A cyclic hexapeptide is a potent antagonist of alpha 4 integrins

The alpha 4 integrins mediate leukocyte adhesion to specific counter-receptors, including vascular cell adhesion molecule-1 (VCAM-1), the fibronectin splice variant containing connecting segment 1 (CS1), and mucosal addressin cell adhesion molecule-1. A series of cyclized peptides based on the LDV sequence of CS1 were synthesized and assayed for inhibition of alpha 4 integrin binding. The most potent peptide, C*WLDVC* (where * indicates disulfide-linked residues), inhibited alpha 4 beta 1-dependent binding of lymphocytes to VCAM-1 and CS1 with half-maximal inhibition achieved at 1 to 3 microM of peptide. The peptide proved more potent when the lymphocytes were activated with 1 mM MnCl2; half-maximal inhibition was reached at 0.4 and 0.05 microM for VCAM-1 and CS1, respectively. This represents a 100- to 800-fold increase in potency over a linear CS1 peptide in these same assays. C*WLDVC* also inhibited alpha 4 beta 7-dependent lymphocyte binding to the ligands mucosal addressin cell adhesion molecule-1, VCAM-1 and CS1. Immunoprecipitation of radiolabeled integrin indicated that the peptide could bind alpha 4 beta 1 and alpha 4 beta 7 directly and elute alpha 4 beta 1 from a CS1-conjugated agarose resin. The peptide showed selectivity for alpha 4 integrins in that it effectively inhibited alpha 4 beta 1-dependent, but not alpha 5 beta 1-dependent, binding of cells to intact fibronectin. Due to its small size and potency, C*WLDVC* may serve as a useful tool for the study of alpha 4 integrin biology and the development of small molecule therapeutics.

A cyclic hexapeptide is a potent antagonist of alpha 4 integrins

The alpha 4 integrins mediate leukocyte adhesion to specific counter-receptors, including vascular cell adhesion molecule-1 (VCAM-1), the fibronectin splice variant containing connecting segment 1 (CS1), and mucosal addressin cell adhesion molecule-1. A series of cyclized peptides based on the LDV sequence of CS1 were synthesized and assayed for inhibition of alpha 4 integrin binding. The most potent peptide, C*WLDVC* (where * indicates disulfide-linked residues), inhibited alpha 4 beta 1-dependent binding of lymphocytes to VCAM-1 and CS1 with half-maximal inhibition achieved at 1 to 3 microM of peptide. The peptide proved more potent when the lymphocytes were activated with 1 mM MnCl2; half-maximal inhibition was reached at 0.4 and 0.05 microM for VCAM-1 and CS1, respectively. This represents a 100- to 800-fold increase in potency over a linear CS1 peptide in these same assays. C*WLDVC* also inhibited alpha 4 beta 7-dependent lymphocyte binding to the ligands mucosal addressin cell adhesion molecule-1, VCAM-1 and CS1. Immunoprecipitation of radiolabeled integrin indicated that the peptide could bind alpha 4 beta 1 and alpha 4 beta 7 directly and elute alpha 4 beta 1 from a CS1-conjugated agarose resin. The peptide showed selectivity for alpha 4 integrins in that it effectively inhibited alpha 4 beta 1-dependent, but not alpha 5 beta 1-dependent, binding of cells to intact fibronectin. Due to its small size and potency, C*WLDVC* may serve as a useful tool for the study of alpha 4 integrin biology and the development of small molecule therapeutics.

Evidence for sex steroid inhibition of lipoprotein lipase in men: comparison of abdominal and femoral adipose tissue

Plasma estradiol has been suggested to suppress adipose tissue lipoprotein lipase (LPL) activity in women. The present study explores the regulation of LPL by sex steroids in sedentary obese men (N = 24) at their usual weight. Femoral adipose tissue LPL activity, eluted with serum and heparin or extracted with detergent, showed significant inverse correlations with plasma levels of testosterone, bioavailable testosterone, dihydrotestosterone, and estradiol. Both measures of femoral LPL activity were also correlated with the weight change occurring despite efforts to maintain a constant weight. Abdominal LPL activity showed significant but weaker inverse correlations with bioavailable testosterone only. Multivariate analysis of potential predictors for eluted femoral LPL activity showed that plasma testosterone, dihydrotestosterone, and estradiol were interdependent, whereas the rate of weight change was an independent variable. In the regression equation, only bioavailable testosterone and weight change were retained, explaining 63% of the variability (R = .79, P = .0002). These results suggest that sex steroids suppress adipose tissue LPL activity in men, and more so in the thigh than in the abdomen, thereby possibly contributing to a central fat accumulation. The data are compatible with a model from male animals suggesting that testosterone effects on adipose tissue LPL are mediated by estradiol formed locally.

Enhanced descending modulation of nociception in rats with persistent hindpaw inflammation

1. The role of descending brain stem modulatory systems in the development of persistent behavioral hyperalgesia and dorsal horn hyperexcitability was studied in rats with unilateral hindpaw inflammation. Inflammation was induced by intraplantar injection of complete Freund's adjuvant (CFA, 0.05 ml of an 1:1 oil/saline emulsion, 25 micrograms Mycobacterium), or lambda carrageenan (1 mg/ 0.1 ml saline). Thermal hyperalgesia was assessed by testing paw withdrawal latency (PWL) to a noxious heat stimulus. Superficial dorsal horn nociceptive (nociceptive specific, NS, and wide dynamic range, WDR) neuronal activity in the lumbar spinal cord was recorded extracellularly in chloralose-anesthetized rats. 2. Bilateral lesions of the dorsolateral funiculus (DLFX) at the T10 level were made in 13 rats, and the development of thermal hyperalgesia in these rats was compared with sham-operated or nonoperated control rats. In rats receiving a 0.05-ml CFA injection, a similar magnitude of hyperalgesia developed in the inflamed paw in DLFX (n = 7) and control (n = 8) rats. In addition, there appeared to be a contralateral hyperalgesia that was most apparent between 2 and 24 h after injection of CFA in DLFX rats. The CFA-induced contralateral effects were significantly different (P < 0.05) from the control rats at 2 and 6 h. 3. The intensity of the thermal stimulus was reduced and a low dose of carrageenan (1 mg) was injected into one hindpaw to further reveal the potentiation of hyperalgesia in DLFX rats. Throughout the 0.5- to 4-h time period after the injection of carrageenan, the PWL of the inflamed paws in DLFX rats (n = 6) was significantly shorter than that of control rats (n = 10; 2-way analysis of variance, F1,14 = 14.04, P < 0.01), suggesting the enhancement of hyperalgesia in DLFX rats. A hyperalgesia on the noninflamed paws was also more apparent in this experiment in DLFX rats, when compared with control rats. DLFX did not affect the baseline PWL of the rats. 4. A reversible spinalization was produced by application of a local anesthetic, lidocaine (2%, 0.1 ml), onto the dorsal surface of the thoracic cord (T10-12). This procedure produced thoracic spinal block that lasted for 90 min. The effects of thoracic lidocaine block on nociceptive neuronal activity were studied in 11 neurons (NS = 7, WDR = 4) in CFA-inflamed rats and 10 neurons (NS = 6, WDR = 4) in noninflamed naive rats. After the thoracic lidocaine block, rats showed increases in background activity, expansion of the receptive fields, and increased responses to noxious thermal, mechanical, and electrical stimuli. 5. Quantitative comparison revealed that the mean change in background firing rate of dorsal horn neurons was greater in inflamed [NS: 18.3 +/- 0.4 Hz, (mean +/- SE) n = 7; WDR: 10.9 +/- 0.7 Hz, n = 4] than that in noninflamed (NS: 2.3 +/- 0.3 Hz, n = 6; WDR: 3.3 +/- 0.4 Hz, n = 4) rats (P < 0.01, t-test) after thoracic lidocaine block. Thoracic saline application produced a 2.8 +/- 0.4 Hz decrease in background activity (2 NS and 2 WDR units). The expansion of the receptive fields after thoracic lidocaine block was also greater in inflamed (NS: 141 +/- 9% control, n = 6; WDR: 240 +/- 36% control, n = 4) than in noninflamed (NS: 114 +/- 9% control, n = 6; WDR: 167 +/- 21% control, n = 4) rats (P < 0.05, t-test). Thoracic saline did not produce a significant change in the receptive field size (105 +/- 9%, n = 4). The increases in responses to noxious thermal and mechanical stimuli after thoracic lidocaine block were also significantly greater in inflamed than in noninflamed rats (P < 0.01). There was no significant difference in the increase in responses to electrical stimulation of the sciatic nerve after lidocaine between inflamed and noninflamed rats.(ASTRACT TRUNCATED)

Descending modulation of Fos expression after persistent peripheral inflammation

The effects of spinal transection on Fos protein expression following complete Freund's adjuvant-induced hindpaw inflammation and hyperalgesia were studied. Fos-like immunoreactivity (LI) was used as a measure of neuronal activity in dorsal horn nociceptive pathways. Induction of Fos-LI in spinally transected rats with 3 days of hindpaw inflammation was significantly increased in ipsilateral lumbar (L 4,5) spinal cord, when compared with control animals with similar inflammation but an intact spinal cord. The contralateral side of spinally transected rats also showed significant induction of Fos-LI compared to the non-inflamed side of control rats. Since Fos induction provides an indication of the level of neuronal activity in response to a given stimulus, these results suggest that the net effect of brain stem descending pathways is to dampen central hyper-excitability in the spinal cord induced by tissue inflammation and hyperalgesia.

Application of nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester, on injured nerve attenuates neuropathy-induced thermal hyperalgesia in rats

This study tested the ability of a nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME), to attenuate behavioral hyperalgesia in a rat model of neuropathic pain [Bennett, G.J. and Xie, Y.-K., Pain, 33 (1988) 87-107]. A mononeuropathy was produced by chronic constriction injury (CCI) of the sciatic nerve. Thermal hyperalgesia was assessed by a reduction of paw withdrawal latency to a noxious heat source. Following CCI, there was significant hyperalgesia in groups of rats treated with D-NAME (n = 7), an inactive isomer of L-NAME, saline (n = 7) or systemic L-NAME (n = 10). In contrast, when L-NAME was applied directly and continuously to the site of CCI (5.0 micrograms/microliter per h for up to 2 weeks) via an osmotic pump implanted at the time of the injury, no significant thermal hyperalgesia was observed (n = 8). The results suggest the involvement of nitric oxide in the development and maintenance of thermal hyperalgesia in a rat model of neuropathy. The blockade of nitric oxide production at the site of injury may provide a new approach for treatment of neuropathic pain.

Increased lipase inhibition in uremia: identification of pre-beta-HDL as a major inhibitor in normal and uremic plasma

The hypertriglyceridemia commonly observed in uremia has been attributed to an abnormally high inhibitor activity in plasma for lipoprotein lipase (LPL) and hepatic lipase (HL), both of which have a key role in lipoprotein metabolism. The purpose of this investigation was to establish a relationship between plasma lipase inhibitor activity and hypertriglyceridemia, identify the main plasma lipase inhibitor, and determine the basis for the greater inhibitor activity in uremia. In a mixed population of normal (N = 8) and uremic subjects (N = 12), log-transformed plasma triglycerides correlated with both inhibitor activity and uremic status. However, inhibitor activity was the only retained predictor variable for triglycerides in a multiple linear regression model (r = 0.91; P < 0.0001). An inhibitor isolated from normal plasma was identified as a particle containing apolipoprotein A-I (apo A-I) and 3% phospholipid. This particle, which has pre-beta electrophoretic mobility and a Stokes' radius of 54 A, therefore corresponds to a form of the previously described pre-beta-HDL (free apo A-I) in the non-lipoprotein fraction of plasma. Comparison of normal and uremic plasma indicated that the greater lipase inhibitor activity in the latter could be attributed to an increased concentration of apo A-I in the non-lipoprotein fraction of plasma (pre-beta-HDL), as well as to increased inhibition by the uremic lipoproteins. The increased plasma lipase inhibitor activity may be important in the pathogenesis of hypertriglyceridemia in chronic renal failure.

An isobolographic analysis of the effects of N-methyl-D-aspartate and NK1 tachykinin receptor antagonists on inflammatory hyperalgesia in the rat

1. The interaction between N-methyl-D-aspartate (NMDA) and NK1 tachykinin receptors was analyzed isobolographically in rats with inflammatory hyperalgesia induced by intraplantar injection of complete Freund's adjuvant-saline emulsion (CFA, 100 micrograms Mycobacterium tuberculosis). 2. Thermal hyperalgesia of the inflamed paw, determined by paw withdrawal response to a heat stimulus, was dose-dependently attenuated by intrathecal administration of an NMDA receptor antagonist, dextrorphan (2.5-40 micrograms, ED50 = 7.2 micrograms), and two NK1 tachykinin receptor antagonists, WIN 51,708 (0.01-200 micrograms, ED50 = 10.4 micrograms) or CP-96,345 (5-200 micrograms, ED50 = 82.1 micrograms). There was no effect of these agents on the nociceptive threshold of the non-inflamed paw. CP-96,344, an enantiomer of CP-96,345 that is inactive as an NK1 tachykinin receptor antagonist, slightly attenuated hyperalgesia at a dose of 200 micrograms. 3. Combinations of dextrorphan and WIN 51,708 were administered at fixed ratios (10%:90%; 41%:59%; 90%:10%). Isobolographic analysis revealed that the ED50s obtained from the three combination ratios were not significantly different from those that were expected from a simple additive effect. 4. Thus, an additive interaction was demonstrated between NMDA and NK1 tachykinin receptor systems at the spinal level. These results suggest that both NMDA and NK1 tachykinin receptors are activated in response to peripheral inflammation, but that they may contribute independently to development of hyperalgesia.

Nerve growth factor alleviates a painful peripheral neuropathy in rats

Nerve growth factor (NGF) reverses some effects of axotomy and prevents toxic neuropathy in adult rodents. We tested the effect of NGF on behavioral hyperalgesia resulting from a chronic constriction injury (CCI) of the sciatic nerve in the rat [5]. CCI rats exhibit thermal hyperalgesia as demonstrated by a reduction of paw withdrawal latency to a noxious thermal stimulus applied to the paw on the side of injury. The mechanical sensitivity of the ipsilateral hindpaw, assessed with von Frey filaments, was also significantly increased. There were no significant changes in nociceptive thresholds on the contralateral side. When NGF was infused directly on the ligated nerve via an osmotic pump (0.5 microgram/microliter/h for 7 days) immediately after the ligation, thermal hyperalgesia was abolished from postoperative days 5 up to at least two weeks. The CCI-induced decrease in mechanical threshold was also abolished by NGF. However, NGF had only a minor effect on the abnormally long response duration, a second measure of mechanical sensitivity, to the mechanical stimulus. Delayed infusion of NGF four days after the ligation failed to block hyperalgesia. Infusion of NGF on the sciatic nerve of rats that had no CCI had no significant effect on paw withdrawal latency. Infusion of anti-NGF antiserum did not enhance hyperalgesia in CCI rats. These results suggest that alterations in neurotrophic factor(s) contribute to the development of behavioral hyperalgesia in an animal model of neuropathy and that NGF may have therapeutic value in the treatment of neuropathic pain in humans.

Use of beta-methylphenylalanine (beta MeF) residues to probe the nature of the interaction of substance P with its receptor: effects of beta MeF-containing substance P analogs on rabbit iris smooth muscle contraction

The effects of substituting (2S,3S)-beta-methylphenylalanine (S-beta MeF) or (2S,3R)-beta-methylphenylalanine (R-beta MeF) for the Phe7 and/or Phe8 residues of the tachykinin substance P (SP, RPKPQQFFGLM-NH2) upon the ability of SP to stimulate contraction of the rabbit iris smooth muscle were investigated. The eight beta MeF-containing SP analogs (four monosubstituted analogs, four disubstituted analogs) 1-8 were synthesized and found to be agonsts of SP in the smooth muscle contraction assay, having EC50 values ranging from 0.15 to 10.0 nM. Three analogs are significantly more active than SP [8R-(beta MeF)SP (4), 7S,8S-(beta MeF)2SP (5), and 7R,8S-(beta MeF)2SP (6)], three analogs are approximately equipotent with SP [7S-(beta MeF)SP (1), 7R-(beta MeF)SP (2), and 7S,8R-(beta MeF)2SP (8)], and two analogs are significantly less active than SP [8S-(beta MeF)SP (3) and 7R,8R-(beta MeF)2SP (7)]. The effects of the beta MeF substitutions upon the activity of SP are not additive and cannot be explained using simple conformational models which focus only on the side chain conformations of the beta MeF residues. It is postulated that the beta MeF residues induce minor distortions in the peptide backbone with resultant consequences upon peptide-receptor binding which are not dictated soley by the side chain conformations. This idea is consistent with 1H-NMR data for the monosubstituted analogs 1-4, which imply that the beta MeF substitutions cause slight distortions in the peptide backbone and that the beta MeF side chains are assuming trans or gauche(-) conformations.

Nitric oxide synthase-containing neurons in sensory ganglia of the rat are susceptible to capsaicin-induced cytotoxicity

Nitric oxide synthase in lumbar dorsal root ganglia of neonatal rat was studied by reduced nicotinamide adenine dinucleotide phosphate diaphorase and in situ hybridization histochemistry. Induction of nitric oxide synthase in neonatal capsaicin-treated rats after sciatic axotomy was compared with the axotomy-induced nitric oxide synthase increase observed in vehicle-treated littermates. In neonatal capsaicin-treated animals, the number of neurons constitutively labeled by reduced nicotinamide adenine dinucleotide phosphate diaphorase was greatly reduced as compared to vehicle-treated littermates. Nitric oxide synthase messenger RNA was not readily identified constitutively in dorsal root ganglion neurons. Seven days after sciatic transection the induction of reduced nicotinamide adenine dinucleotide phosphate diaphorase and nitric oxide synthase messenger RNA found in the vehicle-treated group was not observed in the capsaicin group. The presence of nitric oxide synthase in dorsal root ganglion neurons thus does not appear to protect against Ca(2+)-mediated capsaicin-induced cytotoxicity. However, since some nitric oxide synthase dorsal root ganglion neurons persist after the capsaicin neurotoxicity, nitric oxide synthase expression must occur in a neurochemically diverse subpopulation of small (< 1000 microns2) neurons. The capsaicin sensitivity of most nitric oxide synthase dorsal root ganglion neurons indicates that they have unmyelinated axons and are likely to be involved in nociception.

Identification of polymorphisms in the constant region of IgG3: the missing mouse allotype

We have identified DNA sequence polymorphisms in the C gamma 3 genes of BALB/c and C57BL/6 mice. One of these results in a Ser-->Gly amino acid difference in CH1 at position 129 according to the Wu and Kabat numbering system. There are three additional silent substitutions in the coding region and two polymorphic nucleotides in the 3' untranslated region. According to standard nomenclature in which alleles are numbered according to the order of their identification, these C gamma 3 alleles are designated Igh-8a and Igh-8b respectively. We also describe two polymerase chain reaction-based assays that identify the allelic differences.

Characterization and biological properties of a new staphylococcal exotoxin

Staphylococcus aureus strain D4508 is a toxic shock syndrome toxin 1-negative clinical isolate from a nonmenstrual case of toxic shock syndrome (TSS). In the present study, we have purified and characterized a new exotoxin from the extracellular products of this strain. This toxin was found to have a molecular mass of 25.14 kD by mass spectrometry and an isoelectric point of 5.65 by isoelectric focusing. We have also cloned and sequenced its corresponding genomic determinant. The DNA sequence encoding the mature protein was found to be 654 base pairs and is predicted to encode a polypeptide of 218 amino acids. The deduced protein contains an NH2-terminal sequence identical to that of the native protein. The calculated molecular weight (25.21 kD) of the recombinant mature protein is also consistent with that of the native molecules. When injected intravenously into rabbits, both the native and recombinant toxins induce an acute TSS-like illness characterized by high fever, hypotension, diarrhea, shock, and in some cases death, with classical histological findings of TSS. Furthermore, the activity of the toxin is specifically enhanced by low quantities of endotoxins. The toxicity can be blocked by rabbit immunoglobulin G antibody specific for the toxin. Western blotting and DNA sequencing data confirm that the protein is a unique staphylococcal exotoxin, yet shares significant sequence homology with known staphylococcal enterotoxins, especially the SEA, SED, and SEE toxins. We conclude therefore that this 25-kD protein belongs to the staphylococcal enterotoxin gene family that is capable of inducing a TSS-like illness in rabbits.

Cloning of a DNA binding protein that is a tyrosine kinase substrate and recognizes an upstream initiator-like sequence in the promoter of the preprodynorphin gene

A 90 bp fragment prepared from the promoter region of the rat preprodynorphin gene formed a complex with rat brain nuclear extracts as assessed by gel mobility shift assays. An 8 base pair sequence, CACTCTCC, termed upstream regulatory element (URE), was identified within this fragment as a binding site by DNase 1 footprint analysis and gel mobility shift assays with synthetic oligonucleotides. The URE is a consensus sequence for a transcription initiator (Inr) element although in the preprodynorphin promoter it is located upstream at -208 and overlaps a region conserved between rat and human promoters. A unique 310 amino acid protein (UreB1) that specifically bound the URE was cloned from a rat brain cDNA library using the URE-containing oligonucleotide. Recombinantly expressed, affinity purified UreB1 protein retains specific binding to the URE oligonucleotide. UreB1 contains a tyrosine kinase phosphorylation consensus and binding is enhanced following phosphorylation with the p43v-abl tyrosine kinase. The UreB1 tyrosine phosphoprotein increases transcription in vitro, consistent with a positive transcriptional regulatory function. UreB1 transcripts are well expressed in subsets of neurons in multiple brain areas suggesting that, in addition to regulation of the preprodynorphin gene, it may have a more generalized role in gene transcription.

A comparative study of the calcium-binding proteins calbindin-D28K, calretinin, calmodulin and parvalbumin in the rat spinal cord

Comparison of the immunocytochemical localizations revealed distinct patterns of differential distribution and overlapping of calbindin-D28K (CB-D28K), calretinin (CR), calmodulin (CM) and parvalbumin (PV) in the rat spinal cord. In some areas, one of the four calcium-binding proteins (CBPs) appears to be predominant, for example, CB-D28K in lamina I and ependymal cells, PV at the inner part of laminae II, CR in laminae V and VI and CM in motoneurons of lamina IX. In other regions of the spinal cord, more than one CBPs was abundant. CB-D28K and CR were similarly distributed in lamina II and the lateral spinal and cervical nucleus; CM and PV were similarly abundant in the ventromedial dorsal horn, internal basilar and central cervical nucleus; CR and PV were similarly abundant in the ventromedial dorsal horn, internal basilar and central cervical nucleus; CR and PV were similarly heterogeneous in the gracile fasciculus from caudal to rostral spinal cord. In the sacral dorsal gray commissure, the distribution patterns of CR and PV were clearly complementary. The unilateral ganglionectomies resulted in a substantial reduction of CBP-like immunoreactivity (CBP-LI) in the dorsal columns and a reduction of CM- and PV-LI in the ventromedial dorsal horn. In the motor system, only CM labeled large motoneurons in lamina IX and CB-D28K lightly stained pyramidal tract. The apparent absence of CM-LI in the superficial dorsal horn is contradictory to the presence of a CM-dependent nitric oxide synthase in the region. These data indicate that most CBP-LI in the dorsal column pathway had primary afferent origin, while the superficial dorsal horn exhibited intrinsic CBP immunoreactivity. The differential and selective localizations of CBPs in the spinal cord suggest a role for these proteins in spinal nociceptive processing, visceral regulation and dorsal column sensory pathways.

NMDA receptor antagonists attenuate mechanical hyperalgesia in rats with unilateral inflammation of the hindpaw

The effects of N-methyl-D-aspartate (NMDA) receptor antagonists on mechanical hyperalgesia associated with tissue inflammation were studied. Following an injection of the inflammatory agent, complete Freund's adjuvant, into the rat hindpaw, there was a significant decrease in threshold and an increase in response duration to mechanical stimuli, suggesting that a state of mechanical hyperalgesia was induced. The intrathecal administration of the NMDA receptor antagonists, dizocilpine maleate and (+/-)-2-amino-5-phosphonopentanoic acid, significantly increased mechanical threshold and reduced response duration in the inflamed hindpaw, but had no effect on the non-injected paw. The results suggest that NMDA receptor activation may contribute to the mechanical hyperalgesia that follows peripheral tissue inflammation.

110/140 laminin-binding protein immunoreactivity in spinal dorsal root ganglia: a capsaicin-insensitive reduction induced by constriction injury of the sciatic nerve in rats

The distribution of 110/140 laminin-binding protein (110/140 LBP) in the spinal dorsal root ganglia (DRG) and its regulation by partial constriction of the sciatic nerve was studied in adult rats. The cross-sectional area of neurons with 110/140 LBP-immunoreactivity (-I) showed an approximately normal frequency distribution. The 110/140 LBP-I was observed in neuronal cell bodies exclusive of the nucleus. Following sciatic nerve constriction, the 110/140 LBP-I was downregulated in the ipsilateral L4-5 DRG. DRG neurons with a cross-sectional area > or = 1600 microns 2 were preferentially affected. Neonatal capsaicin-treatment, a procedure that selectively destroys a subpopulation of DRG neurons with fine unmyelinated axons, had no effect on the reduction of 110/140 LBP in the DRG induced by sciatic nerve constriction. Western immunoblot analysis confirmed a reduction of 110/140 LBP on the side ipsilateral to the constriction. These results demonstrate a LBP within primary sensory neurons and its suppression by peripheral nerve injury. The data support a role for LBP in the adult nervous system.

Vagal afferent stimulation-produced effects on nociception in capsaicin-treated rats

1. The effects of electrical stimulation of cervical vagal afferent fibers on the nociceptive tail-flick (TF) reflex and responses of spinal dorsal horn neurons to noxious cutaneous stimulation were studied in adult rats treated as neonates with either capsaicin or vehicle. 2. Vagal afferent stimulation (VAS) produced biphasic, intensity-dependent effects on the TF reflex in vehicle-treated and untreated control rats. The TF reflex was facilitated in both groups of rats at lesser intensities of VAS (2.5-50 microA) and fully inhibited at greater intensities of VAS (50-100 microA). In contrast, biphasic effects of VAS on the TF reflex generally were not produced in rats treated as neonates with capsaicin. Facilitation of the TF reflex was produced in these rats by lesser intensities of VAS as well as by typically "inhibitory" intensities of VAS; the TF reflex was never inhibited in 6/12 rats, even at the greatest intensity of VAS tested (1,000 microA). When the TF reflex was inhibited by VAS in capsaicin-treated rats, the intensities required were significantly greater than those required in vehicle-treated or untreated rats. 3. In electrophysiological experiments, 77 neurons were recorded in the lumbar spinal dorsal horn of pentobarbital sodium-anesthetized, paralyzed rats treated as neonates with either vehicle or capsaicin. The neurons had receptive fields on the glabrous skin of the plantar surface of the ipsilateral hind foot, and all responded to mechanical stimuli of both nonnoxious and noxious intensities; 16/77 neurons also responded to noxious thermal stimulation. In vehicle-treated rats, nociceptive responses of 50% of 30 units studied were biphasically modulated by VAS, 33% were only inhibited, and 17% were only facilitated by VAS at the intensities tested (5-500 microA). In capsaicin-treated rats, nociceptive responses of 32% of 47 units studied were biphasically modulated by VAS, 15% were only inhibited, and 34% were only facilitated by VAS at the intensities tested (5-500 microA). In addition, nociceptive responses of neurons facilitated at lesser intensities of VAS and not affected at greater intensities of VAS were observed in capsaicin-treated rats (19% of the 47-unit sample). Overall, the proportion of the neuronal sample inhibited by VAS was less, and the proportion of the sample facilitated by VAS was greater in capsaicin-treated rats compared with vehicle-treated rats. 4. The efficacy of the capsaicin treatment was evaluated immunocytochemically.(ABSTRACT TRUNCATED AT 400 WORDS)

Binding of lipoprotein lipase to heparin. Identification of five critical residues in two distinct segments of the amino-terminal domain

Binding to heparan sulfate governs many aspects of the physiological action and regulation of the lipolytic enzyme, lipoprotein lipase (LPL). In an attempt to identify the structural determinants which mediate this interaction, basic residues in three segments of the primary sequence of human LPL (residues 147-151, 279-282, and 292-304) were replaced with alanine, either singly or in various combinations, and variant proteins were subjected to affinity chromatography on heparin-Superose. Five basic residues in two distinct segments of the primary sequence were critical determinants of the high affinity for heparin manifested by the active enzyme (R279, K280, R282, K296, R297). By contrast, no such evidence could be detected for basic residues in the first cluster (K147, K148) or for other basic residues in the third cluster (K292, R294, K304), while the evidence for K300 was unresolved. The conformation of this heparin-binding domain can be inferred by reference to the three-dimensional structure of the homologous enzyme, pancreatic lipase (Winkler, F. K., D'Arcy, A., and Hunziker, W. (1990) Nature 343, 771-774). Affinity of the active enzyme for heparin could not be reduced below a threshold, suggesting that other heparin-binding determinants exist elsewhere in the molecule, as supported by recently published evidence (Davis, R. C., Wong, H., Nikazy, J., Wang, K., Han, Q., and Schotz, M. C. (1992) J. Biol. Chem. 267, 21499-21504).

The effect of cyclosporin A on disease progression in proliferative immune complex glomerulonephritis

In rats with the proliferative immune complex glomerulonephritis of chronic serum sickness, kidney function deteriorates in three discrete and readily distinguishable stages: Mild, Moderate, and Severe. The mononuclear cell composition of glomerular inflammation is also different in each stage. The immunosuppressive drug, cyclosporin A, was administered to rats with chronic serum sickness in order to investigate the relationship between glomerular immunopathology and pathophysiology in proliferative immune complex nephritis. When introduced after the onset of proteinuria, daily treatment with cyclosporin A failed to prevent the progression from Moderate to Severe nephritis, which is characterized by the abnormal differentiation and local proliferation of glomerular macrophages, as well as grave deterioration in kidney function. In contrast, when cyclosporin A therapy started before the onset of proteinuria, the course of proliferative glomerulonephritis was altered significantly. Although the levels of proteinuria and macrophage accumulation that are characteristic of the Moderate stage of nephritis were not reduced, progression to Severe nephritis did not occur. The number of glomerular macrophages appeared to increase in two separate phases in this chronic serum sickness model of proliferative immune complex glomerulonephritis. The first phase, which coincided with the onset of proteinuria, did not require T cells and culminated only in moderate hypercellularity and proteinuria. The second increase in the number of glomerular macrophages, which was accompanied by the expression of abnormal macrophage phenotypes, was closely linked to the development of severe kidney insufficiency. The protective effect of cyclosporin A therapy was consistent with, although not conclusive proof for, the hypothesis that local T cell activation may contribute to the progression of proliferative immune complex glomerulonephritis. Since cyclosporin A can also directly influence the responses of macrophages and mesangial cells, the effect of the drug on the course of nephritis in this model might not be related to its immunosuppressive action.

Immunohistochemical localization of calretinin in the dorsal root ganglion and spinal cord of the rat

Calretinin (CR), a recently identified calcium-binding protein, is present in nervous tissue, including sensory pathways, where it may play an important role in regulation of cellular activity. Using immunocytochemistry, we examined the cellular localization of CR in dorsal root ganglia (DRG) and spinal cord of normal rats and after multiple unilateral dorsal root ganglionectomies. In DRG, CR-immunoreactive cell bodies and axons were a small subpopulation (10%) of medium- to large-sized neurons. In the spinal cord, CR-like immunoreactivity (LI) in neurons and fibers was found in all laminae except motoneurons. Dense fiber networks were also found in Clarke's column. The densest staining of both cell bodies and fibers was in the superficial laminae, especially lamina II, and in the lateral spinal and lateral cervical nuclei. CR-immunoreactive fibers were also observed in the fasciculi cuneatus and gracilis. Fasciculus gracilis exhibited the greatest number of labeled axons at the lumbosacral levels, but few labeled axons were found at the rostral thoracic and cervical levels. In contrast, the corticospinal tract at the base of the dorsal column was devoid of CR-immunoreactive fibers. Unilateral multiple lumbar ganglionectomies resulted in a loss of CR-LI in the dorsal columns ipsilateral to the surgery. In the spinal gray matter ipsilateral to the ganglionectomies, CR-LI was reduced in Clarke's column and slightly enhanced in the medial third of lamina II. Our observations demonstrate a unique distribution pattern of CR-LI compared to other calcium-binding proteins in the spinal cord, and suggest a role for CR in nociceptive and proprioceptive pathways.

Synthesis and biological evaluation of novel potent antagonists of the bombesin/gastrin releasing peptide receptor

This paper reports the synthesis and antagonist activity of 20 C-terminal analogues of gastrin releasing peptide (GRP). The ability of each analogue to inhibit bombesin (BN) stimulated amylase release from rat pancreatic acini was determined, and those showing antagonist activity were further evaluated for their ability to inhibit BN-stimulated [3H]thymidine uptake in serum-starved 3T3 cells. The assays also included two known peptide antagonists, C (Leu14,psi 13,14]BN) and H (N-pivaloyl-GRP20-25-(R)-2-methyl-4-nonylamide) as positive controls. On the basis of these assays we suggest that a des-Met27,Leu26-psi[CH2NHCOCH3]GRP C-terminal octapeptide imparts antagonist activity. The two most active compounds are peptides 14 ([D-Phe19,Leu26-psi(CH2NHCOCH3)]GRP19-26) and 18 ([D-Phe19,Gln20,Leu26-psi(CH2NHCOCH3)]GRP19++ +-26). In their ability to inhibit BN-stimulated [3H]thymidine uptake, the IC50 of peptides C, H, 14, and 18 were 43.2, 31.2, 2.7, and 32.5 nM, respectively. In conclusion, the novel C-terminal psi[CH2NHCOCH3] bond promises to be a useful peptide backbone modification for imparting antagonism in GRP/BN analogues.

The intrathecal administration of excitatory amino acid receptor antagonists selectively attenuated carrageenan-induced behavioral hyperalgesia in rats

A single unilateral injection of carrageenan (4.5-6.0 mg in 0.15-0.20 ml saline) into the rat hindpaw induced behavioral hyperalgesia as evidenced by a significant reduction in hindpaw withdrawal latency to a noxious thermal stimulus. The involvement of N-methyl-D-aspartate (NMDA) receptors in this model of hyperalgesia was examined by intrathecal administration of the selective excitatory amino acid (EAA) receptor antagonists: (+/-)-2-amino-5-phosphonopentanoic acid (AP-5), (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), ketamine hydrochloride (ketamine), 7-chlorokynurenic acid (7-Cl kynurenic acid), and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). The effects of dizocilpine maleate (MK-801) were studied under the same conditions and published previously (Ren et al., 1992) and the data are presented for comparison. While the withdrawal latencies of the non-injected paws and of the paws of naive rats were not significantly affected by application of the EAA receptor antagonists at doses tested, the paw withdrawal latencies of the carrageenan-injected paws were elevated dose dependently. The rank order of potency of these agents to reduce hyperalgesia was: MK-801 greater than or equal to AP-5 greater than or equal to CPP = 7-Cl kynurenic acid = ketamine much greater than CNQX greater than 0. In contrast, intrathecal injection of the opioid receptor agonists, [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO, mu-selective) and [D-Pen2,D-Pen5] enkephalin (DPDPE, delta-selective), produced antinociception in both injected and non-injected paws. DAMGO was much more potent, while DPDPE was less potent, than MK-801.(ABSTRACT TRUNCATED AT 250 WORDS)