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Biomedical subjects

S Reichlin

Publications and source records attributed to S Reichlin.

At least 109 records · Page 6Linked to original sources
PubMed1985

Multiple forms of human pancreatic growth hormone releasing factor-like immunoreactivity in teleost brain and pituitary.

Two anatomically distinct neuronal GRF systems in the brain-pituitary of the teleost codfish (Gadus morhua), immunohistochemically localized by use of antisera directed against hpGRF1-44NH2 and hpGRF1-40OH are described. Chromatographic analysis additionally revealed the presence of three molecular variants of immunoreactive hpGRF1-44NH2, two of which differ from the authentic human material. However, all three forms released GH from rat pituitary cells in dispersed culture. These findings indicate that hpGRF is highly conserved in nature and suggest that peptides closely related to this human hypothalamic releasing hormone regulate the teleost pituitary.

Animals↗
PubMed1985

Pantethine, a cysteamine precursor, depletes immunoreactive somatostatin and prolactin in the rat.

Pantethine, a stable disulfide precursor of pantetheine, has been reported to increase intracellular concentration of cysteamine in cultured fibroblasts of patients with cystinosis. In order to determine whether pantethine acts like cysteamine in bringing about depletion of immunoreactive somatostatin (IRS) in rat neural and gastrointestinal tissues and depletion of immunoreactive PRL (IRPRL) in the anterior pituitary, groups of male rats were given pantethine by ip injection at a dose of 0.264 mM or 0.528 mM/100 g body weight or normal saline and killed 4 h later. The interval chosen corresponds to the time of maximum effect after oral cysteamine administration. In cerebral cortex, hypothalamus, duodenal and gastric mucosa, and pancreas, IRS was uniformly depressed by 50% or more as compared with control rats, the most striking changes occurring in the hypothalamus where there was a 64% depletion at the higher dose of drug. Both dosage levels depleted IRPRL in pituitary and serum. At the higher dose, IRPRL was reduced by approximately 85% in the pituitary and 75% in the serum. These findings support the hypothesis that pantethine administration leads to an accumulation of cysteamine within cells throughout the body and that the cysteamine so formed depletes IRS and IRPRL.

Animals↗
PubMed1985

Somatostatin depletion by cysteamine: mechanism and implication for duodenal ulceration.

Cysteamine (CSH) and its close derivatives deplete immunoreactive somatostatin (SS) in rat organs. The effect of CSH is dose and time dependent and reversible. Structural requirements of the analogs are the presence of either -SH or -NH2 on a two- or three-carbon alkyl molecule; both radicals together increase, whereas insertion of carboxyl abolishes potency. The duodenal ulcerogenic potency of CSH derivatives is correlated significantly with their SS-depleting activity in the gastric mucosa. The mechanism of this action of CSH is poorly understood, but it is not caused by increased release, enhanced degradation of the peptide, or selective necrosis of SS cells. It is likely that in the intracellular environment CSH causes a conformational change in the peptide that affects the antigenic and functional properties of SS.

Animals↗
PubMed1984

Distribution of immunoreactive growth hormone releasing factor(1-44)NH2 in the tuberoinfundibular system of the rhesus monkey.

Using an antiserum which reacts with the carboxyl terminus of GRF(1-44)NH2, the distribution of immunoreactive growth hormone releasing factor (GRF) in the rhesus monkey hypothalamus was delineated by peroxidase immunocytochemistry. Immunoreactive material was present in dense terminal fields in the median eminence closely associated with portal capillaries but in a location distinct from that noted for immunoreactive thyrotropin-releasing hormone (TRH) or somatostatin. GRF-immunoreactive cell bodies were identified in the arcuate nucleus and ventromedial nucleus. These studies provide evidence for the presence of GRF(1-44)NH2 in the primate brain and demonstrate that in the hypothalamus it is localized exclusively in cells and fibers corresponding to the tuberoinfundibular system.

Animals↗
PubMed1984

Long-term follow-up of transsphenoidal selective adenomectomy for prolactinoma.

Although transsphenoidal selective resection of prolactinoma has high cure rates and low morbidity, the frequency of late recurrence of adenoma is controversial. Long-term follow-up data were available on 29 of our patients having initial return to normal prolactin levels after microadenoma resection; in 24, prolactin levels remained normal at 50 +/- 3 months' (range, 11 to 81 months) follow-up. Five patients manifested hyperprolactinemia again after intervals of six to 16 months. In five patients with normal prolactin levels immediately after macroadenoma resection, who were available for long-term follow-up, prolactin levels remained normal in four at 41 +/- 3 months; one patient had a relapse 78 months after surgery. Testing of prolactin secretory dynamics six weeks postoperatively was not predictive of who would suffer relapse. It is not known whether these relapses are due to regrowth of tumor remnants or represent new tumor formation.

Adenoma↗
PubMed1984

Recovery of substance P but not somatostatin in the cat spinal cord after unilateral lumbosacral dorsal rhizotomy: a quantitative study.

The dorsal horn of the cat spinal cord contains substance P and somatostatin within nerve endings which arise from cells located in dorsal root ganglia and from cells within the neuraxis. Previous studies from this laboratory have demonstrated that dorsal rhizotomy depletes both peptides from the dorsal horn. However, the changes in the two peptides differ. Substance P is at first severely depleted by dorsal rhizotomy and then recovers in part, whereas somatostatin is diminished less but does not recover. In the present experiments the validity of these conclusions which were based on anatomical observations has been evaluated quantitatively with the use of radioimmunoassay. After a 74% reduction at 10-14 days postoperative, substance P immunoreactivity in the deafferented dorsal horn shows a small, statistically significant recovery by 30 days to 60% of normal values. In contrast, somatostatin is reduced by 46% at 10-14 days but does not return significantly. As previously suggested by immunocytochemistry, dorsal rhizotomy produces no significant decline of either peptide in the ventral horn. The differing response of the two peptides is consistent with the hypothesis that intrinsic spinal substance P-containing neurons increase their projections (or their production of substance P) in the deafferented dorsal horn, but that somatostatin-containing neurons do not. Because synaptic number returns to normal in at least the deafferented lamina II of the cat yet substance P recovers only partially, it is likely that axons which contain transmitters other than substance P or somatostatin also increase the numbers of their terminals in response to dorsal rhizotomy.

Animals↗
PubMed1984

Twenty-four-hour prolactin secretory patterns in women with galactorrhea, normal menses, normal random prolacting levels and abnormal sellar tomograms.

During a systematic study of women with idiopathic galactorrhea, we observed several patients with normal random serum prolactin (PRL) levels and normal menses, but abnormal sellar tomograms characteristic of a pituitary adenoma. To test the hypothesis that these women might have intermittent PRL hypersecretion, we studied PRL secretion by sampling blood every half hour for 24 h in 10 patients and for 17.5 h in another, and compared the findings to those of a group of 5 normal women. The mean 24-h PRL of the 10 patients (16.8 +/- 7.8 ng/ml; mean +/- SD) was not significantly different from that of the normal women (13.6 +/- 3.2 ng/ml), and each patient showed a normal sleep-associated PRL increment. Three individuals exhibited an abnormally elevated 24-h PRL (greater than 20 ng/ml). Increased PRL secretion occurred primarily at night or in the afternoon. Thyrotropin releasing hormone (TRH) administration caused normal or exaggerated PRL responses in all patients tested. High resolution CT scanning of two of the hypersecretors suggested a microadenoma in one case. In another case whose PRL was normal over 17.5 h, transsphenoidal surgery, carried out because of the tomographic findings and the symptom of headaches, demonstrated a 5-mm chromophobe adenoma that did not contain PRL by immunohistochemistry. Postoperatively the galactorrhea persisted. We conclude that most women with galactorrhea, normal PRL, normal menses, and abnormal tomograms have normal PRL secretion. However, a minority of patients with this syndrome do demonstrate intermittent PRL hypersecretion. The etiology of intermittent PRL hypersecretion and its relevance to galactorrhea have not been determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Immunoreactive growth hormone-releasing factor in human stalk median eminence.

Immunoreactive growth hormone-releasing factor was detected in extracts of acetone preserved human stalk median eminence utilizing an antiserum against human GRF-(1-44)-NH2, isolated from a pancreatic tumor. The antibody is highly specific for the C-terminus of GRF-(1-44)-NH2, and has a cross-reactivity less than 0.02% with GRF-(1-40) free acid, a peptide isolated from a different pancreatic tumor. The mean concentration of IR-GRF in 5 pools of 10-15 stalk-median eminence fragments was 57.7 +/- 7.2 ng/mg protein (mean +/- SEM, range 42.5-75.8 ng/mg protein). Gel filtration chromatographic analysis showed that 97% of the IR-GRF coeluted with synthetic hpGRF-(1-44)-NH2 and eluate inhibition of binding in the radioimmunoassay was parallel to that of hpGRF-(1-44)-NH2. These data strongly suggest that human hypothalamic tissue contains a peptide that is similar to hpGRF-(1-44)-NH2.

Chromatography, Gel↗
PubMed1983

Somatostatin.

Explore the source record for details and available documents.

Animals↗
PubMed1983

Thyrotropin-releasing hormone-diphtheria toxin-related polypeptide conjugates. Potential role of the hydrophobic domain in toxin entry.

We have separately coupled a modified thyrotropin-releasing hormone (TRH) molecule to two diphtheria toxin-related polypeptides, CRM26 and CRM45. Both polypeptides are enzymatically active but only CRM45 contains the hydrophobic domain of the toxin molecule. The TRH-CRM45 conjugate caused a 50% inhibition of protein synthesis in GH3 rat pituitary cells at 3 X 10(-9) M. CRM45 alone was 200 to 500 times less toxic than the conjugate. Intoxication by TRH-CRM45 was prevented by excess TRH, preincubation with diphtheria antitoxin, or reduction of the disulfide cross-link. In addition, TRH-CRM45 was no more toxic than CRM45 itself to 3T3 cells which lack TRH receptors. In contrast, TRH-CRM26, although it retained enzymatic activity, was nontoxic for GH3 cells even at 10(-7) M. Binding experiments showed that both conjugates compete for TRH receptors with comparable affinities. The potential role of the hydrophobic domain in toxin entry is discussed.

Animals↗
PubMed1983

CSF somatostatin in affective illness.

Somatostatin is a hypothalamic tetradecapeptide with many actions. We investigated a potential role for somatostatinergic neuron dysfunction in affective disorder by measuring somatostatin in the CSF of 47 patients with affective illness and of 39 normal volunteers. Medication-free depressed patients showed significantly lower levels of CSF somatostatin than normal volunteers (P less than .001) or patients during the improved state (P less than .01). A significant inverse correlation was observed between somatostatin and the duration of sleep on the night of the lumbar puncture. We also observed significant correlations between somatostatin and 5-hydroxyindoleacetic acid and norepinephrine in the CSF. Also noted were the significance of depression-related decreases in CSF somatostatin in relation to information about central somatostatin secretion, reported abnormalities of somatostatin activity, and potential interactions between alterations in somatostatin activity and the pathophysiology of depression.

Adult↗
PubMed1983

The effect of the duodenal ulcerogen cysteamine on somatostatin and gastrin cells in the rat.

Previous studies showed a rapid decrease of somatostatin concentration in the gut and an increase in serum gastrin levels after a single dose of the duodenal ulcerogen cysteamine. An attempt was made to identify morphologic changes that would correlate with these functional changes. Rats were killed 1, 4, 8, or 24 hr after a single dose of cysteamine and sections of gastric mucosa and pancreas were processed for electron and light microscopy. Subtle ultrastructural alterations were seen in D cells of the stomach (e.g., dilation of mitochondrial cristae and endoplasmic reticulum, and apparent increase in electron density of secretory granules) after cysteamine administration. The number of somatostatin-positive cells visualized by the immunoperoxidase technique using light microscopy was decreased in 1-4 hr but returned to normal by 24 hr. The alterations observed in the G cells after cysteamine administration are consistent with release of gastrin from mature granules and increased synthesis of the hormone. The lack of major morphologic changes in the D cells suggests that cysteamine affects somatostatin without causing cell necrosis or alteration in lysosome formation. The effect of the drug may thus be mediated at the biochemical level without marked morphologic alterations.

Animals↗
PubMed1983

Somatostatin depletion of the gut and pancreas induced by cysteamine is not prevented by vagotomy or by dopamine agonists.

The role of endogenous somatostatin in the pathogenesis of duodenal was investigated in the present study by using the cysteamine animal model of the disease. Our previous studies showed a rapid and multiorgan depletion of somatostatin immunoreactivity (SIR) in rats given a single dose of duodenal ulcerogen cysteamine. We now determined whether acetylcholinergic and dopaminergic modulation (both known to influence the development of duodenal ulcer) are accompanied by modification of cysteamine-induced SIR depletion in rat organs. Vagotomy performed either 1 or 18 h before cysteamine administration did not interfere with the chemically induced SIR decrease in pancreas, gastric and duodenal mucosa. Vagal denervation alone had no marked influence on SIR levels but if combined with cysteamine, the SIR depletion in the stomach was significantly more pronounced than after the duodenal ulcerogen alone. Pretreatment with the dopamine agonists bromocriptine or lergotrile (known to prevent the chemically induced duodenal ulcers) did not influence the SIR depletion by cysteamine. Thus cysteamine depletes endogenous somatostatin in peripheral organs (e.g., stomach, duodenum, pancreas) by mechanisms independent of both vagus nerve and dopamine agonists. A role of central somatostatin depletion leading to disinhibition of vagus is also considered in the pathogenesis of experimental duodenal ulcer.

Animals↗
PubMed1983

Prosomatostatin-specific antigen in rat brain: localization by immunocytochemical staining with an antiserum to a synthetic sequence of preprosomatostatin.

Using an antiserum to a 15-amino acid synthetic peptide corresponding to amino acids 63-77 of rat preprosomatostatin (rat somatostatin cryptic peptide, RSCP), we have compared the distribution of immunoreactive RSCP (IR-RSCP) with that of immunoreactive somatostatin-14 in the rat brain. IR-RSCP was present in neuronal cell bodies, processes, and axon terminals in the hypothalamic tuberoinfundibular system as well as in diverse regions of the central nervous system in an identical distribution to immunoreactive somatostatin. These observations indicate that in neurons the somatostatin prohormone or the NH2-terminal extension peptide of somatostatin-28 (or both) is stored and transported intracellularly along with somatostatin 14. In addition, the presence of IR-RSCP in nerve terminals suggests that this material may be secreted as a hormone or neuromodulator and may serve as a biologic marker of somatostatin secretion.

Amino Acid Sequence↗
PubMed1983

Characterisation of somatostatin and TRH release by rat hypothalamic and cerebral cortical neurons maintained on a capillary membrane perfusion system.

We have investigated the nature of the immunoreactive somatostatin (SS) and thyrotropin-releasing hormone (TRH) produced by long-term capillary perfusion cultures of rat fetal cortical and hypothalamic cells. Dispersed cortical and hypothalamic cells from 17-day-old fetal rats were injected on to the outer surfaces of separate capillary membrane perfusion systems. Recirculating nutrient medium (Minimum Essential Medium with added glucose, antibiotics and 10% fetal calf serum) was then perfused via the capillary lumen at a rate of 1.5 ml/min and was changed three times weekly. Medium reservoirs, gaseous exchange coils and capillary columns were maintained in a 95% air/5% CO2 environment with 100% humidity. After 6 and 12 days in continuous perfusion, both cortical and hypothalamic cells demonstrated immuno-reactive SS release following 60 mMK+ depolarization (5- to 7-fold increase from basal secretion levels of 15-20 pg/3 X 10(7) cells/10 min). This response was clearly calcium dependent since it was abolished during washes with Ca2+-free Krebs-Ringer bicarbonate solution. Affinity purified material from pooled neuronal perfusates showed three distinct peaks of somatotropin release-inhibiting factor (SRIF) immunoreactivity following polyacrylamide gel chromatography on Biogel-P10. The dominant form coeluted with synthetic tetradecapeptide-somatostatin (SS-14) and a smaller amount (c 30%) coeluted with synthetic SS-28. (The SS-14 antibody used showed equimolar cross reactivity with SS-28). A larger form of immunoreactive material was also detected with an apparent molecular weight of about 11,500 daltons. Hypothalamic and cortical perfusates produced similar electrophoretic patterns of immunoreactive SS (ISS).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Origin of immunoreactive ACTH in brain sites outside the ventral hypothalamus.

Immunoreactive adrenocorticotropin (IR-ACTH) is widely distributed throughout the brain. Highest concentrations have been localized in the ventral hypothalamus, a recognized site of origin of IR-ACTH containing neuronal cell bodies. To determine whether IR-ACTH arises in other brain sites, we determined the effect on the concentration of IR-ACTH in several regions of rat brain after intracerebroventricular injection of colchicine, an agent that inhibits axoplasmic transport and leads to an accumulation of neuronal secretory products within cell bodies. Three regions (ventral hypothalamus, dorsal hypothalamus, amygdala) showed a significant increase in concentration of IR-ACTH after colchicine, whereas the hippocampus and preoptic area did not. Because neuropeptides, in general, undergo posttranslational processing during axoplasmic transport, it could be predicted that inhibition of transport would lead to a relative increase in 'large', precursor forms of hormone in regions containing cells of origin of neuropeptide tracts. Therefore, the effect of colchicine on the processing of molecular forms of IR-ACTH was also examined. In brain regions showing a significant increase in IR-ACTH after colchicine, the proportion of 'big' ACTH and ACTH1-39 (relative to total IR-ACTH) increased and the proportion of 'small' ACTH (less than 4,500 daltons) declined. In contrast, size distribution of IR-ACTH species in other areas were either the opposite or were unchanged. These studies indicate that in addition to the ventral hypothalamus, IR-ACTH also originates in the dorsal hypothalamus and the amygdala, and that decreased axoplasmic peptide transport is associated with decreased processing of molecular forms.

Adrenocorticotropic Hormone↗
PubMed1983

Somatostatin biosynthesis by cerebral cortical cells in monolayer culture.

We examined the ability of isolated rat cerebral cortical cells to synthesize and secrete immunoreactive somatostatin (IRS). Dispersed telencephalic cells (10(7] from rat embryos contain approximately 24 pg IRS. The IRS content of 10(7) cultured cells increased steadily to a level of 2800 pg by 20 days in vitro. The IRS content in the medium followed a parallel production curve and was, in general, 10% of the cellular content. The nature of this IRS was characterized by gel filtration. Bio-Gel P-10 chromatography resolved four discrete IRS peaks. The first peak had an apparent molecular weight of 11,500. The second peak, which comigrated with synthetic Somatostatin-28, had a molecular weight of 7,000. The third peak had a molecular weight of 1,800, and the fourth peak, which comigrated with Somatostatin-14, had a molecular weight less than 1,800. Incubation with [3H]phenylalanine (Phe) revealed that 3H was incorporated into each peak. Isolation of 3H-labeled peak 4 was carried out by double affinity column purification. Sequential automated Edman degradation of this material revealed [3H] Phe in the positions that Phe occupies in Somatostatin-14. These studies document the ability of isolated rat cerebral cortical tissue to synthesize several forms of IRS, establishing them as endogenous cortical peptides.

Amino Acid Sequence↗