Perioperative or only adjuvant gemcitabine plus nab-paclitaxel for resectable pancreatic cancer (NEONAX)-a randomized phase II trial of the AIO pancreatic cancer group.

BACKGROUND: Data on perioperative chemotherapy in resectable pancreatic ductal adenocarcinoma (rPDAC) are limited. NEONAX examined perioperative or adjuvant chemotherapy with gemcitabine plus nab-paclitaxel in rPDAC (National Comprehensive Cancer Network criteria). PATIENTS AND METHODS: NEONAX is a prospective, randomized phase II trial with two independent experimental arms. One hundred twenty-seven rPDAC patients in 22 German centers were randomized 1 : 1 to perioperative (two pre-operative and four post-operative cycles, arm A) or adjuvant (six cycles, arm B) gemcitabine (1000 mg/m2) and nab-paclitaxel (125 mg/m2) on days 1, 8 and 15 of a 28-day cycle. RESULTS: The primary endpoint was disease-free survival (DFS) at 18 months in the modified intention-to-treat (ITT) population [R0/R1-resected patients who started neoadjuvant chemotherapy (CTX) (A) or adjuvant CTX (B)]. The pre-defined DFS rate of 55% at 18 months was not reached in both arms [A: 33.3% (95% confidence interval [CI] 18.5% to 48.1%), B: 41.4% (95% CI 20.7% to 62.0%)]. Ninety percent of patients in arm A completed neoadjuvant treatment, and 42% of patients in arm B started adjuvant chemotherapy. R0 resection rate was 88% (arm A) and 67% (arm B), respectively. Median overall survival (mOS) (ITT population) as a secondary endpoint was 25.5 months (95% CI 19.7-29.7 months) in arm A and 16.7 months (95% CI 11.6-22.2 months) in the upfront surgery arm. This difference corresponds to a median DFS (mDFS) (ITT) of 11.5 months (95% CI 8.8-14.5 months) in arm A and 5.9 months (95% CI 3.6-11.5 months) in arm B. Treatment was safe and well tolerable in both arms. CONCLUSIONS: The primary endpoint, DFS rate of 55% at 18 months (mITT population), was not reached in either arm of the trial and numerically favored the upfront surgery arm B. mOS (ITT population), a secondary endpoint, numerically favored the neoadjuvant arm A [25.5 months (95% CI 19.7-29.7months); arm B 16.7 months (95% CI 11.6-22.2 months)]. There was a difference in chemotherapy exposure with 90% of patients in arm A completing pre-operative chemotherapy and 58% of patients starting adjuvant chemotherapy in arm B. Neoadjuvant/perioperative treatment is a novel option for patients with resectable PDAC. However, the optimal treatment regimen has yet to be defined. The trial is registered with ClinicalTrials.gov (NCT02047513) and the European Clinical Trials Database (EudraCT 2013-005559-34).

Cost-effectiveness of lenalidomide plus dexamethasone vs. bortezomib plus melphalan and prednisone in transplant-ineligible U.S. patients with newly-diagnosed multiple myeloma.

OBJECTIVE: To conduct a cost-effectiveness assessment of lenalidomide plus dexamethasone (Rd) vs bortezomib plus melphalan and prednisone (VMP) as initial treatment for transplant-ineligible patients with newly-diagnosed multiple myeloma (MM), from a U.S. payer perspective. METHODS: A partitioned survival model was developed to estimate expected life-years (LYs), quality-adjusted LYs (QALYs), direct costs and incremental costs per QALY and LY gained associated with use of Rd vs VMP over a patient's lifetime. Information on the efficacy and safety of Rd and VMP was based on data from multinational phase III clinical trials and a network meta-analysis. Pre-progression direct costs included the costs of Rd and VMP, treatment of adverse events (including prophylaxis) and routine care and monitoring associated with MM. Post-progression direct costs included costs of subsequent treatment(s) and routine care and monitoring for progressive disease, all obtained from published literature and estimated from a U.S. payer perspective. Utilities were obtained from the aforementioned trials. Costs and outcomes were discounted at 3% annually. RESULTS: Relative to VMP, use of Rd was expected to result in an additional 2.22 LYs and 1.47 QALYs (discounted). Patients initiated with Rd were expected to incur an additional $78,977 in mean lifetime direct costs (discounted) vs those initiated with VMP. The incremental costs per QALY and per LY gained with Rd vs VMP were $53,826 and $35,552, respectively. In sensitivity analyses, results were found to be most sensitive to differences in survival associated with Rd vs VMP, the cost of lenalidomide and the discount rate applied to effectiveness outcomes. CONCLUSIONS: Rd was expected to result in greater LYs and QALYs compared with VMP, with similar overall costs per LY for each regimen. Results of this analysis indicated that Rd may be a cost-effective alternative to VMP as initial treatment for transplant-ineligible patients with MM, with an incremental cost-effectiveness ratio well within the levels for recent advancements in oncology.

Prognostic score for recurrence after Whipple's pancreaticoduodenectomy for ampullary carcinomas; results of an AGEO retrospective multicenter cohort.

BACKGROUND: Ampullary carcinoma (AC) is a relatively rare entity often managed as a biliopancreatic carcinoma. AC has a better prognosis than peri ampullary tumors after resection, but more than a third of patients relapse. Factors predictive of recurrence are controversial, mainly because the relevant studies are very small or also included non AC tumors. There are no guidelines on the use of adjuvant or neoadjuvant chemotherapy. The aim of this study was to identify prognostic factors for recurrence after AC resection in a large multicentric cohort, and to establish a simple, practical, predictive score for recurrence in order to guide multidisciplinary decisions. METHODS: We included 152 consecutive patients who underwent Whipple's pancreaticoduodenectomy for ampullary carcinoma from January 2000 to December 2010 in 10 gastrointestinal oncology departments. RESULTS: The estimated overall 5-year disease-free survival rate (DFS) was 47.1%. In multivariate analysis, age≥ 75 years at diagnosis (p < 0.0001), poor general condition (p = 0.01), poorly (p = 0.005) or moderately differentiated tumors (p = 0.01) and TNM stage IIb or III (p = 0.05) were associated with poor DFS. Based on this multivariate analysis, we developed a prognostic score with three levels of risk: DFS at 5 years was 73.5% in the low-risk group and 20.1% in the high-risk group. CONCLUSION: This simple score based on age, general condition, tumor differentiation and TNM stage can classify patients into subgroups with different risks of recurrence and could help with therapeutic decisionmaking.

Improved virological and immunological efficacy of resistance-guided switch in antiretroviral therapy: a Frankfurt HIV cohort analysis.

To evaluate the treatment outcome of antiretroviral therapy, depending on the use and utility of a concept of resistance-guided switch, patients from the Frankfurt HIV cohort have been followed for 24 weeks. If available, prior resistance data have been evaluated and patients were grouped into their expected viral response. The data of 354 patients were thus analysed, taking into account the genotypic sensitivity score of the administered medication (> or ≤2). When looking at the proportion of patients who achieved a viral load of <50/ml, the response rates differed significantly better for patients with a favourable resistance scoring as compared to an unfavourable one (71.9 % as compared to 56.0 %, p = 0.008). Interestingly, patients with a favourable resistance score also showed a better immunological response, as measured by median CD4 cell count of 391/µl [interquartal range (IQR) 250-530/µl] against 287/µl (IQR 174-449/µl) and a larger total increase of 141/µl against 38/µl. A significant virological and immunological benefit could be demonstrated for patients of a cohort with resistance-guided antiretroviral therapy adjustments.

Applications of pathology-assisted image analysis of immunohistochemistry-based biomarkers in oncology.

Immunohistochemistry-based biomarkers are commonly used to understand target inhibition in key cancer pathways in preclinical models and clinical studies. Automated slide-scanning and advanced high-throughput image analysis software technologies have evolved into a routine methodology for quantitative analysis of immunohistochemistry-based biomarkers. Alongside the traditional pathology H-score based on physical slides, the pathology world is welcoming digital pathology and advanced quantitative image analysis, which have enabled tissue- and cellular-level analysis. An automated workflow was implemented that includes automated staining, slide-scanning, and image analysis methodologies to explore biomarkers involved in 2 cancer targets: Aurora A and NEDD8-activating enzyme (NAE). The 2 workflows highlight the evolution of our immunohistochemistry laboratory and the different needs and requirements of each biological assay. Skin biopsies obtained from MLN8237 (Aurora A inhibitor) phase 1 clinical trials were evaluated for mitotic and apoptotic index, while mitotic index and defects in chromosome alignment and spindles were assessed in tumor biopsies to demonstrate Aurora A inhibition. Additionally, in both preclinical xenograft models and an acute myeloid leukemia phase 1 trial of the NAE inhibitor MLN4924, development of a novel image algorithm enabled measurement of downstream pathway modulation upon NAE inhibition. In the highlighted studies, developing a biomarker strategy based on automated image analysis solutions enabled project teams to confirm target and pathway inhibition and understand downstream outcomes of target inhibition with increased throughput and quantitative accuracy. These case studies demonstrate a strategy that combines a pathologist's expertise with automated image analysis to support oncology drug discovery and development programs.

[Tolerance and efficacy of preoperative radiation therapy for elderly patients treated for rectal cancer]. / Tolérance et efficacité de la radiothérapie préopératoire chez les patients âgés atteints d'un cancer du rectum.

PURPOSE: To retrospectively assess the impact of age on tolerance and oncologic outcomes treated by neoadjuvant treatment for patients of 70 years old or above with locally advanced rectal cancer. PATIENTS AND METHODS: Ninety-one consecutive patients were divided into three groups: group 1 from 70 to 75 years (n=31); group 2: 76 to 79 years (n=31) and group 3, patients aged 80 years or above (n=29). Radiation therapy was delivered according two schemes: 25Gy in five fractions (short scheme) or 45 to 50Gy with a classical fractionation (long scheme). Long scheme patients received a concomitant chemotherapy with 5-fluoro-uracile alone or associated with oxaliplatin. RESULTS: The three groups were comparable for performance status, Charlson's score and T staging. Long scheme radiation therapy and chemotherapy were performed in 77.5, 74.5 and 48.3% of patients (P=0.03) and 77.4, 71 and 41.4% (P=0.006) in the groups 1, 2 and 3, respectively. All patients treated with the short scheme irradiation received the treatment without any acute toxicity. In the long scheme group, 65% of patients received the treatment on time and grade 3 or above toxicity was observed in 12% of patients who did not receive oxaliplatin and in 48% of patients who received oxaliplatin. The overall survival rate at 3 and 5 years was 66.9% and 60.8% in the group 1, 90.5% and 75.9% in the group 2 and 80.5% and 73.8% in the group 3 (P=0.15). CONCLUSION: Neoadjuvant treatment is feasible with encouraging survival rates for patients aged 70 years and older. Short scheme radiation therapy seems to be an interesting option in this population.

Cholesterol-lowering properties of different pectin types in mildly hyper-cholesterolemic men and women.

BACKGROUND/OBJECTIVES: Viscous fibers typically reduce total cholesterol (TC) by 3-7% in humans. The cholesterol-lowering properties of the viscous fiber pectin may depend on its physico-chemical properties (viscosity, molecular weight (MW) and degree of esterification (DE)), but these are not typically described in publications, nor required by European Food Safety Authority (EFSA) with respect to its generic pectin cholesterol-lowering claim. SUBJECTS/METHODS: Here, different sources and types of well-characterized pectin were evaluated in humans. Cross-over studies were completed in mildly hyper-cholesterolemic persons receiving either 15 g/day pectin or cellulose with food for 4 weeks. RESULTS: Relative low-density lipoprotein (LDL) cholesterol (LDL-C) lowering was as follows: citrus pectin DE-70=apple pectin DE-70 (7-10% reduction versus control)>apple pectin DE-35=citrus pectin DE-35>OPF (orange pulp fiber) DE-70 and low-MW pectin DE-70>citrus DE-0. In a subsequent 3-week trial with 6 g/day pectin, citrus DE-70 and high MW pectin DE-70 reduced LDL-C 6-7% versus control (without changes in TC). In both studies, high DE and high MW were important for cholesterol lowering. Source may also be important as citrus and apple DE-70 pectin were more effective than OPF DE-70 pectin. Pectin did not affect inflammatory markers high-sensitivity C-reactive protein (hsCRP) nor plasma homocysteine. CONCLUSIONS: Pectin source and type (DE and MW) affect cholesterol lowering. The EFSA pectin cholesterol-lowering claim should require a minimum level of characterization, including DE and MW.

Effects of differential extraction of Verbena officinalis on rat models of inflammation, cicatrization and gastric damage.

Verbena officinalis L. is used in folk medicine for the treatment of inflammatory disorders, skin burns, abrasions, and gastric diseases. Extracts obtained with different solvents (methanol, VoME; enriched flavonoids, VoEF; supercritical CO2, VoCO2) were evaluated for anti-inflammatory, gastroprotective and cicatrizing activities. Additionally, the antioxidant capacity was determined in vitro. In order to confirm the activities investigated, histological observations were performed. All extracts induce a remarkable anti-inflammatory activity. The gastric damage is significantly reduced by all extracts administered, whereby the most pronounced protection is observed for the VoCO2 and VoEF extracts. Finally, a wound healing effect is obtained particularly by the CO2 extract, suggesting the presence of some lipophilic active principles. Histological evidence confirms the results evaluated with the animal procedures. The results obtained after oral administration of V. officinalis extracts are also in agreement with the antioxidant capacity evaluated in vitro, confirming the relationship between pharmacological activities and antiradical efficacy.

Effect of free plant sterols in low-fat milk on serum lipid profile in hypercholesterolemic subjects.

OBJECTIVE: To determine the effect of nonesterified, nonhydrogenated plant sterols solubilized in a partly vegetable oil-filled low-fat milk on serum low-density lipoprotein cholesterol (LDL) in mildly hypercholesterolemic patients. DESIGN: Double-blind, randomized, placebo-controlled three-arm crossover study. SETTING: Outpatient clinical trial. SUBJECTS: A total of 138 patients were screened, providing 81 patients for randomization; 71 patients completed the study. INTERVENTIONS: The study product was a 500 ml milk blend with or without nonesterified, nonhydrogenated sterols. The daily consumption of sterols in the three groups was 0 g/day, control group (C); 1.2 g/day, (Lo); or 1.6 g/day, (Hi), respectively. The patients were randomly assigned to one of three different treatment sequences. Each intervention period was 4 weeks. The total study duration was 12 weeks. RESULTS: The milk product was well tolerated. The placebo-adjusted mean reduction in LDL was 7.13+/-12.31 and 9.59+/-12.44% (mean+/-s.d.) for Lo and Hi groups, respectively (P<0.0001); there was no statistically significant difference in LDL lowering for the Lo and Hi groups. There were no significant changes in serum vitamin E or carotenoid concentrations after standardization with LDL cholesterol during the study period. CONCLUSION: The present study shows for the first time a substantial reduction in LDL cholesterol with a new, partly vegetable oil-filled 1.2% low-fat milk product, containing nonesterified plant sterols from soybean oil, in a randomized, placebo-controlled trial. This result encourages further development of novel low-fat dairy products containing free plant sterols for future use in cholesterol-lowering initiatives.

Effects of non-esterified stanols in a liquid emulsion on cholesterol absorption and synthesis in hypercholesterolemic men.

UNLABELLED: BACKGROUND Numerous studies have shown that dietary plant sterols (phytosterols and phytostanols) and their esters can decrease cholesterol absorption. However, few researchers have examined the effects of plant sterols on cholesterol absorption and synthesis using stable isotope tracers, instead of relying on endogenous pathway precursors. Further, we have worked with non-esterified lecithin-solubilized stanols as opposed to the more frequently studied esterified sterols and stanols. The vehicle was an oil-in-water liquid emulsion rather than the more common spread vehicle typically employed. AIM OF THE STUDY: To determine the effects of relatively low doses of lecithin-solubilized non-esterified stanols in liquid emulsions on cholesterol absorption and synthesis in mildly hypercholesterolemic subjects. METHODS: In a randomized, double blind crossover design, 12 mildly hypercholesterolemic men received either a free phytostanol supplement (3 g/d in 3 servings) or a control treatment for 3 days. Cholesterol endogenous synthesis rate was determined using the rate of incorporation of deuterium from body water into newly formed cholesterol molecules. Cholesterol absorption at the intestinal level was determined using the dual isotope method using 13C cholesterol injected intravenously and 180 cholesterol given orally. RESULTS: Cholesterol absorption was 55.7 +/- 6.5 % for the control and 33.5 +/- 5.3% for the phytostanol treatment. This massive reduction of the cholesterol absorption did not induce, on average, a difference in cholesterol endogenous synthesis which was measured at 0.074 +/- 0.0015 pool/d for plant sterols and 0.0736 +/- 0.0015 pool/d for controls (p > 0.05). CONCLUSIONS: The results demonstrated that lecithin-solubilized stanols administrated during a short period of time (3 days) in an oil-in-water emulsion can dramatically decrease cholesterol absorption, without a consistent, concomitant increase in synthesis, which is highly suggestive of effective LDL cholesterol lowering. The effects of synthesis should be verified in a longer study with more subjects.

Experience with split-course external beam irradiation +/- chemotherapy and integrated Ir-192 high-dose-rate brachytherapy in the treatment of primary carcinomas of the anal canal.

PURPOSE: The effect of the treatment of anal cancer by performing a high-dose-rate (HDR) brachytherapy boost during a short split between the external beam radiotherapy series (EBR) +/- chemotherapy was investigated. METHODS AND MATERIALS: Thirty-nine patients with anal canal cancers, stages T1-T4 N0-2 M0, were treated with split-course EBR (50-50.4 Gy) and a Iridium 192 ((192)Ir-) HDR boost (6 Gy) performed during the 1-2-week split. Patients who failed to achieve a complete tumor response received additional brachytherapy. Chemotherapy with 5-fluorouracil and mitomycin C was offered to patients with tumors > 3 cm and employed concomitantly on days 1-5 and day 1, respectively, of each EBR series. RESULTS: Follow-up ranged from 3 to 140 months (median 31). Median treatment duration was 56 days. The 3-year (5-year) actuarial rates of locoregional control (LRC) and disease-specific survival (DSS) were 81% (76%) and 80% (76%), respectively. The crude rate of anal preservation was 77% overall, and 97% in patients in whom LRC was achieved. Uncompromised anal function was recorded in 93% of these patients. The actuarial 3-year (5-year) rate of colostomy-free survival (CFS) was 78% (73%). There was a statistically significant difference in LRC and DSS according to stage, tumor size, and nodal status. Complications requiring surgical intervention occurred in 7.6% of patients. CONCLUSION: The integration of the HDR boost in a split-course EBR regimen +/- chemotherapy resulted in excellent sphincter function without an increase of severe complications and with rates of LRC, DSS, and CFS, which compare favorably with those reported in the literature.

Isolated hepatic perfusion for lapine liver metastases: impact of hyperthermia on permeability of tumor neovasculature.

BACKGROUND: Hyperthermic isolated hepatic perfusion (IHP) has been shown to cause significant regression of advanced unresectable liver metastases in patients. Although there are different agents and treatment modalities used in IHP, the contribution of perfusion hyperthermia is unknown. PURPOSE: A large animal model of unresectable liver metastases and a technical standard for IHP in this model were established. This model was used to assess the effects of hyperthermia on vascular permeability of tumors and normal liver tissue during IHP. METHODS: Sixty-five New Zealand White rabbits were used in a series of experiments. Disseminated liver tumors were established by direct injection of 1 x 10(6) VX-2 cells into the portal vein by laparotomy in anesthetized animals. Several surgical perfusion techniques were explored to determine a reliable and reproducible IHP model. Vascular permeability in tumor versus liver was then assessed with Evan's Blue labeled bovine albumin under normothermic (tissue temperature 36.5 degrees C +/- 0.5 degree C), moderate hyperthermic (39 degrees C +/- 0.5 degree C), or severe hyperthermic (41 degrees C +/- 0.5 degree C) conditions. RESULTS: Tumor model and perfusion techniques were successfully established with inflow through the portal vein and outflow through an isolated segment of the inferior vena cava. A gravity driven perfusion circuit with stable perfusion parameters and complete vascular isolation was used. Vascular permeability was higher in tumor than in normal tissues (P = .03) at all time points during IHP. Hyperthermia resulted in a significant (up to 5-fold) increase in permeability of neovasculature; when severe hyperthermia was used, tumor vascular permeability was increased even more than normal liver permeability (P = .01). CONCLUSIONS: The VX-2/New Zealand White rabbit system can be used as a reproducible large-animal model for IHP of unresectable liver metastases. It can be used to characterize the contribution and mechanism of action of different treatment parameters used in IHP. Hyperthermia preferentially increases vascular permeability in tumors compared with liver tissue in a dose-dependent fashion, thus providing a mechanism for its presumed benefit during isolated organ perfusion.

Recombinant Bet v 1, the major birch pollen allergen, induces hypersensitivity reactions equal to those induced by natural Bet v 1 in the airways of patients allergic to tree pollen.

BACKGROUND: Atopic allergens produced by recombinant DNA methods are promising tools for diagnosis and therapy of Type I allergy. To evaluate the immunologic properties of these molecules, it is necessary to compare them with natural allergens in vitro and in vivo. OBJECTIVE: The study was carried out to determine whether the potency of recombinant Bet v 1 (rBet v 1) is comparable to that of natural Bet v 1 (nBet v 1) in inducing allergic reactions in the nose and bronchi. METHODS: Thirteen patients allergic to birch pollen with bronchial asthma and/or rhinitis were investigated. Skin prick tests and nasal and bronchial challenges were performed with rBet v 1 and nBet v 1. RESULTS: In patients allergic to birch pollen, both allergens induced comparable skin reactions. In subjects with rhinitis rBet v 1 was equally potent in inducing nasal reactions (mean PD(+60)NR +/- SD, 10.48 +/- 17.42 microg vs 7.98 +/- 8.9 microg, p > 0.05). In patients with asthma, rBet v 1 was equally potent in inducing bronchial reactions (PD20 FEV1, 0.81 +/- 1.74 microg vs 0.62 +/- 1.44 microg, p > 0.05) as nBet v 1. CONCLUSION: No significant differences were observed between natural and recombinant allergen. We conclude that allergens produced by recombinant techniques can induce typical allergic reactions in important target organs of Type I allergy: the nose and bronchi.

Reduced mitogenic stimulation of peripheral blood mononuclear cells as a prognostic parameter for the course of breast cancer: a prospective longitudinal study.

Immunosuppression has been often associated with the course of malignant diseases. In the present study, the proliferation of peripheral blood mononuclear cells (PBMCs) in response to mitogenic stimulation with phytohaemagglutinin (PHA) was assessed prospectively in 90 patients with stage I-III breast cancer. Whereas PHA-induced proliferation of PBMCs derived from patients with breast cancer preoperatively was significantly decreased when compared with data obtained in healthy control individuals (P < 0.001), the degree of the defect in PHA-induced proliferation of PBMCs depended upon the tumour burden as manifested by tumour size and axillary lymph node involvement (P < 0.003 in each case). PHA-induced proliferation of PBMCs dropped significantly in patients who received adjuvant chemotherapy consisting of cyclophosphamide, methotrexate and fluorouracil (CMF) after an observation period of 6 months (P < 0.01), but not in patients under adjuvant treatment with tamoxifen only. After an additional 6 months (i.e. 12 months after surgery), PHA-induced proliferation of PBMCs was similar in patients after adjuvant chemotherapy with CMF and in those receiving continued adjuvant tamoxifen treatment (P > 0.1), but in all patients still significantly decreased as compared with healthy controls (P < 0.001). When data obtained preoperatively and after 12 months were compared, it was found that out of 23 patients whose PBMCs had experienced a drop in their PHA-induced proliferation, 14 (61%) had developed metastatic disease within the subsequent 24 months (i.e. 36 months after surgery). In contrast, out of 59 patients whose PBMCs showed an increase in their PHA-induced proliferation within the first 12 months after surgery, only one (2%) presented with disease progression. We thus conclude that PHA-induced proliferation of PBMCs derived from patients with breast cancer depends upon the tumour load and is a good clinical predictor for the further course of the disease.

Oral capsaicin provides temporary relief for oral mucositis pain secondary to chemotherapy/radiation therapy.

Pain from oral mucositis afflicts from 40% to 70% of patients receiving chemotherapy or radiation therapy. Current methods of clinical pain management (for example, topical anesthetics, systemic analgesics) have limited success. In a pilot study, we examined the ability of oral capsaicin to provide temporary relief of oral mucositis pain. Capsaicin, the active ingredient in chili peppers, desensitizes some neurons and has provided moderate pain relief when applied to the skin surface. Oral capsaicin in a candy (taffy) vehicle produced substantial pain reduction in 11 patients with oral mucositis pain from cancer therapy. However, this pain relief was not complete for most patients and was only temporary. Additional research is needed to fully utilize the properties of capsaicin desensitization and thus optimize analgesia.

Early postnatal development of thyrotropin-releasing hormone (TRH) expression, TRH receptor binding, and TRH responses in neurons of rat brainstem.

We investigated the postnatal development of the thyrotropin-releasing hormone (TRH)-containing raphe system in the brainstem of neonatal rats. Postnatal changes in TRH expression in nucleus (n.) raphe obscurus (ROb) and n. raphe pallidus (RPa) were evaluated by in situ hybridization using an 35S-labeled oligonucleotide probe complementary to TRH precursor mRNA. TRH mRNA expression was low at birth [postnatal day 0 (P0)], but was clearly evident by P7 and increased from that time to reach sustained high levels from P14 to P28. Consistent with this postnatal increase in TRH expression, we found increases in the density of TRH-immunoreactive (IR) fibers, which are derived from ROb and RPa, in the hypoglossal nucleus (nXII). TRH-IR fibers in nXII were very sparse at P0, but increased markedly over the first 2 postnatal weeks. The change in TRH innervation of nXII was closely matched by concomitant increases in 3H-methyl-TRH binding in nXII; specific TRH binding increased from very low levels at birth to high levels of P14. Finally, we recorded intracellularly the electrophysiological responses to TRH of hypoglossal motoneurons (HMs; n = 42) of neonatal rats (P0-P21) in a brainstem slice preparation. The response of neonatal HMs to TRH, in contrast to adult HMs, was highly variable. In some neonatal HMs, even at P0, TRH caused a depolarization with a decrease in input conductance (GN) that was characteristic of the response of all adult HMs. However, in other neonatal HMs, TRH was either without effect or caused a slight depolarization with no apparent change in GN, responses that were unlike those of adult HMs. A response was considered typical (i.e., "adult-like") if GN decreased to < 85% of control. The percentage of cells responding in a typical manner increased progressively from 25% at P0-P2 to 100% after P11. In addition, we found that the density of TRH-sensitive current (normalized to cell capacitance) increased with postnatal age in HMs that responded in a typical manner, suggesting that expression of the TRH-sensitive conductance is also developmentally regulated. Together, these data indicate that the TRH raphe neuronal system of the rat brainstem is not fully mature at the time of birth but develops over the first few postnatal weeks. This was true of levels of TRH mRNA in caudal raphe nuclei, density of TRH-IR fibers and 3H-methyl-TRH binding in nXII, and also the manner and magnitude of electrophysiological responses of HMs to exogenously applied TRH.