroidism has been limited by the development of hypercalcemia and/or hyperphosphatemia due to increased intestinal absorption of these minerals. Recently, selective vitamin D analogs specifically designed to suppress parathyroid hormone (PTH) without causing hypercalcemia or hyperphosphatemia have shown promise for the treatment of secondary hyperparathyroidism in uremia. This case report describes the successful use of doxercalciferol to treat severe secondary hyperparathyroidism in an adult male patient undergoing chronic peritoneal dialysis, with a follow-up period of 9 months. During this period, the patient's hyperparathyroidism was rapidly and easily controlled. Treatment was complicated by a single incident of over suppression of PTH, with concomitant hypercalcemia. This quickly resolved upon temporary discontinuation of doxercalciferol therapy, after which therapy was resumed without further incident.

Administration, Oral↗

PubMed2002

Waist circumference predicts insulin resistance in offspring of diabetic patients.

The purpose of the study was to identify a good abdominal obesity index for insulin resistance in offspring of diabetic patients. A total of 74 non-diabetic subjects (male =36; female =38) were recruited from a diabetic family study. The waist circumference (W), waist-hip ratio (WHR) and conicity index were used as the abdominal obesity indices. The body mass index (BMI) and indices obtained from bioelectric impedance analysis (BIA) (body fat percentage, fat mass and fat mass index) were used as overall obesity indices. Fasting plasma insulin (FPI), homeostasis model assessment for insulin resistance (HOMA-IR) and Matsuda-Defronzo index from oral glucose tolerance test were chosen as the insulin sensitivity indices. We correlated obesity indices with insulin resistance indices with age and family adjusted. W was closely correlated in both sexes of subjects with Matsuda-DeFronzo index (male, r=-0.661,p<0.001; female, r=-0.419,p=0.026), FPI (male, r=0.614,p=0.001; female, r=0.503,p=0.006) and HOMA-IR (male, r=0.609,p=0.001; female, r=0.472,p=0.011). WHR and its log transformation predicted insulin resistance only in males. BMI as an overall obesity index was in good correlation with Matsuda-DeFronzo index (male, r=-0.646,p<0.001; female, r=-0.469,p=0.012), FPI (male, r=0.711,p<0.001; female, r=0.464,p=0.013) and HOMA-IR (male, r=0.708,p<0.001; female, r=0.469,p=0.012). Overall obesity indices from BIA were similar to BMI to predict insulin resistance. In conclusion, W is a good abdominal obesity predictor of insulin resistance in offspring of diabetic patients in Taiwan.

Abdomen↗

PubMed2001

Suppressed gene expression of adipocyte resistin in an insulin-resistant rat model probably by elevated free fatty acids.

Resistin, the peptide specifically secreted from adipocytes, is a hormone antagonistic to insulin action and, thus, may serve as a link between human obesity due to adiposity and insulin resistance associated with type 2 diabetes. To test this hypothesis, we studied the gene expression of resistin in adipocytes isolated from rats fed with a fructose diet which induced insulin resistance. Compared to the control rats (C) on a normal chow diet, the fructose-fed rats (F) developed hyperinsulinemia, glucose intolerance, hypertriglyceridemia and hypertension, a profile reminiscent of the syndrome X of patients with non-insulin-dependent diabetes mellitus (NIDDM). The F rats had significantly elevated plasma free fatty acids (FFA), enlarged epididymal fat pads, and increased adipocyte size compared with the C rats. We examined the glucose transport and the relative quantity of resistin mRNA produced in the adipocytes of these two groups of rats. Compared to the C rats, the F rats had a clearly reduced insulin-stimulated glucose transport. The gene expression of resistin and other adipocyte peptides was measured on the mRNA by semiquantitative RT-PCR; the validity of this technique was established in advance with a rat-fasting and then refeeding experiment. The F rats showed a decreased expression of the resistin gene, whereas gene expression of leptin and angiotensinogen in contrast increased. Free fatty acids were found to suppress the expression of resistin gene in normal rat adipocytes. These results demonstrate that an insulin-resistant instance in the fructose diet rat model exists with the decreased gene expression of resistin.

Adipocytes↗

PubMed2001

A left-lateralized network for reading Chinese words: a 3 T fMRI study.

fMRI was used to investigate brain organization for reading in Chinese. Subjects were shown two-character Chinese words. A control task was used to eliminate the non-linguistic visual and motor confounds. Results show that naming of Chinese logographs is characterized by left-lateralized neuronal networks for the processing of orthographic, phonological, and semantic attributes. The orchestration of the middle frontal cortex, superior temporal cortex, superior parietal cortex, basal temporal area and extrastriate cortices of the left hemisphere may manifest the particularity of the central representation of simple word naming in Chinese.

Adult↗

PubMed2001

Genetic variation in aldosterone synthase predicts plasma glucose levels.

The mineralocorticoid hormone, aldosterone, is known to play a role in sodium homeostasis. We serendipitously found, however, highly significant association between single-nucleotide polymorphisms in the aldosterone synthase gene and plasma glucose levels in a large population of Chinese and Japanese origin. Two polymorphisms--one in the putative promoter (T-344C) and another resulting in a lysine/arginine substitution at amino acid 173, which are in complete linkage disequilibrium in this population--were associated with fasting plasma glucose levels (P = 0.000017) and those 60 (P = 0.017) and 120 (P = 0.0019) min after an oral glucose challenge. A C/T variant in intron 1, between these polymorphisms, was not associated with glucose levels. Arg-173 and -344C homozygotes were most likely to be diabetic [odds ratio 2.51; 95% confidence interval (C.I.) 1.39-3.92; P = 0.0015] and have impaired fasting glucose levels (odds ratio 3.53; 95% C.I. 2.02-5.5; P = 0.0000036). These results suggest a new role for aldosterone in glucose homeostasis.

Adult↗

PubMed2001

Activation of the hypothalamus characterizes the acupuncture stimulation at the analgesic point in human: a positron emission tomography study.

We performed a positron emission tomography study, using regional cerebral blood flow as the index of brain activity, to address the specificity of brain activation pattern by acupuncture stimulation of short duration at the classical analgesic point. Needling manipulation at 2 Hz was performed at a classical point of prominent analgesic efficacy (Li 4, Heku) and a near-by non-classical/non-analgesic point, respectively, in normal subjects. Regions activated by acupuncture stimulation at Li 4 included the hypothalamus with an extension to midbrain, the insula, the anterior cingulate cortex, and the cerebellum. Of note, it was only the stimulation at Li 4 that activated the hypothalamus under the similar psychophysical ratings of acupuncture sensation (deqi) as elicited by the stimulation at the two points, respectively. The data suggested that the hypothalamus might characterize the central expression of acupuncture stimulation at the classical analgesic point and serve as one key element in mediating analgesic efficacy of acupuncture stimulation.

Acupuncture Analgesia↗

PubMed2001

The stimulatory effect of vasoactive intestinal peptides on the cortisol production of guinea pig Zona fasciculata cells: an extra-ACTH regulatory model of the adrenocortical function.

The effect of vasoactive intestinal peptide (VIP) on cortisol production was studied in a primary culture enriched with guinea pig Zona Fasciculata (ZF) cells. In ZF cells, VIP stimulates cortisol secretion and enhances the steroidogenic action of ACTH. Compared to ACTH on an equal molar basis, the cortisol-stimulatory effect of VIP is at least 10-fold less potent. As VIP exhibits a wide range of biological actions with widespread distribution in the body, the steroidogenic action of VIP on the adrenal glands is not tissue-specific. There are VIP receptors in ZF cells. With the aid of a VIP receptor antagonist, we found that ACTH and VIP mutually bind each other's receptors with an affinity-ranking order of ACTH > VIP receptor antagonist > VIP. VIP stimulates cortisol production most likely through the cyclic AMP (cAMP) signaling pathway. Both ACTH receptors and the VIP receptors bind VIP receptor antagonist more avidly than VIP, but the bindings do not lead to a consequential effect on cAMP production and cortisol secretion. However, the VIP receptor antagonist counteracted ACTH and VIP to lower both cAMP and cortisol production. In addition, ASIF and BNP-32, which are the proven ACTH receptor antagonists, reduced the cortisol-stimulatory effect of ACTH and VIP. These results suggest that besides ACTH, VIP be an important factor in regulating the cortisol secretion from the adrenal cortex at the site of ACTH receptors. In cases with hypercortisolemia being detected concomitantly with normal or low ACTH levels, we may need to investigate the influential role of VIP.

Adrenal Cortex↗

PubMed2001

Undiagnosed diabetes mellitus in Taiwanese subjects with impaired fasting glycemia: impact of female sex, central obesity, and short stature.

AIMS: To study the extent and determinants of undiagnosed diabetes mellitus (DM) in Taiwanese subjects with impaired fasting glycemia (IFG) defined by the newly proposed WHO criteria. METHODS: Oral glucose tolerance tests were carried out for 306 IFG subjects identified from 6632 adult participants of two large scale community-based studies: Nutrition and Health Survey in Taiwan (1993-1996) and the Cardiovascular Disease Two-township Study (1994-1997). Similar protocols were used in these two studies to collect data on glycemic status, anthropometric measurements, and other data used in the present study. RESULTS: Subjects with IFG had a non-trivial undiagnosed diabetes mellitus rate (30% in men and 42% in women) and a high rate of glucose intolerance and undiagnosed DM combined (75% in men and 86% in women). Women with IFG had a 1.6 fold higher risk (p = 0.04) for undiagnosed DM and a 2.1 fold higher risk (p = 0.01) for glucose intolerance and DM when compared to men. There were more women than men with an elevated body mass index in undiagnosed DM patients. Among IFG subjects, undiagnosed DM patients were significantly (p < 0.05) older, more centrally obese and shorter than their normal IFG counterparts, irrespective of gender. In men, height was independent of age and waist circumference in predicting undiagnosed DM (p = 0.037). CONCLUSIONS: A high proportion of impaired glucose tolerance and undiagnosed DM was found in subjects with IFG. Its public health impact should not be overlooked. Central obesity, female sex, and short stature were associated with undiagnosed DM status in IFG subjects.

Adult↗

PubMed2001

Sibling-based association study of the PPARgamma2 Pro12Ala polymorphism and metabolic variables in Chinese and Japanese hypertension families: a SAPPHIRe study. Stanford Asian-Pacific Program in Hypertension and Insulin Resistance.

The peroxisome proliferator activated receptor (PPAR) gamma2 is a transcription factor that has been shown to be involved in adipocyte differentiation, adipogenesis, and insulin sensitivity. To address the role of PPARgamma2 in glucose homeostasis and insulin sensitivity, among many other objectives, we conducted a sibling-controlled association study in a multicenter program - the Stanford Asian-Pacific Program in Hypertension and Insulin Resistance (SAPPHIRe). Approximately 2525 subjects in 734 Chinese and Japanese families have been recruited from six field centers for SAPPHIRe. In total, 1702 subjects including parents and siblings from 449 families have been genotyped for PPARgamma2, of which 328 families were Chinese and 121 Japanese. Only 88 subjects of the 1525 siblings screened for the P12A polymorphism were found to be carriers of the A variant, the most common variant of the PPARgamma2 gene. A variant frequencies of the siblings were 4.27% in Chinese and 2.72% in Japanese. A sibling-controlled association study was performed through genetically discordant sibships (i.e., P/P genotype vs. P/A + A/A genotypes). Specifically, we examined whether there were differences in metabolic variables between the discordant siblings within families. In total, 88 subjects carrying either 1 or 2 A alleles had at least one sibling who was discordant for the P12A polymorphism, yielding a total of 180 individuals from 47 families for analyses, among which 92 siblings were homozygous for wild-type P allele. Siblings with the A variant tended to have lower levels of fasting plasma glucose (OG-10), and lower glucose levels at 60 min following oral glucose loading after adjusting for age, gender, and body mass index. Using a mixed model treating family as a random effect, we found that P12A polymorphism of the PPARgamma2 gene contributes significantly to the variance in fasting plasma glucose, glucose level at 60 min, and insulin-resistance homeostasis model assessment. Our results suggest that within families siblings with the A variant in the PPARgamma2 gene may be more likely to have better glucose tolerance and insulin sensitivity independent of obesity in Chinese and Japanese populations.

Adult↗

PubMed2001

A comparison of insulin suppression tests performed with somatostatin and octreotide with particular reference to tolerability.

To evaluate the tolerability of insulin suppression test (IST) using octreotide instead of somatostatin, we compared the steady-state plasma glucose (SSPG) values and the safety during and after the test in 17 normal volunteers. The subject received IST twice (with somatostatin or with octreotide) in random order. During the test, all subjects were infused with regular insulin and glucose simultaneously for 180 min. In addition, either somatostatin or octreotide was infused intravenously over the same period of time. Plasma glucose, insulin and C-peptide were measured. The subject response to the test was recorded during and one day after the test by a structured questionnaire. The SSPG and the steady-state plasma insulin (SSPI) values reached during IST were similar, irrespective of the use of somatostatin or octreotide. There was a positive correlation between the SSPG values obtained from both methods (r = 0.67, P = 0.003). However, the mean intra-individual coefficient of variation is 17.9% for SSPG. The SSPG levels, no matter from which method, correlated positively with the 2-h insulin after oral glucose challenge. Most adverse events (especially gastrointestinal discomfort) occurred after the test, and increased much more after using octreotide than somatostatin (P = 0.002 by chi 2 test). In conclusion, the SSPG values measured by IST using octreotide or somatostatin are similar in normal healthy subjects. Yet, the octreotide method has more adverse events after the test.

Adult↗

PubMed2001

Endothelin-1 increases glucose transporter glut1 mRNA accumulation in 3T3-L1 adipocytes by a mitogen-activated protein kinase-dependent pathway.

The mechanism of enhancing glucose transport by prolonged endothelin-1 (ET-1) treatment of 3T3-L1 adipocytes was examined. Western and Northern blot analyses indicated that ET-1 increased the amount of both GLUT1 protein and mRNA. The degradation rate of GLUT1 mRNA as measured in the presence of actinomycin D, nevertheless, was not significantly altered by ET-1. Whereas various inhibitors for distinct signalling pathways were tested, only the mitogen-activated protein kinase (MAPK) kinase inhibitor, PD98059, was found to decrease significantly the enhancing effect of ET-1. Similar extent of inhibition was observed in cells pretreated with pertussis toxin (PT). Immunoblot analysis revealed that ET-1 may stimulate a transient phosphorylation of p42/p44 MAPK and both PT and PD98059 inhibited this stimulation. In addition, the effect of ET-1 on GLUT1 mRNA accumulation was inhibited by PD98059 and cycloheximide, implying that a trans-activation was involved. Taken together, these results suggest that ET-1 may induce GLUT1 gene expression by a MAPK-dependent mechanism.

3T3 Cells↗

PubMed2001

Abnormal cardiovascular reflex tests are predictors of mortality in Type 2 diabetes mellitus.

AIMS: To determine whether diabetic autonomic neuropathy is an important factor contributing to mortality in Type 2 diabetes mellitus. METHODS: Between 1989 and 1993, 431 men and 181 women with Type 2 diabetes were given diabetic autonomic neuropathy cardiovascular reflex (CVR) tests. These subjects were followed for the subsequent 5--9 years to assess mortality rates. RESULTS: The prevalence rate of abnormal CVR tests was 46.1% in patients with the history of diabetes less than 5 years and up to 69.4% when the history of diabetes exceeded 20 years. During the follow-up period from 1 January 1989 to 31 December 1997 (mean 7.7 years), a total of 135 participants died. The 8-year survival rate for patients with abnormal CVR tests was 63.6% in males and 76.4% in females, compared with 80.9 and 93.3% for patients with normal CVR tests. The results were grouped as: group 1, normal CVR tests without postural hypotension (PHT); group 2, normal CVR tests with PHT; group 3, abnormal CVR tests without PHT; and group 4, abnormal CVR tests with PHT. The 8-year survival rate was 85.4% in group 1, 80.9% in group 2, 74.5% in group 3 and 61.1% in group 4. CONCLUSION: Type 2 diabetic patients with abnormal CVR tests may have increased mortality, and those combined with postural hypotension have higher mortality than those without. Abnormal CVR tests may be important predictors of mortality in Type 2 diabetes mellitus.

Blood Pressure↗

PubMed2001

The clinical and pathologic implications of plasmacytic infiltrates in percutaneous renal allograft biopsies.

Plasmacytic infiltrates in renal allograft biopsies are uncommon and morphologically distinctive lesions that may represent variants of acute rejection. This study sought significant clinical and pathologic determinants that might have influenced development of these lesions and assessed their prognostic significance. Renal allograft biopsies (n = 19), from 19 patients, with tubulointerstitial inflammatory infiltrates containing abundant plasma cells, composing 32 +/- 8% of the infiltrating mononuclear cells, were classified using Banff '97 criteria. Clonality of the infiltrates was determined by immunoperoxidase staining for kappa and lambda light chains and polymerase chain reaction for immunoglobulin heavy-chain gene rearrangements, using V(H) gene framework 3 and JH consensus primers. In situ hybridization for Epstein-Barr virus encoded RNA (EBER) was performed in 17 cases. The clinical features, histology, and outcome of these cases were compared with kidney allograft biopsies (n = 17) matched for time posttransplantation and type of rejection by Banff '97 criteria, with few plasma cells (7 +/- 5%). Sixteen of 19 biopsies (84%) with plasmacytic infiltrates had EBER-negative (in 14 cases tested) polyclonal plasma cell infiltrates that were classifiable as acute rejection (types 1A [4], 1B [10], and 2A [2]). These biopsies were obtained between 10 and 112 months posttransplantation. Graft loss from acute and/or chronic rejection was 50% at 1 year and 63% at 3 years, and the median time to graft failure was 4.5 months after biopsy. There was no significant difference in overall survival or time to graft failure compared with the controls. Three of 19 biopsies (16%) had EBER-negative polyclonal plasmacytic hyperplasia, mixed monoclonal and polyclonal polymorphous B cell hyperplasia, and monoclonal plasmacytoma-like posttransplantation lymphoproliferative disease (PTLD) and were obtained at 17 months, 12 weeks, and 7 years after transplantation, respectively. Graft nephrectomies were performed at 1, 19, and 5 months after biopsy, respectively. Plasmacytic infiltrates in renal allografts comprise a spectrum of lesions from acute rejection to PTLD, with a generally poor prognosis for long-term graft survival.

Adult↗

PubMed2001

Lack of protective effect by intermittent hypoxia on MPTP-induced neurotoxicity in mice.

In the study we report here, several lines of evidence support the preventive action of intermittent hypoxia against oxidative injuries in CNS. Our in vitro data showed that autooxidation and iron-induced lipid peroxidation were attenuated in cortical homogenates of intermittent hypoxia-treated animals. Furthermore, our preliminary study found that iron induced oxidative injuries were abolished in rat brain after intermittent hypoxic treatment (paper submitted). Several antioxidative defensive systems improve in response to intermittent hypoxia. Since attenuation of autooxidation and iron-induced lipid peroxidation were observed in cortical homogenates of intermittent hypoxia-treated mice, the lack of prevention by intermittent hypoxia of MPTP-induced neurotoxicity may be due to the MPTP action that is not oxidative related. Together with our previous studies, in which several antioxidants were shown to successfully prevent oxidative injuries, our data here suggest that intermittent hypoxia may offer a potential treatment for preventing CNS degenerative diseases.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed2001

Electroacupuncture-induced neural activation detected by use of manganese-enhanced functional magnetic resonance imaging in rabbits.

OBJECTIVE: To investigate the effects of acupuncture on neural activity detected by use of manganese-enhanced functional magnetic resonance imaging (fMRI) and elucidate the relationship between somatic acupoint stimulation and brain activation. ANIMALS: 40 New Zealand White rabbits. PROCEDURE: Manganese-enhanced fMRI was performed in anesthetized rabbits manipulated with electroacupuncture (EA) on Zusanli (ST-36) and Yanglingquan (GB-34) acupoints. Image acquisition was performed on a 1.5T superconductive clinical scanner with a circular polarized extremity coil. T1-weighted images were acquired sequentially as follows: baseline, after mannitol injection, after manganese infusion, and 5 and 20 minutes after initiation of EA. RESULTS: Changes in focal neural activity were detected by use of manganese-enhanced fMRI. Stimulation on Zusanli (ST-36) for 5 minutes resulted in activation of the hippocampus, whereas stimulation on Yanglingquan (GB-34) resulted in activation of the hypothalamus, insula, and motor cortex. Activation became less specific after 20 minutes of EA. Furthermore, stimulation on ipsilateral acupoints led to bilateral brain activation. CONCLUSIONS AND CLINICAL RELEVANCE: Each acupoint has a corresponding cerebral linkage, and stimulation on these points resulted in time-dependent neural activation. Understanding the linkage between peripheral acupoint stimulation and central neural pathways may provide a useful guide for clinical applications of acupuncture.

Animals↗