Asymmetrical responses of skin blood flow in ischemic hindlimbs to electrical stimulation of the unilateral forelimb.

The regulation of skin blood flow (SBF) is primarily mediated by the sympathetic nervous system, but the effects of electrical stimulation (ES) of one limb on SBF in the other limbs remain unknown. The present study investigated the effects of unilateral forelimb ES on SBF in the bilateral hindlimbs in anesthetized rats. Bilateral hindlimb ischemia was induced by tourniquet application for 60min. After reperfusion for 24h, ES (3 or 125Hz) was applied to the upper one-fourth of the triceps brachii muscle of the left or right forelimb for 30min. Rats that did not receive ES were used as the controls. Bilateral hindlimb SBF was measured by a laser Doppler line scanner for 20min before ES, 30min during ES, and 9min after ES. The results showed significant differences in SBF in the right but not left hindlimb between the control group and experimental group that received 125-Hz ES of the right forelimb. Right hindlimb SBF significantly increased within 3min following the application of 125-Hz ES to the right forelimb. No significant changes in SBF were observed in the left or right hindlimb when 125-Hz ES was applied to the left forelimb. Moreover, 3-Hz ES of the left or right forelimb did not significantly change SBF in either hindlimb compared with the control group. These results indicate that unilateral forelimb ES causes a differential SBF response in the hindlimb via a specific somatosympathetic reflex, and ES-induced SBF improvements in the ischemic hindlimb are frequency-dependent.

Estradiol enhances the acquisition of lithium chloride-induced conditioned taste aversion in castrated male rats.

The present study examined the effects of short-term treatment with ovarian hormones on the acquisition of conditioned taste aversion (CTA). Adult male rats were castrated and randomly divided into LiCl- and saline-treated groups. Nineteen days after castration, all of the animals were subjected to 23.5-h daily water deprivation for seven successive days (day 1 to day 7). On the conditioning day (day 8), the rats received either a 4 ml/kg of 0.15 M LiCl or the same dose of saline injection immediately after administration of a 2 % sucrose solution during the 30-min water session. Starting from day 6, rats in both groups received one of the following treatments: daily subcutaneous injection of (1) estradiol alone (30 µg/kg; estradiol benzoate (E) group), (2) estradiol plus progesterone (500 µg; E + progesterone (P) group), or (3) olive oil. From day 9 to day 11, all of the rats were given daily two-bottle preference tests during the 30-min fluid session. The estradiol and estradiol plus progesterone treatments in the LiCl groups resulted in significantly lower preference scores for the sucrose solution compared with the olive oil treatment groups, but no difference in preference score was seen between these two groups. These results indicate that both the estradiol and estradiol plus progesterone treatments in the LiCl groups enhanced the acquisition of CTA learning and suggest that estradiol affects the acquisition of CTA mediated by an activational effect in male rats, whereas progesterone treatment does not influence the effects of estradiol on the acquisition of CTA.

Increasing acclimation period improves the reproducibility of short-heating local thermal hyperemia.

OBJECTIVES: The axon reflex (AR) can be induced by the activation of afferent C-fibers during local skin heating. The previously used long-heating local thermal hyperemia (LTH) protocols tested AR flare by normalizing to endothelial-mediated maximal vasodilatation to adjust capillary heterogeneity when the recording sites were randomly selected. The AR flare induced by short local heating can be reproducible without using the data from subsequent longer heating for normalization when the recording sites were fixed with holders in the same session. The aim of this study was to investigate the effect of acclimation period on the intersession reproducibility of short-heating LTH when the recording sites were relocated after a longer interval of 1-3 days. METHODS: After 30 or 60 min acclimation, LTH with 5 min heating was assessed on bilateral human forearms using single-point laser Doppler flowmetry. The test was repeated at the same recording sites again at the same time 1-3 days later. Baseline and heating blood flux were analyzed and the data were expressed as different forms. Reproducibility of two tests was assessed using coefficient of variation (CV) and intra-class correlation coefficient (ICC) statistics. RESULTS: The intersession reproducibility of peak cutaneous vascular conductance (CVC) (CV=18.38%, ICC=0.82), peak CVC change (CV=20.38%, ICC=0.83) and 4 min area-under-the-curve (AUC) (CV=18.66%, ICC=0.75) of the right forearm and time to peak (CV=16.84%, ICC=0.52) of the left forearm were acceptable after 30 min acclimation. When the acclimation period was increased to 60 min, all of these data except 4 min AUC of both sides reached an acceptable level. CONCLUSIONS: The AR flare induced by short local heating is reproducible when the recording sites are relocated by a predefined rule. The reproducibility of LTH on right forearm is different from that on left forearm, and increasing acclimation period improves the reproducibility.

Axon reflex-related hyperemia induced by short local heating is reproducible.

OBJECTIVES: The axon reflex (AR) flare is induced by antidromic activation of afferent C-fibers during nociceptive stimulation. This response has been suggested to be modulated by sympathetic activity and basal level of nitric oxide. In previously used protocols of local thermal hyperemia (LTH), AR flare has been used in combination with maximal vasodilatation to study the integrated endothelial function. The aim of this study was to investigate the intra-session reproducibility of short heating-induced AR flare, the specific neural-mediated portion of LTH, and to compare the reproducibility between different forms of data expression. METHODS: Short-heating LTH was assessed using single-point laser Doppler flowmetry (LDF) on bilateral volar surface of the forearm in 10 men and 10 women. The blood flux measurement included a non-heating process for 5 min, followed by a quick heating process from 33°C to 42°C for 5 min. The test was repeated 45 min later at the same recording sites with fixed holders. Baseline and heating blood flux were recorded and expressed as different forms of data. Reproducibility was assessed using coefficient of variation (CV) and intra-class correlation coefficient (ICC) statistics. RESULTS: The reproducibility of peak cutaneous vascular conductance (CVC) (CV=16.02-17.31%, ICC=0.77-0.78), peak CVC change (CV=14.30-18.12%, ICC=0.80-0.86), and the 4 min area-under-the-curve (CV=18.37-18.70%, ICC=0.60-0.78) was acceptable. The time to peak flux of each recording site ranged from 90 to 209 s and all the peak fluxes have been achieved before 4 min of heating. CONCLUSIONS: Single-point LDF is a reproducible technique of assessing AR flare on volar surface of the forearm when the heating period is reduced to 5 min and the recording sites are fixed. Using this new protocol, short-heating LTH has a potential to be used to evaluate the effects of acute physical or chemical interventions between two short-heating LTH tests to further explore the pathophysiological meaning of heating-induced AR flare.

Different mechanisms of extinction of conditioned taste aversion are dependent on time intervals of extinction following conditioning.

After extinction, the reappearance of a conditioned response induced by an unconditioned stimulus which is weaker than that used during the conditioning training indicates that the extinction procedure does not eliminate the original conditioned memory. Recent studies on fear conditioning have shown that rats exhibited little or no recovery of conditioned responding if the time interval between fear acquisition and extinction was short, suggesting that the extinction process may erase the original conditioning trace in this situation. In the present study, a saving experiment was conducted in rats to investigate whether an aversive response could be recovered following extinction training with different time intervals after acquisition of conditioned taste aversion (CTA). Male Long-Evans rats developed CTA by associating a 0.2% sucrose solution with malaise induced by intraperitoneal injection of 4 ml/kg 0.15 M LiCl and were subjected to extinction training with an interval of 5 h (5H group) or 24 h (24H group) after acquisition of CTA. Rats in the 5H group, but not in the 24H group, exhibited no aversive responding to the sucrose solution followed by the injection of a lower dose of LiCl (1 ml/kg). These findings indicate that the extinction procedure administered at different time points following the acquisition of CTA affects recovery of extinguished aversive memory and suggest that an unlearning process may be involved in the mechanisms of CTA extinction with short intervals between acquisition and extinction.

C-reactive protein and heart rate recovery in middle-aged men with severe obstructive sleep apnea.

OBJECTIVE: The study aimed to evaluate whether the inflammatory marker "high-sensitivity C-reactive protein (hsCRP)" level was associated with impaired heart rate recovery at 1 min after exercise termination (HRR-1) in middle-aged patients with severe obstructive sleep apnea (OSA). METHODS: Thirty middle-aged male patients (40-64 years old) with severe OSA (apnea-hypopnea index [AHI] ≥ 30 h(-1)) and 30 subjects without OSA (AHI < 5 h(-1)), matched with age and body mass index (BMI), were recruited. All subjects underwent an overnight polysomnography and completed a symptom-limited maximal exercise test. Cardiopulmonary parameters included peak oxygen consumption (VO(2peak)) and heart rate response during and immediately after exercise. Fasting blood samples were drawn for hsCRP analysis. RESULT: Patients with severe OSA had significantly higher hsCRP levels (0.18 vs. 0.07 mg/dl, P < 0.01), lower reduced HRR-1, peak heart rate, and VO(2peak) values than those in the controls. The hsCRP levels significantly correlated with HRR-1 in the OSA group (r = -0.69, P < 0.01) after adjustment for VO(2peak) (r = -0.66, P < 0.01). Furthermore, stepwise multiple regression analysis showed that HRR-1 and AHI were significant predictors of hsCRP levels in all participants (adjusted R(2) = 0.53, P < 0.01). CONCLUSIONS: Blunted HRR was shown in middle-aged men with severe OSA, and it was associated with high hsCRP levels significantly.

Cellular localization of the organic cation transporters, OCT1 and OCT2, in brain microvessel endothelial cells and its implication for MPTP transport across the blood-brain barrier and MPTP-induced dopaminergic toxicity in rodents.

The cellular localization of organic cation transporter (OCT) 1 and OCT2 in isolated brain microvessel endothelial cells from humans, rats, and mice and in cultured adult rat brain endothelial cells was examined by confocal microscopy and in isolated luminal and abluminal membrane fractions by Western blot analysis. Cellular uptake of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was measured with or without OCT1/OCT2 silencing. The interaction between MPTP and amantadine was studied by in vitro kinetic analysis and in vivo brain microdialysis. MPTP-induced dopaminergic toxicity was examined by measuring dopamine levels in the brain striatum and by positron emission tomography scanning. The results showed that both OCT1 and OCT2 were mainly expressed on the luminal side of brain microvessel endothelial cells and adult rat brain endothelial cells. Cellular uptake of MPTP was significantly (p < 0.05) decreased by about 53%, 60%, or 91% following silencing of OCT1, OCT2, or both, respectively. Amantadine competitively inhibited MPTP uptake in vitro and significantly (p < 0.05) reduced the area under the time-concentration curve for MPTP and MPP(+) in the brain extracellular fluid in rats and mice by 65-70% and 35-85%, respectively. MPTP-induced dopaminergic toxicity in mice was ameliorated by amantadine without stimulating dopamine turnover. In conclusion, OCT1 and OCT2 are important for MPTP transfer across the blood-brain barrier and amantadine reduces the blood-brain barrier transfer of MPTP and MPTP-induced dopaminergic toxicity in rodents.

Somatosympathetic reflex and acupuncture-related analgesia.

Both acute and chronic pains correspond to nociceptive substances (NSs), which are naturally produced and metabolized by the organism experiencing the pains. The accumulation of NSs in regional tissues triggers a series of pathophysiological reactions and initiates certain threats to the health and the quality of human life. Pharmacological intervention is the most popular treatment for pain relief, which is achieved by either reducing the production of NSs or blocking the transmission of nociceptive signals through the nervous system, but no drug has been developed for the elimination of NSs. Therefore, improving blood circulation to eliminate NSs in painful tissues is an alternative strategy for pain relief. Acupuncture has been proved to be effective for the treatment of certain kinds of pain, but the mechanisms therein remain unclear. The effectiveness of acupuncture analgesia is also variable owing to the uncertainty surrounding the mechanism and the poor standardization of the technique. There is some evidence that acupuncture may induce pain relief by changing the regional blood flow through somatosympathetic reflex (SSR). Therefore, when exploring the mechanisms of SSR in detail, it is helpful to clarify the mechanisms of acupuncture analgesia and to develop a more standardized and effective protocol for acupuncture analgesia. Increasing evidence has suggested that both sympathetic activity and stimulation-induced SSR are differentially controlled in an organ-specific and activity-dependent manner. Vasomotor outflow, which involves the regulation of impaired regional blood circulation, is also differentially controlled in response to specific somatic stimulation. Therefore, we vigorously review the relations between SSR and acupuncture-related analgesia so that we can develop a targeted pain therapy where in certain areas of the body undergo site-specific somatic stimulation, which in turn, can adjust the impaired regional blood circulation.

Repeated transcutaneous electrical nerve stimulation of nonspecific acupoints of the upper body attenuates stress-induced visceral hypersensitivity in rats.

Irritable bowel syndrome (IBS) is a common stress-related gastrointestinal disorder and visceral hypersensitivity (VH) is characteristically found in IBS patients. Transcutaneous electrical nerve stimulation (TENS) applied to certain acupoints has been shown to benefit IBS patients. Here, we investigated whether nonspecific acupoint is involved in the efficacy of TENS treatment for IBS. Twenty-five male rats were randomly assigned to four experimental groups and one sham-control group. The four experimental groups were defined as TENS-RR, TENS-RL, TENS-LR, and TENS-LL based on the location of the two TENS patches [right (R) or left (L)]. The former and latter letter pairs indicate that the patch locations were the upper chest and upper back, respectively. The heterotypic intermittent stress (HIS) protocol was performed for 16 days. VH was assessed by electromyography to evaluate response to rectal distention (RD). Modulated medium-frequency TENS, sweep range 1-10 Hz, amplitude slightly above the supra motor threshold, was applied 30 min per day followed by RD every second day for the final 7 days of the 16-day HIS period. VH was induced after the rats had been subjected to HIS for 10 days. A significant reduction of VH was observed only in the TENS-LL group compared with that in the sham-control group. These data suggest that repeated TENS treatment can alleviate stress-induced VH in rats. Further, whether TENS patches are attached to the left or right side of the body, which are nonspecific acupoints for gastrointestinal functions, may be an important factor in the treatment of stress-associated gastrointestinal symptoms.

Correlation of catecholamine levels in the bed nucleus of the stria terminalis and reduced sexual behavior in middle-aged male rats.

The correlation between dopamine (DA) and norepinephrine (NE) levels in the bed nucleus of the stria terminalis (BNST) and male sexual behavior was examined in middle-aged rats. Male rats (18-19 months) were divided into: (a) Group MIE, consisting of rats showing mounts, intromissions, and ejaculations; (b) Group MI, composed of rats showing mounts and intromissions, but no ejaculation; and (c) Group NC, consisting of noncopulators. Young adult rats (4-5 months) displaying complete copulatory behavior were used as the control. Tissue levels of DA, NE, and DA metabolites in the BNST were measured by high-pressure liquid chromatography. DA, but not NE, levels in MIE rats were significantly lower than those in young controls. DA and NE levels in MIE rats were significantly higher than those in NC rats. These results suggest that DA and NE in the BNST might play an important role in the control of male sexual behavior in middle-aged rats.

Effects of alcohol on the mouse-killing behavior of olfactory bulbectomized rats.

The purpose of the current study was to evaluate the effects of chronic administration of alcohol on the olfactory bulbectomy (OBX)-induced mouse-killing behavior (MKB), an animal model for screening antidepressants. The rats were divided into three groups, which were given alcohol (0, 0.5, or 1 g/kg/day) orally for 28 days. MKB was analyzed before and at the end of each week of the alcohol treatment. The results showed that chronic alcohol treatment produced a significant increase in the latency of MKB, implying that alcohol may have an antidepressant-like activity. This suggests that alcohol dependence or abuse in depressed patients may result from "self-medication". Since it has been reported that OBX causes a decrease in the density of N-methyl-D-aspartate (NMDA) receptors in the brain and that alcohol is a potent and selective inhibitor of NMDA receptors, the possible role of NMDA receptors in this effect is discussed.

Male sexual behavior and catecholamine levels in the medial preoptic area and arcuate nucleus in middle-aged rats.

The correlation between male sexual behavior and catecholamine levels in the medial preoptic area (MPOA) and arcuate nucleus (ARN) was studied in middle-aged rats. Male rats (18-19 months) were assigned to three groups: (1) Group MIE, consisting of rats showing mounts, intromissions, and ejaculations; (2) Group MI, consisting of rats showing mounts and intromissions, but no ejaculation; and (3) Group NC, consisting of non-copulators showing no sexual behavior. Young adult rats (4-5 months) displaying complete copulatory behavior were used as the control group. Dopamine (DA) and norepinephrine (NE) tissue levels in the MPOA and ARN were measured by high pressure liquid chromatography with electrochemical detection. There were no differences between MIE rats and young controls in DA or NE tissue levels in these two brain areas. Furthermore, no differences were found between the MI and NC groups in DA or NE tissue levels in either the MPOA or ARN. DA tissue levels in the MPOA and ARN in the MI and NC groups were significantly lower than those in the MIE group. NE tissue levels in the MPOA of the NC group were significantly lower than those in the MIE group, but no differences in NE tissue levels in the ARN were seen between the four groups. These results suggest that, in male rats, complete male sexual performance is related to tissue levels of DA, but not of NE, in the MPOA and/or ARN. Furthermore, ejaculatory behavior might be associated with critical DA tissue levels in the MPOA and/or ARN in middle-aged rats.

Interaction between nicotine and MPTP/MPP+ in rat brain endothelial cells.

To examine the interaction between nicotine and MPTP/MPP+ in the blood-brain barrier, cellular uptake of MPTP and MPP+ was studied in the presence of nicotine and several compounds, including MPTP/MPP+ analogs and a specific inhibitor of organic cation transporter (OCT) in an adult rat brain microvascular endothelial cell line (ARBEC). The kinetic properties of the uptake of MPTP, MPP+, and nicotine were also examined. In addition, a microdialysis study was performed to evaluate the in vivo effect of nicotine (i.p.) on extracellular levels of MPTP and MPP+ in the brain after intravenous administration of MPTP. The results showed that uptake of MPTP, MPP+, and nicotine was partly mediated by a carrier system that was sensitive to decynium22, a specific OCT inhibitor. RT-PCR showed the presence of OCT1 mRNA in ARBEC. Capacity for uptake of MPTP and nicotine was much higher than that for MPP+ (Km and Vm values of 10.94+/-1.44 microM and 0.049+/-0.007 pmol/mg s, respectively, for MPP+, compared to values of 35.75+/-0.85 microM and 40.95+/-3.56 pmol/mg s for MPTP and 25.29+/-6.44 microM and 51.15+/-14.18 pmol/mg s for nicotine). In addition, nicotine competitively inhibited the uptake of both MPTP and MPP+, with inhibition constants (Ki) of 328 microM and 210 microM, respectively. In vivo microdialysis results showed that nicotine significantly reduced brain extracellular levels of MPTP in the first 30 min (507.4+/-8.5 ng/ml vs. 637.9+/-30.8 ng/ml with and without nicotine pre-treatment, respectively), but did not have significant effect on those of MPP+. In conclusion, nicotine can inhibit in vitro cellular uptake and in vivo transfer of MPTP across the blood-brain barrier, which can be mediated by multiple pathways including OCT1.

Psychoimmunological effects of dioscorea in ovariectomized rats: role of anxiety level.

BACKGROUND: Anxiety levels in rats are correlated with interleukin-2 (IL-2) levels in the brain. The aim of the present study was to investigate the effects of dioscorea (wild yam), a Chinese medicine, on emotional behavior and IL-2 levels in the brain of ovariectomized (OVX) rats. METHODS: One month after ovariectomy, female Wistar rats were screened in the elevated plus-maze (EPM) test to measure anxiety levels and divided into low anxiety (LA) and high anxiety (HA) groups, which were then given dioscorea (250, 750, or 1500 mg/kg/day) by oral gavage for 27 days and were tested in the EPM on day 23 of administration and in the forced swim test (FST) on days 24 and 25, then 3 days later, the brain was removed and IL-2 levels measured. RESULTS: Compared to sham-operated rats, anxiety behavior in the EPM was increased in half of the OVX rats. After chronic dioscorea treatment, a decrease in anxiety and IL-2 levels was observed in the HA OVX rats. Despair behavior in the FST was inhibited by the highest dosage of dioscorea. CONCLUSION: These results show that OVX-induced anxiety and changes in neuroimmunological function in the cortex are reversed by dioscorea treatment. Furthermore, individual differences need to be taken into account when psychoneuroimmunological issues are measured and the EPM is a useful tool for determining anxiety levels when examining anxiety-related issues.

Monoamine levels in the nucleus accumbens correlate with male sexual behavior in middle-aged rats.

The correlation between monoamine levels in the nucleus accumbens (NAcc) and male sexual behavior was studied in middle-aged rats. Male rats (18-19months) were assigned to three groups: (1) Group MIE consisted of rats showing mounts, intromissions, and ejaculations; (2) Group MI was composed of rats showing mounts and intromissions, but no ejaculation; and (3) Group NC were non-copulators showing no sexual behavior. Young adult rats (4-5months), displaying complete copulatory behavior, were used as the control group. Levels of dopamine (DA), serotonin, and norepinephrine and their metabolites in the NAcc were measured by high-pressure liquid chromatography with electrochemical detection. No difference was seen in DA levels between MIE rats and young controls, whereas DA levels in NC rats were significantly lower than those in both MIE and MI rats. Serotonin levels in NC rats were significantly higher than those in MIE and MI rats. Conversely, norepinephrine levels in NC rats were lower than those in MIE rats. These results suggest that monoamine levels in the NAcc correlate with sexual performance in male rats and that changes in NAcc monoamine levels might affect male sexual behavior in middle-aged rats.

Behavioral effects of d-cycloserine in rats: the role of anxiety level.

It has been reported that the glutamatergic N-methyl-D-aspartate (NMDA) receptor is involved in stress responses and that anxiety is the primary response to stress. Although individual differences in anxiety levels of rats have been demonstrated by using the elevated plus-maze (PM) test, the role of NMDA receptor activity in such individuality of anxiety is not clear. Here, we examined whether low (LA) and high (HA) anxiety rats might respond differently to treatment with d-cycloserine (DCS), a partial agonist of the glycine binding site located on NMDA receptors. Male Wistar rats were screened by using the PM and divided into LA and HA subgroups. On the next day, these rats were again tested in the PM, 30 min after the treatment with DCS (5, 10, or 30 mg/kg ip). Five days later, the rats were subjected to a 2-day forced swim (FS) test, receiving the DCS treatment again 30 min before the second day session. The PM data showed that DCS had anxiogenic effects in LA but not HA rats. The immobility of LA or HA rats in the FS test was not affected by DCS. The results indicate that the behavioral effects of DCS depend on the anxiety level of rats and have task-dependent behavioral consequences, suggesting that glycine binding sites on NMDA receptors are involved in individual differences of anxiety level.

Lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, induces apoptosis and differentiation in human anaplastic thyroid carcinoma cells.

Although only 1% of differentiated thyroid cancers transform into anaplastic thyroid cancer, this disease is always fatal. Differentiation therapy may provide a new therapeutic approach to increasing the survival rate in such patients. 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are reported to promote cellular apoptosis and differentiation in many cancer cells; these effects are unrelated to lipid reduction. Recently, we found that TNFalpha induces cytomorphological differentiation in anaplastic thyroid cancer cells and increases thyroglobulin expression; however, TNF is cytotoxic for normal human tissue. The aim of this study was to determine whether lovastatin, an HMG-CoA reductase inhibitor, could induce apoptosis and differentiation in anaplastic thyroid cancer cells. Anaplastic thyroid cancer cells were treated with lovastatin, then examined for cellular apoptosis and cytomorphological differentiation by DNA fragmentation, phosphatidylserine externalization/flow cytometry, and electron microscopy. Thyroglobulin levels in the culture medium were also measured. Our results showed that at a higher dose (50 micro M), lovastatin induced apoptosis of anaplastic thyroid cancer cells, whereas at a lower dose (25 micro M), it promoted 3-dimensional cytomorphological differentiation. It also induced increased secretion of thyroglobulin by anaplastic cancer cells. Our results show that lovastatin not only induces apoptosis, but also promotes redifferentiation in anaplastic thyroid cancer cells, and suggest that it and other HMG-CoA reductase inhibitors merit further investigation as differentiation therapy for the treatment of anaplastic thyroid cancer.

Circulating soluble Fas ligand correlates with disease activity in Graves' hyperthyroidism.

Apoptosis of thyrocytes may play an important role in the pathogenesis of autoimmune thyroiditis. Meanwhile, the Fas/Fas ligand (FasL) apoptosis pathway has received much attention in physiological homeostasis and immune regulation in various thyroid diseases, including Graves' hyperthyroidism (GD). FasL is a type II membrane protein of the tumor necrosis factor family, and induces apoptosis when it binds to Fas. Soluble FasL (sFasL) may also exert cytotoxic activity against Fas-expressing cells by producing trimerization of Fas molecule, but soluble Fas (sFas) is an apoptotic inhibitor. To determine the role of circulating sFas/sFasL in modulating disease activity of GD, we examined the circulating levels of sFas/sFasL in GD patients with various levels of anti-thyrotropin-stimulating hormone (TSH) receptor antibodies (TRAb). Serum samples were obtained from 22 consecutive untreated hyperthyroid GD patients with higher TRAb level (63.8% +/- 12.5%, group I) and 22 treated euthyroid GD patients, who were in a state of disease remission, with lower TRAb level (7.9% +/-5.9%, group II). The levels of sFas were significantly higher in group I (1.56 +/- 0.26 ng/mL) than in group II (0.76 +/- 0.26 ng/mL, P <.01). The levels of sFasL were also significantly higher in group I patients (0.153 +/- 0.018 ng/mL) than in group II patients (0.126 +/- 0.012 ng/mL, P <.01). A significant correlation was found between sFasL levels and TRAb activity in all GD patients (r = 0.69, P <.01). Because changes in sFasL levels and TRAb levels occur in parallel, increased serum sFasL in patients with GD may contribute to homeostasis in the thyroid. Serum sFasL may be considered to be a candidate marker for evaluating disease aggression or regression in GD.

Effects of incisor-cutting on muricidal behavior induced by olfactory bulbectomy in rats.

Muricidal behavior in rats is composed of two main components, attacking and killing performance. Since a large number of mice could be killed by rats during behavioral experiments, research has been limited in the past decade possibly because of ethical considerations. In preliminary studies, we found that the rat incisors play a key role in muricidal behavior in rats, so, in the present study, we cut off the incisors and assessed the following parameters of muricidal behavior: attack latency, first attack site, lethal attack site, attack frequency, total attack duration and mean attack duration. If after incisor-cutting (IC) rats still tried to demonstrate muricidal activity, but failed to kill the mouse, this would be an ideal model for studying the mechanisms of muricidal behavior. Since muricide can be induced in rats by olfactory bulbectomy (OBX), young adult male Wistar rats with OBX displaying muricidal behavior were tested for muricidal activity 4 h after IC, then every 24 h for 3 days. At 4 and 28 h after IC, only 9% and 36% of rats killed mice, but these values rose to 73% and 82% 52 and 76 h after IC, respectively. At 4, 28 and 52 h after IC, there was no significant difference in attack latency, first attack site, lethal attack site or mean attack duration between IC-treated rats (both killers and nonkillers) and sham-operated controls, while the attack frequency was obviously increased in IC nonkiller rats, and a significantly longer total attack duration was seen in both IC killer and nonkiller rats compared to controls. Since IC treatment increases attack frequency and prolongs the total attack duration without affecting other basic components of muricidal behavior in rats, these results suggest that the killer rats treated with IC may provide a suitable model for research on muricidal behavior.

MK-801 suppresses muricidal behavior but not locomotion in olfactory bulbectomized rats: involvement of NMDA receptors.

In rats, olfactory bulbectomy (OBX) causes changes in glutamatergic function in the amygdala (AMG) and induces mouse-killing behavior (MKB). The medial AMG (mAMG) plays an important role in the initiation and maintenance of OBX-induced MKB. In the present study, systemic injection or intra-mAMG perfusion of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) was used to determine the effects of MK-801, a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, on the expression of OBX-induced MKB in male Wistar rats that had undergone OBX 1 month previously. The effects of MK-801 on locomotion in OBX rats were also examined using the open-field test. Intraperitoneal injection of MK-801 at doses of 0.10 and 0.15 mg/kg resulted in reversible suppression of MKB, the effect being maximal within 1 h after drug treatment, then gradually disappearing over 6 h. Locomotor distance in OBX rats was not affected using 0.10 mg/kg of MK-801, but increased after treatment with 0.15 mg/kg of MK-801; both doses, however, caused the rats to spend longer in the central area of the open field. MKB was also reversibly suppressed by local perfusion of 1 mM MK-801 at a rate of 1 microl/min into the mAMG through microdialysis probes. These results suggest that NMDA receptors, at least, in the mAMG, are involved in the expression of OBX-induced MKB.