Comparative data on emotional (psychotic) aggressive biting behavior in mice of ddY strain measured by using two devices; Aggressive response meter and powerlab-compatible type aggressive response meter.

The Aggressive Response Meter (ARM) has been validated for measuring emotional (psychotic) aggression triggered by mental irritation in mice. In the present article, we newly developed a device, pARM (PowerLab-compatible type ARM). We collected on the aggressive biting behavior (ABB) intensity and ABB frequency of 20 male and female mice of ddY strain studied over a period of 6 days by using pARM and the former ARM. We calculated Pearson's correlation between the values of pARM and those of ARM. The accumulated data can be referred as a basis for demonstrating the consistence of pARM and the former ARM, and used in future research to augment the understanding of stress-induced emotional aggression in mice.

Kamishoyosan (a Japanese traditional herbal formula), which effectively reduces the aggressive biting behavior of male and female mice, and potential regulation through increase of Tph1, Tph2, and Esr2 mRNA levels.

Kamishoyosan (KSS), a Japanese traditional herbal formula, is used to treat symptoms related to the autonomic nervous system in men and women; it is especially known for improving the symptoms of irritability (e.g., bad temper and persistent anger). Although clinical and ethological studies of KSS have been conducted, its efficacy in reducing irritability remains to be validated. In the present study, male and female ddY-strain mice were isolation-reared for 8 weeks (from the third postnatal week) to induce pathologically aggressive biting behavior (ABB), which was used as an indicator of irritability. The ABB of mice toward metal rods was measured using the Aggressive Response Meter. An intraperitoneal administration of KSS (100 mg/kg) effectively reduced ABB in male and female mice at 2 h after the administration; however, this effect was canceled by prior administration of WAY-100635 [a 5-hydroxytryptoamine (5-HT)-1A receptor antagonist; 0.5 mg/kg] and bicuculline (a type-A gamma-aminobutyric acid receptor antagonist; 1.0 mg/kg). Additionally, tamoxifen, ICI-182780, and G-15 (all estrogen receptor antagonists) inhibited the action of KSS in a dose-dependent manner. Furthermore, gene expression of tryptophan hydroxylase (Tph) 1 and Tph2 were increased and 5-HT immunofluorescence was slightly increased in the dorsal raphe nucleus (DRN) of isolation-reared mice administered with KSS. Collectively, these results indicate that KSS effectively reduces ABB in isolation-reared male and female mice through stimulation of 5-HT production in the DRN. Our findings also suggest that gene expression of estrogen receptor (Esr) 2 increased in the DRN might be associated with the reduction of ABB.

Evaluation of aggressiveness of female mice using a semi-automated apparatus for measurement of aggressive biting behavior toward an inanimate object.

BACKGROUND: Most laboratory research on aggressive behavior has focused on intraspecific intermale aggression tests. The intraspecific confrontation is not available for the evaluation of female aggressiveness, since androgens are critical for maintenance of this behavior, whereas aggressive biting behavior toward inanimate objects (ABI) occurs in both males and females. NEW METHOD: We propose an experimental method for evaluating female aggressiveness. We improved the previously developed semi-automated apparatus (Aggression Response Meter, ARM) to apply it to measurement of female ABI, and measured changes of ABI in stressed mice and drug actions on ABI. RESULTS: ABI assessment was performed daily in sexually mature female mice using ARM. The intensity and number of ABI in one session did not significantly change during an estrous cycle, suggesting that ABI is not influenced by the dynamics of sex hormones. Additional female mice were socially isolated for 7 weeks and then re-socialized for 2 weeks, and ABI was monitored weekly. ABI significantly increased during the isolation period, and then significantly decreased during re-socialization; both were time-dependent. In prolonged-isolated aggressive mice, a serotonin 1A receptor agonist, buspirone, significantly decreased ABI. COMPARISON WITH EXISTING METHOD: There are no experimental methods or apparatus available for evaluating female aggressiveness using one individual repeatedly. We could measure ABI semi-quantitatively using the ARM. CONCLUSIONS: ABI is a useful behavioral paradigm in the evaluation of aggressiveness in female mice, regardless of the estrous cycle, and can also be used for evaluating the actions of drugs on aggressiveness.

Caspr4 interaction with LNX2 modulates the proliferation and neuronal differentiation of mouse neural progenitor cells.

Contactin-associated protein 4 (Caspr4), also known as contactin-associated protein-like protein (CNTNAP4), is expressed in various regions of the brain. Recent reports suggest that CNTNAP4 is a susceptibility gene of autism spectrum disorders (ASDs). However, the molecular function of Caspr4 in the brain has yet to be identified. In this study, we show an essential role of Caspr4 in neural progenitor cells (NPCs). Caspr4 is expressed in NPCs in the subventricular zone (SVZ), a neurogenic region in the developing cortex. Knocking down of Caspr4 enhances the proliferation of NPCs derived from the SVZ of embryonic day 14 mouse. Neuronal differentiation is increased by overexpression of Caspr4, but decreased by knocking down of Caspr4 in cultured mouse NPCs. Transfection of the intracellular domain of Caspr4 (C4ICD) rescues the abnormal decreased neuronal differentiation of Caspr4-knocking down NPCs. Ligand of Numb protein X2 (LNX2), a binding partner of Numb, interacts with Caspr4 in a PDZ domain-dependent manner and plays a similar role to Caspr4 in NPCs. Moreover, transfection of LNX2 rescues the decreased neuronal differentiation in Caspr4-knocking down NPCs. In contrast, transfection of C4ICD fails to do so in LNX2-knocking down NPCs. These results indicate that Caspr4 inhibits neuronal differentiation in a LNX-dependent manner. Therefore, this study reveals a novel role of Caspr4 through LNX2 in NPCs, which may link to the pathogenesis of ASDs.

A novel semi-automated apparatus for measurement of aggressive biting behavior in mice.

BACKGROUND: Currently, behavioral research of aggressiveness is often conducted with intraspecific intermale aggression tests. Intraspecific aggression is not detectable in early stages of psychiatric disorders or in female animals, except during the nursing period. NEW METHOD: We developed a semi-automated apparatus (ARM: Aggression Response Meter) for measurement of aggressive biting behavior (ABB) in mice. The apparatus is loaded with computer-controlled sticks that stimulate the mouse through touch, inducing irritation and anger. When the mouse bites the sticks in anger, a load sensor attached to the sticks detects ABB dynamically. Changes in ABB were assessed with isolation-reared/re-socialized mice using the ARM, and additional isolation-reared mice were tested using both the ARM and the resident-intruder test, and then buspirone, a serotonin 1A receptor agonist, was administered. RESULTS: ABB significantly increased during isolation rearing, and then significantly decreased throughout the re-socialization period; both changes were time-dependent. The ARM also detected ABB of female mice after 3 weeks of isolation rearing. Buspirone significantly inhibited aggressive behavior in both tests in a similar manner. COMPARISON WITH EXISTING METHOD: The ARM detects aggressiveness in psychiatric disorders at an earlier stage and in both male and female mice. CONCLUSIONS: ABB toward inanimate objects is a reliable paradigm that makes it possible to detect aggressiveness in the early stage of psychiatric disorders. The ARM is useful for the quantification of aggressiveness using the same individual repeatedly, and for objective evaluation of the effects of drugs on aggressiveness. The ARM can be used with both male and female mice.

Acupuncture Improves Sleep Conditions of Minipigs Representing Diurnal Animals through an Anatomically Similar Point to the Acupoint (GV20) Effective for Humans.

Acupuncture, an alternative medicine, has been widely applied for people with sleep disturbances; therefore, the effects should be evaluated objectively. Micro-minipigs (MMPigs), the smallest miniature pigs for animal experiments, were used. Acupuncture was performed at two different points: Dafengmen is located on the head and is an anatomically similar point to human-Baihui (GV20), an effective acupoint for sleep disturbances in humans; pig-Baihui is on the back. The procedure was performed as follows: shallow, within 5 mm depth for several seconds; deep, 10-20 mm depth for 20 min. The sleep conditions were evaluated by actigraph, and the amount of catecholamine in pooled urine after acupuncture treatment. MMPigs with deep acupuncture at Dafengmen showed significantly efficient values on actigraph and catecholamine analysis as compared with untreated MMPigs. The effective acupoint for sleep conditions in the porcine model is at an anatomically similar point to humans, rather than the point determined by traditional Chinese medicine.

Role of medullary GABA signal transduction on parasympathetic reflex vasodilatation in the lower lip.

In the orofacial area, noxious stimulation of the orofacial structure in the trigeminal region evokes parasympathetic reflex vasodilatation, which occurs via the trigeminal spinal nucleus (Vsp) and the inferior/superior salivatory nucleus (ISN/SSN). However, the neurotransmitter involved in the inhibitory synaptic inputs within these nuclei has never been described. This parasympathetic reflex vasodilatation is suppressed by GABAergic action of volatile anesthetics, such as isoflurane, sevoflurane, and halothane, suggesting that medullary GABAergic mechanism exerts its inhibitory effect on the parasympathetic reflex via an activation of GABA receptors. The aim of the present study was to determine the role of GABA(A) and GABA(B) receptors in the Vsp and the ISN in regulating the lingual nerve (LN)-evoked parasympathetic reflex vasodilatation in the lower lip. Under urethane anesthesia (1g/kg), change in lower lip blood flow elicited by electrical stimulation of the LN was recorded in cervically vago-sympathectomized rats. Microinjection of GABA (10 µM; 0.3 µl/site) into the Vsp or the ISN significantly and reversibly attenuated the LN-evoked parasympathetic reflex vasodilatation. Microinjection of the GABA(A) receptor-selective agonist muscimol (100 µM; 0.3 µl/site) or the GABA(B) receptor-selective agonist baclofen (100 µM; 0.3 µl/site) into the Vsp or the ISN significantly and irreversibly reduced this reflex vasodilatation, and these effects were attenuated by pretreatment with microinjection of each receptor-selective antagonists [GABA(A) receptor selective antagonist bicuculline methiodide (1mM; 0.3 µl/site) or GABA(B) receptor selective antagonist CGP-35348 (1mM; 0.3 µl/site)] into the Vsp or the ISN. Microinjection of these antagonists alone into the Vsp or the ISN had no significant effect on this reflex vasodilatation. In addition, microinjection (0.3 µl/site) of the mixture of muscimol (100 µM) and baclofen (100 µM) into the Vsp or the ISN also significantly reduced this reflex vasodilatation. These results suggest that medullary GABA signal transduction inhibits the parasympathetic reflex vasodilatation in the rat lower lip via GABA(A) and GABA(B) receptors in the Vsp and the ISN.

Role of the spinal trigeminal nucleus in the rat autonomic reflex.

The goal of the present study was to investigate the regional differences between the three subnuclei (oralis, interpolaris, and caudalis) of the spinal trigeminal nucleus (Vsp) in eliciting parasympathetic and sympathetic reflex autonomic responses. We evoked changes in lower lip blood flow (LBF) and systemic arterial blood pressure (SABP) by electrically stimulating these subnuclei in artificially ventilated, urethane-anaesthetised, cervically vago-sympathectomized rats. The LBF increases evoked by electrical stimulation of the Vsp at interpolaris were much larger than those at the sites of the oralis and caudalis. No significant difference in SABP increase was observed by Vsp stimulation between the interpolaris and caudalis, although the SABP increase evoked by electrical stimulation of the oralis was much smaller than in the interpolaris and caudalis. The present findings show that the Vsp at the interpolaris subnucleus of the Vsp participates as a relay in lingual nerve- and Vsp-evoked somato-autonomic reflex.

Contactin-associated protein (Caspr) 2 interacts with carboxypeptidase E in the CNS.

To identify proteins interacting with the intracellular domain of the neural cell adhesion molecule contactin-associated protein 2 (Caspr2), yeast two-hybrid screening was performed. We identified carboxypeptidase E (CPE) as a Caspr2-interacting candidate protein. Glutathione S-transferase pull-down and immunoprecipitation analyses indicated that Caspr2 was associated with CPE in vitro and in vivo. Both Caspr2 and CPE were expressed predominantly in the CNS. Immunohistochemical analyses revealed that both Caspr2- and CPE-like immunoreactivities were found to co-localize in the apical dendrites and cell bodies of rat cortical neurons. In subcellular localization analysis, Caspr2- and CPE-like immunoreactivities were co-migrated in the fractions of Golgi/ER. Additionally, in COS-7 cells co-transfected with CPE and Caspr2 cDNAs, Caspr2- and CPE-immunoreactivities were co-localized in both Golgi and membrane, whereas it was only observed in Golgi of either COS-7 cell transfected with CPE or Caspr2 cDNA alone. It is known that the membrane-bound form of CPE functions as a sorting receptor of prohormones in the trans-Golgi network. Taken together, our data suggest that CPE may be a key molecule to regulate Caspr2 trafficking to the cell membrane.

Up-regulation of matrix metalloproteinase-3 in the dorsal root ganglion of rats with paclitaxel-induced neuropathy.

Paclitaxel-induced painful peripheral neuropathy is a major dose-limiting factor. Recently, it has been reported that macrophages accumulated in the dorsal root ganglion of paclitaxel-treated rats, and their activation is suggested to contribute to generation and development of the neuropathy. However, the mechanism for macrophage activation is still unknown. In this study, to explore candidate genes involved in the mechanism for macrophage activation in the dorsal root ganglion of paclitaxel-treated rats, we developed model rats for paclitaxel-induced neuropathic pain and performed a microarray assay to analyze the changes of gene expressions in the dorsal root ganglion. Among the genes with changed expression levels, we focused on matrix metalloproteinase-3 (MMP-3, stromelysin-1) and CD163, a macrophage marker. By reverse transcription-polymerase chain reaction, the expression levels of MMP-3 and CD163 were markedly up-regulated in paclitaxel-treated dorsal root ganglion. As a result of immunohistochemical study, large ganglion neurons, but neither Schwann cells nor macrophages, predominantly expressed MMP-3. This MMP-3 up-regulation occurred prior to macrophage accumulation in the dorsal root ganglion. In addition, recombinant MMP-3 led to the activation of RAW264 macrophages in vitro. Taken together, the up-regulation of MMP-3 and following macrophage activation caused in the dorsal root ganglion might be a significant event to trigger a series of reactions developing paclitaxel-induced peripheral neuropathic pain.

Effect of pre-treatment with St John's Wort on nephrotoxicity of cisplatin in rats.

An herbal health care supplement, St John's Wort (SJW, Hypericum perforatum) has become widely used in the treatment of depression, and is known to interact with therapeutic drugs. Here we report a preventive effect of SJW on cisplatin nephrotoxicity in rats. Rats were given SJW (400 mg/kg/day, p.o.) for 10 consecutive days, and were injected with cisplatin (5 mg/kg, i.v.) on the day after the final SJW treatment. Cisplatin treatment increased the serum creatinine level, which is an index of nephrotoxicity, to 1.51+/-0.22 mg/dl (mean+/-SE) from 0.28+/-0.05 mg/dl (control) on day 5 after the cisplatin injection. This increase fell significantly to 0.86+/-0.13 mg/dl by pre-treatment with SJW. Cisplatin-induced histological abnormality of the kidney was blocked by pre-treatment with SJW. When SJW was administered for 10 days, the amounts of renal metallothionein (MT) and hepatic multidrug resistance protein 2 (Mrp2) were increased to 164.8+/-13.0% and 220.8+/-39.3% (mean+/-SE) of controls, respectively. GSH levels in the kidney and liver were not changed. Total and free cisplatin concentration in serum was not influenced by SJW treatment. In conclusion, the results suggest that pre-treatment with SJW may diminish cisplatin nephrotoxicity.

Fasting-induced reduction in locomotor activity and reduced response of orexin neurons in carnitine-deficient mice.

We found reduced locomotor activity (LA) under fasting in systemic carnitine-deficient juvenile visceral steatosis (jvs(-/-)) mice. When food was withdrawn at 8:00 a.m. (lights-off at 7:00 p.m., 12h/cycle), the nocturnal LA of jvs(-/-) mice was much less than the control (jvs(+/+) and jvs(+/-)) mice. LA recovered under carnitine or sucrose administration, but not under medium-chain triglyceride. In addition, fasted jvs(-/-) mice, without any energy supply, were activated by modafinil, a stimulator of the dopamine pathway. These results suggest that the reduced LA is not adequately explained by energy deficit. As the fasted jvs(-/-) mice showed lower body core temperature (BT), we examined the central nervous system regulating LA and BT. We found lower percentage of c-Fos positive orexin neurons in the lateral hypothalamus and reduced orexin-A concentration in the cerebrospinal fluid of fasted jvs(-/-) mice. Sleep analysis revealed that fasted jvs(-/-) mice had disruption of prolonged wakefulness, with a higher frequency of brief episodes of non-REM sleep during the dark period than fasted jvs(+/+) mice. These results strongly suggest that the reduced LA in fasted jvs(-/-) mice is related to the inhibition of orexin neuronal activity.

Parasympathetic mediated pupillary dilation elicited by lingual nerve stimulation in cats.

PURPOSE: To determine the autonomic efferent nerve pathways for the reflex pupillary dilation elicited by somatic stimulation in cats. METHODS: Cats anesthetized with a mixture of alpha-chloralose (50 mg/kg) and urethane (100 mg/kg) were intubated and paralyzed by intravenous injection of pancuronium bromide. The central cut end of the lingual nerve (LN) was stimulated electrically to simulate somatic stimulation, and 1 microL of lidocaine (2%) was microinjected into the Vsp or the EW nucleus to determine its effect on the pupillary dilation induced by LN stimulation. The effect of electrically stimulating the Vsp or sectioning the superior cervical sympathetic nerve (CSN) on the pupillary response was also examined. RESULTS: Stimulation of the LN or the trigeminal spinal nucleus (Vsp) evoked pupillary dilation in a frequency- and intensity-dependent manner. These responses were not affected by sectioning the ipsilateral or both CSNs. The pupillary responses were markedly suppressed by microinjecting lidocaine into the ipsilateral Vsp or the Edinger-Westphal (EW) nucleus, but not by injection into the contralateral Vsp. CONCLUSIONS: These results indicate that the Vsp and EW nucleus act as bulbar relay centers for pupillary dilation elicited by LN stimulation and suggest that the efferent arc of the response is a parasympathetic pathway. The contralateral pupillary dilation appears to be mediated, at least in part, by fibers projecting from the Vsp to the contralateral EW nucleus.

Prolonged expression of c-Fos protein in the lateral habenular nucleus of the Japanese monkey (Macaca fuscata) after eye enucleation.

To elucidate the effect of traumatic stress on the lateral habenular nucleus, we investigated the time course of the expression of c-Fos protein in this nucleus of the Japanese monkey (Macaca fuscata) after enucleation of one eye using c-Fos protein immunocytochemistry. c-Fos protein-like immunoreactive neurons were significantly increased; the increase started 1 h after the enucleation and remained high for 3-9 h in the lateral habenular nucleus on both sides. These results suggest that the prolonged expression of c-Fos protein occurred in the lateral habenular nucleus after traumatic stress through multiple transsynaptic activations.

Dioxin exposure down-regulates nitric oxide synthase and NADPH-diaphorase activities in the hypothalamus of Long-Evans rat.

In this study, we investigated the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) gastric administration on the expression of neuronal nitric oxide synthase (nNOS) and the NADPH-diaphorase (NADPH-d) activities in the brain of the Long-Evans rat. A single dose of TCDD (dissolved in olive oil, 50 microg/kg) or olive oil alone was administered to the rats by gavage. nNOS Western blotting experiment indicated a marked decrease in nNOS immunoreactivity at 1 and 2 weeks after TCDD treatment. NADPH-d histochemistry results showed a marked decrease in the number of NADPH-d stained cell bodies in the paraventricular hypothalamic nucleus, lateral hypothalamic area and perifornical nucleus in the TCDD-treated rats. The present study suggests that TCDD administration down-regulates nitric oxide product in the hypothalamus, which may be partially responsible for TCDD-induced feeding inhibition.

Morphological study of orexin neurons in the hypothalamus of the Long-Evans rat, with special reference to co-expression of orexin and NADPH-diaphorase or nitric oxide synthase activities.

Orexins, novel neuropeptides, are exclusively localized in the hypothalamus and implicated in the regulation of a variety of activities, including food intake and energy balance. Nitric oxide (NO), an unconventional neurotransmitter, is widely present in numerous brain regions including the hypothalamus, and has similar physiological roles to those of the orexins. The present study was undertaken to examine the distribution of orexin neurons and the presence of neuronal nitric oxide synthase (nNOS) in the orexin neurons to clarify whether NO interacts with the orexins in the neuronal regulation activities in the Long-Evans rat. We used two double-labeling methods: nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry in combination with orexin immunohistochemistry, and double-labeling fluorescent immunohistochemistry for orexin and nNOS. The majority of the orexin immunoreactive neurons were localized mainly in the areas of the dorsomedial hypothalamic nucleus (DMN), the dorsal part of the perifornical nucleus (PEF) and lateral hypothalamic area. The orexin immunoreactive cell bodies were medium in size, and triangular, round, elliptic, and fusiform in shape. The sizes and shapes of orexin neurons in the different parts were similar. Cell bodies coexpressing the orexin and nNOS or NADPH-d were present in the areas of the DMN and the PEF, and the nerve fibers containing orexin and nNOS were distributed in the DMN and PEF, arcuate nucleus (ARN) and ventromedial hypothalamic nucleus (VMH). These results provide morphological evidence that there exists a population of nNOS- or NADPH-d-/orexin-coexpressing neurons in the orexinergic cell group in the hypothalamus, and taken together with previous findings, suggest that NO may play a role in the mechanisms by which orexin neurons regulate food intake and energy balance.

Up-regulation of methionine-enkephalin-like immunoreactivity by 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment in the forebrain of the Long-Evans rat.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is considered to be one of the most toxic environmental contaminants, named dioxin. Exposure to TCDD induces a plethora of intoxication symptoms, including anorexia and hypothermia, in several mammals and human. Enkephalin, an endogenous pentapeptide, is an important neuroregulator of autonomic functions, such as food intake and body temperature. In this study, we investigated the effects of TCDD gastric administration on methionine-enkephalin (MEK) immunoreactivity in the brain of the Long-Evans rat, the species strain considered to be the most TCDD-susceptible, using immunohistochemical staining. A single dose of TCDD (dissolved in olive oil, 50 microg/kg) or olive oil alone was administrated to the rats by gavage. Compared with the vehicle-treated rat, a marked increase in the density of MEK immunoreactive cell bodies, fibers and terminals was found 2 weeks after TCDD treatment in the forebrain of the TCDD-treated rat, i.e. the central amygdaloid nucleus, field CA3 of the hippocampus, paraventricular hypothalamic nucleus, medial preoptic nucleus, interstitial nucleus of the posterior limb of the anterior commissure, lateral globus pallidus, ventral pallidum and lateral division of the bed nucleus of the stria terminalis. These results demonstrated for the first time a site-specific increased enkephalinergic activity in certain brain regions of the Long-Evans rat. It is suggested that the increased MEK immunoreactivity may act as a compensatory adaptation for the pathophysiological alterations caused by TCDD exposure.

Reduction in parasympathetic reflex vasodilatation following stereotaxic ear-bar insertion: importance of reduced afferent input.

As in our previous report, when cats were fitted with stereotaxic ear-bars 'type A' animals (26 out of 41) still exhibited a parasympathetic reflex lip blood flow (LBF) increase in response to lingual nerve stimulation, while in 'type B' animals (the remaining 15) it was greatly reduced or abolished. We compared (in both magnitude and in their sensitivity to hexamethonium, 10 mg/kg, i.v.) the LBF responses evoked by electrical stimulation of various sites within the reflex arc (lingual nerve, trigeminal ganglion, spinal trigeminal nucleus (Vsp)) in type A and type B animals to examine where the suppressive effect of ear-bar insertion might be exerted (using artificially ventilated, cervically vago-sympathectomized cats deeply anesthetized with alpha-chloralose and urethane). After ear-bar insertion: (a) in type A animals, stimulation of both lingual nerve and Vsp evoked a similar, hexamethonium-sensitive LBF increase; (b) in type B animals (in which lingual-nerve stimulation evoked no LBF increase), Vsp stimulation evoked a hexamethonium-sensitive LBF increase; (c) in both type A and type B animals, trigeminal ganglion stimulation consistently elicited an LBF increase (abolished by hexamethonium in type A, but reduced by only 50% in type B). These results suggest (i) that abolition of the lingual nerve-induced parasympathetic reflex vasodilatation by ear-bar insertion is due to reduced afferent traffic (in peripheral trigeminal or facial nerves) rather than to a damaged efferent output, and (ii) this effect in type B animals seems somehow to allow an antidromic (hexamethonium-insensitive) vasodilatation to occur on trigeminal ganglion stimulation.

Role of the vestibular nuclei in endothelin-1-induced barrel rotation in rats.

The fourth or lateral ventricular injection of endothelin-1 resulted in a dose-dependent increase in the barrel rotation and produced marked induction of c-Fos-positive cells in the vestibular nuclei. The doses of the former injection were lower and had shorter mean latent periods compared with the later injection. c-Fos expression after endothelin-1 injection was prevented by the pretreatment with the endothelin ET(A) receptor antagonist, cyclo(D-alpha-aspartyl-L-propyl-D-valyl-L-leucyl-D-tryptophyl) (BQ-123), the glutamate NMDA receptor antagonist, dizocilpine maleate (MK-801), or the L-type Ca(2+) channel antagonist, verapamil, in addition to the incidence of the rotational behavior. There was a significant difference in c-Fos expression between the right and left medial vestibular nuclei, and the number of c-Fos-labeled neurons in the medial vestibular nucleus was markedly increased on the opposite side of the rotational direction. These results suggest that the elicitation of the barrel rotation may be mediated by endothelin ET(A) receptors, glutamate NMDA receptors, and L-type Ca(2+) channels. The changes in the receptor and channel systems induced by endothelin-1 injections appeared to exert crucial influences on the vestibular nuclei and then on the maintenance of equilibrium. The direction of the barrel rotation has a deep connection with the imbalance of neuronal activity in the left and right medial vestibular nuclei.

Simultaneous measurement of parasympathetic reflex vasodilator and arterial blood pressure responses in the cat.

We measured the changes in lower lip blood flow and systemic arterial blood pressure evoked by lingual nerve or trigeminal spinal nucleus (Vsp) stimulation to gain an insight into the brainstem integration of sympathetic and parasympathetic responses to nociceptive stimulation. We used artificially ventilated, cervically vago-sympathectomized cats deeply anesthetized with alpha-chloralose and urethane. A lip blood flow increase occurred in an intensity- and frequency-dependent manner following electrical stimulation of Vsp or lingual nerve regardless of whether systemic arterial blood pressure increased or decreased. In contrast, there was no apparent optimal frequency for the changes in systemic arterial blood pressure elicited by electrical stimulation of Vsp or lingual nerve. No relationship was found between the amplitude of the lip blood flow increase and that of the systemic arterial blood pressure change. Microinjection of lidocaine or kainic acid into the Vsp evoked, respectively, reversible and irreversible inhibition of the lip blood flow increase and systemic arterial blood pressure change evoked by lingual nerve stimulation. When microinjected unilaterally directly into the ipsilateral Vsp, the GABA agonist muscimol abolished both lingual nerve-evoked effects (increase in lip blood flow and changes in systemic arterial blood pressure) without changing basal systemic arterial blood pressure, suggesting the presence in the Vsp of GABA receptors serving to modulate both the parasympathetically mediated lip blood flow increase and the sympathetically mediated systemic arterial blood pressure change. Lidocaine microinjection into the salivatory nucleus caused a significant attenuation of the lingual nerve-induced blood flow increase, but had no effect on the lingual nerve-induced systemic arterial blood pressure change. Thus, the neural pathway mediating the lingual nerve-induced lip blood flow increase seems to be simple, requiring a minimum of four neurons: trigeminal afferent-Vsp-parasympathetic pre-ganglionic neurons with cell body located in the inferior salivatory nucleus-otic postganglionic neuron. On the other hand, the pathway underlying the evoked systemic arterial blood pressure changes, presumably mediated via altered sympathetic activity, seems to be more complicated and could be affected by more numerous factors.