Mandibular condylar process remodeling in rats with different bite-altering devices.

The objective was to compare different dental splint models and materials for inducing abnormal loading on the gross morphology and histological appearance of the mandibular condylar processes of Sprague Dawley rats. Three different types of dental splints (resin molar, aluminum incisor, stainless-steel incisor) were placed unilaterally to induce occlusal perturbation for 4 weeks. At that time, mandibular condylar processes were assessed by gross appearance and histology. Quantitative measurements were also conducted on the hematoxylin and eosin images for condyle shape. The results showed that although the condylar cartilage was affected by all splint types, the resin molar splint was associated with the most extensive mandibular condylar process remodeling, which was primarily a slant (skewness) of the lateral aspect of the condylar process. Additionally, quantitative measurements on the histological specimens demonstrated that the split and tilt angle of the left (ipsilateral) condylar processes in the resin molar group (124.8 ± 12.7° and 104.1 ± 12.7°, respectively) increased significantly (p < 0.05) when compared to right (contralateral) condylar processes (104.7 ± 5.8°and 91.6 ± 4.4°, respectively). However, no changes were noted on the thickness of the fibrocartilage layer at medial, central, and lateral regions of the condylar process. Another major finding is the high variability of morphology of the naïve animals. Future studies will assess the impact of longer durations of splinting, age, and sex on the remodeling of the mandibular condylar process, allowing for the development of diagnostics and therapies.

Recovery of brain structural abnormalities in morbidly obese patients after bariatric surgery.

BACKGROUND/OBJECTIVES: Obesity-related brain structural abnormalities have been reported extensively, and bariatric surgery (BS) is currently the most effective intervention to produce sustained weight reduction in overtly obese (OB) people. It is unknown whether BS can repair the brain circuitry abnormalities concomitantly with long-term weight loss. SUBJECTS/METHODS: In order to investigate whether BS promotes neuroplastic structural recovery in morbidly OB patients, we quantified fractional anisotropy (FA), mean diffusivity (MD) and gray (GM) and white (WM) matter densities in 15 morbidly OB patients and in 18 normal weight (NW) individuals. OB patients were studied at baseline and also 1 month after laparoscopic sleeve gastrectomy surgery. RESULTS: Two-sample t-test between OB (baseline) and NW groups showed decreased FA values, GM/WM densities and increased MD value in brain regions associated with food intake control (that is, caudate, orbitofrontal cortex, body and genu of corpus callosum) and cognitive-emotion regulation (that is, inferior frontal gyrus, hippocampus, insula, external capsule) (P<0.05, family-wise error correction). Paired t-test in the OB group between before and after surgery showed that BS generated partial neuroplastic structural recovery in the OB group, but the differences had relative less strength and smaller volume (P<0.001). CONCLUSIONS: This study provides the first anatomical evidence for BS-induced acute neuroplastic recovery that might in part mediate the long-term benefit of BS in weight reduction. It also highlights the importance of this line of gut-brain axis research employing the combined BS and neuroimaging model for identifying longitudinal changes in brain structure that correlated with obesity status.

Elevated IL-5 and IL-13 responses to egg proteins predate the introduction of egg in solid foods in infants with eczema.

BACKGROUND: Egg allergy is a leading cause of food allergy in young infants; however, little is known about early allergen-specific T-cell responses which predate the presentation of egg allergy, and if these are altered by early egg exposure. OBJECTIVE: To investigate the early T-cell responses to multiple egg proteins in relation to patterns of egg exposure and subsequent IgE-mediated egg allergy. METHODS: Egg-specific T-cell cytokine responses (IL-5, IL-13, IL-10, IFNγ and TNFα) to ovomucoid (OM), ovalbumin (OVA), conalbumin (CON) and lysozyme (LYS) were measured in infants with eczema at 4 months of age (n = 40), before randomization to receive 'early egg' or a placebo as part of a randomized controlled trial (Australian New Zealand Clinical Trials Registry number 12609000415202) and at 12 months of age (n = 58), when IgE-mediated egg allergy was assessed by skin prick test and food challenge. RESULTS: In 4-month-old infants, who had not directly ingested egg, those who subsequently developed egg allergy already had significantly higher Th2 cytokine responses to multiple egg allergens, particularly elevated IL-13 responses to OVA (P = 0.004), OM (P = 0.012) and LYS (P = 0.003) and elevated IL-5 to the same antigens (P = 0.031, 0.04 and 0.003, respectively). IL-13 responses (to OVA and LYS) and IL-5 responses (to LYS) at 4 months significantly predicted egg allergy at 12 months. All responses significantly declined with age in the egg-allergic infants, and this did not appear to be modified by 'early' introduction of egg. CONCLUSIONS & CLINICAL RELEVANCE: Elevated egg-specific Th2 cytokine responses were established prior to egg ingestion at 4 months and were not significantly altered by introduction of egg. Th2 responses at 4 months of age predicted egg allergy at 12 months, suggesting that this could be used as a biomarker to select infants for early prevention and management strategies.

The properties, distribution and function of Na(+)-Ca(2+) exchanger isoforms in rat cutaneous sensory neurons.

The Na(+)-Ca(2+) exchanger (NCX) appears to play an important role in the regulation of the high K(+)-evoked Ca(2+) transient in putative nociceptive dorsal root ganglion (DRG) neurons. The purpose of the present study was to (1) characterize the properties of NCX activity in subpopulations of DRG neurons, (2) identify the isoform(s) underlying NCX activity, and (3) begin to assess the function of the isoform(s) in vivo. In retrogradely labelled neurons from the glabrous skin of adult male Sprague-Dawley rats, NCX activity, as assessed with fura-2-based microfluorimetry, was only detected in putative nociceptive IB4+ neurons. There were two modes of NCX activity: one was evoked in response to relatively large and long lasting (∼325 nm for >12 s) increases in the concentration of intracellular Ca(2+) ([Ca(2+)]i), and a second was active at resting [Ca(2+)]i > ∼150 nm. There also were two modes of evoked activity: one that decayed relatively rapidly (<5 min) and a second that persisted (>10 min). Whereas mRNA encoding all three NCX isoforms (NCX1-3) was detected in putative nociceptive cutaneous neurons with single cell PCR, pharmacological analysis and small interfering RNA (siRNA) knockdown of each isoform in vivo suggested that NCX2 and 3 were responsible for NCX activity. Western blot analyses suggested that NCX isoforms were differentially distributed within sensory neurons. Functional assays of excitability, action potential propagation, and nociceptive behaviour suggest NCX activity has little influence on excitability per se, but instead influences axonal conduction velocity, resting membrane potential, and nociceptive threshold. Together these results indicate that the function of NCX in the regulation of [Ca(2+)]i in putative nociceptive neurons may be unique relative to other cells in which these exchanger isoforms have been characterized and it has the potential to influence sensory neuron properties at multiple levels.

Randomized controlled trial of fish oil supplementation in pregnancy on childhood allergies.

BACKGROUND: Diets high in n-3 long chain polyunsaturated fatty acids (LCPUFA) may modulate the development of IgE-mediated allergic disease and have been proposed as a possible allergy prevention strategy. The aim of this study was to determine whether n-3 LCPUFA supplementation of pregnant women reduces IgE-mediated allergic disease in their children. METHODS: Follow-up of children (n = 706) at hereditary risk of allergic disease in the Docosahexaenoic Acid to Optimise Mother Infant Outcome randomized controlled trial. The intervention group (n = 368) was randomly allocated to receive fish oil capsules (providing 900 mg of n-3 LCPUFA daily) from 21 weeks' gestation until birth; the control group (n = 338) received matched vegetable oil capsules without n-3 LCPUFA. The diagnosis of allergic disease was made during medical assessments at 1 and 3 years of age. RESULTS: No differences were seen in the overall percentage of children with IgE-mediated allergic disease in the first 3 years of life between the n-3 LCPUFA and control groups (64/368 (17.3%) vs 76/338 (22.6%); adjusted relative risk 0.78; 95% CI 0.58-1.06; P = 0.11). Eczema was the most common allergic disease; 13.8% of children in the n-3 LCPUFA group had eczema with sensitization compared with 19.0% in the control group (adjusted relative risk 0.75; 95% CI 0.53-1.05; P = 0.10). CONCLUSIONS: Overall, n-3 LCPUFA supplementation during pregnancy did not significantly reduce IgE-associated allergic disease in the first 3 years of life. Further studies should examine whether the nonsignificant reductions in IgE-associated allergies are of clinical and public health significance.

Sex differences in the inflammatory mediator-induced sensitization of dural afferents.

Approximately 20% of the adult population suffers from migraine. This debilitating pain disorder is three times more prevalent in women than in men. To begin to evaluate the underlying mechanisms that may contribute to this sex difference, we tested the hypothesis that there is a sex difference in the inflammatory mediator (IM)-induced sensitization of dural afferents. Acutely dissociated retrogradely labeled dural afferents from adult Sprague-Dawley rats were examined with whole cell patch-clamp recordings. Baseline passive and active electrophysiological properties of dural afferents from both sexes were comparable. However, while IM-induced increases in the excitability of dural afferents from male and female rats were also comparable, the proportion of dural afferents from female rats sensitized by IM (~100%) was significantly greater than that of dural afferents from male rats (~50%). This appeared to be due to differences downstream of IM receptors, as tetrodotoxin-resistant sodium current was increased by IM in a majority of male dural afferents (13/14). These data indicate that there are both quantitative and qualitative differences in the IM-induced sensitization of dural afferents that may contribute to the sex difference in the manifestation of migraine.

Legal impediments to data linkage.

Large numbers of electronic health data collections have been accumulated by both government and non-government agencies and organisations. Such collections primarily assist with the management of health services and the provision of health care programs, with only a minority of these data collections also intended for research purposes. A number of constraints are placed on access to such data for the purposes of research, including data linkage. This article examines those factors arising from the intricacies of Australia's privacy legislation landscape which impede access to such collections. The relevant issues discussed include issues relating to the existence of multiple privacy and health privacy Acts, the recommendations made by the Australian Law Reform Commission in relation to the Privacy Act 1988 (Cth) and the constraints placed on the conduct of data-linkage research which arise from legislation that relates specifically to certain data collections.

Efficacy of m-Health for the detection of adverse events following immunization - The stimulated telephone assisted rapid safety surveillance (STARSS) randomised control trial.

INTRODUCTION: Passive surveillance is recommended globally for the detection of adverse events following immunisation (AEFI) but this has significant challenges. Use of Mobile health for vaccine safety surveillance enables a consumer-centred approach to reporting. The Stimulated Telephone Assisted Rapid Safety Surveillance (STARSS) a randomised control trial (RCT) sought to evaluate the efficacy and acceptability of SMS for AEFI surveillance. METHODS: Multi-centre RCT, participants were adult vaccinees or parents of children receiving any vaccine at a trial site. At enrolment randomisation occurred to one of two SMS groups or a control group. Prompts on days 2, 7 and 14 post-immunisation, were sent to the SMS group, to ascertain if a medical event following immunisation (MEFI) had occurred. No SMS's were sent to the control participants. Those in the SMS who notified an MEFI were pre-randomised to complete a computer assisted telephone interview or a web based report to determine if an AEFI had occurred whilst an AEFI in the controls was determined by a search for passive reports. The primary outcome was the AEFI detection rate in the SMS group compared to controls. RESULTS: We enrolled 6,338 participants, who were equally distributed across groups and who received 11,675 vaccines. The SMS group (4,225) received 12,675 surveillance prompts with 9.8% being non-compliant and not responding. In those that responded 90% indicated that no MEFI had been experienced and 184 had a verified AEFI. 6 control subjects had a reported AEFI. The AEFI detection rate was 13 fold greater in the SMS group when compared with controls (4.3 vs 0.3%). CONCLUSION: We have demonstrated that the STARSS methodology improves AEFI detection. Our findings should inform the wider use of SMS-based surveillance which is particularly relevant since establishing robust and novel pharmacovigilance systems is critical to monitoring novel vaccines which includes potential COVID vaccines.

Consumer acceptability and validity of m-Health for the detection of adverse events following immunization - The Stimulated Telephone Assisted Rapid Safety Surveillance (STARSS) randomised control trial.

INTRODUCTION: Monitoring for adverse events following immunisation (AEFI) is critical for vaccine pharmacovigilance. Given the global and expanding availability of mobile phones their utility for consumer-based vaccine safety surveillance is of interest but little is known about consumer acceptability. This study nested within the Stimulated Telephone Assisted Rapid Safety Surveillance (STARSS) randomised control trial sought to evaluate the acceptability of SMS for AEFI surveillance. METHODS: The primary STARSS study was a multi-centre RCT evaluating the efficacy of repeated SMS prompts for AEFI surveillance with participants being adult vaccinees or parents of children receiving any vaccine. This nested study enrolled primary RCT participants who completed a detailed computer assisted telephone interview to determine their attitudes towards SMS-based surveillance and ascertain their knowledge and attitudes toward vaccine safety, efficacy, data privacy and use of electronic health records. Attitudes to surveillance and related behaviour were used as measures of acceptability. RESULTS: 20% (1200/6555) of the participants were enrolled and 1139 completed the full-length questionnaire. 96% indicated that SMS-based surveillance after immunisation to check the safety of the vaccine "should be done" but 62% of all respondents said it should be done but consent should be sought first. Neither vaccine safety attitudes nor attitudes toward privacy were associated with opposition to SMS-based surveillance. In terms of SMS related behaviour demographic rather than attitudinal factors were associated with non-compliance. CONCLUSION: Overall, the attitude towards SMS-based surveillance was very favourable. Experiencing the SMS surveillance has the effect of reducing opposition to an SMS surveillance system, and at the same time increasing the likelihood of a preference for prior consent. Detection of a vaccine safety signal could be impeded in particular demographic groups who are non-compliant and we should undertake further research to understand why these groups are non-compliant and how this can be improved.

HSV vector-mediated modification of primary nociceptor afferents: an approach to inhibit chronic pain.

Chronic pain is a serious medical condition with millions of sufferers for whom long-term therapies are either lacking or inadequate. Here we review the use of herpes simplex virus vectors as therapeutic tools to treat chronic pain by gene therapy. We describe an approach to inhibit chronic pain signaling whereby vector-mediated genes transferred to sensory nerves will modify the primary afferent nociceptor to prevent pain signaling to second-order nerves in the spinal cord. This approach may be used to reverse the chronic pain state of the nociceptor and could affect downstream pain-related changes in the central nervous system.

Bioequivalence study of low-dose diclofenac potassium tablet formulations.

BACKGROUND AND AIM: Diclofenac is a nonsteroidal antiinflammatory drug with potent analgesic and anti-inflammatory properties. An immediate-release formulation containing a low dose of 12.5 mg diclofenac-potassium (-K) is marketed as over the counter (OTC) medication in most European countries. An immediate-release formulation containing 25 mg diclofenac-K has now also been approved for OTC use. This study assessed the bioequivalence of two immediate-release diclofenac formulations when administered at the same dose. SUBJECTS AND METHODS: A randomized, crossover, open-label study was conducted in 29 healthy volunteers to assess the bioequivalence of single 25 mg dose of diclofenac-K in two formulations: 2 x 12.5 mg as film-coated tablets and 1 x 25 mg as sugar-coated tablet. Blood samples for pharmacokinetic analyses were obtained over 10 hours post administration. RESULTS: Plasma time courses of diclofenac were similar for the tested formulations. Mean AUC yen was 798 +/- 281 ng x h/ml (mean +/- SD) for the film-coated and 776 +/- 249 ng x h/ml for the sugar-coated formulation, respectively. The 2-sided 90% confidence interval for the mean test/reference ratio of AUCinfinity (95.5 - 107.5) fell within the predetermined equivalence range of 80 - 125%. Both formulations were rapidly absorbed; median time to maximal plasma concentration was 35 min in each group. Adverse events (peripheral erythema on the hand, headache, hypoesthesia) reported during the study were of mild severity and were considered as unlikely to be drug-related. CONCLUSION: The two diclofenac-K immediate release formulations were pharmacokinetically similar. It can be concluded that the new sugar-coated tablet formulation is equivalent to the available film-coated tablet formulation with respect to the extent of diclofenac absorption.

Inflammation-induced increase in evoked calcium transients in subpopulations of rat dorsal root ganglion neurons.

The concentration of intracellular Ca(2+) ([Ca(2+)](i)) influences neuronal properties ranging from excitability to neurotransmitter release. Persistent inflammation is associated with changes in the properties of primary afferent neurons ranging from excitability to transmitter release. The purpose of the present study was to determine whether previously described inflammation-induced changes in excitability and transmitter release are associated with changes in the regulation of [Ca(2+)](i). Acutely dissociated dorsal root ganglion (DRG) neurons harvested from adult rats 3 days following a hind-paw injection of complete Freund's adjuvant (CFA) or naïve controls, were stimulated with 30 mM K(+) (High K(+)). High K(+) evoked changes in [Ca(2+)](i) were assessed with fura-2 ratiometric microfluorimetry. Subpopulations of DRG neurons were defined by cell body diameter, isolectin B4 (IB4) binding, capsaicin (CAP) sensitivity and target of innervation (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbo-cyanine perchlorate labeling). Inflammation was associated with significant increases in resting [Ca(2+)](i) and increases in the magnitude and decreases in the decay, of the evoked increase in [Ca(2+)](i). The changes in evoked transients were larger in neurons innervating the site of inflammation. Furthermore, there were differences among subpopulations of DRG neurons with respect to changes in magnitude and/or decay of the evoked transient such that the increase in magnitude was larger in small- and medium-diameter neurons than in large diameter neurons while the decrease in the decay was greater in CAP responsive, IB4 positive, small- and medium-diameter neurons than in CAP unresponsive, IB4 negative and/or large-diameter neurons. These changes in the regulation of [Ca(2+)](i) were not due to inflammation-induced changes in passive or active electrophysiological properties. Importantly, an inflammation-induced increase in evoked Ca(2+) transients in putative nociceptive afferents may contribute to the pain and hyperalgesia associated with persistent inflammation via facilitation of transmitter release from these afferents.

Effect of maternal egg consumption on breast milk ovalbumin concentration.

BACKGROUND: Maternal dietary avoidance of egg has been recommended to treat egg allergy in breastfed infants. However, only one of three randomized controlled trials have produced evidence in favour of this recommendation. OBJECTIVE: Our objective was to assess human milk ovalbumin (OVA) concentration after daily maternal ingestion of one cooked egg for 3 weeks. METHODS: Mothers with egg-sensitive, eczematous breastfed infants were randomly allocated to consume one muffin per day containing one egg (egg group, n=16) or a similar egg-free muffin (control group, n=16) for 21 days (Days 3-23). All mothers and infants followed an egg-free diet. Breast milk samples were collected at two hourly intervals for 6 h after eating the test muffins on Days 3, 12 and 23 and breast milk OVA concentration measured. Infant eczema was assessed at the commencement and completion of the trial. RESULTS: Women in the egg group had higher OVA concentrations in breast milk than the control group at all time-points. Within each dietary group, OVA excretion did not change with time. OVA was not detected in breast milk of 25% of women in the egg group. In contrast, infant eczema symptom scores significantly reduced with time for both groups. CONCLUSION: Human milk OVA is related to maternal dietary egg intake, but a significant proportion of women either have a delayed excretion or may not excrete OVA in their breast milk.

Serotonin type 1D receptors (5HTR) are differentially distributed in nerve fibres innervating craniofacial tissues.

We tested the hypothesis that the 5HT(1D)R, the primary antinociceptive target of triptans, is differentially distributed in tissues responsible for migraine pain. The density of 5HT(1D)R was quantified in tissues obtained from adult female rats with Western blot analysis. Receptor location was assessed with immunohistochemistry. The density of 5HT(1D)R was significantly greater in tissues known to produce migraine-like pain (i.e. circle of Willis and dura) than in structures in which triptans have no antinociceptive efficacy (i.e. temporalis muscle). 5HT(1D)R-like immunoreactivity was restricted to neuronal fibres, where it colocalized with calcitonin gene-related peptide and tyrosine hydroxylase immunoreactive fibres. These results are consistent with our hypothesis that the limited therapeutic profile of triptans could reflect its differential peripheral distribution and that the antinociceptive efficacy reflects inhibition of neuropeptide release from sensory afferents. An additional site of action at sympathetic efferents is also suggested.

Mechanotransducers in rat pulpal afferents.

The hydrodynamic theory suggests that pain associated with stimulation of a sensitive tooth ultimately involves mechanotransduction as a consequence of fluid movement within exposed dentinal tubules. To determine whether putative mechanotransducers could underlie mechanotransduction in pulpal afferents, we used a single-cell PCR approach to screen retrogradely labeled pulpal afferents. The presence of mRNA encoding BNC-1, ASIC3, TRPV4, TRPA1, the alpha, beta, and gamma subunits of ENaC, and the two pore K+ channels (TREK1, TREK2) and TRAAK were screened in pulpal neurons from rats with and without pulpal inflammation. ASIC3, TRPA1, TREK1, and TREK2 were present in approximately 67%, 64%, 14%, and 10% of pulpal neurons, respectively. There was no detectable influence of inflammation on the proportion of neurons expressing these mechanotransducers. Given that the majority of pulpal afferents express ASIC3 and TRPA1, our results raise the possibility that these channels may be novel targets for the treatment of dentin sensitivity.

Inflammation increases the excitability of masseter muscle afferents.

Temporomandibular disorder is a major health problem associated with chronic orofacial pain in the masticatory muscles and/or temporomandibular joint. Evidence suggests that changes in primary afferents innervating the muscles of mastication may contribute to temporomandibular disorder. However, there has been little systematic study of the mechanisms controlling the excitability of these muscle afferents, nor their response to inflammation. In the present study, we tested the hypotheses that inflammation increases the excitability of sensory neurons innervating the masseter muscle of the rat and that the ionic mechanisms underlying these changes are unique to these neurons. We examined inflammation-induced changes in the excitability of trigeminal ganglia muscle neurons following intramuscular injections of complete Freund's adjuvant. Three days after complete Freund's adjuvant injection acutely dissociated, retrogradely labeled trigeminal ganglia neurons were studied using whole cell patch clamp techniques. Complete Freund's adjuvant-induced inflammation was associated with an increase in neuronal excitability marked by a significant decrease in rheobase and increase in the slope of the stimulus response function assessed with depolarizing current injection. The increase in excitability was associated with significant decreases in the rate of action potential fall and the duration of the action potential afterhyperpolarization. These changes in excitability and action potential waveform were associated with significant shifts in the voltage-dependence of activation and steady-state availability of voltage-gated K(+) current as well as significant decreases in the density of voltage-gated K(+) current subject to steady-state inactivation. These data suggest that K(+) channel subtypes may provide novel targets for the treatment of pain arising from inflamed muscle. These results also support the hypothesis that the underlying mechanisms of pain arising from specific regions of the body are unique suggesting that it may be possible, if not necessary to treat pain originating from different parts of the body with specific therapeutic interventions.

Using the protirelin test to distinguish mania from schizophrenia.

To explore the possible utility of the protirelin test in differentiating manic and schizophrenic patients, we gave a test dose of protirelin to 30 consecutive euthyroid inpatients who met Research Diagnostic Criteria for mania, 30 who met criteria for schizophrenia, undifferentiated subtype, and 20 normal volunteer controls. The mean maximal thyroid-stimulating hormone (TSH) response (delta TSH) to protirelin in the manic patients was lower than in the schizophrenic patients and in the controls. This mean difference was not attributable to differences in age, sex, baseline thyroid functioning, cortisol levels, or medication, but there was a considerable overlap of values in the patient groups. However, with a delta TSH less than or equal to 7.0 I microunits/mL to identify manic patients in the overall group, the sensitivity of the protirelin test was 60% and the specificity was 84%.

Transient red blood cell aplasia in association with viral hepatitis. Occurrence four years apart in siblings.

Transient pure red blood cell aplasia was verified during the course of viral hepatitis in two siblings whose illnesses occurred four years apart. The duration and course of the anemia was very similar in the two subjects, and in both the hepatitis progressed to a chronic active form. Autoimmune phenomena were prominent in one patient and suggested in the other, but a cytotoxic antibody to erythroblasts could not be demonstrated in the one patient in whom it was sought. The unique occurrence of such a syndrome in siblings, widely separated in time, suggests the possibility of a genetic predisposition governing the unusual response to a common illness.

Sensory neuron subpopulation-specific dysregulation of intracellular calcium in a rat model of chemotherapy-induced peripheral neuropathy.

The purpose of the present study was to test the prediction that the unique manifestation of chemotherapeutic-induced peripheral neuropathy (CIPN) would be reflected in a specific pattern of changes in the regulation of the intracellular Ca(2+) concentration ([Ca(2+)]i) in subpopulations of cutaneous neurons. To test this prediction, we characterized the pattern of changes in mechanical nociceptive threshold associated with paclitaxel administration (2mg/kg, iv, every other day for four days), as well as the impact of target of innervation and paclitaxel treatment on the regulation of [Ca(2+)]i in subpopulations of putative nociceptive and non-nociceptive neurons. Neurons innervating the glabrous and hairy skin of the hindpaw as well as the thigh were identified with retrograde tracers, and fura-2 was used to assess changes in [Ca(2+)]i. Paclitaxel was associated with a persistent decrease in mechanical nociceptive threshold in response to stimuli applied to the glabrous skin of the hindpaw, but not the hairy skin of the hindpaw or the thigh. However, in both putative nociceptive and non-nociceptive neurons, resting [Ca(2+)]i was significantly lower in neurons innervating the thigh after treatment. The magnitude of the depolarization-evoked Ca(2+) transient was also lower in putative non-nociceptive thigh neurons. More interestingly, while paclitaxel had no detectable influence on either resting or depolarization-evoked Ca(2+) transients in putative non-nociceptive neurons, in putative nociceptive neurons there was a subpopulation-specific decrease in the duration of the evoked Ca(2+) transient that was largely restricted to neurons innervating the glabrous skin. These results suggest that peripheral nerve length alone, does not account for the selective distribution of CIPN symptoms. Rather, they suggest the symptoms of CIPN reflect an interaction between the toxic actions of the therapeutic and unique properties of the neurons deleteriously impacted.

Inflammation-induced increase in nicotinic acetylcholine receptor current in cutaneous nociceptive DRG neurons from the adult rat.

The goals of the present study were to determine (1) the properties of the nicotinic acetylcholine receptor (nAChR) currents in rat cutaneous dorsal root ganglion (DRG) neurons; (2) the impact of nAChR activation on the excitability of cutaneous DRG neurons; and (3) the impact of inflammation on the density and distribution of nAChR currents among cutaneous DRG neurons. Whole-cell patch-clamp techniques were used to study retrogradely labeled DRG neurons from naïve and complete Freund's adjuvant inflamed rats. Nicotine-evoked currents were detectable in ∼70% of the cutaneous DRG neurons, where only one of two current types, fast or slow currents based on rates of activation and inactivation, was present in each neuron. The biophysical and pharmacological properties of the fast current were consistent with nAChRs containing an α7 subunit while those of the slow current were consistent with nAChRs containing α3/ß4 subunits. The majority of small diameter neurons with fast current were IB4- while the majority of small diameter neurons with slow current were IB4+. Preincubation with nicotine (1 µM) produced a transient (1 min) depolarization and increase in the excitability of neurons with fast current and a decrease in the amplitude of capsaicin-evoked current in neurons with slow current. Inflammation increased the current density of both slow and fast currents in small diameter neurons and increased the percentage of neurons with the fast current. With the relatively selective distribution of nAChR currents in putative nociceptive cutaneous DRG neurons, our results suggest that the role of these receptors in inflammatory hyperalgesia is likely to be complex and dependent on the concentration and timing of acetylcholine release in the periphery.