Messenger RNA levels of chromogranin B, secretogranin II, and VGF in rat brain after AF64A-induced septohippocampal cholinergic lesions

The mRNA levels of secretogranin II, chromogranin B, and VGF were compared in brains of control and AF64A-treated rats. This toxin induces specific lesions of the septohippocampal cholinergic pathway. As a consequence of this treatment, the chromogranin B message was elevated in the dentate gyrus granule cells of the hippocampus. In the paraventricular nucleus of the hypothalamus, a concomitant elevation of the messages of secretogranin II and corticotropin-releasing factor occurred in the parvocellular neurons, and an increase of those of secretogranin II and VGF occurred in a subgroup of magnocellular neurons. Further increases for secretogranin II were seen in the amygdaloid nuclei and the reticular thalamic nuclei and increases for chromogranin B in the temporal cortex, substantia nigra compacta, and ventral tegmental area. These results indicate that the toxin-induced lesion of the cholinergic pathway innervating the hippocampus apparently leads to the stimulation of several defined groups of neurons that react with an increase in the mRNA levels of their secretory peptides. We suggest that changes in mRNA expression of these peptides are useful parameters for defining neurons under chronic stimulation.

The adrenal chromaffin granule: a model for large dense core vesicles of endocrine and nervous tissue

More than 25 years have elapsed since R. E. Coupland made his classic observations on the ultrastructure of chromaffin granules, on the histochemical differentiation of noradrenaline and adrenaline storage granules and on their release by exocytosis. This essay attempts to demonstrate that subsequent studies on the biochemistry of chromaffin granules have yielded analytical and functional data relevant for all large dense core vesicles of endocrine and nervous tissue.

Glycoprotein III (clusterin, sulfated glycoprotein 2) in endocrine, nervous, and other tissues: immunochemical characterization, subcellular localization, and regulation of biosynthesis

Specific antisera were raised against the A and B chains of glycoprotein III. Immunoblotting revealed that in adrenal medulla both chains migrate very closely together in two-dimensional electrophoresis. Both chains with slightly differing molecular sizes are found in several endocrine tissues and in brain, kidney, liver, and serum. The mRNA has an analogous widespread distribution. In primary cultures of chromaffin cells the level of message becomes significantly increased by treatment with histamine or 12-O-tetradecanoylphorbol 13-acetate/forskolin. However, the increase is small when compared with that of secretogranin II. The subcellular localization of glycoprotein III in endocrine organs and in the posterior pituitary was investigated by subcellular fractionation and immunoelectron microscopy. Glycoprotein III was found to be confined to the large dense-core vesicles of these organs. For a discussion of the function of glycoprotein III, its localization in these organelles has to be taken into account.

Different degrees of processing of secretogranin II in large dense core vesicles of bovine adrenal medulla and sympathetic axons correlate with their content of soluble PC1 and PC2

We investigated the processing of secretogranin II in large dense core vesicles of adrenal medulla and sympathetic nerve. Despite the fact that both types of vesicles have a very similar biochemical composition, the degree of processing of secretogranin II in vesicles from splenic nerve was significantly higher. The endoproteases PC1 and PC2, two likely candidates for secretogranin II cleavage, are found in both types of vesicles, however, relative to secretogranin II the nerve vesicles have a much higher content of these enzymes. This probably explains the fast and more extensive processing of secretogranin II in these vesicles.

Reserpine causes differential changes in the mRNA levels of chromogranin B, secretogranin II, carboxypeptidase H, alpha-amidating monooxygenase, the vesicular amine transporter and of synaptin/synaptophysin in rat brain

Brains of rats treated with a high dose of reserpine were analyzed by in situ hybridization. The mRNA levels of several components of large dense core and small synaptic vesicles were determined. After drug treatment the secretogranin II message was elevated in the parvocellular neurons of the paraventricular nucleus, in the zona incerta, dorsal raphe, locus coeruleus and in the nucleus tractus solitarius. The levels of chromogranin B mRNA were increased in the dorsal raphe and in the substantia nigra compacta. In control animals messages for synaptin/synaptophysin could be found in most of the nuclei investigated, that of the vesicular amine transporter was only detectable in substantia nigra compacta, the dorsal raphe and the locus coeruleus whereas those of carboxypeptidase H and the alpha-amidating monooxygenase could only be determined in the paraventricular nucleus. All these messages were not changed after reserpine. We conclude that the chromogranin B/secretogranin II messages are regulated concomitantly with various neuropeptides. They represent useful general markers to identify stimulated neurons. Our results are consistent with the concept that stimulation of neurons leads to an increased synthesis of secretory peptides and consequently to large dense core vesicles filled with higher quanta of peptides.

Cytokine-inducible expression in endothelial cells of an I kappa B alpha-like gene is regulated by NF kappa B

The transient expression of many different genes is mediated by the inducible transcription factor p50-p65 NF kappa B, which in turn is regulated by complex formation with its inhibitor I kappa B alpha. We describe here that in porcine aortic endothelial cells, either IL-1 alpha, TNF alpha or LPS upregulates an inhibitor of NF kappa B which we refer to as ECI-6. ECI-6 is by structural and functional criteria an I kappa B alpha protein, the porcine homologue of MAD-3, pp40 and RL/IF-1. We have studied the promoter of the ECI-6/I kappa B alpha gene and provide three lines of evidence that its expression is directly regulated by NF kappa B. First, the 5' regulatory region of ECI-6/I kappa B alpha contains two sites that bind NF kappa B in electrophoretic mobility shift assays. Second, expression following transfection of an ECI-6/I kappa B alpha promoter-luciferase reporter construct is dependent on a co-transfected NF kappa B-p65 subunit. Third, pretreatment of endothelial cells with antioxidants, agents that inhibit activation of NF kappa B, inhibit the expression of ECI-6/I kappa B alpha. We conclude that the regulated expression of ECI-6/I kappa B alpha could represent a novel feedback mechanism by which NF kappa B downregulates its own activity after transient activation of target genes has been achieved.

Vesicle monoamine transporters 1 and 2: differential distribution and regulation of their mRNAs in chromaffin and ganglion cells of rat adrenal medulla

The expression and synthesis regulation of the vesicle monoamine transporter was investigated in rat adrenal medulla. Previous studies established two genes for monoamine transporters by molecular techniques. In rat adrenal medulla, a differential expression of the corresponding mRNAs was found by in situ hybridization. The mRNA of monoamine transporter 2 was localized in chromaffin cells whereas monoamine transporter 1 mRNA occurred only in ganglion cells of the adrenal medulla. Insulin-induced hypoglycemia, a model for short neurogenic stimulation of the adrenal medulla, did not alter steady-state mRNA levels of both monoamine transporters.

Concomitant changes of messenger ribonucleic acid levels of secretogranin II, VGF, vasopressin and oxytocin in the paraventricular nucleus of rats after adrenalectomy and during lactation

In situ hybridization was used to study the mRNA levels for secretogranin II and VGF in comparison with those of oxytocin and vasopressin in the hypothalamus of rats. VGF is a widespread constituent of large dense core vesicles which is selectively induced in PC12 cells by nerve growth factor. After adrenalectomy the mRNA levels of secretogranin II, VGF and vasopressin were increased 4- to 5-fold in the parvocellular neurons of the paraventricular nuclei. In lactating rats the message for oxytocin and secretogranin II were significantly elevated in the magnocellular neurons of the paraventricular and supraoptic nuclei, whereas for VGF only a smaller non-significant increase was observed. As shown by immunoelectron microscopy secretoneurin (a peptide derived from secretogranin II) and oxytocin are co-stored in the large dense core vesicles of the hypothalamo-neurohypophysial neurons. These results demonstrate that stimulation of both parvo- and magnocellular neurons of the hypothalamus induces a concomitant increase of the messages for secretogranin II and VGF together with those of vasopressin and oxytocin.

Secretogranin II is synthesized and secreted in astrocyte cultures

Astrocyte cultures from rat brain were analyzed for their ability to synthesize and secrete secretogranin II (chromogranin C). Northern blot analysis of polyA-selected RNA established the presence of secretogranin II mRNA in these cells. By radioimmunoassay, 11.6 fmol/10(6) astrocytes of secretogranin II was found in these cells. About twice the amount was released into the medium within 3 days. Secretogranin II within the astrocytes was practically unprocessed, as shown by HPLC. These results establish for the first time that astrocytes in vitro synthesize and secrete a protein of the acidic chromogranin family.

Chromogranin A, secretogranin II and vasoactive intestinal peptide in phaeochromocytomas and ganglioneuromas

By means of immunohistochemistry we analysed the distribution of chromogranin A, secretogranin II and vasoactive intestinal peptide (VIP) in 16 phaeochromocytomas, two cases of combined phaeochromocytoma-ganglioneuroma and four adrenal ganglioneuromas. Chromogranin A was found in the majority of phaeochromocytes and in mixed phaeochromocytomas-ganglioneuromas. Secretogranin II was present to a lesser degree in phaeochromocytes, but strong immunostaining was found in most ganglion cells of phaeochromocytomas, in the ganglioneuroma component of combined tumours and in adrenal ganglioneuromas. Vasoactive intestinal peptide was present in some ganglion cells of phaeochromocytomas, in the ganglioneuroma component of mixed tumours and in three of four adrenal ganglioneuromas. On semi-adjacent sections a co-localization of VIP and secretogranin II was demonstrated. These results indicate that neuronal differentiation is accompanied by an increased immunohistochemical expression of secretogranin II. Therefore, secretogranin II may be a useful marker for ganglion cell differentiation.

Distribution of secretoneurin, a peptide derived from secretogranin II, in rat brain: an immunocytochemical and radioimmunological study

The distribution of secretoneurin, a peptide derived from its precursor secretogranin II by proteolytic processing, was studied in the central nervous system of the rat by immunocytochemistry and radioimmunoassay and compared to the distribution of secretogranin II messenger RNA by using in situ hybridization. With a specific antiserum a distinct staining of fibers and to a lesser extent also of perikarya was observed throughout the central nervous system. A high density of immunoreactive fibers and terminals was found in several brain areas, i.e. the lateral septum, the medial parts of the amygdala, some medial thalamic nuclei, the hypothalamus, habenula, nucleus interpeduncularis, locus coeruleus, nucleus tractus solitarii, the substantiae gelatinosae of the caudal trigeminal nucleus and of the spinal cord. The quantitative distribution as measured by a radioimmunoassay agreed well with the varying densities of immunoreactivity found by immunocytochemistry. The highest concentrations of this peptide were present in the hypothalamus, in particular, in the median eminence and are comparable to those of the most highly concentrated neuropeptides. The distribution of immunopositive perikarya corresponded well with that of secretogranin II messenger RNA obtained by in situ hybridization. The pattern of secretoneurin expression in rat brain was widespread and unique, partially overlapping with established chemical transmitters and neuropeptides. The functional significance of this new brain peptide remains to be established.

Secretoneurin releases dopamine from rat striatal slices: a biological effect of a peptide derived from secretogranin II (chromogranin C)

Proteolytic processing of secretogranin II (chromogranin C) in brain leads to the formation of a 33-amino acid peptide which we have named secretoneurin. All the properties of secretoneurin are consistent with the concept that this peptide represents a neuropeptide. However, a biological function has not yet been demonstrated. Therefore, we have now investigated whether secretoneurin could alter transmitter release in brain. Slices of rat caudate-putamen were superfused in an in vitro system and dopamine was measured in the superfusate. Secretoneurin dose-dependently increased the outflow of dopamine. This response was abolished in Ca(2+)-free medium. The secretoneurin-response could also be blocked by preincubation of the peptide with a specific antiserum and was subject to rapid specific and reversible desensitization. This effect on dopamine release constitutes the first discovered biological effect found for a peptide derived from secretogranin II. Thus, secretoneurin can be added to the ever-growing number of neuropeptides.

In situ hybridization: mRNA levels of secretogranin II, VGF and peptidylglycine alpha-amidating monooxygenase in brain of salt-loaded rats

The mRNA levels of secretogranin II (SgII), VGF and peptidylglycine alpha-amidating monooxygenase (PAM) were studied in brains of salt loaded rats by in situ hybridization. In these rats the levels of the message for secretogranin II and VGF were increased in the paraventricular, supraoptic and retrochiasmatic nuclei and in the subfornical organ. The increases ranged from 416 to 721% for SgII and from 778 to 890% for VGF. The PAM message was also elevated in these brain regions; however, the maximal increase was only 221%. We conclude that the message for all secretory peptides investigated so far, i.e. vasopressin, galanin, secretogranin II and VGF are upregulated to a similar degree in the hypothalamus of salt-located rats. The relative increase in mRNA for the enzyme peptidylglycine alpha-amidating monooxygenase occurred to a much lower extent, and was comparable to the limited changes previously seen for carboxypeptidase H.

Secretoneurin--a neuropeptide generated in brain, adrenal medulla and other endocrine tissues by proteolytic processing of secretogranin II (chromogranin C)

Secretogranin II (chromogranin C), originally described as tyrosine sulfated protein of the anterior pituitary, is present in large dense core vesicles of several endocrine cells and neurons. We raised antisera in rabbits to conjugates of two synthetic peptides (bovine secretogranin 133-151 and rat secretogranin 154-186) flanked in the primary structure of secretogranin II by pairs of basic residues and used them to investigate the proteolytic processing of this protein by immunoblotting and a newly developed radioimmunoassay. The sensitivity of this assay was 30 fmol for secretogranin 154-186 and 60 fmol for secretogranin 133-151. The highest degree of processing of secretogranin II (> 90%) occurs in brain. One of the peptides (secretogranin 133-151) is not generated to any significant extent. The other peptide, secretogranin 154-186, however, is formed in vivo, and in brain the free peptide apparently represents the predominant form. The highest concentrations of secretogranin 154-186 are found in the hypothalamus, two- to six-fold lower levels are present in the hippocampus, caudate nucleus, thalamus and brainstem. These concentrations are comparable to those of established neuropeptides. In order to indicate the special relevance of secretogranin II and of this peptide for brain we have named this peptide secretoneurin. The newly developed radioimmunoassay for this peptide will be a useful tool to establish its physiologic role in brain.

Seminal vesicle congestion as a cause of postprostatectomy dysuria

A series of benign prostatic hypertrophy patients were routinely evaluated, including transrectal echography, before and at regular intervals following surgery. Five patients had persistent symptoms of dysuria at 14-30 months after surgery. There was no infection, residual urine or malignancy to explain their symptoms. The seminal vesicles (SVs) were severely dilated on transrectal echography, a finding which was definitely not present on initial examination. The patients were treated by transrectal echo-guided aspiration of the SVs by the perineal approach. The fluid aspirated was examined, and antibiotics were directly injected into the SVs. In 4 of the patients, there was a dramatic relief of symptoms with prolonged improvement. In only 1 case, following transurethral resection, there was but slight improvement. Dilated, obstructed SVs after prostatectomy, clearly diagnosed on transrectal echography, may be the cause of persistent irritative urinary symptoms. Treatment can be instituted by echo-guided aspiration of the fluid with simultaneous injection of a potent antibiotic, resulting in probable immediate relief.

Temporal lobe epilepsy of the rat: differential expression of mRNAs of chromogranin B, secretogranin II, synaptin/synaptophysin and p65 in subfield of the hippocampus

We have investigated by in situ hybridization changes in the content of mRNAs encoding for chromogranin B, secretogranin II, synaptin/synaptophysin and p65 after kainic acid-induced seizures and pentylenetetrazol kindling. Kainic acid seizures resulted in marked but transient increases in secretogranin II mRNA concentrations in the granule cell layer and throughout the pyramidal cell layers of the hippocampus (by 100-500%) as well as in various areas of the cerebral cortex (by up to 900%) and the thalamus (up to 300%) 12 h after injection of the toxin. Chromogranin B mRNA concentrations were persistently increased in granule cells (but not in pyramidal cells) of the hippocampus (suprapyramidal blade, 450%) and in cortical areas (250%) at all time intervals after kainic acid injection (12 h to 60 days). Accordingly chromogranin B immunoreactivity was enhanced in the terminal field of mossy fibers and in the inner part of the molecular layer 30 days after kainic acid. Secretogranin II immunoreactivity was also markedly increased in CA1, the paraventricular thalamic nucleus and in the central amygdala. In rats kindled with pentylenetetrazol only chromogranin B (by 200%) but not secretogranin II mRNA was increased in dentate granule cells. In contrast to the mRNAs of these secretory proteins concentrations of mRNAs encoding synaptin/synaptophysin and p65, two membrane proteins of synaptic vesicles, were not altered in any of these brain structures. These data demonstrate that in brain the biosynthesis of chromogranin B and secretogranin II is regulated like that of neuropeptides which is consistent with a role of these secretory polypeptides as precursors of functional peptides. Activation of neurons induces an increased synthesis of neuropeptides but not a concomitant synthesis of membrane proteins of synaptic vesicle. This might lead to an increased quantal content available for transmission.

Secretogranin II expression in Ewing's sarcomas and primitive neuroectodermal tumors

Production of chromogranins, the acidic components of the chromaffin granules regarded as specific neuroendocrine markers, was analyzed by immunocytochemistry and hybridization (Northern blotting and in situ hybridization) in primary lesions and cell lines of Ewing's sarcomas, primitive neuroectodermal tumors (PNETs), and neuroblastomas. Antibodies and probes specific for chromogranin A (CgA), chromogranin B (CgB), and secretogranin II (SgII) were used. Ewing's sarcomas and PNETs, unlike neuroblastomas, were negative for CgA and CgB. Two primary Ewing's sarcomas, one primary PNET (an Askin tumor), and one PNET cell line (TC32) were found to strongly express the SgII gene, as shown by the presence of specific mRNA. This result supports the hypothesis that some Ewing's sarcomas represent a most primitive form of neuroectodermal tumor; in addition, it indicates a diagnostic role of SgII in cases of Ewing's sarcomas and PNETs.