60 YEARS OF POMC: Lipotropin and beta-endorphin: a perspective.

Many important fields of research had a humble origin. In the distant past, A J P Martin's discovery that amino acids could be separated by paper chromatography and Moore and Stein's use of columns for quantitative amino acid analysis provided the first steps towards the determination of structure in complex biologically active molecules. They opened the door to reveal the essential relationship that exists between structure and function. In molecular endocrinology, for example, striking advances have been made by chemists with their expertise in the identification of structure working with biologists who contributed valuable knowledge and experience. Advantage was gained from the convergence of different background, and it is notable that the whole is greater than the sum. In the determination of structure, it may be recalled that four of the world's great pioneers (Archibald Martin, Rodney Porter, Fred Sanger and Vincent du Vigneaud) were acknowledged for their fundamental contributions when individually they were awarded the Nobel Prize. They foresaw that the identification of structure would prove of outstanding importance in the future. Indeed, study of the structures of ß-endorphin and enkephalin and the different forms of opiate activity they engender has led to a transformation in our understanding of chemical transmission in the brain.

Involvement of human peroxisomes in biosynthesis and signaling of steroid and peptide hormones.

Although peroxisomes exert essential biological functions, cell type-specific features of this important organelle are still only superficially characterized. An intriguing new aspect of peroxisomal function was recently uncovered by the observation that the peptide hormones ß-lipotropin (ß-LPH) and ß-endorphin are localized to peroxisomes in various human tissues. This suggests a functional link between peptide hormone metabolism and peroxisomes. In addition, because endocrine manifestations that affect steroid hormones are often found in patients suffering from inherited peroxisomal disorders, the question has been raised whether peroxisomes are also involved in steroidogenesis. With this chapter, we will review several crucial aspects concerning peroxisomes and hormone metabolism.

Effects of corticotropin-releasing hormone on proopiomelanocortin derivatives and monocytic HLA-DR expression in patients with septic shock.

Little is known about interactions between immune and neuro-endocrine systems in patients with septic shock. We therefore evaluated whether the corticotropin-releasing hormone (CRH) and/or proopiomelanocortin (POMC) derivatives [ACTH, ß-endorphin (ß-END), ß-lipotropin (ß-LPH), α-melanocyte stimulating hormone (α-MSH) or N-acetyl-ß-END (Nac-ß-END)] have any influences on monocyte deactivation as a major factor of immunosuppression under septic shock conditions. Sixteen patients with septic shock were enrolled in a double-blind, cross-over and placebo controlled clinical study; 0.5µg/(kgbodyweighth) CRH (or placebo) were intravenously administered for 24h. Using flow cytometry we investigated the immunosuppression in patients as far as related to the loss of leukocyte surface antigen-DR expression on circulating monocytes (mHLA-DR). ACTH, ß-END immunoreacive material (IRM), ß-LPH IRM, α-MSH and Nac-ß-END IRM as well as TNF-α and mHLA-DR expression were determined before, during and after treatment with CRH (or placebo). A significant correlation between plasma concentration of α-MSH and mHLA-DR expression and an inverse correlation between mHLA-DR expression and TNF-α plasma level were found. Additionally, a significant increase of mHLA-DR expression was observed 16h after starting the CRH infusion; 8h later, the mHLA-DR expression had decreased again. Our results indicate that the up-regulation of mHLA-DR expression after CRH infusion is not dependent on the release of POMC derivatives. From the correlation between plasma concentration of α-MSH and mHLA-DR expression, we conclude that in patients with septic shock the down-regulation of mHAL-DR expression is accompanied by the loss of monocytic release of α-MSH into the cardiovascular compartment.

The mass transfer kinetics in columns packed with Halo-ES shell particles.

The average mesopore size of the new Halo-ES-Peptide shell particles is 160 Å, markedly larger than that of the classical Halo shell particles (90 Å). We found that this change causes a considerable decrease of the film mass transfer resistance measured for columns packed with these particles. We analyze data obtained by systematic measurements of the C term of the van Deemter equation for the peptide ß-lipotropin (MW = 769 Da), the protein insulin (MW = 5800 Da), and a series of non-retained polystyrene standards (MW = 6400 and 13,200). The improvement in column performance is explained by an increase of the fraction of the external surface area of the shell that allows the entrance of the sample molecules inside the particle. The fraction of the shell surface accessible to a probe controls the rate of its external film mass transfer, i.e. its rate of transfer between the interstitial and the stagnant eluent. Although measurable, the increase in sample diffusivity through the porous shells does not account for the better performance of Halo-ES-peptide columns. Furthermore, the analysis of the HETPs data of small molecules (uracil, acetophenone, toluene, and naphthalene, MW< 150) reveals that the eddy diffusion (A) term of these new columns is 25% lower than that of the classical Halo columns. This result is consistent with the impact of intra-particle diffusivity on the eddy diffusion mechanism in packed columns. As shell diffusivity increases, so does the rate of transfer of sample molecules between the eluent stream-paths flowing through the packed particles and across the column diameter. Dispersion through short-range inter-channel and trans-column eddies is reduced.

Hemodynamic actions of corticotropin-releasing hormone and proopiomelanocortin derivatives in septic patients.

Proopiomelanocortin (POMC) derivatives and mRNA of POMC have been detected in cardiomyocytes and vascular smooth muscle cells. Increased plasma levels of POMC derivatives have been found in septic patients during cardiovascular deregulation; therefore, we evaluated whether corticotroph-type (ACTH, ß-endorphin, ß-lipotropin) or melanotroph-type (α-melanocyte-stimulating hormone and N-acetyl-ß-END) POMC derivatives have influences on patients' hemodynamics during sepsis. Seventeen septic patients were monitored by pulmonary artery catheter and corticotropin-releasing hormone (CRH) tests were performed by intravenous administration of 100 µg CRH. Before, 15, 30, 45, and 60 minutes after CRH administration, hemodynamic variables were measured, and plasma concentrations of POMC derivatives were determined. After CRH administration, heart rate, cardiac index, and stroke index increased, and the systemic vascular resistance index decreased; moreover, a correlation between ACTH concentration and stroke index as well as an inverse correlation between (α-melanocyte-stimulating hormone concentration and systemic vascular resistance index was observed. CRH and ACTH may have opposite effects on the blood pressure (mean arterial pressure). Immediately after CRH injection mean arterial pressure decreased. ACTH (in contrast to ß-endorphin or ß-lipotropin), released into the cardiovascular compartment 15 minutes after CRH injection, might have raised mean arterial pressure as compatible with the correlation between ACTH levels and stroke index. (α-melanocyte-stimulating hormone appears to have a vasodilative effect during sepsis.

Peroxisomal localization of the proopiomelanocortin-derived peptides beta-lipotropin and beta-endorphin.

The peptide hormones ACTH, MSHs, ß-lipotropin (ß-LPH), and ß-endorphin are all derived from the precursor molecule proopiomelanocortin (POMC). Using confocal laser microscopy and immunoelectron microscopy in human pituitary gland, we demonstrate a peroxisomal localization of ß-endorphin and ß-LPH in cells expressing the peroxisomal ATP-binding cassette-transporter adrenoleukodystrophy protein (ALDP). The peroxisomal localization of ß-LPH and ß-endorphin was not restricted to the pituitary gland but was additionally found in other human tissues that express high levels of ALDP, such as dorsal root ganglia, adrenal cortex, distal tubules of kidney, and skin. In contrast to the peptide hormones ß-LPH and ß-endorphin, which are derived from the C terminus of POMC, the N-terminal peptides ACTH, α-MSH, and γ-MSH were never detected in peroxisomes. This novel peroxisomal localization of ß-endorphin and ß-LPH in ALDP-positive cells was confirmed by costaining with ALDP and the peroxisomal marker catalase. Moreover, peroxisomal sorting of ß-LPH could be modeled in HeLa cells by ectopic expression of a POMC variant, modified to allow cleavage and release of ß-LPH within the secretory pathway. Although ß-LPH and ß-endorphin were only associated with peroxisomes in cells that normally express ALDP, the transporter activity of ALDP is not necessary for the peroxisomal localization, as demonstrated in tissues of X-linked adrenoleukodystrophy patients lacking functional ALDP. It remains to be elucidated whether and how the peroxisomal localization of POMC-derived hormones has a role in the endocrine dysfunction of peroxisomal disease.

Response of proopiomelanocortin and gonado- or lactotroph systems to in-vitro fertilisation procedures stress.

OBJECTIVE: To analyse for the first time the response of the corticotroph-type and the melanotroph-type pituitary proopiomelanocortin (POMC) system with regard to in-vitro fertilisation (IVF) treatment using self-developed highly specific non-cross-reacting radioimmunoassay. SETTING: University hospital. patients: A total of 28 patients undergoing IVF oocyte retrieval. Cross sectional exploratory study, one factorial design with repeated measurements on one factor, non-parametric tests. Blood was collected before anaesthesia (t(A)) (n=28) and immediately after oocyte retrieval (t(B)) (n=28). MAIN OUTCOME MEASURE(S): beta-endorphin immunoreactive material (IRM), acetyl-N-beta-endorphin IRM, beta-lipotropin IRM, ACTH, cortisol, estradiol, progesterone, prolactin, luteinizing hormone, and follicle-stimulating hormone. For determination of authentic beta-endorphin [beta-endorphin (1-31)] a highly specific two-site fluid phase immunoprecipitation radioimmunoassay was developed, which did not cross-react with any beta-endorphin derivative or any other opioid peptide tested. RESULTS: No response of acetyl-N-beta-endorphin IRM and of authentic beta-endorphin (1-31) was observed to oocyte retrieval in contrast to a significant increase of corticotroph-type proopiomelanocortin derivatives. A significant rise in prolactin plasma concentration indicates a pronounced lactotroph response to oocyte retrieval stress. No significant correlation between POMC derivates and prolactin and between POMC derivatives and gonadotropins or sexual steroids except for ACTH and progesterone and for beta-endorphin IRM and estradiol was observed. CONCLUSION: IVF treatment stress led to significant corticotroph-type POMC and lactotroph responses, but not to responses of authentic beta-endorphin or melanotroph-type POMC in women undergoing oocyte retrieval.

The role of lipotropins as hematopoietic factors and their potential therapeutic use.

Lipotropins are peptides that act as hormones that are released from a common precursor together with other physiologically important peptides; their function is to mobilize the lipids that are stored in adipocytes as an energy reserve. This review will explain the existing scientific evidence on the action of lipotropins in adipocytes and, specifically, when these lipotropins activate bone marrow adipocytes to function as hematopoietic factors and suggest the potential therapeutic use of lipotropins based on these effects.

Molecular cloning and characterization of preproopiomelanocortin (prePOMC) cDNA from the ostrich (Struthio camelus).

To date proopiomelanocortin (POMC), the precursor protein for melanotropin (MSH), adrenocorticotropin (ACTH), lipotropins (LPH), and beta-endorphin (beta-END) in the pituitary gland, has been studied extensively over a wide spectrum of vertebrate classes. A paucity of information exists, however, with regard to POMC in the avian class, where to date POMC from only one species, the domestic chicken, appears to have been fully characterized. In the present study, we report the use of three clones of cDNA to provide the complete nucleotide sequence of ostrich prePOMC cDNA, consisting of 1072 bp (excluding the poly(A) tail). The deduced amino acid sequence of 253 amino acid residues includes the N-terminal signal peptide of 17 amino acid residues. The predicted amino acid sequence in the overall arrangement of its domains, conforms to that found in other tetrapods. Sequence domains for gamma-MSH, ACTH, alpha-MSH, gamma-LPH, beta-MSH, and beta-END are located at positions 74-85, 134-172, 134-146, 175-220, 203-220, and 223-253, respectively, in ostrich prePOMC, but some of them may not be released in the ostrich pituitary gland, despite the presence of nine potential processing sites consisting of 2-4 dibasic amino acids each. Substitution of glutamic acid for a dibasic amino acid at position 202 in ostrich prePOMC could prevent release of beta-MSH. To date the release of pro-gamma-MSH, beta-LPH, ACTH, gamma-LPH, and beta-END have been confirmed by direct isolation and characterization from ostrich pituitary extracts. In the present study, we have also identified ACTH, gamma-LPH and beta-END in a single frozen ostrich pituitary slice by means of MALDI-TOF mass spectrometry. When compared to a wide range of vertebrate prePOMC molecules, ostrich prePOMC revealed a high level of amino acid sequence identity (77%) with chicken prePOMC, which is the only other avian sequence available. As with other vertebrate classes, considerable intraclass differences were also evident between chicken and ostrich prePOMCs, which belong to different avian orders. Identity of ostrich prePOMC with non-avian tetrapod counterparts is only moderate (53-56%), whereas lower identities (20-49%) are evident over a range of fish prePOMCs.

Plasma levels of corticotroph-type pro-opiomelanocortin derivatives such as beta-lipotropin, beta-endorphin(1-31), or adrenocorticotropic hormone are correlated with severity of postoperative pain.

BACKGROUND: In the pituitary of lower species, pro-opiomelanocortin is expressed in corticotroph cells of the anterior and in melanotroph cells of the neurointermediate lobe; enzymatic processing in the corticotrophs results in the release of adrenocorticotropic hormone, beta-lipotropin, or beta-endorphin. In the melanotrophs, these fragments are further modified, eg, by N-terminal acetylation. In the human pituitary, these enzyme systems are located within the same cells in the anterior lobe. We studied the reactions of the pro-opiomelanocortin system under preoperative conditions as well as under postoperative pain. METHODS: In 17 patients undergoing hip or knee arthroplasty, we determined plasma concentrations of N-acetyl-beta-endorphin immunoreactive material, authentic beta-endorphin [beta-endorphin(1-31)], adrenocorticotropic hormone, beta-lipotropin immunoreactive material, and cortisol, as well as pain severity rated by the patients using a visual analogue scale before surgery, after surgery but still under spinal anesthesia, under postoperative pain, and 1 day after surgery. RESULTS: Only low levels of N-acetyl-beta-endorphin immunoreactive material were measured in 16 out of 17 patients. High concentrations (1st quartile/median/3rd quartile; pmol/L) of adrenocorticotropic hormone (22.5/55.8/124) and beta-lipotropin immunoreactive material (6.6/34.6/142) were observed under postoperative pain, accompanied by a small increase of beta-endorphin(1-31) concentrations (0.0/6.1/10.9). Preoperatively small but significantly elevated levels of corticotroph-type and melanotroph-type pro-opiomelanocortin derivatives were observed; in contrast, spinal anesthesia suppressed all pro-opiomelanocortin fragment release. Postoperative pain severity correlated with postoperative adrenocorticotropic hormone, beta-lipotropin immunoreactive material, and beta-endorphin(1-31) concentrations. CONCLUSIONS: We conclude that the melanotroph-type pro-opiomelanocortin system is not activated under postoperative pain; the increase of corticotroph-type pro-opiomelanocortin fragment levels is different in quantity and proportion under preoperative conditions or postoperative pain, respectively.

Preoperative concentration of beta-lipotropin immunoreactive material in cerebrospinal fluid: a predictor of postoperative pain?

Levels of beta-endorphin immunoreactive material (IRM) in cerebrospinal fluid (CSF) have been reported to correlate inversely with postoperative morphine requirement. Considering proopiomelanocortin (POMC) derivatives as predictors for sensitivity to postoperative pain, we determined authentic beta-endorphin (beta-endorphin(1-31)), beta-lipotropin IRM, N-acetyl-beta-endorphin IRM and ACTH in CSF of 17 patients undergoing hip or knee arthroplasty, before surgery (t(A)), immediately after termination of propofol infusion and still under spinal anesthesia (t(B)), under postoperative pain (t(C)) and one day after surgery (t(D)); patients rated their severity of pain on a visual analogue scale (VAS) at those four times. In all patients CSF concentrations of N-acetyl-beta-endorphin IRM and beta-lipotropin IRM were found to be increased after terminating the propofol infusion with spinal anesthesia still effective at t(B). Patients did not feel pain at times t(A), t(B) or t(D); however, they reported moderate to considerable pain at t(C). There were no correlations of postoperative pain severity at t(C) with ACTH, beta-endorphin(1-31) or N-acetyl-beta-endorphin IRM concentrations in CSF. In contrast, we observed significant inverse correlations (Spearman's rank correlation coefficients between -0.83 and -0.85, p<0.01) for postoperative pain severity with beta-lipotropin IRM concentrations in CSF at t(C), and, in addition, at t(A), t(B) and t(D); thus, postoperative pain severity appeared to be dependent on a central system controlling sensitivity to pain, linked to a POMC system releasing beta-lipotropin IRM into CSF and already active at times t(A) and t(B). We conclude that beta-lipotropin IRM in CSF might be considered to serve as a predictor of sensitivity to postoperative pain.

Expression of three proopiomelanocortin subtype genes and mass spectrometric identification of POMC-derived peptides in pars distalis and pars intermedia of barfin flounder pituitary.

Proopiomelanocortin (POMC) is a common precursor of adrenocorticotropic hormone (ACTH), melanophore-stimulating hormone (MSH), and endorphin (END). In pituitary gland, POMC receives posttranslational processing by which different peptides are generated in the pars distalis (PD) and pars intermedia (PI). Recently, we cloned three subtypes of the POMC gene in pituitary gland of barfin flounder. The present study was undertaken to elucidate whether the three POMC genes are expressed in both the PD and PI of barfin flounder pituitary, and to identify peptides derived from POMCs in these lobes. We amplified the transcripts of POMC-A, -B and -C in both the PD and PI by the reverse transcription-polymerase chain reaction. In situ hybridization also detected signals for these three subtypes in the PD and PI. These results demonstrated that all three POMC genes are expressed in both the PD and PI of barfin flounder pituitary. By mass spectrometric analyses, ACTH-A, Des-acetyl (Ac)-alpha-MSH-A/B (amino acid sequence of alpha-MSH-A is identical to that of alpha-MSH-B), beta-MSH-A, corticotropin-like intermediate lobe peptide (CLIP)-A, and N-terminal peptide (N-POMC)-A were identified in the PD. Moreover, Des-Ac-alpha-MSH-A/B, alpha-MSH-A/B, beta-MSH-A and -B, N-beta-lipotropin-A, CLIP-A, N-Ac-beta-END-A(1-41) (C-terminally truncated form of N-Ac-beta-END-A), and N-POMC-A were identified in the PI. Predominant detection of POMC-A-derived peptides indicates the greatest production of POMC-A and no detection of POMC-C-derived peptides indicates the lowest production of POMC-C in both the PD and PI. ACTH-A is specifically produced in the PD, however, the occurrence of Des-Ac-alpha-MSH-A, CLIP-A, and beta-MSH-A shows that the entire POMC-A is further cleaved into small peptides as in the PI. In the PI, some peptides receive modification or truncation as shown by the occurrence of alpha-MSH-A/B and N-Ac-beta-END-A(1-41). These results show differential posttranslational processing of POMC between the PD and PI in barfin flounder pituitary.

Detection of mRNA transcripts of truncated opiate precursor (POMC) in human cartilage.

In the present study, we have investigated the presence of pro-opiomelanocortin C-terminal fragment derived-peptides in human articular cartilage and cultured chondrocytes. beta-Lipotropin and beta-endorphin were monitored in different cell cultures and biopsies using different techniques. Biopsies were taken from patients undergoing total knee arthroplasty due to osteoarthritis. Both fresh tissue sections and chondrocytes cultured in monolayer were used in the study. Immunohistochemistry, immunocytochemistry, reverse transcriptase-polymerase chain reaction and qualitative Western blots were carried out. The results of the reverse transcriptase-polymerase chain reaction showed transcription of a truncated-form of mRNA for pro-opiomelanocortin in native cartilage and cultured chondrocytes. There was no detection of endogenous production of beta-lipotropin or beta-endorphin in human articular chondrocytes, either in situ or in vitro. Whether pro-opiomelanocortin-derived peptides of non-cartilaginous origin are present in articular cartilage itself still remains unclear.

[Molecular and genetic study of the role of hormones, receptors, and enzymes in regulation of reproduction, lipid metabolism, and other human physiological functions].

Prevalence of uterine progesterone receptors over estrogen ones, high uterine cAMP level, and low uterine prostaglandin level are necessary conditions of normal pregnancy. In cases of spontaneous and antiprogestin RU486-induced abortions, estrogen receptors prevail over progesterone ones, cAMP level decreases, and prostaglandin concentration in decidual tissue increases. Porcine and bovine beta-lipotropines were the first proteins, whose correct amino acid sequence was first determined in Russia. Several research centers carried out collaborative studies of the nucleotide sequences of human and animal proopiomelanocortin (lipotropin precursor) and prolactin cDNA. Researchers constructed genetic engineering producers of human pre-proinsulin and somatostatin, identified structural genes expressed in pancreatic beta-cells, studied antigenic properties of glutamic acid decarboxylase (GAD), which determine insulin-dependent diabetes, and identified the cholesterase determinant. They revealed mutations in the genes of proopiomelanocortin and melanocortin receptors (MC4-P), which inhibit leptin regulation of appetite and are associated with human obesity.

Corticotropin-releasing hormone reduces pressure pain sensitivity in humans without involvement of beta-endorphin(1-31), but does not reduce heat pain sensitivity.

In the present study the effects of intravenously administered corticotropin-releasing hormone (CRH) on the release of proopiomelanocortin (POMC) derivatives such as adrenocorticotropic hormone (ACTH), beta-lipotropin (beta-LPH) and beta-endorphin (beta-END) as well as direct effects of CRH on pain sensitivity were examined. In 16 healthy volunteers we studied the effects of 100 microg intravenously administered CRH in absence or presence of 12 mg naloxone on heat or pressure pain sensitivity, using a double-blind, cross-over and placebo-controlled design. To evaluate analgesic effects of CRH via release of POMC derivatives, we determined plasma concentrations of beta-END-immunoreactive material (IRM), authentic beta-END (beta-END(1-31)) and beta-LPH IRM, in parallel with heat and pressure pain tolerance thresholds before and 15 and 30 min after treatment with CRH (or placebo), and 5 min after naloxone (or placebo) administration which was administered 40 min after CRH (or placebo) injection. CRH increased levels of beta-END IRM, beta-END(1-31) and beta-LPH IRM. As compared to beta-END IRM levels measured by a commercial RIA kit, the beta-END(1-31) levels determined by a highly specific two-site RIA, proved to be remarkably small. Furthermore, CRH did not induce increases of heat pain tolerance thresholds, but of pressure pain tolerance thresholds, which, however, were not reversible by naloxone. Neither beta-END nor beta-LPH IRM nor beta-END(1-31) levels correlated with heat or pressure pain tolerance thresholds. We conclude that CRH does not modulate heat, but pressure pain; POMC derivatives like beta-END IRM, beta-END(1-31) or beta-LPH do not mediate this effect.

Elevated plasma beta-endorphin/beta-lipotropin concentration following a radius fracture.

Plasma beta-endorphin/beta-lipotropin concentration was assessed soon after a fracture. Blood samples from 14 patients with radius fractures were obtained from both arms soon after admission to the hospital (mean 245 min) after the accident. Follow-up samples were taken after healing of the fractures. Higher plasma beta-endorphin/beta-lipotropin concentrations were found in blood samples taken soon after a fracture in both arms compared with the concentrations after healing of the fracture. At admission, mean beta-endorphin/beta-lipotropin concentrations in the fractured and the contralateral arms were 12.7 pmol/L and 13.2 pmol/L, and after recovery 11.1 pmol/L and 11.5 pmol/L (p = 0.012 and p = 0.041), respectively. The pain decreased according to the visual analogue scale (VAS) (0-10) from 4.64 at admission to 0.58 after healing (p < 0.001). In conclusion, this study showed that beta-endorphin/beta-lipotropin concentrations are increased in both arms following a radius fracture compared to the level after the fracture has healed.

Effects of corticotropin-releasing hormone (CRH) on the synthesis and secretion of proopiomelanocortin-related peptides in the anterior pituitary: a study using CRH-deficient mice.

Corticotropin-releasing hormone (CRH) mainly regulates the synthesis and secretion of adrenocorticotropin (ACTH) in the anterior pituitary (AP). By using CRH-deficient mice (CRH KO), we investigated the role of CRH in the processing of proopiomelanocortin (POMC), a precursor of ACTH, beta-lipotropic hormone, and beta-endorphin (EP). In the basal condition, the plasma ACTH level was similar in CRH KO and wild-type mice (WT), while its response to pain stress in CRH KO was smaller than that in WT. Immunoreactive (ir) beta-EP contents in the AP of CRH KO were not significantly different from those of WT. In order to determine the different molecule profile of POMC-related peptides between WT and CRH KO, ir beta-EP contents extracted from AP of WT and CRH KO were assayed by gel filtration chromatography. The gel filtration analyses revealed that a higher molecular weight form of ir beta-EP, putative POMC, was increased in CRH KO, but the beta-EP peak level was small and similar between two groups. These results suggest that CRH has little influence on the basal release of ACTH and prohormone convertase-2 processing enzyme. On the other hand, it is essential for ACTH secretion under stress conditions, and CRH would affect on the prohormone convertase-1/3 processing enzyme in AP.