Effects of a new endothelin antagonist, TAK-044, on post-ischemic acute renal failure in rats

Protective effects of a new endothelin (ET) receptor antagonist, TAK-044, were studied in a model of acute renal failure (ARF) in rats. ARF was induced by clamping the left renal pedicle for 45 minutes with contralateral nephrectomy and subsequent reperfusion of the left kidney. Plasma creatinine concentration (Pcr) increased to 2.28 mg/dl 24 hours after reperfusion of the ischemic kidney. Intravenous administration of TAK-044 (1-10mg/kg) prior to renal occlusion dose-dependently but partially attenuated the increase in Pcr and the morphological damages of the kidney. ET-1 and ET-3 increased perfusion pressure in isolated kidney preparations with similar potency, indicating that the renal vasoconstriction evoked by these ET isomers is mainly via ETB receptors, and TAK-044 (10nM) shifted the ET-1 dose-response curve to the right by a factor about 10. In a rat renal membrane fraction, ET-1 showed competitive inhibition of specific [125I]ET-1 binding with an IC50 value of 0.34nM and a Hill slope of 1.10. ET-3 did so with a higher IC50 value (3.3nM) and a lower Hill slope (0.56), suggesting that rat kidney contains both ETA and another receptor subtype, probably ETB. TAK-044 inhibited ET-1 binding with an IC50 value of 6.6nM and a Hill slope of 0.41. Plasma concentrations of immunoreactive TAK-044 were maintained over 7nM for 8 hours following i.v. injection of 10mg/kg TAK-044. These results suggest that endogenous ET is involved in the pathogenesis of post-ischemic ARF, at least, in part and that TAK-044 provided protective effects against ARF by blocking ET receptors, possibly both ETA and ETB receptors in renal vasculature and parenchymal cells.

Endothelin family peptides in human plasma and urine: their molecular forms and concentrations

Molecular forms and concentrations of endothelin (ET) family peptides in normal human plasma and urine were investigated using five different sandwich-type enzyme immunoassays (sandwich-EIAs) and reverse-phase high performance liquid chromatography (RP-HPLC). We found that immunoreactive (IR-) big ET-3 and IR-big ET-2 were the major species in both plasma and urine from normal humans. Big ET-2(1-38) was found to be the major form of IR-big ET-2 in plasma. Urinary IR-big ET-2 and plasma and urinary IR-big ET-3 were heterogeneous, and the IR-big ET-3s were larger (M(r) 6,000-12,000) than authentic big ET-3. IR-big ET-1, IR-ET-1, and IR-ET-3 were found at relatively low concentrations in human plasma and urine, and their major forms were identical to authentic big ET-1, ET-1, and ET-3, respectively. Although ET-1 and other ET family peptides have often been measured using RIAs with board-spectrum antibodies, the presence of high concentrations of IR-big ET-2 and IR-big ET-3, but not IR-ET-1, in plasma and urine indicates that the clinical significance of ET family peptides should be investigated with assay methods specific to each ET and big ET.

Purification and characterization of the receptor for pituitary adenylate cyclase-activating polypeptide

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a 38-amino acid peptide (PACAP38) or a truncated peptide with the same 27 amino-terminal residues (PACAP27). The PACAP receptor was solubilized from bovine brain membranes with digitonin and purified 30-fold by the combination of DEAE-Toyopearl and hydroxylapatite chromatographic analyses. The partially purified PACAP receptors were mixed with biotinylated PACAP27 to form receptor-ligand complexes and then adsorbed onto avidin-agarose. The adsorbed PACAP receptors were eluted with an acidic buffer containing 1.0 M NaCl (pH 4.0). The eluted receptors were purified further by hydroxylapatite and gel filtration chromatography. A single protein band with a M(r) = 55,000-60,000 was found in the final preparation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. Affinity labeling of the purified receptors with 125I-PACAP27 labeled the M(r) 55,000-60,000 protein specifically. The dissociation constant and the specific activity of the purified receptors were 25.8 pM and 17.2 nmol of ligand binding per mg of protein, respectively. Inhibitory constants determined by competitive binding experiments were 30.0 pM for PACAP27, 4.6 pM for PACAP38, and 37.3 nM for vasoactive intestinal peptide. Therefore, the purified PACAP receptor retained high affinity and ligand specificity. The sequence of the amino-terminal 29 residues was derived from the purified receptor.

Endothelin-1 analogues substituted at both position 18 and 19: highly potent endothelin antagonists with no selectivity for either receptor subtype ETA or ETB

Novel endothelin-1 (ET-1) analogues which are highly potent endothelin antagonists at both receptor subtype ETA and ETB are reported. The replacement of Asp18 with the Thr18 and of Ile19 with a hydrophobic amino acid whose side-chain branches on the gamma-carbon such as Leu, cyclohexylalanine, and gamma-methylleucine (gamma-MeLeu) resulted in loss of or significantly decreased the biological activity of ET-1, while high affinity for the ETA (IC50 = 0.42-0.70 nM) and ETB (IC50 = 0.17-0.43 nM) receptor was retained. These compounds were shown to have high antagonist activities in ET-1-induced vasoconstriction of porcine coronary artery (pA2 7.4-7.7) and in Sarafotoxin S6c-induced vasoconstriction of rabbit pulmonary artery ([Thr18, gamma-MeLeu19]ET-1: pA2 8.4). Among these compounds, [Thr18, gamma-MeLeu19]ET-1 has the desirable characteristic of possessing no agonist activity at either receptor subtype.

Molecular cloning and functional expression of a cDNA encoding a human pituitary adenylate cyclase activating polypeptide receptor

A functional cDNA clone for a human pituitary adenylate cyclase activating polypeptide (PACAP) receptor was isolated from a human pituitary cDNA library. The cDNA encoded a polypeptide consisting of 525 amino acids with putative seven hydrophobic domains. Chinese hamster ovary (CHO)-K1 cells transfected with the cDNA specifically bound PACAP and mediated PACAP-triggered intracellular accumulation of cAMP, indicating that this cDNA encoded a functional human PACAP Type I receptor. This receptor was structurally related to the vasoactive intestinal peptide (VIP), secretin, calcitonin and parathyroid hormone receptors and is much more homologous to a rat PACAP receptor. Northern blot analysis revealed that PACAP receptor mRNAs were expressed mainly in the brain and widely distributed in the central nervous system.

White pulp reconstitution after human bone marrow transplantation

To reveal the reconstitution process of the white pulp after bone marrow transplantation (BMT), spleens of 24 marrow recipients whose survival times ranged from 34 to 303 days after BMT, were analyzed at the histopathological and immunohistochemical level. Up to 3 months after BMT, the white pulp was atrophic and consisted mainly of T cells forming periarteriolar lymphatic sheaths (PALS). Approximately 100 days after BMT, B cells aggregated in some of the white pulp, forming primary follicles, whereas marginal zones could not be detected. Beyond 4 months after BMT, the PALS, the lymphoid follicle, and the marginal zone of the white pulp could be seen in most of the recipients' spleens. However, the recovery of the marginal zone was poor up to 10 months after BMT. Thus, the white pulp was reconstituted sequentially, beginning in the PALS, followed by reconstitution in lymphoid follicles, and finally in the marginal zone. The development of the PALS corresponded well with the appearance of interdigitating dendritic cell, as did the development of lymphoid follicles with the appearance of follicular dendritic cell. The sequential reconstitution of the white pulp demonstrated in this study provides the morphological basis for the functional immune recovery of marrow recipients. In particular, the delay of the marginal zone reconstitution seems to be responsible for the functional asplenia of long-term survivors.

Molecular cloning and functional expression of rat cDNAs encoding the receptor for pituitary adenylate cyclase activating polypeptide (PACAP)

Two types of cDNA encoding PACAP receptors were isolated from the rat brain cDNA library by homology screening with a cDNA probe for VIP receptor. Nucleotide sequence analysis indicated that these two types of receptor mRNA were generated by alternative splicing mechanisms. These two cloned cDNAs were introduced into CHO cells respectively. Resultant transformants showed specific binding to [125I]PACAP27 which was displaced by unlabeled PACAP27 but not by VIP. Thus, these receptors are two subtypes of Type I PACAP receptor (Type I-A and Type I-B). The amino acid sequences of rat PACAP receptors deduced by the cDNAs showed a remarkable similarity with rat receptors for VIP, secretin, glucagon, and GHRH. A 6.5 kb significant hybridizing signal of the PACAP receptor mRNA was detected in the rat brain, and slight signal was also detected in the lung and the liver.

Effects of vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) on the spontaneous release of acetylcholine from the rat hippocampus by brain microdialysis

Vasoactive intestinal polypeptide (VIP) has been suggested to have a presynaptic effect on cholinergic terminals in the rat hippocampus, which results in an activation of acetylcholine (ACh) synthesis. Recently, a VIP-related novel peptide, pituitary adenylate cyclase activating polypeptide (PACAP) was isolated from the ovine hypothalamus, and we previously demonstrated in the rat that PACAP binding site densities were high in the hippocampus. In the present study, we investigated the effects of VIP and PACAP on the release of ACh from the rat hippocampus. We succeeded in detecting the spontaneous release of ACh from the dorsal hippocampus in the conscious rat using microdialysis and HPLC-ECD. VIP, PACAP38 and PACAP27 were applied through a microinjection cannula placed in a region adjacent to the tip of a microdialysis tube. Injections of VIP, PACAP38 and PACAP27 (12, 120 pmol) resulted in dose-related increases in ACh release. The ability to enhance ACh release was VIP > PACAP38 > PACAP27. The increased release of ACh caused by these peptides was highly calcium-dependent. Tetrodotoxin (10(-6) M) added to the perfusion medium significantly reduced both the release of ACh enhanced by these peptides and the basal release. The present results suggest that VIP, PACAP38 and PACAP27 presynaptically stimulate cholinergic activity in the hippocampus, which may be reflected by an increase in ACh synthesis to maintain releasable terminal stores of ACh.

Production of immunoreactive pituitary adenylate cyclase activating polypeptide (PACAP) by human neuroblastoma cells, IMR-32: detection and characterization with monoclonal and polyclonal antibodies against different epitopes of PACAP

Sensitive and specific two-side enzyme immunoassays (two-site EIAs) for pituitary adenylate cyclase activating polypeptides, PACAP38, and PACAP27, have been established using six monoclonal antibodies against PACAP38, and a rabbit antibody against a C-terminal portion of PACAP27. In extracts of rat hypothalamus, these EIAs detected not only PACAP38 and PACAP27 but also an immunoreactive (ir-) PACAP lacking an epitope of a monoclonal antibody, PA-1C, which recognizes the C-terminal portion of PACAP38. By the use of these EIAs, it was found that one of the human neuroblastoma cell lines, IMR-32, produced ir-PACAP. In reverse-phase (RP-)HPLC, intracellular and extracellular ir-PACAPs were separated into two peaks, of which one was eluted at a position close to that of PACAP38 and the other in rather hydrophobic fractions. Those ir-PACAPs also lacked PA-1C epitope of PACAP38. SDS-PAGE and immunoblot analysis of the two peaks of the RP-HPLC indicated that they consisted of several components including those with apparent molecular weights of 6.5 k and 10 k for the first peak ir-PACAP, and 14 k and 20 k for the second peak ir-PACAP. These results indicate that IMR-32 produces a precursor of PACAP and related peptides generated in various processing steps. Although the significance of the modification in the C-terminus of PACAP38 is unknown, IMR-32 may be a cell line useful for studying the regulation of the biosynthesis of PACAP.

Studies of a key protein in the mechanism of the excitation-contraction coupling process of frog skeletal muscle, using phenylglyoxal

The excitation-contraction (E-C) coupling process in single twitch fibres from frog toe muscle was inhibited selectively by phenylglyoxal (PGO), a specific guanidyl modifying reagent. A new protein (31.5 kDa), which has PGO-binding ability and seems to play a key role in the E-C coupling process, was solubilized from transverse tubule membrane-junctional sarcoplasmic reticulum complexes (TTM-JSR) of frog skeletal muscles, using 14C-PGO. The monoclonal antibody against this protein applied extracellularly inhibited the E-C coupling process of the single fibres. This protein appears to constitute the very first step of input for E-C coupling. It is considered to behave as an indispensable part of an 'electrometer' to measure membrane potentials. Therefore, the name 'electrometrin' is suggested for the new protein.

Dilated cardiomyopathy in a patient receiving continuous ambulatory peritoneal dialysis

We describe a unique case of a 10 year old girl with dilated cardiomyopathy who has been receiving continuous ambulatory peritoneal dialysis. She responded to treatment with a beta 1-agonist. We note that electrocardiography and echocardiography are effective for early recognition of the onset of dilated cardiomyopathy and that a thallium scan should be performed to assess the severity of dilated cardiomyopathy in patients with chronic renal insufficiency.

Regional distribution of pituitary adenylate cyclase activating polypeptide (PACAP) in the rat central nervous system as determined by sandwich-enzyme immunoassay

We investigated endogenous levels of a novel peptide, pituitary adenylate cyclase activating polypeptide (PACAP), in the rat central nervous system. The amount of PACAP was measured by means of highly specific and sensitive sandwich-enzyme immunoassay. This assay system following HPLC analysis revealed that PACAP38 was a major portion of the total PACAP immunoreactivity and PACAP27 levels were negligibly low in the brain. Therefore, we measured the amount of PACAP38 in 62 regions punched out from frozen tissue sections. High amounts of PACAP38 were found in the lateral septal nucleus (intermediate part), diagonal band, central amygdaloid nucleus, several parts of the hypothalamus (suprachiasmatic, supraoptic, periventricular and arcuate nuclei), central gray, interpeduncular nucleus and dorsal raphe. The suprachiasmatic, paraventricular and periventricular hypothalamic nuclei showed the highest levels. A moderate amount of the peptide was observed in the lateral septal nucleus (dorsal part), medial septal nucleus, medial amygdaloid nucleus, thalamus (paraventricular, paratenial, central medial, ventromedial, reuniens and rhomboid nuclei), hypothalamus (lateral hypothalamic area and mammillary body), ventral tegmental area, interfascicular nucleus and in the locus coeruleus. Such a distribution of endogenous PACAP38 did not parallel the localization of PACAP binding sites which we had demonstrated recently. Moreover, the topographical distribution of PACAP38 observed in the present study differed from that of VIP which had been previously reported. The present results suggest that PACAP38 may have a neurotransmitter/neuromodulator role which is different from that of VIP in the central nervous system.

Design and synthesis of ETA receptor antagonists and study of ETA receptor distribution

Many oligopeptides were designed to find ETA receptor antagonists on the hypothesis that an ETA receptor can recognize two hydrophobic parts of ET-1, i.e., Val-Tyr-Phe and Ile-Ile-Trp, over a short distance. They were synthesized from the benzyl ester of the C-terminal amino acid by stepwise chain elongation using the solution method. The binding affinity of the synthetic peptides to the endothelin receptors was examined in porcine cardiac ventricular muscle membrane for ETA receptor and in bovine whole brain membrane for ETB receptor. Hexamethyleneiminocarbonyl-Leu-trp-ala-beta ala-tyr-phe (TTA-386) was selected as an ETA receptor-selective competitive antagonist to ET-1. It competed against ET-1 at ETA receptor sites and showed one-third the binding affinity of ET-1 for ETA receptor and < 1/10,000 the affinity for ETB receptor. It inhibited the ET-1-induced increase of cytosolic free calcium concentration in A-10 cells. The 125I-labeled hexapeptide (125I-TTA-386) was prepared to distinguish the distribution of ETA receptor from ETB receptor. Scatchard plot analysis of saturation binding of 125I-TTA-386 to porcine cardiac membranes showed the same Bmax value as that of 125I-ET-1. Autoradiographic studies showed that ETA receptors are most abundant in the cardiac muscle, intestine, large bowel, spleen, and testis.

Cloning and sequence analysis of a snake, Atractaspis engaddensis gene encoding sarafotoxin S6c

A 469 base pair genomic DNA, which encodes the mature region of a snake cardiotoxic peptide, sarafotoxin S6c, was isolated from the liver of the burrowing asp, Atractaspis engaddensis. The nucleotide sequence encoding the mature peptide region showed a high sequence homology with those of mammalian vasoconstrictor peptides, endothelin family as expected from the high homology of their amino acid sequences. In contrast, both of the upper and lower flanking sequences of sarafotoxin gene and the deduced amino acid sequence of the sarafotoxin precursor were quite different from those of endothelin family. These results suggest that the ancestral gene and biosynthetic pathway of sarafotoxins are different from those of endothelin.

Contribution of the 6-120 disulfide bond of alpha-lactalbumin to the stabilities of its native and molten globule states

The unfolding and refolding of a derivative of alpha-lactalbumin, in which the disulfide bond between Cys6 and Cys120 is selectively reduced and S-carboxymethylated, are investigated by equilibrium and kinetic circular dichroism measurements. The native conformation of this derivative is known to be essentially identical to that of intact alpha-lactalbumin. The equilibrium unfolding of the derivative involves a stable intermediate, which is also similar to the molten globule state of the disulfide intact protein. The results of stopped-flow circular dichroism experiments show that the same intermediate is formed rapidly as a transient intermediate in kinetic refolding. The conformational stabilities for the native and intermediate states have been estimated and compared with the stabilities for the corresponding states of intact alpha-lactalbumin. The stabilization of the native state by the disulfide has been interpreted in terms of a decrease in chain entropy in the unfolded state and elimination of the strain imposed on the disulfide bond in the native state. The molten globule state is also stabilized by the disulfide bond, although the degree of stabilization of the molten globule state is smaller than of the native state. The results suggest that, in the molten globule state, some ordered structures are present within the loop moiety formed by the 6-120 disulfide.

Pituitary adenylate cyclase activating polypeptide stimulates gallbladder motility in conscious dogs

We investigated whether pituitary adenylate cyclase activating polypeptide (PA-CAP27 and PACAP38) had any effect on gallbladder motility in conscious dogs, in which force transducers were chronically implanted in the gastric antrum, duodenum and gallbladder. PACAP27 and PACAP38 were administered intravenously during the digestive and interdigestive states at doses of 30, 100 and 300 pmol/kg. By way of comparison, cholecystokinin octapeptide (CCK-OP) was administrated at doses of 3, 9 and 27 pmol/kg. As a result, each peptide evoked transient and tonic contractions both in the digestive and interdigestive states, and the effect on the motor index was dose dependent. PACAP27 and PACAP38 were 0.11 +/- 0.03 and 0.04 +/- 0.01 as potent as CCK-OP in the digestive state, and 0.18 +/- 0.04 and 0.02 +/- 0.01 in the interdigestive state, respectively, on a molar basis. Although PACAP27 and PACAP38 belong to the vasoactive intestinal polypeptide (VIP) family, intravenous administration of 300 pmol/kg of VIP had no effect on interdigestive gallbladder motility, but on the other hand inhibited gallbladder motility in the digestive state. The contractile effects of PACAP27 and PACAP38 were almost completely abolished by pretreatment with atropine or hexamethonium, but not with L364718. An in vitro study using canine gallbladder strips showed that PACAP27 and PACAP38 had no effect on spontaneous gallbladder motor activity evoked by electric field stimulation, CCK-OP or acetylcholine. It was concluded that PACAP27 and PACAP38 stimulate gallbladder motility in conscious dogs through a preganglionic cholinergic mechanism.

[Study on local recurrence in patients undergoing curative surgical resection of lung cancer]

Clinical features of recurrence in patients of lung cancer undergoing curative surgical resection were examined with special reference to the local recurrence. Subjects were 308 patients, consisting of 160 adenocarcinomas, 121 squamous cell carcinomas, 15 large cell carcinomas, 12 small cell carcinomas. They underwent curative resection in our department between 1973 and 1987. Local recurrence developed in 54 patients (18%). There was no significant difference in the incidence of local recurrence among the four histological types of carcinoma. According to the pathological stage, the incidence was 9% in stage I, 15% in stage II, and 35% in stages IIIA+IIIB. The local recurrence was subdivided into the following patterns: 1) lymphatic metastases to the hilar, mediastinal, or supraclavicular sites, 2) recurrence at the surgical margin, 3) malignant pleuritis or pericarditis, 4) so-called "endobronchial metastasis". The incidence of recurrence according to the patterns was 15%, 2%, 2% and 1%, respectively. The incidence of recurrence due to lymphatic metastases was correlated significantly with the pN factor but not with the pT factor. Patients with central type lung cancer showed a significantly higher incidence of lymphatic recurrence than patients with the peripheral type. Patients having postoperative radiotherapy to prevent local recurrence showed a lower incidence of lymphatic recurrence than patients having no radiotherapy. In conclusion, lymphatic recurrence was the most frequent pattern in local recurrence after curative resection of lung cancer, and therefore improvements in the operative procedure of lymphatic dissection, as well as in postoperative adjuvant therapy including radiotherapy will be urgently required for the purpose of reducing local recurrence.

Pituitary adenylate cyclase activating polypeptide (PACAP) with 27 residues. Conformation determined by 1H NMR and CD spectroscopies and distance geometry in 25% methanol solution

The conformation of pituitary adenylate cyclase activating polypeptide with 27 residues (PACAP27) has been determined by two-dimensional NMR and CD spectroscopies and distance geometry in 25% methanol. Residues 9-20 and 22-25 have well-defined conformations but other residues do not show ordered conformations. The conformation of residues 9-20 is composed of three distinct regions of beta turn-like conformation (residues 9-12), alpha helix (residues 12-14) and the looser helical conformation (residues 15-20), while residues 22-24 form alpha helix. PACAP27 has a 2 helices separated by a disordered region similar to a VIP analog reported by Fry et al. but is distinct from the VIP analog in the position of the first helix, which is shifted by 2 residues toward the C-terminus, and in the form of the second helix [Fry, D.C., Madison, V.S., Bolin, D.R., Greeley, D.N., Toome, V. and Wegrzynski, B.B. (1989) Biochemistry 28, 2399-2409].

[Analysis of lymph node metastatic pattern in relation to prognosis and recurrence in pN2 resected lung cancer patients]

Lymph node metastasis was analyzed quantitatively with 4 categories and relation to post surgical survival and recurrence pattern was studied in patients with pN2 primary lung cancer who underwent relatively curative or relatively noncurative resection of the tumors. There was no relation between metastatic coefficient and post surgical survival, however, better survival was observed when the metastatic ratio and metastatic frequency were low and metastatic mode was random or skip pattern rather than sequential pattern. Metastatic coefficient and metastatic frequency were higher in cases with recurrence in lymph nodes but the former was lower and the latter was higher in cases with recurrence in intra-pulmonary dissemination or metastasis. There was no relation between metastatic coefficient and distant metastasis but metastatic frequency was lower in cases with recurrence in distant metastasis. Cases with sequential lymph node metastasis showed a tendency of lymph node recurrence and intrapulmonary metastasis and those with random or skip metastasis of lymph nodes had a tendency of distant metastasis.

[A case of occult breast carcinoma with micronodular shadows on chest x-ray film]

A 57-year-old woman was admitted to our hospital for the evaluation of roentgenological micronodular shadows of the bilateral middle and lower lung fields. Physical findings were normal except for left axillary lymph adenopathy. The level of tumor marker NCC-ST-439 was markedly elevated (2800 U/ml). Histological examination of the transbronchial biopsy and the swollen lymph node biopsy specimens showed proliferation of identical tumor cells. Breast or lung carcinoma was suspected as the primary site. Echogram of the left breast showed microcalcification without a mass. The biopsy specimen obtained from the calcified lesion indicated occult breast carcinoma. From these findings the diffuse micronodular shadows on the chest roentgenogram were considered to be the metastatic lesions of occult breast carcinoma. This case indicates that occult breast carcinoma should be considered as a possible primary site for diffuse pulmonary metastatic lesions.

Binding sites for pituitary adenylate cyclase activating polypeptide (PACAP): comparison with vasoactive intestinal polypeptide (VIP) binding site localization in rat brain sections

Pituitary adenylate cyclase activating polypeptide (PACAP) is structurally similar to vasoactive intestinal polypeptide (VIP). We investigated the characteristics and topographical distribution of [125I]PACAP binding sites compared with those of [125I]VIP binding sites in the rat brain. Radiolabeled PACAP and VIP showed highly specific binding to sections at the level of the dorsal hippocampus. The specific binding of [125I]PACAP was 10 times higher than that of [125I]VIP in hippocampal sections. [125I]PACAP binding was scarcely displaced by unlabeled VIP, while [125I]VIP binding was effectively displaced by unlabeled PACAP. Therefore, PACAP binding sites may reflect both PACAP specific binding sites and VIP/PACAP binding sites. However, the amount of VIP/PACAP binding sites was negligibly low. Autoradiography revealed that [125I]PACAP binding sites were dense in the piriform cortex, diagonal band, accumbens nucleus, anterior part of the striatum, hippocampal formation, habenular nucleus, lateral hypothalamic area, superior colliculus and dorsal raphe nucleus. Moderate to high labeling was observed in the medial septal nucleus, olfactory tubercle, caudal part of the striatum, most parts of the thalamus, supraoptic and periventricular hypothalamic nuclei, central gray, substantia nigra pars compacta, locus coeruleus, pontine reticular nucleus and cerebellum. Distribution pattern was remarkably different from that of [125I]VIP binding sites in the hippocampal formation, lateral hypothalamic area, substantia nigra pars compacta, pontine reticular nucleus and cerebellum. The present results suggest that PACAP may have a physiological role in the regulation of the central nervous system.

Expression of human pituitary adenylate cyclase activating polypeptide (PACAP) cDNA in CHO cells and characterization of the products

cDNA encoding human PACAP precursor was expressed in non-neuroendocrine Chinese hamster ovary cells, CHO-K1, The cells were transfected with expression vector (pTS705) containing the human PACAP cDNA by electroporation. A cell line which produced more than 80 ng/ml of immunoreactive PACAP (ir-PACAP) into the conditioned medium was established. RP-HPLC analysis of culture medium of this established cell line exhibited the presence of two types of PACAP, i.e. PACAP38 and PACAP27. At the same time, it was also revealed that immunoreactive PACAP-related peptide (ir-PRP) was secreted into the cultured medium. The ir-PACAPs were confirmed to ahve biological activities such as induction of cAMP and neurite outgrowth in rat pheochromocytoma PC12h cells.

Pituitary adenylate cyclase activating polypeptide provokes cultured rat chromaffin cells to secrete adrenaline

Pituitary adenylate cyclase activating polypeptide (PACAP) provoked the rat chromaffin cells to secrete adrenaline. Within 20 min, the amount of adrenaline secreted by PACAP (10(-8) M) was as much as that caused by acetylcholine (10(-4) M). PACAP, but not acetylcholine, induced a long-term (over 120 min) increase in secretion of adrenaline. PACAP also activated adenylate cyclase and elevated cytosolic Ca2+ concentration. Furthermore, we found immunoreactive PACAP and PACAP binding sites in the rat adrenal medulla. These results suggest that PACAP has an important role in stimulating secretion of adrenaline in the adrenal medulla.