Biosynthesis of corticotropin-releasing hormone in human T-lymphocytes

Effect of the corticotrophin releasing hormone precursor on interleukin-6 release by human mononuclear cells

A growing body of evidence suggests that corticotrophin releasing hormone (CRH) may exert direct modulatory effects on immune cells. In the present study we assessed the effects of its precursor molecule, proCRH, on interleukin-6 (IL-6) release by human peripheral blood mononuclear cells (MNC). Human MNC were incubated with the corresponding stimuli for 24 hr. The supernatants were collected and IL-6 measured by ELISA. Conditioned medium from CHO-K1 cells stably transfected with the recombinant plasmid pEE14/rat pre-proCRH cDNA was used as the source of proCRH. Western blot analysis of this medium, using an antibody specific for the intact precursor, showed that no proCRH degradation products were present. The proCRH had an inhibitory effect on basal and LPS-stimulated release of IL-6. These results suggest that the full length CRH precursor may possess immunomodulatory properties.

Expression of genes encoding corticotropin-releasing factor (CRF), type 1 CRF receptor, and CRF-binding protein and localization of the gene products in the human ovary

Recently, the presence of immunoreactive corticotropin-releasing factor (IrCRF) in the thecal-stromal cells of the human ovary and the ability of CRF to suppress estrogen production by human granulosa cells in vitro have been reported. To understand the functional role of ovarian CRF requires characterization of the human ovarian CRF system, which includes CRF, type 1 CRF receptor (CRF-R1), and the high affinity CRF-binding protein (CRF-BP). Accordingly, we have examined the ovarian CRF system and the cellular distribution of these proteins and their messenger ribonucleic acids (mRNAs) using immunohistochemistry and in situ hybridization, respectively. Normal ovaries from 10 premenopausal women undergoing hysterectomy with ovariectomy were used in the analyses. IrCRF and its mRNA were localized in thecal cells of small antral and mature follicles. A low abundance of IrCRF and mRNA was also detected in stromal cells of both stages of follicles. Expression of the gene encoding CRF was more prominent in mature follicles than in small antral follicles. CRF-R1 mRNA signal was found exclusively in thecal cells of mature follicles and moderately in small antral follicles. Granulosa cells were devoid of CRF and CRF-R1 mRNAs and proteins. The IrCRF-BP, but not its transcript, was detected in thecal cells and luman of capillary vessels of the thecal/stromal compartment of mature follicles. The absence of CRF-BP gene transcript in human ovarian follicles was confirmed by reverse transcription-PCR, indicating that the IrCRF-BP detected is not derived from the ovarian transcript and suggesting that the presence of IrCRF-BP and luman of capillary vessels in the thecal compartment originates from the peripheral circulation. Thecal cells of mature follicles, relative to those of small antral follicles, exhibited an intensive immunostaining and mRNA signal for 17 alpha-hydroxylase (P450c17) indicative of androgen biosynthesis. We conclude that the thecal compartment of the human ovary contains a CRF system endowed with CRF and CRF-R1 and the blood-derived CRF-BP. Granulosa cells are devoid of the CRF system. The parallel increases in intensity of CRF, CRF-R1, and 17 alpha-hydroxylase proteins and gene expression with follicular maturation suggest that the intraovarian CRF system may play an autocrine role in androgen biosynthesis with a downstream effect on estrogen production by the granulosa cells. The functionality of the ovarian CRF system may be conditioned by the relative presence of circulating CRF-BP by virtue of its ability to compete with CRF for the CRF receptor.

An antisense oligodeoxynucleotide complementary to corticotropin-releasing hormone mRNA inhibits rat splenocyte proliferation in vitro

Expression of neuropeptides in immune tissues has been implicated in the paracrine control of immune functions. The effects of the endogenous splenic neuropeptide corticotropin-releasing hormone (CRH) on immune cell proliferation were investigated by incubating splenocytes from adult male Wistar rats in vitro with a specific antisense oligodeoxynucleotide probe complementary to CRH mRNA. Incubation of cells with 1 microgram/ml phosphodiester antisense probe for 24 h prior to stimulation with concanavalin A (Con A) resulted in a 30-65% decrease in 3H-thymidine uptake compared to controls. In spleen cells incubated with a random base sequence (nonsense) probe the uptake of 3H-thymidine was not different to that in control cells. Incubation of cells with either antisense or nonsense phosphorothioate-protected probes resulted in variable uptake of 3H-thymidine, demonstrating that these probes, unlike the phosphodiester probes, have non-specific effects on cells. Addition of synthetic CRH to the cells incubated with the antisense phosphodiester probe partially restored the proliferative response of splenocytes to Con A. Immunoreactive (ir) CRH measured by radioimmunoassay in splenocytes incubated with the antisense probe was significantly less than ir-CRH in splenocytes incubated with the nonsense probe or without probe, indicating that the expression of splenic CRH mRNA was specifically impaired. This attenuation of the cell proliferative response following reduced expression of splenic ir-CRH provides functional evidence for the involvement of endogenously synthesised immune ir-CRH in splenocyte activation.

Corticotropin-releasing factor in antinociception and inflammation

Corticotropin-releasing factor (CRF) plays a major role at the level of the hypothalamus and pituitary to control the body's response mechanisms to stressful stimuli. The recent discovery of CRF outside the central nervous system suggests that CRF may well play a similar role in peripheral tissues, most likely in a paracrine manner. While its effects in many other peripheral tissues is not known yet, CRF and its receptors are upregulated in inflammatory pain states pointing to a key role under these circumstances. Indeed, locally expressed CRF seems to act on CRF receptors on immune cells which have migrated into the area of the inflamed tissue, and induce the release of opioid peptides synthesized within these immune cells. These opioids subsequently act on peripheral opioid receptors located on peripheral sensory nerves to inhibit the transmission of painful stimuli. CRF may also affect the inflammatory response; however, these data are still controversial. The peripheral paracrine effects of CRF may be similar to those of hypothalamic CRF, i.e., to counterbalance local stressful events, such as inflammation and pain, so that they do not threaten the homeostasis of the body. Interestingly, CRF-like peptides have been identified not only in mammalians, but also in species such as the frog (Stenzel-Poore et al., 1992, Mol. Endocrinol. 6, 1716) and the teleost fish (Okawara et al., 1988, Proc. Natl. Acad. Sci. USA 85, 8439) indicating that this is a peptide that has been conserved over a long period (200 million years) across species (Lederis et al., 1990, Prog. Clin. Biol. Res. 342, 467) and that the release of ACTH-like peptides by peptides of the CRF family may represent an ancestral type of stress response (Ottaviani et al., 1992, Gen. Comp. Endocrinol. 87, 354; Tran et al., 1990, Gen. Comp. Endocrinol. 78, 351).

CRH and the immune system

Inflammatory cytokines released during immune system activation can stimulate the hypothalamic-pituitary-adrenal axis and cause increased secretion of corticotropin-releasing hormone (CRH), adrenocorticotropin and glucocorticoids. Identification of CRH peptide and mRNA, as well as its receptors in immune tissues, suggested a role for this peptide as a mediator of the neuroendocrine-immune interactions. Experimental evidence suggests that CRH may modulate the immune and inflammatory responses via two pathways: an antiinflammatory one operated by centrally released CRH, most likely through stimulation of glucocorticoid and catecholamine release, and one proinflammatory, through direct action of peripherally released CRH. This review highlights these concepts. In addition preliminary data on immune activation and inflammatory response in CRH-deficient mice created in our laboratory are discussed.

Local production of corticotropin releasing hormone is increased in experimental intestinal inflammation in rats

BACKGROUND/AIMS

Corticotropin releasing hormone (CRH) suppresses immunological functions via stimulation of the pituitary-adrenal axis, but is also found in peripheral tissues. Peripheral proinflammatory activity of CRH is suggested by increased tissue concentrations in arthritis and in vitro immunostimulatory effects. This study evaluated intestinal CRH concentrations, immunolocalisation, and synthesis in chronic enterocolitis and investigated in vitro responsiveness of lamina propria mononuclear cells to CRH.

METHODS

Chronic granulomatous enterocolitis was induced by intramural injection of peptidoglycan-polysaccharide polymers in the ileocaecal region of Lewis rats. CRH protein was measured in caecal specimens by immunohistochemistry and radioimmunoassay and caecal CRH mRNA expression was analysed by reverse transcriptase polymerase chain reaction.

RESULTS

In the chronically inflamed caecum abundant immunoreactive CRH was found in inflammatory cells, mesenchymal cells, as well as in myenteric plexi. In contrast, only a few CRH containing cells were detected in normal and HSA injected control caecums. Moreover, caecal CRH protein levels were increased during chronic enterocolitis. Local CRH synthesis as indicated by mRNA expression was considerably increased in chronic enterocolitis whereas it was undetectable or low in uninflamed caecum. In addition, CRH stimulated in vitro proliferation of lamina propria mononuclear cells and inhibited mitogen induced proliferation.

CONCLUSION

Increased CRH protein and mRNA expression in chronic enterocolitis and responsiveness of intestinal mononuclear cells to CRH indicate an immunomodulatory role for locally produced CRH in intestinal inflammation.

Neuroendocrine immune responses to inflammation: the concept of the neuroendocrine immune loop

The neuroendocrine and immune responses to inflammatory stress represents an integrated circuit whose basis is reviewed in this chapter. Pro-inflammatory cytokines such as IL-1 beta, TNF-alpha and IL-6 released from inflammatory foci initiate local anti-inflammatory mechanisms and travel via the blood stream to the brain where they trigger a variety of neuroendocrine counter-regulatory mechanisms. There is therefore an important neuroendocrine-immune loop in which stimulatory signals are received by the neural systems from inflammatory foci. These signals are transduced by the hypothalamus which initiates a complex hormonal cascade reaction aimed at modulating inflammation and returning the organism to normal physiological homeostasis once the trigger has been neutralized. Abnormalities in this cross-talk can profoundly influence the susceptibility to developing chronic inflammatory disease. Thus, in conclusion, the neuroendocrine-immune loop has important pathophysiological implications for disease processes.

Cytokines and thyroid function

Cytokines play a crucial role in autoimmune thyroid disease (ATD) through various mechanisms. They are produced in the thyroid by intrathyroidal inflammatory cells, in particular lymphocytes, as well as by the thyroid follicular cells (TFC) themselves and may thus act in a cascade to enhance the autoimmune process (Fig. 1). Cytokines upregulate the inflammatory reaction through stimulation of both T and B cells, resulting in antibody production and tissue injury. In addition, intrathyroidal cytokines induce immunological changes in TFC including enhancement of both major histocompatibility complex (MHC) class I and class II molecule expression, and upregulation of adhesion and complement regulatory molecule expression. Cytokines can also modulate both growth and function of TFC and have a role in extrathyroidal complications of ATD, most importantly thyroid-associated ophthalmopathy (TAO), where they induce fibroblast proliferation and enhance the production of glycosaminoglycans (GAG), resulting in proptosis and the other clinical features of the disease. In addition to these effects, exogenous administration of cytokines has been associated with impairment of thyroid function ranging from the appearance of autoantibodies alone to the development of frank thyroid dysfunction. Cytokines have also been implicated in subacute thyroiditis (SAT) and amiodarone-induced thyroid dysfunction, as well as in thyroid function abnormalities occurring in patients with non-thyroidal illnesses (NTI). Genetic variations in cytokine genes represent potential risk factors for ATD, and disease associations have been described for polymorphisms in IL-1ra and TNF beta genes. Recent experimental evidence suggests the possibility of novel cytokine-based therapeutic approaches for ATD and its complications, in particular TAO.

Brain monoaminergic and neuropeptidergic variations in human aging

The effect of age on the monoamines 5-hydroxytryptamine (5-HT), noradrenaline (NA) and dopamine (DA), their metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), 3,4-dihydroxphenylacetic acid (DOPAC), and the 5-HT precursor 5-hydroxy-L-tryptophan (5-HTP), together with the peptides neuropeptide Y (NPY), somatostatin (SOM), and corticotropin-releasing factor (CRF), was studied in frontal cortex, gyrus cinguli and hypothalamus from 23 healthy control subjects, aged 16-75 years. After correcting for postmortem interval, significant decreases in gyrus cinguli NA, NPY and CRF, and hypothalamic DA, HVA, and 5-HIAA concentrations were obtained with advancing age. The involvement of the monoaminergic system in several functional abnormalities appearing in senescence is suggested. Furthermore, evidence is given of the participation of the peptidergic systems in the aging process.

A role for CRH and the sympathetic nervous system in stress-induced immunosuppression

Central CRH coordination of the behavioral and physiologic sequelae of stress has been well established, and so it is parsimonious to suggest that CRH might also coordinate the immunologic sequelae. The studies presented here lend support to this suggestion. CRH administration into the brain was shown to modulate aspects of both cellular and humoral immune function, and the inhibition of CRH release in the brain following stress inhibited stress-associated immunosuppression. The effects of CRH appear to be mediated by the sympathetic branch of the autonomic nervous system, as chemical sympathectomy and pharmacological blockade of beta-adrenergic receptors both reversed the effects of CRH on immune function. In contrast, removal of the adrenal glands did not alter the immunologic effects of CRH. These links among CRH in the brain, sympathetic activation, and immune function suggest the possibility that immune function may be altered in other conditions characterized by elevated sympathetic tone, such as depression and aging, and that these alterations may be attributed to CRH dysregulation in the brain. These studies shed light on the intricate relationship between the brain and the immune system, and also illuminate its complexity. The differential regulation of CRH in the brain and the periphery is one example of the latter. These findings also set the stage for potential clinical intervention with CRH antagonists, for example, to treat compromised immune function associated with chronic stress, depression, or aging.

Co-localisation of autoimmune antibodies specific for double stranded DNA with procorticotrophin-releasing hormone within the nucleus of stably transfected CHO-K1 cells

Human autoantibodies and corticotrophin-releasing hormone (CRH)-specific antibodies have been used in a double-labelling immunofluorescence technique to demonstrate that immunoreactive CRH structures are co-localised with immunostaining produced by double stranded DNA-specific human autoantibodies within the nucleus of cultured ovarian cells of Chinese hamsters (CHO-K1). This co-localisation was confirmed using confocal microscopy. A metabolic labelling technique was used to investigate the role of the cytoskeleton in mediating nuclear translocation of proCRH within stably transfected CHO-K1 cells and showed that microtubule and actin disrupting agents had no effect upon the nuclear translocation of proCRH. These results, therefore, suggest that nuclear translocation of proCRH is not affected by drugs which disrupt the cytoskeleton and, consequently, modify the diameter of the nuclear pores.

Generation and characterization of an antiserum reactive with a proteolytic processing site within rat procorticotrophin-releasing hormone

In this paper we report the generation of an antibody specific for the cleavage site within procorticotrophin-releasing hormone (proCRH) at the N-terminus proCRH/CRH (1-41) junction. Using radioimmunoassay techniques were show that the antibody generated (781) cross-reacts specifically with the proCRH (137-150) Tyr fragment, corresponding to the cleavage site within the full length precursor molecule. The anti-cleavage site antibody does not crossreact with the endoproteolytic products originated from the CRH precursor molecule, i.e. CRH (1-41) or proCRH (125-151) or with any of the CRH-immunoreactive fragments tested i.e. CRH (36-41), CRH (1-20) and CRH (30-41). It also shows no cross-reactivity with CRH-related substances from other species, i.e. urotensin I (fish) and sauvagine (frog). The cleavage site antibody (781), recognizes the full length proCRH molecule in Western blotting and in liquid phase radioimmunoassay from transfected CHO-K1 cells expressing the full length pre-proCRH cDNA. Using immunofluorescence and immunoprecipitation techniques followed by SDS-PAGE and autoradiography, we confirm the presence of the intact CRH precursor molecule within the nucleus and the cytoplasm of stably transfected CHO-K1 cells expressing immunoreactive proCRH. The immunofluorescence studies using primary cultures of hypothalamic neurons, show that immunoreactive (IR) proCRH is localized within the perinuclear region and was also seen along the neuronal processes where it accumulates at their tips. Our results, therefore, show that this antibody will be an invaluable tool in the study of intracellular trafficking in relation to the endoproteolytic processing of the CRH precursor molecule.

Cerebrospinal fluid neuropeptides in Alzheimer's disease and vascular dementia

Cerebrospinal fluid (CSF) levels of several neuropeptides have been suggested as candidate markers in neurodegenerative disorders. We have examined the levels of corticotropin-releasing hormone (CRH), beta-endorphine (BEND), delta sleep-inducing peptide (DSIP), somatostatin (SRIF), and neuropeptide Y (NPY) in CSF samples obtained under highly standardized conditions from healthy aged controls and from patients suffering from Alzheimer's disease (AD) or vascular dementia (VAD). The influence of some potentially confounding factors was evaluated. CRH and BEND were markedly decreased in both AD and VAD patients, and BEND levels correlated negatively with degree of dementia within the patient population. SRIF was decreased in both AD and VAD patients. DSIP was slightly increased in AD, but not in VAD. NPY did not differ between groups. For none of the peptides did CSF concentrations correlate significantly with duration of illness, nor, with the exception of BEND, with its degree. Present data do not support the hypothesis that specific neuropeptide changes occur in different neurodegenerative disorders, but are in agreement with previous reports suggesting that neuropeptide systems are differentially affected by neurodegeneration.

Changes in ACTH and beta-endorphin immunoreactivity in immune tissues during a chronic inflammatory stress are not correlated with changes in corticotropin-releasing hormone and arginine vasopressin

We have previously demonstrated that the chronic inflammatory stress of adjuvant-induced arthritis in rats can alter levels of the neuropeptides adrenocorticotropin (ACTH), beta-endorphin, arginine vasopressin (AVP) and corticotropin-releasing hormone (CRH) in tissues of the immune system. We now present data showing that the patterns of these changes in the spleens and thymuses of Piebald-Viral-Glaxo rats are quite dissimilar throughout the course of the disease. Immunoreactive (ir)-CRH, AVP, ACTH and beta-endorphin were measured by radioimmunoassays in spleen and thymic extracts taken at days 3, 7, 11 and 14 following injection of adjuvant. AVP was increased in the spleen at day 14 compared to the controls (79.4 +/- 4.4 and 60.0 +/- 9.0 fmol/g tissue respectively), but no change occurred in the thymus. CRH contents were increased in the spleen at day 14 (33.4 +/- 3.5) compared to controls (22.1 +/- 2.4 fmol/g tissue), and in the thymus at day 11 (24.0 +/- 2.3) compared to controls (14.1 +/- 2.5 fmol/g tissue). Increases in ACTH content were observed in spleens from arthritic rats at days 3 (365 +/- 23), 11 (359 +/- 32) and 14 (355 +/- 45 fmol/g tissue) compared to controls (198 +/- 37 fmol/g tissue). In the thymus, however, ACTH was elevated only at day 14. Beta-Endorphin levels in the spleen were elevated only at day 14 (289 +/- 41) compared to controls (97 /+- 22 fmol/g tissue).(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of biologically active procorticotrophin-releasing hormone (proCRH) in stably transfected CHO-K1 cells: characterization of nuclear proCRH

Corticotrophin-releasing hormone (CRH) is a 41 amino acid neuropeptide which is cleaved at a pair of dibasic amino acids from a larger precursor molecule (pre-proCRH) by the action of endopeptidases. In cells possessing a regulated secretory pathway, sorting of proneuropeptides and prohormones occurs within the trans-Golgi network, where they are finally packaged into secretory vesicles to be released in response to an external stimulus. Such cells also possess a constitutive secretory pathway, and neuropeptides are also translocated into this subcellular compartment. We have recently established stably transfected CHO-K1 cells expressing the rat pre-proCRH cDNA, and shown that proCRH was localized within the secretory pathway and the nucleus of transfected cells. Both the cytoplasmic and nuclear species of IR-CRH displayed an apparent molecular weight approximately 19 kDa, consistent with the size of the uncleaved CRH precursor molecule. In this paper, we further characterized the bitopological, i.e. nuclear and cytoplasmic localization of proCRH within transfected CHO-K1 cells. Immunoreactive nuclear CRH was not extractable using detergents (Triton X-100 and CHAPS), 10 mM salt washes or RNase digestion but could be abolished by digestion with DNase I. These results therefore suggest that nuclear proCRH is in close association with DNA/chromatin. Treatment of transfected cells with inhibitors of protein and RNA synthesis for up to 24 h had no effect upon immunoreactive nuclear CRH, indicating that it is very stable with a long half life. Brefeldin A treatment had no effect upon the nuclear translocation of newly synthesized proCRH, suggesting that late stages of the secretory pathway (i.e. post rough endoplasmic reticulum compartments) of the transfected cells do not play a role in proCRH nuclear transport. We also demonstrate that proCRH synthesized within stably transfected CHO-K1 cells is capable of stimulating ACTH release from primary cultures of anterior pituitary cells, therefore showing for the first time that the intact precursor is also biologically active and could act as an ACTH secretagogue in-vivo.

Mitogenic effects and nuclear localisation of procorticotrophin-releasing hormone expressed within stably transfected fibroblast cells (CHO-K1)

To investigate the intracellular localisation and biological activity of procorticotrophin-releasing hormone (proCRH), we have established stably transfected CHO-K1 cells expressing the rat pre-proCRH cDNA. Using immunoblot analysis of cell lysates of transfected CHO-K1 cells, we detected a major CRH immunoreactive band with an apparent molecular weight of approximately 19 kDa. This 19 kDa band could account for full length proCRH molecule which has not undergone post-translational modifications. Metabolic labelling followed by immunoprecipitation, SDS-PAGE and autoradiography indicated that no endoproteolytic processing of proCRH takes place within the transfected CHO-K1 cells. Immunofluorescence staining localises the CRH precursor to both the cytoplasm and to the nucleus in transfected CHO-K1 cells. This result was confirmed using subcellular fractionation techniques on radiolabelled CHO-K1 cells expressing immunoreactive CRH. A major CRH-immunoreactive band of 19 kDa was detected both in the microsomal and secreted fractions, indicating the presence of proCRH within the secretory pathway of these cells. This was also evident in the nuclear fraction, therefore confirming the nuclear localisation of proCRH. Analysis of DNA concentration, cell number and DNA synthesis showed that stably transfected CHO-K1 cells expressing proCRH have a higher proliferation and DNA synthesis rate than wildtype CHO-K1 cells or CHO-K1 cells transfected with pEE14 alone. Our results therefore suggest a mitogenic role for the intact proCRH molecule within CHO-K1 cells. Furthermore, treatment of mouse corticotrophic tumour cells (AtT20/D16-16) with conditioned medium from transfected CHO-K1 cells expressing proCRH, stimulated both DNA synthesis and cell proliferation above basal levels. Our results constitute the first reported direct evidence of a mitogenic role for proCRH acting on a corticotrophic cell population.

Magnesium sulphate infusion decreases circulating calcitonin gene-related peptide (CGRP) in women with primary Raynaud's phenomenon

The effects of two different vasodilating agents (MgSO4 infusion and the calcium antagonist nifedipine) on circulating levels of calcitonin gene-related peptide (CGRP) were studied in 12 women with pronounced primary Raynaud's phenomenon (PRP) and in 12 healthy females. There were no significant differences with regard to basal levels of circulating CGRP between women with PRP and the control group; median 15.5 (range 10-48) vs. 14 (range 10-69) pmol l-1, respectively. However, treatment with MgSO4 infusion significantly decreased circulating CGRP in women with PRP only from median 15.5 (range 10-48) to 10 (range 10-110) pmol l-1) (P < 0.05). On the other hand 14 days of treatment with nifedipine did not affect circulating CGRP in either of the investigated groups. Erythrocyte magnesium (ery-Mg) levels increased significantly after MgSO4 infusion in women with PRP (2.43 +/- 0.13 vs. 2.52 +/- 0.15 mmol l-1, P < 0.05) but not in the controls (2.51 +/- 0.24 vs. 2.57 +/- 0.28 mmol l-1, ns). In conclusion, the decrease of circulating CGRP after MgSO4 infusion in women with PRP provides further evidence that magnesium plays a significant role in the pathophysiology of PRP.

Contents of corticotropin-releasing hormone and arginine vasopressin immunoreactivity in the spleen and thymus during a chronic inflammatory stress

We have previously found that proopiomelanocortin (POMC) mRNA and levels of adrenocorticotropin (ACTH) and beta-endorphin peptides are increased in the spleen and thymus of rats with adjuvant-induced arthritis (AA), and immunologically mediated inflammatory disease. To determine whether alterations in immune tissue POMC during AA are also accompanied by changes in immune tissue corticotropin-releasing hormone immunoreactivity (ir-CHR) and arginine vasopressin (AVP), we measured ir-CRH and AVP by radioimmunoassays in spleen and thymic extracts 14 days following injection of adjuvant. Ir-CRH was detectable in all extracts of spleen and thymus. Total contents of ir-CRH in the spleen and thymus were not altered following arthritis, although a significant decrease was observed in splenic extracts from arthritis rats (40.0 +/- 4.2 fmol/g tissue) compared to controls (69.5 +/- 8.4 fmol/g tissue) when contents were expressed as amount per weight of tissue. Low levels of AVP were also detected in immune tissues, with contents significantly increased in spleens from arthritis animals (17.4 +/- 1.6 fmol/g tissue) compared to controls (10.6 +/- 1.9 fmol/g) but thymic contents of AVP were not altered by arthritis (10.6 +/- 1.3 fmol/g) compared to controls (9.2 +/- 0.7 fmol/g). Control levels of AVP were significantly higher in spleens and thymuses from female rats (53 +/- 5 and 25 +/- 4 fmol/g tissue, respectively) compared to males. G-50 chromatography revealed that the principal form of splenic ir-CRH is CRH(1-41), although in non-arthritic animals some ir-CHR eluted in a position indicating a slightly larger form.(ABSTRACT TRUNCATED AT 250 WORDS)