Insights into the clinical development of regenerative medical products through a comparison of three cell-based products recently approved for limbal stem cell deficiency

Three regenerative medical products for limbal stem cell deficiency (LSCD), a rare and intractable ocular surface disease, have recently been approved in Japan. To our knowledge, this is the first time multiple stem-cell-based medical products have been approved for the same ocular disease. Development plans and study designs for each product differ, resulting in differences in indications. Since cell-based products have a heterogeneous formulation and often target rare diseases, they require a flexible approach to development. This review article describes the status and prospects of the clinical development of regenerative medical products by summarizing the issues of the three products from the Pharmaceuticals and Medical Devices Agency (PMDA) standpoint. Implementing stem cell-based products is challenging, requiring scientific and flexible review by regulatory authorities. To overcome these issues in the development process, developers and regulatory authorities need to communicate and fully discuss study protocols from the early stage of development.

Historical Overview of Regulatory Approvals and PMDA Assessments for Biosimilar Products in Japan During 2009-2022

A biosimilar product is defined as "a biological product that is highly similar to an existing, approved biological product (known as originator or reference product) in terms of structure, function, quality, and clinical efficacy and safety". Recently, biosimilar products have been actively developed around the world, and part of the reason for this is to combat the rapid growth of medical expenses in many countries, including Japan, the United States (US), and Europe. The use of biosimilar products has been promoted as a measure to address this issue. The review of marketing authorization applications for biosimilar products in Japan is conducted by the Pharmaceuticals and Medical Devices Agency (PMDA), which reviews the comparability of the quality, efficacy, and safety based on the data submitted by the applicants. As of December 2022, 32 biosimilar products have been approved in Japan. Through this process, the PMDA has gained much experience and knowledge regarding the development and regulatory approval of biosimilar products; however, details of the regulatory approvals for biosimilar products in Japan have not been reported until now. Therefore, in this article, we present the details of regulatory history and revised guidelines for approval of biosimilar products in Japan, questions and answers, other relevant notifications, and consideration for comparability evaluations for analytical, non-clinical, and clinical studies. In addition, we provide details about the approval history, number, and types of biosimilar products that have been approved between 2009 and 2022 in Japan.

Unusually strong electronic correlation and field-induced ordered phase in YbCo2

We report the first study of electrical resistivity, magnetization, and specific heat on YbCo₂. The measurements on a single-phased sample of YbCo₂bring no evidence of magnetic ordering down to 0.3 K in a zero magnetic field. The manifestations of low Kondo temperature are observed. The specific heat value divided by temperature,C/T, keeps increasing logarithmically beyond 7 J/mol K²with decreasing temperature down to 0.3 K without no sign of magnetic ordering, suggesting a very large electronic specific heat. Analysis of the magnetic specific heat indicates that the large portion of the low-temperature specific heat is not explained simply by the low Kondo temperature but is due to the strong intersite magnetic correlation in both the 3dand 4felectrons. Temperature-dependent measurements under static magnetic fields up to 7 T are carried out, which show the evolution of field-induced transition above 2 T. The transition temperature increases with increasing field, pointing to a ferromagnetic character. The extrapolation of the transition temperature to zero field suggests that YbCo₂is in the very proximity of the quantum critical point. These results indicate that in the unique case of YbCo₂, the itinerant electron magnetism of Co 3d-electrons and the Kondo effect within the vicinity of quantum criticality of Yb 4f-local moments can both play a role.

Regulatory Issues: PMDA - Review of Sakigake Designation Products: Oncolytic Virus Therapy with Delytact Injection (Teserpaturev) for Malignant Glioma

In June 2021, the Ministry of Health, Labor and Welfare approved Delytact Injection as a regenerative medical product for oncolytic virus therapy. The active substance of Delytact Injection is teserpaturev, a genetically engineered herpes simplex virus type 1 (strain F) in which the α47 gene and both copies of the γ34.5 gene have been deleted and the infected cell protein 6 (ICP6) gene has been inactivated by the insertion of the lacZ gene from Escherichia coli. Delytact Injection, when intratumorally administered to patients with malignant glioma, is expected to exert the following effects: (1) the mutant virus selectively replicates in tumor cells and destroys the infected cells through the replication process, exerting a cytocidal effect, and (2) the administration leads to induction of tumor-responsive T cells, which activates antitumor immunity and thus prolongs the survival of patients with malignant glioma. A Japanese phase II study (Study GD01) was conducted in patients with glioblastoma who had residual or recurrent tumors after radiotherapy with concomitant temozolomide. In Study GD01, however, stable disease continued for an extended period in some patients with glioblastoma. Hence, Delytact Injection is expected to be effective to a certain level. In line with this, Delytact Injection has been approved as an option for the treatment of malignant glioma, with one of the 3 approval conditions including conducting a use-results comparison survey and resubmission of the marketing authorization application within the granted time period of 7 years, under the conditional and time-limited approval scheme described in Article 23-26 of Act on Securing Quality, Efficacy and Safety of Products Including Pharmaceuticals and Medical Devices.

Regulatory Aspects of Cell and Gene Therapy Products: The Japanese Perspective

Regulations for regenerative medicine for human use, such as cell and gene therapy (CGT), have evolved in accordance with advancements in clinical experience, scientific knowledge, and social acceptance of these technologies. In November 2014, two acts, "The Act on the Safety of Regenerative Medicine" (ASRM) and the "Pharmaceuticals, Medical Devices, and Other Therapeutic Products Act" (PMD Act), came into effect in Japan. The responsibilities of medical institutions in ensuring the safety and transparency of such medical technologies are described under ASRM. The PMD Act provides the option of a new scheme for obtaining conditional and time-limited approval for CGT products. Overall, research and development on CGT products, especially gene therapy products, is progressing. New legislative frameworks have been designed to promote the timely development of new technologies and safe and effective CGT products for Japanese patients.

Transition from spin glass to paramagnetism in the magnetic properties of PrAu2Si2

It is unexpected that a spin-glass (SG) transition, which generally occurs only in systems with some form of disorder, was observed in the ThCr₂Si₂-type compound PrAu₂Si₂at a temperature of ∼3 K. This puzzling phenomenon was later explained based on a novel dynamic frustration model that does not involve static disorder. We present the results of re-verification of the reported SG behaviors by measuring the physical properties of three polycrystalline PrAu₂Si₂samples annealed under different conditions. Indeed, in the sample annealed at 827 °C for one week, a SG transition does occur at a temperature ofT_f∼ 2.8 K as that reported previously in the literature. However, it is newly found that the SG effect is actually more pronounced in the as-cast sample, and almost completely disappears in the well-annealed (at 850 °C for four weeks) sample. The annealing effect observed in PrAu₂Si₂, that is, SG to paramagnetism transition is discussed by comparing with earlier results reported on the same system and other isomorphic compounds.

Humanized NOD/SCID/IL2rγnull mice exhibit functionally augmented human regulatory T cells associated with enzymatic up-regulation of H3K27me3 in comparison with humans

Humanized non-obese diabetic/severe combined immunodeficiency/interleukin-2 receptor-γ-null (NOD/SCID/IL2rγ^null ) [humanized (huNSG)] mice engrafted with human hematopoietic cells have been used for investigations of the human immune system. However, the epigenetic features of the human regulatory T (T_reg ) cells of huNSG mice have not been studied. The objective of this study was to clarify the characteristics of human T_reg cells in huNSG mice, especially in terms of the epigenetic aspects. We compared the populations, inhibitory molecule expression and suppressive capacity of human T_reg cells in spleens harvested from the huNSG mice 120 days after the engraftment of human umbilical cord blood CD34⁺ cells with human peripheral blood mononuclear cells (PBMCs). Histone modifications and enhancer of zeste homolog 2 (Ezh2), an H3K27 methyltransferase, of human T_reg cells were quantified in huNSG mice and human PBMCs. The effect of Ezh2 inhibitor on human T_reg cells exposed to interleukin (IL)-6 was also compared between them. Human T_reg cells in the spleens of huNSG mice showed an increased proportion among CD4⁺ T cells, higher expressions of forkhead box protein 3 (FoxP3), cytotoxic T lymphocyte antigen 4 (CTLA-4) and glucocorticoid-induced tumor necrosis factor-related protein (GITR), a higher production of IL-10 and enhanced suppressive capacity when compared with those in human PBMCs. H3K27me3 and Ezh2 were specifically up-regulated in human T_reg cells of huNSG mice in comparison with those of human PBMCs. The decrease in T_reg cells induced by IL-6 exposure was attenuated in huNSG mice when compared with human PBMCs, while the difference between them was cancelled by addition of Ezh2 inhibitor. In conclusion, huNSG mice exhibit functionally augmented human T_reg cells owing to enzymatic up-regulation of H3K27me3.

Magnetic and transport properties of new ternary uranium-based germanide U2Rh3Ge5

A new ternary uranium germanide U₂Rh₃Ge₅ has been successfully synthesized and investigated by means of magnetic susceptibility χ(T, H), isothermal magnetization M(T, H), electrical resistivity ρ(T), and specific heat C(T, H) measurements. This compound is found to crystallize in the U₂Co₃Si₅-type orthorhombic structure. The low-field χ(T) shows a clear peak at T _N = 41.5 K corresponding to an antiferromagnetic transition. The M(H) curve measured up to 70 kOe exhibits an H-linear behavior at 2 K with very small induced magnetic moments, while it shows upward curvature with increasing temperature, implying the possible presence of a metamagnetic transition in high-field region above 70 kOe. As the temperature decreases, ρ(T) increases slowly at T > T _N and decreases rapidly at T < T _N, which can be understood based on a semiconductor-like narrow band gap model (or the c-f hybridization effect) and an antiferromagnetic spin-wave model, respectively. No evidence of heavy-fermion behavior or superconductivity transition is observed at temperatures as low as 0.4 K. The obtained experimental results are discussed by comparing with those reported for the isomorphic compound U₂Ir₃Si₅ and the quasi-isomorphic compound U₂Rh₃Si₅.

AB0122 DETECTION OF CIRCULATING M3 MUSCARINIC ACETYLCHOLINE RECEPTOR REACTIVE TH17 CELLS IN PATIENTS WITH PRIMARY SJÖGREN’S SYNDROME

Background:

Sjögren’s syndrome (SS) is an autoimmune disease which is characterized by lymphocytic infiltration including CD4+IL-17 producing helper T (Th17) cells to the lacrimal and salivary glands. We previously detected anti-M3 muscarinic acetylcholine receptor (M3R) antibodies (1) and M3R reactive CD4+IFNγ producing helper T (Th1) cells (2) in SS patients. Moreover, we clarified that M3R reactive Th1 and Th17 cells had pathogenic roles in the development of auto-immune sialadenitis in SS mouse model (3).

Objectives:

The purpose of this study was to identify circulating M3R reactive Th17 cells among primary SS (pSS) patients, and to determine functional properties of those cells.

Methods:

1)Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood of 10 pSS patients, age gender matched 10 healthy controls (HC), and 5 IgG4-related disease (IgG4-RD) patients. According to their HLA-DRB1 typing, top 10 ranked 20 mer peptides from the full length of M3R, which were highly predicted to bind to each HLA molecules according to the immune epitope database website, were selected for each subjects. PBMCs were stimulated with these selected M3R peptides mixed for 40 hours, and M3R peptide reactive IL-17 secreting cells were detected by IL-17 enzyme-linked immunospot assay (ELISpot).

2)PBMCs from 5 pSS patients who were positive for M3R specific IL-17 secreting cells, were stimulated with selected 12-20 mer M3R peptides separately, to identify the dominant M3R peptides responsible for IL-17 secretion by ELISpot.

3)To identify whether detected IL-17 secreting cells were Th17 cells or not, isolated CD4+T cells from 3 pSS patients who were positive for M3R specific IL-17 secreting cells, were co-cultured with auto-monocyte derived dendritic cells (DCs), and stimulated with the dominant IL-17 secreting M3R peptides detected in method 2.

4)Anti-M3R antibodies were examined using ELISA method.

5)Clinical features were compared between M3R specific Th17 cells positive and negative pSS patients.

Results:

1)5 of 10 (50%) pSS patients, while none of 10 (0%) HC, and 5 (0%) IgG4-RD patients, showed significantly increased IL-17 positive spots against selected M3R peptides mixed stimulation compared with non-stimulation in ELISpot (Figure 1). M3R specific IL-17 secreting cells were detected significantly more frequently in pSS (5/10, 50%) than in HC (0/10, 0%) (p=0.03).

2)All 5 pSS patients, who were positive for M3R specific IL-17 secreting cells, showed significantly increased IL-17 positive spots against M3R AA76-95 peptides.

3)Co-culturing CD4+ T cells with DCs, stimulated with identified dominant M3R peptides in method 2, showed significantly increased spots, clarifying that IL-17 secreting cells were peripheral M3R reactive Th17 cells.

4)Titers of anti-M3R antibodies were significantly higher among M3R reactive Th17 cells positive pSS patients than negative pSS patients.

5)5 pSS patients positive for M3R reactive Th17 cells had significantly higher disease activity score (ESSDAI: 8.0±4.3) than 5 negative pSS patients (2.8±1.7) (P=0.01).

Conclusion:

We detected circulating M3R reactive Th17 cells in pSS patients using ELISpot, whose T cell epitopes were shown to be included in M3R AA76-95. Moreover, M3R reactive Th17 cells might correlate with higher disease activity and production of anti-M3R antibodies in pSS patients.

References:

[1]Tsuboi H, et al. New epitopes and function of anti-M3 muscarinic acetylcholine receptor antibodies in patients with Sjögren’s syndrome.Clin Exp Immunol2010;162:53-61

[2]Naito Y, et al. Altered peptide ligands regulate muscarinic acetylcholine receptor reactive T cells of patients with Sjögren’s syndrome.Ann Rheum Dis2005;65:269-71

[3]Iizuka M, et al. Pathogenic role of immune response to M3 muscarinic acetylcholine receptor in Sjögren’s syndrome-like sialoadenitis.J Autoimmun.2010;35:383-9

Disclosure of Interests:

None declared

Extended stability range of the non-Fermi liquid phase in UCoAl

High pressure was used to investigate the stability of the non-Fermi liquid (NFL) state, observed in electrical resistivity of uranium-based band metamagnet UCoAl in a pure form (paramagnet) or with Fe substitution (ferromagnetic ground state), both in a single-crystal form. By combining the pressure variations of magnetization and resitivity in these materials the phase diagram for UCoAl had been constructed. The band metamagnet transforms into the ferromagnetic state as the critical metamagnetic field is reduced to zero by the lattice expansion analogous to the negative pressure. Within the same diagram, the increasing hydrostatic pressure drives the critical metamagnetic field upwards while reducing the magnetization increment at the transition. The NFL state persists to about 4-5 GPa. Although spin fluctuations play an important role in the character of UCoAl, they do not exhibit any criticality in the sense of divergence of parameters describing the resistivity around the Ferro-NFL phase transition, which is of the first order type.

Role of valence fluctuations in the superconductivity of Ce122 compounds

Pressure dependence of the Ce valence in CeCu(2)Ge(2) has been measured up to 24 GPa at 300 K and to 17 GPa at 18-20 K using x-ray absorption spectroscopy in the partial fluorescence yield. A smooth increase of the Ce valence with pressure is observed across the two superconducting (SC) regions without any noticeable irregularity. The chemical pressure dependence of the Ce valence was also measured in Ce(Cu(1-x)Ni(x))(2)Si(2) at 20 K. A very weak, monotonic increase of the valence with x was observed, without any significant change in the two SC regions. Within experimental uncertainties, our results show no evidence for the valence transition with an abrupt change in the valence state near the SC II region, challenging the valence-fluctuation mediated superconductivity model in these compounds at high pressure and low temperature.

Possibility of valence-fluctuatsion-mediated superconductivity in Cd-doped CeIrIn(5) probed by In NQR

We report on a pressure-induced evolution of exotic superconductivity and spin correlations in CeIr(In(1-x)Cd(x))(5) by means of in-nuclear-quadrupole-resonance (NQR) studies. Measurements of an NQR spectrum and nuclear-spin-lattice-relaxation rate 1/T(1) have revealed that antiferromagnetism induced by Cd doping emerges locally around Cd dopants, but superconductivity is suddenly induced at T(c)=0.7 and 0.9 K at 2.34 and 2.75 GPa, respectively. The unique superconducting characteristics with a large fraction of the residual density of state at the Fermi level which increases with T(c) differ from those for anisotropic superconductivity mediated by antiferromagnetic correlations. By incorporating the pressure dependence of the NQR frequency pointing to the valence change of Ce, we suggest that unconventional superconductivity in the CeIr(In(1-x)Cd(x))(5) system may be mediated by valence fluctuations.

Central neurocytoma with unusually intense FDG uptake: case report

Central neurocytoma is a benign neuronal tumor with a favorable prognosis. This tumor is typically characterized by decreased uptake of 18F-fluorodeoxy glucose (FDG) and any increased uptake of FDG in patients suffering from this tumor would be highly unusual. A case of central neurocytoma with an intense FDG uptake, combined with atypical histopathological features and a high proliferation index is reported in this paper. A 45-year-old male had a two months' history of right hemiweakness. Magnetic resonance (MR) imaging showed a large tumor in the right lateral ventricle. Positron emission tomography (PET) with FDG revealed high glucose metabolism in the tumor. The histological diagnosis was central neurocytoma with atypical features characterized by microvascular proliferation. The MIB-1 labeling index, ordinarily smaller than 2.0%, was 7.0%. Conventional radiotherapy, with a total dose of 50 Gy, was administered after the surgical treatment. The patient returned to his normal daily activities after the cessation of radiation therapy.

Properties of cattle bone powder-coated composite particles as high-performance and open column liquid chromatographic column packings

Cattle bone powder (CBP) from natural resources was employed as a protein adsorbent instead of chemically synthesized hydroxyapatite (HA). Though a small amount of impurities was detected, CBP possessed a crystallinity similar to HA. Using CBP/40PE prepared from CBP and polyethylene beads (40 microns) by dry impact blending as an HPLC column packing, considerable correlation was observed between the elution concentrations of proteins and their pI. Such behavior was caused by the relatively large adsorption capacity for basic proteins. CBP/40PE could completely separate gamma-globulin from BSA also as an open column chromatographic support, under relatively low concentration.

Chemical synthesis of H-phosphonate DNA without using N-protecting groups

Oligodeoxyribonucleotides were synthesized by using N-unprotected H-phosphonate monomers. It was found that the amino groups of nucleosides were not modified during condensation where benzotriazolyloxy carbonium and phosphonium types of compounds were employed as condensing reagents. The most effective condensing reagent for rapid internucleotidic bond formation was found to be 2-(benzotriazol-1-yloxy)-1,1-dimethyl-2-(pyrrolidin-1- yl)-1,3,2- diazaphospholidinium hexafluorophosphate (BOMP). In the present H-phosphonate approach, 2-benzenesulfonyl-3-(3-nitrophenyl)oxaziridine (BNO) was successfully employed as a new oxidizing reagent for oxidation of the H-phosphonate linkages under anhydrous conditions.

High-pressure system for Compton scattering experiments

High-pressure apparatus for Compton scattering experiments has been developed to study the momentum distribution of conduction electrons in metals and alloys at high pressure. This apparatus was applied to observe the Compton profile of metallic Li under pressure. It was found that the Compton profile at high pressure could be obtained within several hours by using this apparatus and synchrotron radiation. The result on the pressure dependence of the Fermi momentum of Li obtained here is in good agreement with that predicted from the free-electron model.

Resin glycosides. XXV. Multifidins I and II, new jalapins, from the seed of Quamoclit x multifida

Alkaline hydrolysis of the ether-soluble resin glycoside fraction of seeds of Quamoclit (Q.) x multifida, a hybrid between Q. pinnata and Q. coccinea, gave new glycosidic acids, multifidinic acids A and B, along with two known glycosidic acids, quamoclinic acid A and operculinic acid A, and three organic acids, (2S)-2-methylbutyric acid, n-decanoic acid and n-dodecanoic acid. Further, as major ether-soluble resin glycosides, new jalapins named multifidins I and II, were isolated accompanied by quamoclins I-IV, which were previously obtained from seeds of Q. pinnata. The structures of multifidins I and II, and multifidinic acids A and B have been determined on the basis of chemical and spectral data.

[Experimental study on local cooling of the eyeball in ocular surgery (4). The local cooling effect on uveal blood circulation, intraocular pressure, and intravitreous pressure]

The effects of local cooling on the uveal blood circulation, intraocular pressure, and intravitreous pressure were evaluated. Saline solutions maintained at 10 degrees C and 35 degrees C were dripped on the rabbit ocular surface. After 5-minute dripping of 10 degrees C saline solution, the temperature decreased by 10.6 degrees C at the ciliary body, 7.7 degrees C at the choroid and 2.9 degrees C at the central region of the vitreous. Hydrogen clearance with electrolytically generated hydrogen gas was employed to measure the tissue blood flow, which fell to 82.9% of normo-thermal value at the ciliary body and 86.3% at the choroid. The intravitreous pressure dropped by 2.8 mmHg. After 30-minute dripping of 10 degrees C saline solution, the intraocular pressure dropped by 3.0 mmHg. We consider that the reduction of intraocular and intravitreous pressure during local cooling of the ocular surface is related to decrease in the uveal blood flow.

[The local cooling effect of anterior chamber irrigation on the blood-aqueous barrier]

Local cooling effect on the breakdown of the blood-aqueous barrier (BAB) following anterior chamber irrigation, including additional direct irritation of the iris, was evaluated fluorophotometrically. The rabbit anterior chamber was irrigated with simulated aqueous humor (S-MA 2) the temperature of which was maintained at 35 degrees C or 10 degrees C. The fluorophotometry was performed before and 4, 24, 48 hours and 7 days after irrigation for 30 or 60 minutes. The temperature changes in the anterior chamber, retrolental vitreous body and posterior retina were also measured with a thermocouple during irrigation at 10 degrees C. The temperature of the anterior chamber and the retrolental vitreous fell to 15.0 degrees C and 28.2 degrees C, respectively, within 30 minutes after starting irrigation, whereas the temperature drop in the posterior retina was only 2.0 degrees C after 60 min. At 4 hours after 60-minute irrigation, the breakdown of the BAB was greater than following 30-minute irrigation. There was no significant difference in the BAB breakdown between eyes irrigated at 10 degrees C and 35 degrees C.

Backward walking induced by L-5-hydroxytryptophan in mice

An intraperitoneal administration of large doses of L-5-hydroxytryptophan (L-5HTP) induced dose-dependently a behaviour characterized by backward walking in mice. D-5-hydroxytryptophan (D-5HTP) and L-3,4-dihydroxyphenylalanine (L-DOPA) in the same doses failed to induce such behaviour. The backward walking induced by L-5HTP was blocked by a decarboxylase inhibitor, DL-alpha-methyl-DOPA, but was potentiated by a monoamine oxidase inhibitor (MAOI), tranylcypromine or pargyline. An intracerebral injection of L-5-hydroxytryptamine (5-HT) induced a similar backward walking which was potentiated by a MAOI. The backward walking induced by L-5HTP was completely inhibited by 5-HT and dopamine (DA) receptor blockers, but was not inhibited by alpha- or beta-adrenergic blocker, antihistamine or anticholinergic drug. On the other hand, zimelidine and clomipramine, 5-HT uptake inhibitors, markedly potentiated the backward walking, while desipramine had no effect. From the results, it appears that excess amounts of 5-HT formed from L-5HTP produced the backward walking by directly stimulating the central 5-HT receptors, and DA is also involved in the behaviour. This behaviour may serve as a good model to assess the central serotonergic activity of drugs.

Dopamine receptor blocking activity of sulpiride in the canine exocrine pancreas

The inhibitory effect of sulpiride on dopamine receptors was investigated in the exocrine pancreas of dogs anesthetized with pentobarbital and with the stomach ligated at the pylorus. All test substances were given intravenously. Dopamine, acetylcholine, histamine and secretin produced a dose-related increase in pancreatic juice secretion, though the dose-effect curves of these secretagogues differed in shape. Epinephrine, norepinephrine, isoproterenol, methamphetamine and serotonin had no secretagogue effects. The effects of acetylcholine and histamine were inhibited by atropine and cimetidine, respectively. The effect of dopamine was blocked by haloperidol, but not by atropine, cimetidine, phentolamine and propranolol. These results suggest that dopamine acts on specific dopamine receptors related to the exocrine pancreatic secretion. Haloperidol had no effect on the effects of acetylcholine and histamine, but did inhibit the secretin-induced secretion, though the inhibitory effect was to a lesser extent than on the dopamine response. Sulpiride and chlorpromazine also suppressed dose-dependently the dopamine-induced secretion. The inhibitory activity of sulpiride was almost the same as that of haloperidol, and 12 times more potent than that of chlorpromazine. Sulpiride was found to be a potent dopamine antagonist in the canine exocrine pancreas.

A simple histochemical screening method for amine uptake

A simple histochemical method for screening amine uptake in vitro is described. The filum terminale and the Vibratome sections of the caudate nucleus of reserpinized rats were used as the sources of noradrenaline (NA) and 5-hydroxytryptamine (5-HT), and as the sources of dopamine (DA) containing neurons, respectively. When incubated in an oxygenated medium (Krebs-Ringer) containing the corresponding amines, these preparations effectively accumulated the amines. 6-Hydroxytryptamine (6-HT) was used instead of 5-HT because of its stronger fluorescence and lower photo-decomposition of beta-carboline formed from 6-HT. The inhibitory patterns of representative uptake inhibitors obtained by the present method agreed well with those reported previously by biochemical methods. Effects of other types of drugs were also studied. The present method is a simple, rapid and non-radioisotopic method for determining amine uptake inhibiting action of a drug and the degree and selectivity in which it acts on the three kinds of amines.

Amines and the rat exocrine pancreas: (2) Effects of receptor blockers on turnover of L-5HTP

The metabolism of L-5HTP by the rat exocrine pancreas, and effects of blockers on the metabolism were studied by fluorescent histochemical and chemical methods. Histochemically, 5-hydroxytryptamine (5-HT) blockers (methyserigide and cyprohepatdine) and dopamine (DA) blockers (haloperidol and sulpiride) produced no apparent changes in fluorescence pictures after injection of L-5HTP. alpha-blockers (phenoxybenzamine and phentolamine) and monoamine oxidase (MAO) inhibitor (iproniazide) produced an increased accumulation of 5-HT fluorescence in the apical regions of acinar cells where the zymogen granules are stored. Chemically, the 5-HT blockers decreased the 5-HT content after injection of L-5HPT. Sulpiride had no effect. Haloperidol decreased the 5-HT content. MAO inhibitor resulted in a vast accumulation of L-dopa: e.g. (1) L-5HTP was more slowly eliminated, and (2) 5-HT blockers produced a decreased content of 5-HT after injection of L-5HTP, in contrast to the finding that DA-blockers produced an incresed content of DA after injection of L-dopa. The mechanism responsible for the differences is discussed in relation to the possible pharmacological effects of L-5HTP and L-dopa on the secretion from the exocrine pancreas of rats.

Amines and the rat exocrine pancreas: (1). Effects of receptor blockers on turnover of L-dopa

The acinar cells of the exocrine pancreas have the capacity of efficiently take up and metabolize L-dopa. In the present study, the metabolism of L-dopa by the exocrine pancreas of the rat and effects of receptor blockers on the metabolism were studied by fluorescent histochemical and chemical methods. After i.v. administration of L-dopa (50 mg/kg), a large amount of dopamine (DA) was detected in the exocrine pancreas, and in the pancreatic juice large amounts of DA and its metabolites. DA-blockers (haloperidol, sulpiride, and pimozide) and alpha-blockers (phenoxybenzamine, and phentolamine) produced a significant increase in the accumulation of DA after administration of L-dopa. On the other hand, beta-blockers (propranolol, and oxprenolol) were without effects. The excretion of DA into the pancreatic juice appeared to be associated with the secretion of zymogen granules, thus DA serves as an indicator of pancreatic secretory activity, especially of enzyme secretion. Because DA- and alpha-blockers produced an increase in the accumulation of DA, dopaminergic and/or alpha-adrenergic mechanisms probably exist in the exocrine pancreas of the rat and these mechanisms modify the enzyme secretion.

Amines and the rat exocrine pancreas: (3) Effects of amines on pancreatic secretion

Effects of L-dopa, L-5HTP, a few amines, and related compounds on the pancreatic rate of flow, protein secretion, and bicarbonate secretion were studied in conscious rats. Single injections of L-dopa, DA and apomorphine did not modify the rate of flow, while an increase was seen with infusion of DA. L-dopa stimulated the protein secretion. L-5HTP and 5-HT decreased the rate of flow and protein secretion. Effects of L-dopa and L-5HTP on the protein secretion were prevented by DA- and 5-HT blockers, respectively. Neither L-dopa nor L-5HTP had any effect on the bicarbonate secretion. Secretin and cholinergic agents (acetylcholine and carbamylcholine) strongly stimulated the rate of flow of pancreatic juice. alpha-Agonists (phenylephrine and clonidine) decreased the rate of flow, and the effects were inhibited by an alpha-blocker. The alpha-agonists had no effect on protein secretion. Although, alpha-blockers (phenoxybenzamine and phentolamine) had no effects on the rate of flow, they did decrease the protein secretion. Isoproterenol was a potent secretagogue, and the effect was suppressed by a beta-blocker. Histamine had no effect on the rate of flow. The results were discussed in relation to our previous histochemical and chemical findings, and the species difference between rats and dogs in response to the amines.

Role of brain amines in the fetal hyperpyrexia caused by tranylcypromine in LiCl-pretreated rats

Tranylcypromine (TCP), a monoamine oxidase inhibitor, caused a fatal hyperpyrexia in rats pretreated with LiCl once a day for 4 days. Pretreatment with LiCl alone did not alter the level of serotonin (5-HT), dopamine (DA) and norepinephrine (NE) in the brain. In fatal hyperpyrexia caused by LiCl plus TCP, the brain 5-HT and DA levels were increased, whereas the brain NE level was decreased. Reserpine and alpha-methyl-p-tyrosine completely prevented the hyperpyrexia, but FLA-63 did not show any effect. The hyperpyrexia was completely prevented by p-chlorophenylalanine (PCPA) given 72 hours before TCP but not by PCPA given 24 hours before TCP. Haloperidol and chlorpromazine, DA receptor blockers, inhibited the fatal hyperpyrexia, while cyproheptadine and methysergide, 5-HT receptor blockers, did not. These results suggest that DA plays an essential role in the hyperpyrexia induced by the combination of TCP and LiCl in rats, but the involvement of 5-HT is inconclusive.

Effect of isoprenaline and phenylephrine on the adenosine 3',5'-monophosphate content and mechanical activity of cold-stored and fresh taenia caecum from the guinea-pig

1. Cold storage treatment of the guinea-pig taenia caecum had a greater inhibitory effect on the isoprenaline-induced relaxation than that induced by phenylephrine. Prolonged cold storage (12-14 days) almost abolished the effect of isoprenaline but only reduced the phenylephrine effect. The ED50 of cyclic adenosine 3',5'-monophosphate (cyclic AMP) that elicited muscle relaxation was not altered by the prolonged cold storage. 2. After cold storage treatment, tissue cyclic AMP content was decreased; however, isoprenaline still caused a dose-dependent increase in the cyclic AMP level. The threshold dose of isoprenaline for cyclic AMP accumulation was the same in fresh and cold-stored preparations. 3. In the fresh preparation, the onset of the isoprenaline (10(-6)M)-induced relaxation preceded the increase in tissue cyclic AMP. 4. Isoprenaline, phenylephrine, adrenaline and noradrenaline at doses (ED50) sufficient to induce muscle relaxation did not always increase the cyclic AMP level. 5. Similarly, the responses to papaverine and nitroglycerine were not accompanied by an increase in cyclic AMP. 6. The adenylate cyclase and phosphodiesterase (low and high Km) activities of taenia caecum were not attenuated by the prolonged cold storage. 7. Propranolol inhibited both the isoprenaline-induced relazation and cyclic AMP accumulation; however, the pA2 values were significantly different for the two events. 8. Based on these results, both the relaxation and cyclic AMP accumulation caused by isoprenaline are mediated by activation of beta-adrenoceptors but are independent phenomena.

Dopamine receptor blocking activity of sulpiride in the central nervous system

Effects of sulpiride on the central nervous system were studied in catalepsy induction (I) and antagonism to gnawing behaviour (II) induced by apomorphine and methamphetamine in normal rats, and in antagonism to rotational behaviour (III) induced by apomorphine and methamphetamine in rats with substantia nigra unilaterally lesioned chronically by microinjection of 6-hydroxydopamine. Sulpiride was administered orally and intraventricularly, and the effects of sulpiride were compared to those of haloperidol and chlorpromazine administered through the same routes. In oral administration, sulpiride was almost inactive in (I), and was several hundreds to a thousand times less potent than haloperidol in (II) and (III), while chlorpromazine was 20 to 150 times stronger than sulpiride. In intraventricular administration, sulpiride was almost equipotent to haloperidol in (I), and was equally effective to or 2 to 3 times more effective than halopridol in (III), although several times less in all respects. These findings suggest that sulpiride is essentially a potent inhibitory substance on dopamine receptors in the central nervous system and the rather weak central effects of peripherally given sulpiride are due to poor penetration through the blood brain barrier.

Adenosine 3',5'-cyclic monophosphate as a possible mediator of rotational behaviour induced by dopaminergic receptor stimulation in rats lesioned unilaterally in the substantia nigra

A possible involvement of c-AMP in the rotational behaviour induced by a stimulation of dopamine receptors in corpus striatum of rats was investigated. Rats were lesioned unilaterally in the substantia nigra with 6-hydroxydopamine. Intraventricular injection of dopamine, norepinephrine and apomorphine induced rotational behaviour towards the intact side as did dibutyryl c-AMP (dB-c-AMP). Dopamine, norepinephrine and apomorphine could activate adenylate cyclase in homogenates of caudate nucleus. The activation by dopamine was blocked by haloperidol. I.p. injected apomorphine increased c-AMP content bilaterally in caudate nucleus and caused turning towards the intact side; theophylline potentiated and haloperidol blocked the effect. In non-lesioned rats, dopamine and norepinephrine, when injected unilaterally into the caudate nucleus, elicited truning twoards the non-injected side if the rats were pretreated with reserpine and tranylcypromine. c-AMP and dB-c-AMP given similarly to rats pretreated with theophylline also produced turning towards the non-injected side regardless the pretreatment with reserpine and tranylcypromine. All these results emphasize the possibility that c-AMP acts as a second messenger in the central dopaminergic pathway in rats. The supersensitivity of the dopaminergic system which developed after denervation is also discussed.