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Background Lancovutide activates a chloride channel (TMEM-16A) other than the cystic fibrosis (CF) transmembrane conductance regulator protein and could benefit CF patients. Methods In this randomized, multi-center, double-blind, placebo-controlled, parallel-group trial 161 patients ≥12 years with a confirmed diagnosis of CF were randomized to either placebo (saline) or active drug in 3 different dosing schemes of 2.5mg inhaled lancovutide (once daily, every other day or twice a week) for eight weeks. The primary endpoint was the change in the forced expiratory volume in 1 second (FEV1) percent predicted. Secondary endpoints included further lung function parameters (FEV1 (absolute), functional vital capacity percent predicted, forced expiratory flow percent predicted, pulse oximetry), quality of life assessment, pulmonary exacerbations, hospitalization due to pulmonary exacerbations, time to first pulmonary exacerbation, duration of anti-inflammatory, mucolytic or antibiotic treatment, and safety. Results There was no significant difference in the change in FEV1 percent predicted, quality of life, other lung function parameters, pulmonary exacerbations or requirement of additional treatment between groups. Overall, the inhalation of lancovutide was safe although a higher rate of adverse events, especially related to the respiratory system, occurred as compared to placebo. Conclusions Lancovutide did not improve FEV1 percent predicted when compared to placebo (NCT00671736).

Anagrelide is an established therapy for essential thrombocythemia. Common adverse effects have been linked to peak plasma concentrations of anagrelide and its 3OH metabolite. Our study was performed to investigate the pharmacokinetics (PK) of a novel anagrelide extended‐release (AER) formulation and its active metabolites. Thirty healthy volunteers were randomized to receive either 2 mg AER (under fasting and fed conditions) or 2 mg commercially available reference product (CARP) in an open‐label, 3‐way crossover trial with washout periods of 6 days. Plasma concentrations of anagrelide and its active metabolites were assessed by tandem mass spectrometry. The PK differed significantly between all treatment periods. Bioavailability of AER was 55% of the CARP under fasting conditions and 60% under fed conditions. Cmax, AUCt, and AUC∞ were significantly higher and Tmax and T1/2 were significantly shorter after the CARP compared with AER. Food had a significant impact on the PK of AER, increasing the Cmax and AUCt while reducing the T1/2, plateau, and mean residence time. Both formulations were well tolerated, with a trend toward more frequently occurring adverse events after the CARP. The PK of AER and the CARP differed significantly in all parameters. Food enhanced the bioavailability of AER.

Primary myelofibrosis (PMF) is a clonal stem cell disorder currently classified as myeloproliferative neoplasm (MPN). Median survival in PMF is estimated with 6 years, but can range from few months to several decades in early pre-fibrotic PMF. The disease course is almost always complicated by progressive anemia, symptomatic splenomegaly and severe constitutional symptoms. Causes of death include leukemic transformation with marrow failure and complications from bleeding, thrombosis, portal hypertension or infections. While PMF patients in advanced stages benefit from a JAK2 inhibitor therapy, there is no evidence for prevention of disease progression to overt MF by an early therapeutic intervention. Interferon alpha has been shown to reduce white cell counts, elevated platelet counts and improve splenomegaly and there are some observations of its disease modifying capability in the earlier phase of PMF. The aim of the present phase II study was to test the capability of a novel pegylated interferon compound (Ropeginterferon-alfa-2b) to improve hematologic parameters, splenomegaly and to monitor the course of the disease concerning clinical symptoms in a homogeneous cohort of early pre-fibrotic PMF patients. The endpoints of the study were hematological response, maintenance or improvement of quality of life and the symptom scales during a period of 2 years interferon treatment, and interferon tolerability. Twenty-five patients were included in the study. Nine patients were pretreated with pegylated interferon alfa 2b (PegIntron or Pegasys) during at least 3 years and 16 patients were interferon naïve. At start of therapy the median red blood cell count was 4.3 T/l (3.3 - 5.2); median hemoglobin level was 12.5 g/dl (9.6 - 14.7 g/dl), median WBC count was 7.7 G/l (2.44 - 27.55 G/l) and the median platelet count was 435 G/l (124 - 1161 G/l). Median LDH-level was 263.5 U/l (163 - 538 U/l) and the median spleen size was 11.2 cm (8 - 22 cm). 13 patients were JAK2 positive, and 12 patients were CALR positive. Detailed patient characteristics in 6-month intervals for pretreated and interferon naïve patients are given in Table 1. At study entry, 12 patients presented with anemia, 12 with thrombocytosis, 9 with leukocytosis, 14 with elevated LDH levels and 7 with splenomegaly. After 24 months of treatment, 6 patients improved their anemia (N=2 pretreated, 4 treatment-naïve), 6 their thrombocytosis (N=6 treatment-naïve), 7 their leukocytosis (N=7 treatment-naïve), 6 normalized LDH levels (N=1 pretreated, 5 treatment-naïve) but none showed response in the form of significant spleen size reduction. The fact that no patient showed disease progression in any single parameter after 2 years of treatment can already be considered a success. The most common side effects observed during this study include flu-like symptoms (N=7 pretreated, 15 treatment-naïve), lack of concentration (N=3 pretreated, 8 treatment-naïve), pruritus (N=2 pretreated, 7 treatment-naïve), infections (N=2 pretreated, 5 treatment-naïve) and bleeding (N=2 pretreated, 4 treatment-naïve). Generally, pretreated patients suffered from fewer side effects than treatment-naïve patients in every category. This may be due to the fact that those patients had already been exposed to an interferon in previous treatment regimen. Two patients had to be withdrawn from the study after approximately 12 months due to psychological side effects, both from the treatment-naïve group. Additionally to conventional symptom screening, the EORTC-QLQ-C30 questionnaire was used to assess therapy-response. With this tool, function scales, symptom scales and quality-of-life were recorded. After 24 months of treatment, almost every category showed improvement for both pretreated and treatment-naïve patients. Detailed results about symptom scales are shown in Figure 1. In conclusion, the data demonstrate that Ropeginterferon-alfa-2b is able not only to induce hematologic responses but also to improve constitutional symptoms and overall quality of life in prefibrotic PMF. Thus ropeginterferon-alfa-2b warrant further investigation as a treatment option in prefibrotic PMF, where only very limited alternatives exist. Disclosures Gisslinger: Shire: Consultancy, Honoraria; Janssen Cilag: Consultancy, Honoraria; Novartis: Honoraria, Research Funding; AOP Orphan Pharmaceuticals AG: Consultancy, Honoraria, Research Funding. Krejcy:AOP Orphan Pharmaceuticals: Employment. Widmann:AOP Orphan Pharmaceuticals: Employment. Kralovics:MyeloPro Diagnostics and Research GmbH: Equity Ownership. Krauth:Novartis: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.

Anagrelide hydrochloride is an anti-thrombotic agent indicated for the treatment of essential thrombocythemia (ET). In various previously published clinical trials of 2 branded formulations of anagrelide in patients with ET at high risk for thrombohemorrhagic events, the rates of adverse events and discontinuation were strikingly divergent between brands. Because the formulations and manufacturers differed, the differences in tolerability, as well as platelet counts, might have been related to differences in pharmacokinetic properties between the 2 formulations.The present series of investigations (1) determined the pharmacokinetic profile of anagrelide and its metabolites; (2) compared the pharmacokinetic profiles of the test and reference formulations of anagrelide; (3) investigated the in vitro release of anagrelide as a marker of intragastric anagrelide release of the test and reference formulations; and (4) compared the platelet-reducing effects of the test and reference formulations in patients with thrombocythemia in 2 longitudinal studies over 4 weeks.A series of 4 in vivo studies and 1 in vitro study were conducted. In a pilot, prospective, singledose study in healthy volunteers, the pharmacokinetic properties (C(max), T(max), and AUC(0-infinity)) of a test formulation of anagrelide were assessed using high-performance liquid chromatography analysis of plasma samples. Based on the results from that study, a single-dose, randomized, double-blind, 2-period crossover study in healthy volunteers was conducted to determine bioequivalence of 2 formulations of anagrelide 2 mg/d (taken as 4 capsules). In vitro dissolution properties of the test or reference formulation containing 0.5 mg anagrelide as the active ingredient were studied in an assay mimicking gastrointestinal release. To test for effects on platelet counts of switching from the reference formulation (previous treatment on stable dose for 3 months) to the test formulation, two 4-week longitudinal trials were conducted: one in patients with ET (in Germany), and one in patients with thrombocythemia associated with chronic myeloproliferative disorders (CMPDs) (in Austria).The pilot pharmacokinetic study of the test formulation in 16 volunteers (10 women, 6 men; mean [SD] age, 20.5 [1.5] years; weight, 69.0 [10.0 kg) suggested that anagrelide was metabolized to 3-hydroxyanagrelide (AUC(0-infinity) 50% compared with anagrelide) and the inactive metabolite 2-amino-5,6-dichloro-,4-dihydroquinazolone. The subsequent bioequivalence study in 24 volunteers (14 women, 10 men; mean [SD] age, 23 [4] years; white, 100%; weight, 67.5 [10.2] kg) found that the test formulation was associated with a significantly lower C(max) (point estimation [PE], 66%; 90% CI, 58%-76%; P0.001) and AUC(0-infinity) (PE, 77%; 90% CI, 68%-86%; P = 0.001). T(max) values for anagrelide and 3-hydroxyanagrelide were 1 hour longer with the test formulation compared with the reference formulation. The total number of adverse events with the reference formulation was 46; the test formulation, 29 (P = 0.05). In vitro, anagrelide from the reference formulation was immediately released (89.1% at 5 minutes), whereas there was a delayed release (93.6% at 30 minutes) from the test formulation (P0.05). In the last 2 studies, 2 cohorts of white patients (cohort 1, 15 patients with ET; 10 women, 5 men; mean [SD] age, 49.0 [10.7] years [range, 31-66 years]; weight, 73.2 [12.6] kg; cohort 2, 19 patients with thrombocythemia associated with CMPD; 12 women, 7 men; age, 62.6 [12.4] years [range, 38-80 years]; weight, 66.1 [13.3] kg) who had received treatment foror =3 months with the reference formulation were switched to the same dose of the test formulation and maintained on this dose for 4 weeks. Platelet counts did not change significantly from baseline over 4 weeks and stayed within a predefined margin of 150 x 10(3) cells/microL.The pharmacokinetic properties, adverse event rates, and in vitro dissolution profile differed between the test and reference anagrelide formulations in these healthy volunteers. In patients with ET or thrombocythemia associated with CMPD, platelet counts did not differ significantly from baseline at 4 weeks when subjects were switched from the reference to the test anagrelide formulation.

Duramycin (Moli1901) is being developed for the treatment of reduced mucociliary clearance in cystic fibrosis. This study was conducted to estimate lung residence time and systemic exposure and to assess whether duramycin causes an inflammatory response. Six volunteers were administered a single dose (7.5 mg) of nebulized duramycin and underwent bronchoscopies to obtain a composite data set for pharmacokinetic analysis; duramycin was measured in the cellular fraction of bronchoalveolar lavage fluid (BALF) (mainly alveolar macrophages) and brush biopsies (bronchial epithelial cells). The estimated t(1/2) of duramycin was approximately 5 days in brush biopsies and 25 to 91 days in BALF cells. Levels of duramycin in BALF (C (max) 800 ng/mg) exceeded those in brush biopsies by approximately 20-fold. Duramycin was absent from plasma and did not cause any detectable inflammatory response in pulmonary tissue as judged from the BALF profile of 14 relevant cytokines. Our data suggest that duramycin qualifies for intrapulmonary administration in cystic fibrosis (CF) patients.

Background : Anagrelide hydrochloride (ana), is a well-known compound used to selectively normalize platelet counts (plc) by inhibiting megakaryocyte development and maturation. Common side-effects of licensed formulations may be largely due to peak plasma concentrations of ana and its 3OH-metabolite, whereas efficacy is proportional to the Area under the curve (AUC). A novel extended-release formulation (ana retard, AR) has superior pharmacokinetics (Petrides 2015) and has been demonstrated to be equally effective as the licensed formulation (Gisslinger 2016). Here, we investigate a "treat-early" concept in non-high risk ET patients. Study design:AR was compared to placebo in a phase 3, randomized, parallel group, multicenter, subject- and sponsor-blinded trial in patients diagnosed with ET according WHO 2008 and a defined risk status including JAK2 mutation, protein C/S or antithrombin III deficiency, factor V Leiden or prothrombin mutation, cardiovascular risk factors. The primary endpoint was time to first ET-related event adjudicated by a blinded expert panel, or progressive thrombocytosis (plc≥1000G/L or plc increase >300G/L within 3 months) requiring medical intervention. Secondary endpoints included plc response and change of risk status. Results : 146 patients were randomized and dosed (all Caucasian, mean age 43 years, 74% females), and 112 completed the first year with drop-out rates of 22% in AR and 25% in placebo. Only 49% of placebo patients vs. 74% of AR patients consented to enter the extension phase. Consequently, over the entire study duration, median exposure times differed significantly with 123 weeks for AR and 62 weeks for placebo. The primary endpoint was met in all analysis sets, with p Conclusions: Long term treatment of ET patients with defined risk status, using this novel modified-release anagrelide formulation proofed well tolerable, normalized plc in a vast majority, significantly reduced progression to high-risk status and most importantly was associated with significantly less clinical ET related events. These data have important implications for the optimal management of ET and support a "treat-early" approach. References Results of a phase I, single dose, randomized, 3-way crossover study, to assess the bioavailability of a novel anagrelide extended release (ER) formulation in comparison to a commercially available anagrelide reference product (CARP) in healthy volunteers, Petrides P, Zagrijtschuk O, Klade C, DGHO, 2015 Phase 3 trial TEAM-ET in 106 high-risk Essential Thrombocythemia patients, demonstrating non-inferiority of Anagrelide Retard, a novel, extended-release anagrelide formulation, to the licensed comparator Gisslinger H, Radinoff A, Karyagina E,Kyrcz-Krzemień S, Abdulkadyrov K, Gerbutavicius R,Melikyan A, Burgstaller S, Hus M, Kłoczko J, Yablokova V, Tzvetkov N, Całbecka M, Shneyder T, Warzocha K, Jurgutis M, Kaplanov K, Hodisch J, Klade C, Buxhofer-Ausch V, European School of Hematology EHA 21st Congress, 2016 Disclosures Gisslinger: AOP Orphan Pharmaceuticals AG, Novartis, Celgene, Baxalta: Consultancy, Honoraria, Research Funding. Klade:AOP Orphan: Employment. Kyrcz-Krzemien:AOP Orphan Pharmaceuticals AG, Novartis, BMS, Medac: Honoraria. Warzocha:BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Grohmann-Izay:AOP Orphan Pharmaceuticals AG: Employment. Hodisch:AOP Orphan Pharmaceuticals: Employment. Widmann:AOP Orphan Pharmaceuticals: Employment. Kralovics:Qiagen: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Research Funding. Schwarz:AOP Orphan Pharmaceuticals: Consultancy. Kiladjian:Novartis: Research Funding; AOP Orphan: Research Funding.

Background In cystic fibrosis (CF) patients, the absence or dysfunction of the chloride channel CF transmembrane conductance regulator (CFTR) results in reduced chloride ion transport in respiratory epithelial cells. Moli1901 stimulates an alternative chloride channel and may thus compensate for the CFTR deficiency in the airway epithelium of CF patients. Methods A phase II, placebo-controlled, double-blinded, single-center, multiple (5 consecutive days), rising-dose (daily dose, 0.5, 1.5, or 2.5 mg of Moli1901) study was conducted to investigate the safety and tolerability of multiple doses of aerosolized inhaled Moli1901 in 24 patients with CF and stable lung disease. Results Moli1901 was well tolerated in all but one CF patient, in whom a transient significant decrease in FEV 1 developed following inhalation, which resolved spontaneously, and in a second patient in whom transient throat numbness developed during drug inhalation. A significant improvement of FEV 1 was observed in the group receiving treatment with 2.5 mg/d Moli1901 compared to the group receiving placebo (p = 0.01 [Wilcoxon test]). Moli1901 was not detected in the plasma of the highest dose group. Conclusions The inhalation of Moli1901 up to a total cumulative dose of 12.5 mg appears to be safe in adult patients with CF. In addition, Moli1901 had a sustained beneficial effect on pulmonary function, which supports further studies of its efficacy in CF patients.

The ANAHYDRET study group involving 27 centers in 11 countries, sponsored by the AOP Orphan Pharmaceuticals, initiated a prospective randomized single blind multicenter phase III trial in order to compare efficacy and tolerability of anagrelide with hydroxyurea in high risk ET patients diagnosed according to the WHO classification. The study was designed as a non-inferiority trial as the limited number of treatment naïve ET patients available and the expected low number of ET related events following treatment with a cytoreductive therapy would not have allowed the conduct of a conventional superiority trial. At the stage of final analysis 258 patients with high risk ET previously untreated, were randomized to receive anagrelide (n=122, median age 58,1 years, rage 19–90 years; 46 male, 76 female) or to receive hydroxyurea (n=136, median age 56,4 years, range 22–83 years, 47 male, 89 female). Anagrelide, a novel non-immediate release formulation, was started with a dose of 1mg/day and hydroxyurea was initiated using a dose of 1500mg/day. Confirmatory proof of non inferiority of anagrelide after 6 months therapy (short term objective) was achieved based on predefined equivalence criteria for the course of platelet and white cell counts, hemoglobin levels, (difference of +/− 10% within CI 95%), and for the rate of ET related events (Odds ratio >0,404, medium sized difference corresponding to Cohens’s standardized difference of 0.5). Neutrophile counts remained unchanged in the anagrelide arm but were significantly reduced by hydroxyurea. There was no difference in the number of patients with at least 1 adverse event between the anagrelide treated group (73%) and the hydroxyurea treated group (73%). Five patients were discontinued in each group because of adverse events. However, the results showed an advantage of anagrelide over hydroxyurea concerning leukopenia and flue like symptoms while the angrelide treated patients had more frequently tachycardia, palpitations and headache. The final data analysis after 12 months therapy revealed that non- inferiority of anagrelide compared to hydroxyurea with regard to the platelet lowering effect, hemoglobin levels and ET related symptoms was maintained (p

Cysteamine and its dimeric form cystamine have been applied to the rat striatum by local injection. Both compounds resulted in a dose-dependent decrease of somatostatin levels. Maximal reduction of somatostatin (by about 50%) was obtained at a dose of 50 micrograms of cysteamine or cystamine after about 6 h. All three molecular weight forms of somatostatin--somatostatin-14, somatostatin-28, and the 13,000 molecular weight form of somatostatin--were reduced, as shown by size exclusion HPLC. Injection of radiolabeled cystamine revealed a fast conversion of the compound to cysteamine, suggesting it is active in the monomeric form. The levels of neuropeptide Y, which is colocalized with somatostatin in striatal neurons, failed to be changed by local or intraperitoneal injection of cysteamine, suggesting that this treatment does not affect vesicles of somatostatin/neuropeptide Y neurons.

The molecular forms of somatostatin contained in the rat striatum were separated by size-exclusion HPLC. Three major peaks of somatostatin-like immunoreactivity (SLI) were resolved. Two peaks cochromatographed with synthetic somatostatin-14 (SS-14) and somatostatin-28 (SS-28), respectively. One peak exhibited a higher molecular weight (about 10,000) and may contain a proform of somatostatin. Local injection of the neurotoxin kainic acid (1 μg) into the left striatum resulted in a persistent decrease (65–85%) of all three forms of somatostatin. In the contralateral—not injected—striatum a decrease of SLI was also observed which was maximal (45%) after 2 days and was largely abolished after 7 days. This decrease of SLI in the contralateral striatum, however, was due mainly to a decrease of SS-14 and SS-28 but not of the putative proform. Our data suggest that kainic acid causes a destruction of somatostatin-containing perikarya in the injected striatum, whereas in the contralateral striatum increased release with subsequent inactivation of SS-14 and SS-28 takes place. The putative somatostatin proform may serve as neurochemical marker for somatostatin-containing perikarya in the striatum.

The topographical distribution of the proposed amine transmitters dopamine (DA), serotonin (5-HT), noradrenaline (NA), adrenaline and histamine (HA) and of the metabolites of DA and 5-HT has been investigated in the neostriatum of the rat. DA and, less pronounced, its metabolites 3,4-dihydroxyphenylacetic acid, homovanillic acid and 3-methoxytyramine exhibited gradients with highest levels in dorso-rostal areas and the lowest content in the ventro-caudal part of the striatum. In contrast to this 5-HT, 5-hydroxyindoleacetic acid, and NA exhibited levels which increased from frontal and dorsal areas to the ventro-caudal part of the striatum. The rostral nucleus accumbens and the pallidum were low in DA and high in 5-HT and NA when compared with the dorsal striatum. The turnover rates of DA and 5-HT as judged by the metabolite/amine ratios followed a distribution which was opposite to the respective amine levels. Adrenaline was evenly low in the striatum and only slightly higher in the n. accumbens and pallidum. The levels of HA were considerably lower than those of the other amines. Although HA was also unevenly distributed within the striatum, no clear pattern was found. The topographical distribution of the amines suggests a preferential role of DA in the dorsal striatum and of 5-HT and NA in the ventral part of the striatum including the n. accumbens and the pallidum.

The origin of afferent somatostatin-containing fibers terminating in medial and ventral parts of the striatum has been investigated by performing various neurochemical and surgical lesions in the rat. Lesions of the anterior hypothalamus, amygdala, and the hippocampal commissure as well as lesions with 6-hydroxydopamine and 5,7-dihydroxytryptamine failed to decrease striatal somatostatin levels. However, thermal coagulation of the globus pallidus or knife-cut lesions performed ventrally to the striatum resulted in significant decreases in striatal somatostatin content. Analysis of the topographical distribution of somatostatin within the striatum after thermal lesions of the globus pallidus as well as after kainic acid-induced seizures revealed a preferential loss of the peptide in medial and ventral portions of the striatum, the site of terminating afferent somatostatin nerve fibers. The data suggest that the striatal afferent somatostatin-containing neurons may originate in the area of the globus pallidus.

Pronounced changes in the content of cholecystokinin octapeptide (CCK-8) have been found after limbic seizures induced by i.p. injection of kainic acid. Three hours after injection of the toxin a significant decrease in CCK-8 was observed in the frontal cortex and amygdala/pyriform cortex reflecting an increased release during acute seizures. A persistent decrease in the content of the peptide in the amygdala/pyriform cortex suggests destruction of the respective neurons. In the substantia nigra and in the striatum and, more moderately, in the hippocampus and frontal cortex increases in CCK-8 were observed 10 days after injection of kainic acid suggesting an increased synthesis or decreased release of the peptide in these brain areas subsequently to the acute seizures.

Cysteamine (100 μg) markedly reduces the number (by about 60%) and intensity of staining of NADPH diaphorase-reactive neurons 6 h after local injection into the striatum. This effect was reversible (after 24 h) and was only observed when the indirect staining procedure was applied in which NADPH formed by endogenous malate dehydrogenase is used. However, no direct effect of cysteamine on the malate dehydrogenase reaction was found. The decrease in NADPH diaphorase activity parallels the previously reported cysteamine induced decrease in somatostatin contained in the same neurons and may point to a biochemical interrelation of somatostatin and NADPH diaphorase in these neurons.

The mechanism of somatostatin depletion induced by cysteamine [2-mercaptoethylamine (CySH)] was studied in isolated nerve endings (synaptosomes) from rat brain in vitro. A dose-dependent reduction of somatostatin-like immunoreactivity (SLI) was observed which reached its maximal extent (41%) at a concentration of 300 microM CySH after 1-5 min. There was no release of somatostatin into the incubation medium. CySH at concentrations of up to 10 mM did not interfere in the RIA. Among a variety of compounds, structurally related to CySH 4-aminothiophenol, 2-aminothiophenol and N,N-dimethylaminothiol exhibited the highest efficacy in decreasing somatostatin (60%, 50%, 30%, respectively, at 10 mM and 10 min). The disulfide form of CySH cystamine and dimercaprol resulted in about 15% reduction after 10-min incubation, whereas taurine, alanine, cysteine, and mercaptoethanol were inactive. A saturable, sodium-dependent uptake process was found for the disulfide form of [35S]CySH cystamine [Michaelis-Menten constant (Km) = 18.6 microM, maximum velocity (Vmax) = 2.3 nmol/mg protein X 3 min) which was inhibited by cysteine (87% at 1 mM). [35S]CySH, at concentrations of 20 microM or less, was not stable in buffer solution. It underwent considerable nonenzymatic conversion into its dimeric form (60% at 37 C and 3 min), however it exhibited the same kinetic data for its uptake. Size exclusion HPLC of purified hypothalamic synaptosomes revealed a major SLI peak coeluting with synthetic somatostatin-14 and two minor peaks representing somatostatin-28 and a 13,000 mol wt protein. The three molecular forms of somatostatin were reduced to varied extent by CySH (somatostatin-14 by about 70%, somatostatin-28 by 15%, and the high mol wt form by 30%). Our experiments suggest that high affinity uptake of CySH may precede its action in decreasing somatostatin levels. Increased release or inhibition of synthesis of somatostatin have been excluded as possible mechanisms. It is suggested that SLI is equally affected in nerve endings and in perikarya.

The neuropeptides somatostatin, neurotensin and substance P were investigated in rats during and after limbic seizures induced by systemic injection of kainic acid (10mg/kg, i.p.). Three hours after injection of the toxin, pronounced decreases (40–50%) in somatostatin-like immunoreactivity in frontal cortex, striatum, dorsal hippocampus and amygdala/pyriform cortex were observed. Concomitantly, neurotensin-like and substance P-like immunoreactivities were also reduced in the frontal cortex and the hippocampus. These early decreases in peptide levels may result from increased release and subsequent inactivation of the peptides during acute seizures. At later time intervals, 3, 10 and 30 days after injection of kainic acid, the initially decreased peptide levels were partially normalized. However, the reduction in somatostatin-like immunoreactivity in amygdala/pyriform cortex and striatum persisted up to 30 days. Neurotensin-like immunoreactivity remained decreased in the frontal cortex. On the other hand, neurotensin- and substance P-like immunoreactivities were increased in the striatum and substantia nigra 10–30 days after injection of kainic acid. These late changes in peptide levels may suggest destruction of peptidergic neurons or adaptive changes induced by the convulsions. Pretreatment of rats with cysteamine (100 mg/kg, i.p.), an agent which decreases brain somatostatin levels, had no effect on the intensity of kainic acid induced convulsions, although a slightly earlier onset of seizures was observed. The changes in peptide levels, especially the marked decreases in somatostatin content after systemic injection of kainic acid, suggest considerable acute and chronic alterations in peptidergic systems caused by limbic convulsions.