Peripheral and central substrates involved in the rostrad transmission of nociceptive information

Thermal sensation and the skin sensation test: regional differences and their effects on the issue of reliability of temperature ranges

This study assesses the differences in temperature sensitivity of skin areas. The subjects were required to associate the water content of test-tubes with the different heat sensations. The side of the test-tube was placed on the skin area and the temperature was matched with the subject's response. Analyses were limited to the warmth and cold sensations as generalizations can be made from these in terms of differences in the skin areas in heat perception. In the face, the temperature associated with warmth was significantly lower than in the forearm and the leg. This trend was different between the three areas in terms of the cold temperatures. The intra-individual difference suggests that results of skin sensation tests should be interpreted with some caution.

Specificity of Sensory and Motor Neurons Associated with BL40 and GB30 in the Rat: A Dual Fluorescent Labeling Study

The purpose of this study is to investigate the specific innervations on “Weizhong” (BL40) and “Huantiao” (GB30) by using a dual neural tracing technique. After Alexa Fluor 488 and 594 conjugates of cholera toxin subunit B (AF488/594-CTB) were, respectively, injected into BL40 and GB30 in the same rat, the labeled sensory and motor neurons were examined in the rat's dorsal root ganglia (DRGs) and spinal cord at thoracic (T) and lumbar (L) segments with a laser scanning confocal microscope. In the cases of BL40 injection, AF488-CTB labeled sensory and motor neurons were located in L_2–6 DRGs and on the mediolateral part of spinal ventral horn from L₃ to L₅ segments, respectively. By contrast, in the cases of GB30 injection, AF594-CTB labeled sensory and motor neurons were distributed in T₁₃-L₆ DRGs and on the anterolateral part of spinal ventral horn from L₁ to L₅ segments, respectively. These results indicate that the sensory and motor neurons associated with BL40 and GB30 are located in different spinal segments and regions in the nervous system, providing the neuroanatomical evidence to serve the specificity of acupoints.

Evaluation of analgesic effect of two different doses of fentanyl in combination with bupivacaine for surgical site infiltration in cases of modified radical mastoidectomy: A double blind randomized study

Background:

Limited evidence supports the efficacy of peripheral route fentanyl and local anesthetic combination for postoperative analgesia. Our study was therefore designed to demonstrate the analgesic efficacy of two different doses of fentanyl in combination with bupivacaine for surgical site infiltration in patients undergoing modified radical mastoidectomy (MRM).

Materials and Methods:

60 patients undergoing MRM under general anesthesia were randomly allocated into two groups, first group receiving 0.5% bupivacaine at a dose of 2 mg/kg body weight with 50 μg fentanyl and second group receiving bupivacaine 0.5% at a dose of 2 mg/kg body weight with 100 μg fentanyl as infiltration of operative field in and around the incision site, after the incision and just before completion of surgery. In postoperative period pain, nausea-vomiting and sedation was recorded at 0 hr, 2, 4, 6, 12 and 24 hrs.

Results:

Both the combinations of bupivacaine and fentanyl (Group I and Group II) were effective for postoperative analgesia. In both the groups the Visual Analogue Scale (VAS) score was less than 3 at each time interval. None of the patients required rescue analgesia. The comparison of VAS scores at different intervals showed that group II had lower VAS scores at all time points.

Conclusions:

Fentanyl and bupivacaine combinations in doses of 50 and 100 μg along with 0.5% bupivacaine at a fixed dose of 2 mg/kg body weight are effective in the management of postoperative pain. Patients who received 100 μg fentanyl (Group II) had lower VAS scores as compared to the patients who received 50 μg fentanyl (Group I) with similar side effects.

Acupuntura no cuidado de enfermagem ao paciente com cisto pilonidal: um relato de experiência assistencial

O presente estudo de caso assistencial, com caráter qualitativo, descritivo e participante, denota o uso da acupuntura no tratamento complementar de um paciente em acompanhamento médico e de enfermagem, possuindo cisto pilonidal sacrococcígeo recidivo com complicação infecciosa nos tecidos circunjacentes. Tem como objetivo identificar esse suporte em saúde complementar como uma estratégia potencial de utilização nos cuidados de enfermagem implementados aos pacientes. Observou-se que a acupuntura e o acompanhamento multiprofissional beneficiaram a recuperação tecidual local, o combate à infecção, contribuindo sobremaneira, ao fazer a consulta de enfermagem, para o enfrentamento positivo da enfermidade e a melhor adesão do paciente às orientações dos cuidados de enfermagem. De imediato, observa-se a necessidade de maiores estudos e aprofundamentos científicos sobre as contribuições das práticas orientais em saúde na enfermagem.

Slack and Slick KNa channels are required for the depolarizing afterpotential of acutely isolated, medium diameter rat dorsal root ganglion neurons

AIM

Na+-activated K+ (K(Na)) channels set and stabilize resting membrane potential in rat small dorsal root ganglion (DRG) neurons. However, whether K(Na) channels play the same role in other size DRG neurons is still elusive. The aim of this study is to identify the existence and potential physiological functions of K(Na) channels in medium diameter (25-35 microm) DRG neurons.

METHODS

Inside-out and whole-cell patch-clamp were used to study the electrophysiological characterizations of native K(Na) channels. RT-PCR was used to identify the existence of Slack and Slick genes.

RESULTS

We report that K(Na) channels are required for depolarizing afterpotential (DAP) in medium sized rat DRG neurons. In inside-out patches, K(Na) channels represented 201 pS unitary chord conductance and were activated by cytoplasmic Na+ [the half maximal effective concentration (EC50): 35 mmol/L] in 160 mmol/L symmetrical K+o/K+i solution. Additionally, these K(Na) channels also represented cytoplasmic Cl(-)-dependent activation. RT-PCR confirmed the existence of Slack and Slick genes in DRG neurons. Tetrodotoxin (TTX, 100 nmol/L) completely blocked the DRG inward Na+ currents, and the following outward currents which were thought to be K(Na) currents. The DAP was increased when extracellular Na+ was replaced by Li+.

CONCLUSION

We conclude that Slack and Slick K(Na) channels are required for DAP of medium diameter rat DRG neurons that regulate DRG action potential repolarization.

Contusive spinal cord injury evokes localized changes in NADPH-d activity but extensive changes in Fos-like immunoreactivity in the rat

The histological detection of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d), a marker for nitric oxide-producing cells, was used to evaluate ongoing changes in the neural biochemistry of the rat spinal cord 1 week following contusive spinal cord injury (SCI). In addition, the immunohistochemical detection of the immediate-early gene c-fos was used to identify basal patterns of neural activity at this time. The numbers and laminar locations of NADPH-d- and c-fos-positive cells were examined in spinal segments adjacent to the site of injury (T12-S3) as well as those distant from the injury (C3-C5) in both SCI and un-injured rats. Our data show that contusive SCI results in a significant reduction in NADPH-d labelling in the superficial dorsal horn, and a significant increase in NADPH-d expression in small bipolar neurons and large motoneurons in the ventral horn at the site of the injury. In spinal segments distant to the injury site (C3-C5), NADPH-d activity did not differ from that of uninjured controls. Furthermore, significant reductions in the levels of c-fos expression were observed in SCI rats, in spinal segments both at and distant to the site of injury for all spinal laminae. The only exception was a dramatic increase observed in the sacral parasympathetic nucleus. These data suggest that increased NADPH-d expression is related to conditions specific to the site of injury, whereas the changes in c-fos expression probably indicate more global changes in neuronal activity following SCI.

Effects of ageing on touch

A decline in the main sensory modalities is well reported to occur with ageing. This article outlines the normal pathways involved in touch sensation and includes a review of available evidence relating to the study of ageing and touch. The authors try to use what is known about the neuroanatomy and neurophysiology of ageing to explain the impact on some broad functional deficits seen in the elderly population. The importance of understanding how the normal ageing process affects touch sensation is emphasised.

The involvement of central cholinergic system in (+)-matrine-induced antinociception in mice

The antinociceptive effect of (+)-matrine was examined in mice by writhing, tail-pressure and hot-plate tests. (+)-Matrine (5, 10 and 20 mg/kg s.c.) produced antinociception in a dose-dependent manner. In hot-plate test, the antinociception produced by (+)-matrine (10 mg/kg s.c.) was attenuated by muscarinic receptor antagonists atropine (5 mg/kg i.p.) and pirenzepine (0.1 mug/mouse i.c.v.) and acetylcholine depletor hemicholinium-3 (HC-3) (1 mug/mouse i.c.v.), but not by opioid receptor antagonist naloxone (2 mg/kg i.p.), dopamine D(2) receptor agonist (-)-quinpirole (0.1 mg/kg i.p.) or catecholamine depletor reserpine (2.5 mg/kg i.p.). Radioligand binding assay demonstrated that (+)-matrine had no affinity for mu-, kappa- or delta-opioid receptors in a wide concentration range (1 x 10(-11)-1 x 10(-3) M). The results suggest that (+)-matrine exerts its antinociceptive effect through multiple mechanism(s) such as increasing cholinergic activation in the CNS rather than acting on opioid receptors directly.

Opioid research in amphibians: an alternative pain model yielding insights on the evolution of opioid receptors

This review summarizes the work from our laboratory investigating mechanisms of opioid analgesia using the Northern grass frog, Rana pipiens. Over the last dozen years, we have accumulated data on the characterization of behavioral effects after opioid administration on radioligand binding by using opioid agonist and antagonist ligands in amphibian brain and spinal cord homogenates, and by cloning and sequencing opioid-like receptor cDNA from amphibian central nervous system (CNS) tissues. The relative analgesic potency of mu, delta, and kappa opioids is highly correlated between frogs and other mammals, including humans. Radioligand binding studies using selective opioid agonists show a similar selectivity profile in amphibians and mammals. In contrast, opioid antagonists that are highly selective for mammalian mu, delta, and kappa opioid receptors were not selective in behavioral and binding studies in amphibians. Three opioid-like receptor cDNAs were cloned and sequenced from amphibian brain tissues and are orthologs to mammalian mu, delta, and kappa opioid receptors. Bioinformatics analysis of the three types of opioid receptor cDNAs from all vertebrate species with full datasets gave a pattern of the molecular evolution of opioid receptors marked by the divergence of mu, delta, and kappa opioid receptor sequences during vertebrate evolution. This divergence in receptor amino acid sequence in later-evolved vertebrates underlies the hypothesis that opioid receptors are more type-selective in mammals than in nonmammalian vertebrates. The apparent order of receptor type evolution is kappa, then delta, and, most recently, the mu opioid receptor. Finally, novel bioinformatics analyses suggest that conserved extracellular receptor domains determine the type selectivity of vertebrate opioid receptors.

Bronchopulmonary afferent nerves

Vagal afferent nerves are the primary communication pathways between the bronchopulmonary system and the central nervous system. Input from airway afferent nerves to the CNS is integrated in the brainstem and ultimately leads to sensations and various reflex outputs. Afferent nerves innervating the airways can be classified into various distinct phenotypes. However, there is no single classification scheme that takes all features, including conduction velocity, cell body diameter, ganglionic origin, and stimuli to which they respond (modality) into account. At present, bronchopulmonary afferent nerves are typically considered to belong to one of three general categories, namely C-fibres, rapidly adapting stretch receptors (RARs), and slowly adapting stretch receptors (SARs). As our understanding of bronchopulmonary afferent nerves continues to deepen, we are likely to see more sophisticated classification schemes emerge. It is clear that the function of afferent fibres can be substantively influenced by airway inflammation and remodelling. The perturbations and perversions of afferent nerve function that occur during these states almost certainly contributes to many of the signs and symptoms of inflammatory airway disease. A more lucid characterization of bronchopulmonary afferent nerves, and a better understanding of the mechanisms by which these nerves influence pulmonary physiology during health and disease anticipates future research.

The relationship between movement-evoked versus spontaneous pain and peak expiratory flow after abdominal hysterectomy

The pathogenesis of postoperative lung dysfunction implies a role for movement-evoked pain (e.g., splinting/hypoventilation because of pain avoidance). However, interactions between evoked pain and respiratory physiology are poorly understood. Thus, we examined the relationship between evoked versus spontaneous pain and one index of pulmonary function. In 25 patients having undergone a hysterectomy, visual analog scale ratings (100 mm) for spontaneous pain (REST) and pain during sitting (SIT), forced expiration (BLOW), and coughing (COUGH) were measured together with peak expiratory flow (PEF) at eight time points during postoperative Days 1 and 2. Secondary outcome measures included oxygen saturation and oxygen requirements. Pain was significantly correlated with PEF for COUGH, SIT, BLOW, and REST at eight, seven, four, and two of the eight studied time points, respectively. Mean visual analog scale scores [SE] for COUGH (26.1 mm [1.7]) and SIT (21.5 mm [1.5]) were greater (P < 0.05) than REST (10.5 mm [0.8]), and COUGH was greater (P < 0.05) than BLOW (16.8 mm [1.3]). All pain measures diminished (P < 0.05), and PEF reductions improved (P < 0.05) across the study period. We hypothesize that the consistent negative correlation of COUGH-evoked pain with PEF is, in part, caused by avoidance of coughing, which ultimately limits deep inspiration, lung reexpansion, and clearance of secretions.

IMPLICATIONS

Movement-evoked pain may be an important contributor to postoperative complications, but its mechanisms are poorly understood. This study provides the first evidence that postoperative evoked pain correlates with lung function and highlights the need for future research on mechanisms and implications of this phenomenon.

Effects of ethosuximide, a T-type Ca(2+) channel blocker, on dorsal horn neuronal responses in rats

Plasticity in transmission and modulatory systems are implicated in mechanisms of neuropathic pain. Studies demonstrate the importance of high voltage-activated Ca(2+) channels in pain transmission, but the role of low voltage-activated, T-type Ca(2+) channels in nociception has not been investigated. The Kim and Chung rodent model of neuropathy [Pain 50 (1992) 355] was used to induce mechanical and cold allodynia in the ipsilateral hindpaw. In vivo electrophysiological techniques were used to record the response of dorsal horn neurones to innocuous and noxious electrical and natural (mechanical and thermal) stimuli after spinal nerve ligation. Spinal ethosuximide (5-1055 microg) exerted dose-related inhibitions of both the electrically and low- and high-intensity mechanical and thermal evoked neuronal responses and its profile remained unaltered after neuropathy. Measures of spinal cord hyperexcitability were most susceptible to ethosuximide. This study, for the first time, indicates a possible role for low voltage-activated Ca(2+) channels in sensory transmission.

Mechanical stimuli induce intracellular calcium response in a subpopulation of cultured rat sensory neurons

Cultured dorsal root ganglion neurons from newborn rats were mechanically deformed with a fine-tipped glass capillary, and the change in the intracellular Ca2+ concentration ([Ca2+]i) was recorded by Fura-2-based microfluorimetry. The deformation evoked elevation in [Ca2+]i from 18.7 +/- 5.4 nM (mean +/- S.E.M., n = 35) to 137.1 +/- 15.2 nM in some subpopulations of cells, especially those larger than 20 microm in diameter. The largest mechanosensitive cell group was that of cells 20-25 microm in diameter; 56% of the mechanosensitive cells were of this cell size. All of the cells larger than 25 microm in diameter displayed the Ca2+ increase when prodded. The depletion of extracellular Ca2+ diminished the Ca2+ elevation. Verapamil and nickel, blockers of voltage-dependent Ca2+ channels, did not influence the Ca2+ response, whereas gadolinium, a relatively selective blocker of mechanosensitive channels, diminished the response. Na+-free conditions did not influence the response. We concluded that the mechanical stimulation induced a Ca2+ influx in large dorsal root ganglion neurons through mechanosensitive Ca2+-permeable channels.

Calcium signaling in cold cells studied in cultured dorsal root ganglion neurons

Thermosensitive cold cells were identified in cultured dorsal root ganglion neurons from newborn rats. The neurons were loaded with a calcium indicator, Fura-PE3, and the change in intracellular Ca2+ concentration ([Ca2+]i) of the neurons was measured with microfluorimetry. Thirteen per cent of the cells responded to the cold stimulation. The diameter of the responder cells was 16.3+/-3.2 microm (mean+/-S.D., n = 25). The lowering of the temperature from 35 degrees C to 20 degrees C increased [Ca2+]i from 59.6+/-10.6 nM to 203.4+/-14.8 nM (n = 25). The [Ca2+]i response was dependent on the intensity of the cold stimulation. The depletion of extracellular Ca2+ diminished the Ca2+ elevation. However, a Na(+)-free condition did not influence the response. We concluded that the cold stimulation opens Ca2(+)-permeable channels in putative cold cells from dorsal root ganglion neurons.

Serotonergic modulation of hyperpolarization-activated current in acutely isolated rat dorsal root ganglion neurons

1. The effect of serotonin (5-HT) on the hyperpolarization-activated cation current (IH) was studied in small-, medium- and large-diameter acutely isolated rat dorsal root ganglion (DRG) cells, including cells categorized as type 1, 2, 3 and 4 based on membrane properties. 5-HT increased IH in 91 % of medium-diameter DRG cells (including type 4) and in 67 % of large-diameter DRG cells, but not other DRG cell types. 2. The increase of IH by 5-HT was antagonized by spiperone but not cyanopindolol, and was mimicked by 5-carboxyamidotryptamine, but not (+)-8-hydroxydipropylaminotetralin (8-OH-DPAT) or cyanopindolol. These data suggested the involvement of 5-HT7 receptors, which were shown to be expressed by medium-diameter DRG cells using RT-PCR analysis. 3. 5-HT shifted the conductance-voltage relationship of IH by +6 mV without changing peak conductance. The effects of 5-HT on IH were mimicked and occluded by forskolin, but not by inactive 1,9-dideoxy forskolin. 4. At holding potentials negative to -50 mV, 5-HT increased steady-state inward current and instantaneous membrane conductance (fast current). The 5-HT-induced inward current and fast current were blocked by Cs+ but not Ba2+ and reversed at -23 mV, consistent with the properties of tonically activated IH. 5. In medium-diameter neurons recorded from in the current clamp mode, 5-HT depolarized the resting membrane potential, decreased input resistance and facilitated action potential generation by anode-break excitation. 6. The above data suggest that in distinct subpopulations of DRG neurons, 5-HT increases cAMP levels via activation of 5-HT7 receptors, which shifts the voltage dependence of IH to more depolarized potentials and increases neuronal excitability.

Distinct ATP-activated currents in different types of neurons dissociated from rat dorsal root ganglion

Rat dorsal root ganglion neurons can be classified into at least three distinct groups based on cell size, afferent fiber diameter, electrophysiological properties, sensitivity to vanilloid agonists such as capsaicin, and function. In the present study, ATP-activated current in these neurons was characterized using whole-cell patch-clamp recording. Small diameter (<30 microm) cells had high capsaicin sensitivity, high affinity for ATP, and rapidly desensitizing ATP-activated current. Medium diameter (30-50 microm) cells had no capsaicin sensitivity, lower affinity for ATP and slowly desensitizing ATP-activated current. Large diameter (>50 microm) cells were insensitive to both capsaicin and ATP. These findings suggest that distinct types of ATP receptor-ion channels are expressed in different types of dorsal root ganglion neurons, and may contribute to the functional differences among these types of neurons.

Warm cells revealed by microfluorimetry of Ca2+ in cultured dorsal root ganglion neurons

Warm cells were identified by Fura-PE3-based microfluorimetry of Ca2+ in cultured dorsal root ganglion (DRG) neurons. In response to a physiologically relevant stimulus temperature (43 degrees C), a subpopulation of small DRG neurons from new born rats increased the intracellular Ca2+ concentration ([Ca2+]i). Seven percent of the cells responded to the warm stimulus. The stimulus evoked elevation in [Ca2+]i from 52.5 +/- 9.5 nM (mean +/- S.D., n = 18) to 171.0 +/- 15.6 nM in cells between 15 and 25 microns in diameter. The depletion of extracellular Ca2+ diminished the Ca2+ elevation. The Na(+)-free condition also diminished the response. We concluded that the heat stimulation opens nonselective cation channels in putative warm cells from DRG neurons.

Spinal cord stimulation is effective in the management of reflex sympathetic dystrophy

OBJECTIVE

The purpose of this study was to determine the efficacy of spinal cord stimulation (SCS) in patients with symptoms of reflex sympathetic dystrophy (RSD), a disabling clinical condition with significant consequences of morbidity and loss of productivity.

METHODS

We have used epidural SCS for pain control during the past 15 years. An analysis of our records revealed 12 consecutive patients diagnosed as having RSD before undergoing SCS. Eight of the 12 patients had undergone previous ablative sympathectomy. The mean age of the nine men and three women was 38.2 years. All suffered extremity injuries from a variety of causes.

RESULTS

All 12 patients experienced relief of pain after trial stimulation and had their systems permanently implanted. At an average of 41 months follow-up, all patients were using their stimulators regularly and only two were receiving adjunctive minor pain medication. The level of pain present pre- and postoperatively was determined by administering a modified McGill Pain Questionnaire and a visual analog scale to each patient. Eight patients reported excellent pain relief, and four patients described good results. Five minor complications occurred.

CONCLUSION

SCS is an effective treatment for the pain of RSD, including recurrent pain after ablative sympathectomy. The low morbidity of this procedure and its efficacy in patients with refractory pain related to RSD suggest that SCS is superior to ablative sympathectomy in the management of RSD.

Synchronicity of nociceptive and non-nociceptive adjacent neurons in the spinal dorsal horn of the rat: stimulus-induced plasticity

Current knowledge of spinal processing of sensory information is largely based on single-cell recordings; however, temporal correlation of multiple cell discharges may play an important role in sensory encoding, and single electrode recordings of several neurons may provide insights into the functions of a neuronal network. The technique was applied to the lumbar spinal dorsal horn of pentobarbital-anaesthetized rats during background activity, steady-state noxious heat stimulation (48 degrees C, 100 s), cold block spinalization or radiant heat-induced inflammation of the skin, and the recordings were evaluated by means of auto-correlation, autospectral and cross-correlation analysis. Background patterns obtained by these three methods were extremely stable in time. Autocorrelation with short lag peaks was observed in 72.2% of neurons (n = 223). Background correlated discharges were found in 83.6% of the neuron pairs (n = 134). Cross-correlation with a central peak, suggestive of common input to the recorded cells, was the most common pattern observed in almost all laminae and was associated with high incidence (91.8%) of overlapping receptive fields and with neurons with initial peak autocorrelation pattern. Cross-correlations with central trough were associated with increase autocorrelation patterns. Bilateral peaks in cross-correlation, suggestive of reverberating circuitry, were observed only for pairs of neurons located in laminae IV and V and were associated with rhythmic discharges in one or in both simultaneously-recorded neurons. Lagged peaks or troughs were observed in 4.6% and 2.2% of neuronal pairs, respectively. Long-lasting skin heating induced qualitative changes (pattern changes) in the cross-correlation of 21.6% of the neuron pairs and quantitative changes in 85.7% of them. During skin inflammation qualitative changes in the cross-correlation pattern were observed in 30.8% of the neuron pairs, and quantitative changes (strength and/or synchronization time) in about 57.7% of them. Spinalization induced quantitative changes in cross-correlation in the vast majority of neuron pairs. The results of the present study suggest that discharges of neighbouring spinal dorsal horn neurons are strongly synchronized probably by propriospinal and primary afferent sources. The existence of functional reverberating circuitry was also evidenced. Finally, the functional synchronicity in the spinal dorsal horn presents stimulus-induced plasticity which consists mainly of changes on the strength and/or time of the synchronization and rarely of activation of new connectivities.

Cholecystokinin octapeptide reverses the kappa-opioid-receptor-mediated depression of calcium current in rat dorsal root ganglion neurons

Although the cholecystokinin octapeptide (CCK-8) is reported to antagonize the kappa-opioid-receptor-mediated analgesic effect in spinal cord, its mechanism and sites of action remain obscure. In the present study, the whole-cell patch-clamp recording technique was employed to examine the effect of kappa-opioid agonist U50488H on voltage-gated calcium channels and the interaction between the CCK-8 and U50488H in acutely isolated rat dorsal root ganglion neurons. The results indicate that the calcium currents elicited in dorsal root ganglion neurons can be depressed by U50488H, an effect readily reversed by the kappa-opioid receptor antagonist Nor-BNI or by the antiopioid peptide CCK-8. The effect of the CCK-8 can be abolished by the CCK-B receptor antagonist, L365,260. While CCK-8 showed a potent opioid-reversal effect, it by itself exerted a slight inhibitory effect on calcium current. This novel observation in the dorsal root ganglion neurons indicates that CCK-8 can antagonize the kappa-opioid-receptor-mediated depressant effect on voltage-gated calcium current, and this antagonizing effect appears to be mediated via CCK-B receptor.

Treatment of chronic paranasal sinus pain with minimal sinus disease

A common problem for otolaryngologists are patients who present with recurrent, persistent sinus pain that appears out of proportion to the findings on physical examination. Often these patients have a history of recurrent sinusitis that required antibiotics or surgical intervention. Many have had repeated surgical procedures because of this pain. Other common past medical histories may include allergic rhinitis, facial trauma, or dental disease. Patients who have experienced documented acute sinusitis in the past will often present de novo with similar symptoms, but lack any objective evidence of a new active sinus infection. However, the diagnosis of sinusitis is not clearly removed from the patient's or clinician's mind, and the patient is further frustrated by the lack of adequate diagnosis, treatment, and resolution of symptoms. These patients may or may not be experiencing an upper respiratory tract infection or allergy with nasal drainage. Often, they are emotionally distraught from recurrent and persistent pain, the lack of resolution of their symptoms, dependency on narcotics and other analgesics, multiple consultations with a variety of clinicians, and the impingement of their symptoms on employment, interpersonal relationships, and societal and family obligations. If sinusitis is not found to be present, the otolaryngologist must help the patient understand this point, reassure him or her that the otolaryngologist will still be vigilant for the development of sinusitis, and refocus the history and workup for some other cause of the recurrent and persistent paranasal pain. We review various treatment approaches to paranasal pains that are not the result of sinusitis.

The effect of age on A delta- and C-fibre thermal pain perception

It has been suggested that ageing may have a differential effect on C fibre-mediated protopathic/tonic pain versus epicritic/phasic pain perception mediated by A delta fibres. The present study attempted to independently assess age-related changes in the function of A delta- and C-nociceptive fibres by examining CO2 laser-induced thermal pain thresholds before, during and after a compression block of the superficial radial nerve in 15 young and 15 healthy elderly adult subjects. Nerve block efficacy was monitored via measures of cold, warm and mechanical threshold, and simple reaction time. During nerve compression block, reaction time and mechanical threshold increased, cold sensation became impaired while warm sensation remained unaffected throughout the test in both groups. With respect to pain sensitivity, young adults exhibited significant increases in thermal pain threshold during A-fibre block while pain threshold remained relatively stable across the 3 test periods in the elderly group. It would appear that elderly adults rely predominantly on C-fibre input when reporting pain whereas younger adults utilise additional input from A delta fibres. Subsequent analysis revealed that during pre- and post-block periods, older adults exhibited a significant elevation in thermal pain threshold; however, when A delta-fibre function was impaired and only C-fibre information was available, both groups responded similarly. These findings support the notion of a differential age-related change in A-fibre-mediated epicritic pain perception versus C-fibre-mediated protopathic pain.

Bradykinin-evoked release of [3H]noradrenaline from the human neuroblastoma SH-SY5Y

Bradykinin (BK) evoked [3H]noradrenaline ([3H]NA) release from the human neuroblastoma SH-SY5Y and this was enhanced by pre-treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) for 8 min. This effect of BK was inhibited by 500 microM [D-Phe7]BK and 100 microM [Thi5,8,D-Phe7]BK but not by 500 microM [Des-Arg9,Leu8]BK. The BK (B1)-agonist [Des-Arg9]BK did not evoke [3H]NA release. This suggested that SH-SY5Y expressed BK (B2)-receptors coupled to the release of [3H]NA. BK acting at B2-receptors, also elevated intracellular calcium and depolarized SH-SY5Y cells. Although pre-treatment of SH-SY5Y cells with TPA enhanced BK-evoked [3H]NA release, the elevation of intracellular calcium [Ca2+]; was decreased by about 50%. BK-evoked release of [3H]NA in cells not pre-treated with phorbol ester was only 23% dependent on extracellular calcium. In comparison, following phorbol ester treatment approximately 40% of [3H]NA release was dependent on extracellular calcium. Nifedipine (5 microM), CoCl2 (1 mM) and NiCl2 (1 mM) inhibited NA release in SH-SY5Y cells pre-treated with TPA by 16.0, 47 and 44%, respectively. The results of this study showed that BK, acting at B2-receptors, activated [3H]NA release in SH-SY5Y. Part of this effect appeared to be due to activation of L-type calcium channels but the majority of BK-evoked [3H]NA release in SH-SY5Y cells appeared to depend on [Ca2+]i.

Preoperative infiltration of the surgical area enhances postoperative analgesia of a combined low-dose epidural bupivacaine and morphine regimen after upper abdominal surgery

In a randomized, blinded trial we assessed the value of adding preoperative infiltration of the surgical area with bupivacaine to a low dose epidural regimen for postoperative pain treatment. Forty-nine patients scheduled for major upper abdominal surgery during combined thoracic epidural (bupivacaine + morphine) and general anaesthesia were studied. Postoperative analgesia was epidural bupivacaine 10 mg/hr-1 + morphine 0.2 mg/hr-1 for 72 h. The patients randomly received preoperative infiltration of the surgical area with bupivacaine 0.25%, 40 ml (group I); or no infiltration (group II). Pain was evaluated at rest, during cough and during mobilization six and eight h after start of surgery, and at 8 a.m. and 4 p.m. on the following days until 72 h after start of surgery. The sensory level of analgesia was evaluated by pin prick. We found no difference between the two groups during rest and cough. However, during mobilization group I had lower pain scores compared to group II (P < 0.05). There was a significant reduction in the need for supplemental intramuscular morphine in the treatment group compared to the control group (P < 0.05). Thus an enhanced analgesic effect was demonstrated by adding preoperative infiltration of the surgical area with local anaesthetic to a low dose epidural bupivacaine/morphine regimen after upper abdominal surgery.

Purification and characterisation of B2 bradykinin receptor from rat uterus

A B2 bradykinin (BK) receptor was solubilised and partially purified from rat uterine membranes by a combination of ammonium sulphate precipitation, desalting on Sephadex G-50, and hydroxyapatite and wheat germ agglutinin affinity chromatography. The partially purified BK receptor, enriched 1,500-fold, was then cross-linked to 125I-Tyr0-BK using disuccinimidyl suberate and purified to homogeneity as a single protein species on two-dimensional gel electrophoresis with a molecular mass of 81 kDa. This molecular size was in agreement with the value of 80-120 kDa estimated from Sephacryl 300 size exclusion column chromatography of the B2 receptor. The partially purified and the crude solubilised B2 BK receptor from rat uterus showed similar affinities for BK and the BK analogues iodo-Tyr0-Bk, D-Phe7-BK, and des-Arg9-BK, indicating that the ligand binding specificity of the receptor had been retained during the purification procedures. The biochemical properties of the solubilised B2 BK receptor correspond to those of a hydrophobic acidic glycoprotein (isoelectric focusing gave a value of 4.5-4.7) that binds specifically to wheat germ agglutinin but has no affinity for either concanavalin A or lentil lectin, suggesting the absence of terminal mannose or glucose residues.

Postoperative epidural analgesia

Administration of epidural opioids is a technique that is currently being used by many veterinary anesthesiologists and surgeons to provide postoperative analgesia. The duration of analgesia is prolonged and the degree of sedation is much less than that which occurs with parenterally administered opioids and the risks appears to be minimal.

Modulation of voltage-activated Ca currents by pain-inducing agents in a dorsal root ganglion neuronal line, F-11

Whole cell currents evoked by pain-inducing agents--bradykinin (Bk), capsaicin (Cap), and reciniferatoxin (RTX), and their modulation of voltage-activated Ca currents were examined in F-11 cells using a patch electrode voltage clamp technique. Most F-11 cells generated action potentials under current clamp if their membrane potentials were held sufficiently negative. Average peak inward Na current (INa) was 100 microA/cm2 and the INa was abolished by 10(-6) M tetrodotoxin. At least two types of Ca currents could be clearly distinguished on the basis of voltage dependency and kinetics; a low threshold transient ICa(t) and a high threshold sustained ICa(l). In addition, another high threshold transient Ca current, presumably ICa(n), was observed. About 30% of the cells produced inward current for these pain-inducing agents, when activated at the membrane holding potential of -70 mV. In some F-11 cells, the amplitude of action potential was observed to increase during 10(-6) M Cap-induced depolarization. Both low and high threshold Ca currents were reduced by 10(-6) M Bk in the majority of the cells. Similarly, both 10(-6) M Cap and 10(-9) M RTX reduced these Ca currents. However, a considerable number of cells showed an initial enhancement followed by reduction in the amplitude of these Ca currents. With higher concentrations of these ligands, all Ca currents were suppressed. Such modulation of voltage-activated Ca currents by pain-inducing agents occurred in both the presence and absence of apparent receptor-activated current flows in the cells. In pertussis toxin (PTX)-treated cells, the inhibitory modulation of Ca currents by pain-inducing agents was suppressed. In contrast, in cholera toxin (CTX)-treated cells, this inhibitory modulation appeared to be enhanced. These data indicate that the inhibitory modulation of Ca channel currents by Cap and RTX, similarly to that of Bk, involves a PTX-sensitive inhibitory G protein (Gi).

Behavior of patients with lung cancer: description and associations with oncologic and pain variables

Although reflexes are recognized as protective responses to noxious stimuli, less is known about voluntary behavioral responses to cancer pain, which could provide clinicians with important diagnostic and therapeutic information. Forty-five patients with lung cancer were studied in their homes on 2 occasions to identify pain behaviors and to examine relationships between behaviors and selected variables. Patients completed the McGill Pain Questionnaire (MPQ) and Visual Analogue scale (VAS). Using a videotape observation method, patients sat, stood, walked, and reclined for 10 min. Videotapes were scored using 5 position-related and 31 pain-related behavior definitions. Within 3 days scored behaviors were described to patients who reported whether each scored behavior was performed: to express pain; because pain prevented usual behavior; to control pain; or as a habit. Patients reported that pain was controlled by 42 different behaviors; the number of different pain-reduction behaviors was correlated with pain intensity (r = 0.44) and pain quality (r = 0.64). Simultaneous multiple regression indicated that length of time pain was experienced, number of pain sites, pain quality, and pain intensity accounted for 41% of the variance in the number of pain control behaviors. None of the taped behaviors was reported as performed to express pain, and few of the patients reported that pain prevented behavior during the video session. Results clarify the pain-behavior construct, provide insight about the multidimensional nature of lung cancer pain, and suggest directions for behavioral interventions to augment pharmacological therapy for lung cancer pain.

Bradykinin stimulates arachidonic acid release through the sequential actions of an sn-1 diacylglycerol lipase and a monoacylglycerol lipase

In cultured dorsal root ganglion (DRG) neurons prelabeled with [3H]arachidonic acid [( 3H]AA), bradykinin (BK) stimulation resulted in increased levels of radioactive diacylglycerol, monoacylglycerol, and free AA. The transient increases in content of radioactive diacylglycerol and monoacylglycerol preceded the increase in level of free AA, suggesting the contribution of a diacylglycerol lipase pathway to AA release. An analysis of the molecular species of diacylglycerols in unstimulated cultures revealed the presence of two primary [3H]AA-containing species, 1-palmitoyl-2-arachidonoyl and 1-stearoyl-2-arachidonoyl diacylglycerol. BK stimulation resulted in a preferential increase in content of 1-stearoyl-2-arachidonoyl diacylglycerol. When DRG cultures were labeled with [3H]stearic acid, treatment with BK increased the amount of label in diacylglycerol and free stearic acid, but not in monoacylglycerol. This result suggested that AA release occurred through the successive actions of an sn-1 diacylglycerol lipase and monoacylglycerol lipase. Other data supporting a diacylglycerol lipase pathway was the significant inhibition of [3H]AA release and consequent accumulation of diacylglycerol by RG 80267, which preferentially inhibits diacylglycerol lipase. Analysis of the molecular species profiles of individual phospholipids in DRG neurons indicated that phosphoinositide hydrolysis may account for a significant portion of the rapid increase in content of 1-stearoyl-2-arachidonoyl diacylglycerol. We were unable to obtain evidence that the phospholipase A2 pathway makes a significant contribution to BK-stimulated AA release in DRG cultures. Under our assay conditions there were no BK-stimulated increases in levels of radioactive lysophosphatidylinositol, lysophosphatidylcholine, or lysophosphatidylethanolamine in cultures prelabeled with [3H]inositol, [3H]choline, or [3H]-ethanolamine, respectively.

Brainstem excitatory amino acid receptors in nociception: Microinjection mapping and pharmacological characterization of glutamate-sensitive sites in the brainstem associated with algogenic behavior

In awake, freely moving rats, the intracerebral administration of the excitatory amino acid L-glutamate (30 nmol/0.5 microliters) into discrete regions of the brainstem resulted in a transient and spontaneous pain-like syndrome characterized by an initial vocalization and vigorous escape behavior. Systematic microinjection mapping studies were carried out at sites distributed caudally from the lower medulla and rostrally into diencephalon. These studies revealed that the spontaneous pain-like behavior was observed to occur after glutamate injection in 13% of 331 microinjected sites, and these sensitive sites were largely limited to the mesencephalic periaqueductal gray matter. The behavioral syndrome was dose-dependent and antagonized in a dose-dependent fashion by the glutamate receptor antagonists MK 801 and DL-2-amino-5 phosphonovalerate but not by gamma-D-glutamyl-amino-methylsulfonic acid. The pain-like behavior was also produced by the other excitatory amino acid receptor agonists N-methyl-D-aspartate, quisqualate and to a certain extent by kainate in a dose-dependent manner with the order of potency being N-methyl-D-aspartate = kainate greater than quisqualate greater than D-glutamate. The effects of N-methyl-D-aspartate and quisqualate were antagonized by MK 801 and DL-2-amino-5 phosphonovalerate but not by gamma-D-glutamyl-amino-methylsulfonic acid. It is suggested that the pain-like behavioral syndrome is the result of focal occupation of N-methyl-D-aspartate receptors on neuronal populations in the terminal regions of rostrally projecting spinomesencephalic systems.

NGC-evoked nociceptive behaviors: I. Effect of nucleus gigantocellularis stimulation

The role of the nucleus gigantocellularis (NGC) in nociception was examined by investigating behavioral responses that are supported by NGC stimulation in rats. Analyses indicated that NGC stimulation will support escape, active avoidance, and increases in behaviors that are thought to reflect fear in rats. A variety of behavior patterns were elicited by NGC stimulation, including gross peripheral motor movements such as walking, circling and rearing, and specific orofacial movements such as eye closure, ear movement, jaw opening and facial muscle contractions. No major differences in avoidance, affect, or escape behaviors were revealed between the various electrode placements, suggesting functional homogeneity within this neural region. The results of this study suggest that NGC stimulation generates several components of nociception, including behavioral arousal, autonomic nervous system-mediated responses, aversive affect, and motor responses.

Calcium current variation between acutely isolated adult rat dorsal root ganglion neurons of different size

1. The distribution of pharmacologically and/or biophysically unique Ca2+ current subtypes was studied in different diameter rat dorsal root ganglion (DRG) neuron cell bodies. DRG cells which fell into three diameter ranges, small (20-27 microns), medium (33-38 microns) and large (45-51 microns), were studied. T-type Ca2+ current was defined as low-threshold, rapidly inactivating current evoked by a weak test depolarization (-50 mV) from negative holding potentials (-80 to -100 mV), and which was sensitive to changes in holding potential. L-type Ca2+ current was defined as peak high-threshold Ca2+ current evoked from a holding potential of -60 mV and sensitive to blockade by 2 microM-nimodipine. N-type Ca2+ current was defined as peak high-threshold Ca2+ current evoked from a holding potential of -60 mV and sensitive to blockade by 0.9 microM-omega-conotoxin GVIA. 2. T-type Ca2+ currents were observed in small and medium diameter, but not in large diameter, DRG cell bodies. Large diameter DRG cell bodies had a small amount of low-threshold Ca2+ current but this current did not inactivate and was insensitive to a change in holding potential from -80 to -90 mV, and thus did not appear to be conducted through T-type Ca2+ channels. The T-type Ca2+ currents observed in medium diameter DRG cell bodies were considerably larger in amplitude (1-6 nA) than those observed in small diameter DRG cell bodies (100 pA-1 nA). This difference could not be accounted for by the difference in membrane surface area of small versus medium diameter DRG cell bodies. 3. The T-type Ca2+ currents observed in medium diameter DRG cells were sensitive to blockade by amiloride. Amiloride (500 microM) blocked 79.4 +/- 0.9% (mean +/- S.E.M.) of T-type Ca2+ current amplitude in six medium diameter DRG cell bodies which were held at -80 mV and depolarized to -50 or -40 mV. Amiloride (500 microM) failed to block high-threshold current in five medium diameter DRG cell bodies, indicating that it was specific for T-type Ca2+ current in these cells. 4. The percentage of peak whole-cell L-type Ca2+ current was significantly larger in small diameter DRG cell bodies (52.9 +/- 4.7% of total whole-cell Ca2+ current) than in medium diameter DRG cell bodies (6.6 +/- 3.9% of total whole-cell Ca2+ current) or large diameter DRG cell bodies (19.4 +/- 5.7% of total whole-cell Ca2+ current).(ABSTRACT TRUNCATED AT 400 WORDS)

Alternatives to the use of mammals for pain research

The study of pain and analgesia is an important area of biomedical research which has led to a number of significant advances in the treatment of acute and chronic pain in the clinic. This area of research examines the physiology of pain transmission and the pharmacology of analgesic drugs by employing a variety of in vitro and in vivo animal models. To date, the vast majority of in vivo models for pain research have used mammalian species, primarily rodents and, to a lesser extent, canines, felines, and primates. The present review summarizes the special considerations of animal use in pain research and the philosophic and scientific basis for developing adjunct models using lower vertebrates. Existent literature on pain research using non-mammalian vertebrates is reviewed, with a special focus on amphibian species. Given the ethical concerns of experimental animal use and the importance of a comparative approach to the basic understanding of pain-processing, the further development of non-mammalian models for pain research should be encouraged.

Identification of B2 bradykinin binding sites on cultured cortical astrocytes

Bradykinin was found to bind to specific high-affinity sites in cultured cortical astrocytes from rat brain, and this binding appeared to be specific for the B2 bradykinin receptor subtype. Nonlinear regression analysis of saturation experiments using a computer programme revealed a single KD of 16.6 +/- 2.6 nM and a Bmax of 352.2 +/- 30.7 fmol/mg of protein. These results indicate that astrocytes possess bradykinin receptors and that these are predominantly of the B2 subtype.

Substance P and neurodegenerative disorders. A speculative review

The causes of the neurodegenerative disorders of Parkinson's disease (PD), Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS) are unknown. It is proposed that all these disorders result primarily from a loss of trophic peptidergic neurotransmitter, possibly Substance P (SP). This loss in turn produces the classical neuronal degeneration seen in each of these diseases and occurs due to a combination of natural aging and chronic autoimmune destruction following a viral infection of the CNS, early in life. The loss is therefore slow and by the time of clinical presentation the inflammatory process is disappearing as the antigenic stimulus lessens with its removal. The implications of the theory in terms of future research and therapy are briefly discussed.

Synergistic analgesic interactions between the periaqueductal gray and the locus coeruleus

Opiates modulate pain perception at a number of different levels within the central nervous system and the importance of synergistic spinal and supraspinal influences have been well documented. In the present study we demonstrate synergistic interactions between the periaqueductal gray and locus coeruleus. Administered either systemically or intracerebroventricularly (i.c.v.), ethylketocyclazocine elicits a potent naloxonazine-sensitive analgesia, indicating a mu 1 action. mu 1 Receptors also play a major role in opioid analgesic mechanisms in the periaqueductal gray and the locus coeruleus. However, microinjection of EKC into either the periaqueductal gray or locus coeruleus failed to elicit an analgesic response at any dose tested (0.1-20 micrograms) and, in additional studies, antagonized the analgesic actions of coadministered morphine or [D-Ser2,Leu5]enkephalin-Thr6 (DSLET). However, the simultaneous administration of EKC into both the periaqueductal gray (10 micrograms) and the locus coeruleus (10 micrograms; total combined dose 20 micrograms) produced a potent naloxonazine-sensitive analgesia greater than that observed with 50 micrograms i.c.v. These results suggest that EKC is a partial mu 1 agonist which lacks the efficacy to elicit analgesia when microinjected into either of the two brain regions alone. However, when exposed to several regions at once, either through simultaneous microinjections into the periaqueductal gray and locus coeruleus or by injection into the ventricle, EKC is a potent mu 1 analgesic. These results point out the existence of synergistic supraspinal interactions between the periaqueductal gray and the locus coeruleus, similar to the spinal/supraspinal interactions observed previously.

Substance P- and calcitonin gene-related peptide immunoreactivity in primary afferent neurons of the cat's knee joint

The distribution of substance P and calcitonin gene-related peptide was determined in primary afferent neurons of the medial and posterior articular nerve of the cat's knee joint. Perikarya of articular afferents were visualized by retrograde labelling with the fluorescent dye Fast Blue which was applied at the transected end of the peripheral nerves. Substance P was found in about 17% of labelled medial articular afferents and in about 16% of labelled posterior articular afferents, respectively, whereas calcitonin gene-related peptide was present in about 35 and 32% of the medial and posterior articular nerve cells, respectively. Taking into account that these neuropeptides are known to be co-localized, probably not more than one-third of the joint afferents contain substance P and/or calcitonin gene-related peptide. Quantification of cell diameters revealed that substance P was found only in small- or intermediate-sized perikarya (less than 50 microns) indicating that this peptide is predominantly found in unmyelinated neurons. Calcitonin gene-related peptide was present mainly in small- and intermediate- but also in some large-sized neurons (greater than 50 microns) providing evidence that this peptide is found in unmyelinated and to a lesser extent in myelinated neurons. This is consistent with previous studies that show that substance P and calcitonin gene-related peptide are present primarily in unmyelinated and thinly myelinated primary afferents. When the portion of substance P-positive neurons of the medial articular nerve is compared to the number of articular afferents displaying a nociceptive function as determined in earlier electrophysiological studies, it can be calculated that at most 30% of the nociceptive-specific articular afferents contain this neuropeptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Centrally-mediated antinociceptive action of RWJ-22757 (formerly McN-5195): involvement of spinal descending inhibitory pathways (an hypothesis)

The present studies were an attempt to examine the mechanism of action of the novel antinociceptive compound RWJ-22757, (+/-)-trans-3-(2-bromophenyl)-octahydroindolizine (McN-5195). Intracerebroventricular (i.c.v.) administration of RWJ-22757 produced dose-related antinociception in the mouse tail-flick (48 degrees C) and rat hot-plate (51 degrees C) tests (ED50 = 243.3 and 261.3 micrograms, respectively). In contrast, intrathecal (i.t.) administration was without effect. The antinociception produced by peripherally (i.p.) or centrally (i.c.v.) administered RWJ-22757 was attenuated by i.t. administration of 2 micrograms phentolamine, 5 micrograms yohimbine, or 10 micrograms methysergide. I.t. administration of naloxone, at a dose (0.5 micrograms) that significantly attenuated the antinociceptive effects of peripherally or centrally administered morphine, had no effect on RWJ-22757-induced antinociception. We conclude from these results, coupled with the overall pharmacological and neurochemical profile of RWJ-22757, that the data are consistent with the hypothesis that RWJ-22757 produces antinociception predominantly at a site or sites located supraspinally with little or no activity at the spinal level and that RWJ-22757 activates adrenergic and serotonergic descending inhibitory pathways, increasing the tonic activity of endogenous antinociceptive systems.

[Acute pain in children and its treatment]

Pain in paediatrics has long been underestimated. The numerous scientific studies carried out during the last decade show that its existence can no longer be doubted: in fact, pain already exists during the neonatal period, and probably throughout the last trimester of gestation as well. Pain pathways mature during the embryonic period and peripheral receptors develop between the 7th and 20th week. A-delta and C fibers, as well as spinal roots and nerves, are completely differentiated before the end of the second month. The development of specific neurotransmitters and thalamic and cortical dendritic branching occurs later on; it is well enough developed to allow perception of painful stimuli (slow or protopathic component) from the beginning of the foetal period onwards. The discriminative rapid component develops in parallel to myelinisation, and the psycho-affective component, which requires a long and complex learning process, will not be fully operative until the end of puberty. Assessing pain, already a difficult task in the adult, is all the more so in children because of lesser verbal communicative capabilities, difficulty in handling abstract concepts, lack of experience of painful stimuli to make comparisons, and ignorance of their body image. In the very young child, diagnosing pain relies on suggestive circumstances, and an altered behaviour, knowing that no one symptom in pathognomonic. As the child grows up, methods for self-assessment of pain become usable, such as coloured scales and simplified verbal scales. However, behavioural tests remain the mainstay until the prepubertal period. The treatment of acute pain requires a reasoned approach which takes into account the state of the child, that of the aetiological investigations, the likely course of the lesions, as well as the patient's analgesic requirements. Therapeutic means do not differ from those for adult patients; however, the differences of distribution of body water, the small possibilities of linking with plasma proteins, and limited conjugation with glucuronate must be taken into account, especially during the first months of life. Local and regional anaesthetic block techniques are of great interest in elective and emergency surgery, as well as in trauma: they can provide complete pain relief, mostly without having any effect on the patient's physiological state (haemodynamics and consciousness). Peripherally acting analgesic agents, which are well supported on the whole, as well as co-analgesics, have a great part to play, although there are less drugs available than for adults. The most useful ones are paracetamol, followed by the salicylates, propionic acid derivatives and non steroid anti-inflammatory drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of descending inhibition and facilitation from the nuclei reticularis gigantocellularis and gigantocellularis pars alpha in the rat

Descending influences on the spinal nociceptive tail-flick (TF) reflex produced by focal electrical stimulation and glutamate microinjection in the nuclei reticularis gigantocellularis (NGC) and gigantocellularis pars alpha (NGC alpha) were examined and characterized in rats lightly anesthetized with pentobarbital. Both inhibition and facilitation of the TF reflex were produced by electrical stimulation at identical sites in the NGC/NGC alpha; glutamate microinjection only inhibited the TF reflex. The chronaxie of stimulation for inhibition of the TF reflex was 169 +/- 28 microseconds. Inhibition of the TF reflex by stimulation was produced throughout the NGC and NGC alpha; intensities of stimulation for inhibition were least in the ventral NGC and in the NGC alpha. At threshold intensities of stimulation, inhibition of the TF reflex did not outlast the period of stimulation. Facilitation of the TF reflex was produced at many of the same sites at which stimulation inhibited the TF reflex, but always at lesser intensities of stimulation (mean, 10 microA vs. 43 microA for inhibition, n = 25). Stimulation in the NGC/NGC alpha at threshold intensities for facilitation or inhibition of the TF reflex did not significantly affect blood pressure. Strength-duration characterization of electrical stimulation and microinjection of glutamate into identical sites in the NGC and NGC alpha suggest that descending inhibition of the TF reflex results from activation of cell bodies in the NGC and NGC alpha.

Characterization of bradykinin receptors solubilized from rat uterus and NG108-15 cells

In this paper we report the solubilization of bradykinin B2 binding sites from membranes prepared from NG 108-15 tumours and rat uterus with retention of binding activity. Digitonin was found to solubilize the receptors from both tissues, and the addition of CHAPS increased the yield of soluble receptor from rat uterus only. The affinity of a range of bradykinin analogues has been shown to have the same rank order for both the soluble and membrane receptors from both tissues, and in corresponding functional assays. In addition, the binding of bradykinin ligands to the soluble and membrane receptors is similarly modulated by the presence of sodium ions. We conclude that the soluble binding sites correspond to the physiological bradykinin B2 receptor present in these tissues.

Stimulation of mono- and diacylglycerol lipase activities by bradykinin in neural cultures

Neural cultures of fetal mouse spinal cord, mouse neuroblastoma (N1E-115) and mixed primary glial cell cultures from neonatal rat brain display measurable activities of mono- and diacylglycerol lipases. Treatment of fetal mouse spinal cord cultures with bradykinin (10 nM) for 1-4 min resulted in a marked increase in specific activities of mono- and diacylglycerol lipases. This is the first direct demonstration that bradykinin can act through the lipase pathway. The increase in activities of lipases was dose and time dependent. The bradykinin response was blocked by [Thi5,8, D-Phe7]bradykinin, a bradykinin B-2 receptor antagonist, indicating that the bradykinin induced stimulation of lipase activities involves bradykinin receptors.