Compound A attenuates proinflammatory cytokine-induced endoplasmic reticulum stress in beta cells and displays beneficial therapeutic effects in a mouse model of autoimmune diabetes.

Type 1 diabetes (T1D) is characterized by an immune-mediated progressive destruction of the insulin-producing ß-cells. Proinflammatory cytokines trigger endoplasmic reticulum (ER) stress and subsequent insulin secretory deficiency in cultured ß-cells, mimicking the islet microenvironment in T1D. ß-cells undergo physiologic ER stress due to the high rate of insulin production and secretion under stimulated conditions. Severe and uncompensated ER stress in ß-cells is induced by several pathological mechanisms before onset and during T1D. We previously described that the small drug Compound A (CpdA), a selective glucocorticoid receptor (GR/NR3C1, nuclear receptor subfamily 3, group C, member 1) ligand with demonstrated inflammation-suppressive activity in vivo, is an effective modulator of effector T and dendritic cells and of macrophages, yet, in a GR-independent manner. Here, we focus on CpdA's therapeutic potential in T1D cellular and animal models. We demonstrate that CpdA improves the unfolded protein response (UPR) by attenuating ER stress and favoring the survival and function of ß-cells exposed to an environment of proinflammatory cytokines. CpdA administration to NODscid mice adoptively transferred with diabetogenic splenocytes (from diabetic NOD mice) led to a delay of disease onset and reduction of diabetes incidence. Histological analysis of the pancreas showed a reduction in islet leukocyte infiltration (insulitis) and preservation of insulin expression in CpdA-treated normoglycemic mice in comparison with control group. These new findings together with our previous reports justify further studies on the administration of this small molecule as a novel therapeutic strategy with dual targets (effector immune and ß-cells) during autoimmune diabetes.

Guía práctica para la solicitud de marcadores humorales de autoinmunidad y estudios genéticos en diabetes mellitus / A practical guide to request humoral autoimmunity markers and genetic tests in diabetes mellitus

La diabetes mellitus (DM) es una enfermedad heterogénea que presenta fenotipos clínicos diversos, todos con hiperglucemia. Históricamente se han utilizado cuatro factores para identificar esta diversidad: la edad de inicio, la gravedad de la enfermedad o grado de pérdida de la función de la célula beta, el grado de resistencia a la insulina y la presencia de autoanticuerpos asociados a la enfermedad. Actualmente, los parámetros empleados para clasificar los diferentes tipos de DM dificultan el diagnóstico y tratamiento de los pacientes. Las distintas presentaciones clínicas requieren una clasificación diagnóstica más eficaz para un abordaje terapéutico más preciso, valiéndose del avance de la inmunogenética y la bioquímica clínica. Esta guía está orientada a clasificar con precisión las presentaciones clínicas que a menudo generan incertidumbre dentro de los dos tipos principales de DM.

Diabetes mellitus (DM) is a heterogeneous disease, with diverse clinical phenotypes, all with hyperglycemia. Historically, four factors have been used to identify this diversity: the age at onset, the severity of the disease, that is, the degree of loss of beta cell function and insulin resistance, and the presence of circulating autoantibodies. Currently, the parameters used to classify the different types of DM make it difficult to diagnose and treat patients. The different clinical manifestations require an accurate diagnosis to achieve an effective therapeutic approach through the use of immunogenetics and clinical biochemistry. This practical guide aims to accurately classify the often uncertain clinical presentations within the two main types of diabetes.

Guía práctica para la solicitud de marcadores humorales de autoinmunidad y estudios genéticos en diabetes mellitus / A practical guide to request humoral autoimmunity markers and genetic tests in diabetes mellitus

Resumen La diabetes mellitus (DM) es una enfermedad heterogénea que presenta fenotipos clínicos diversos, todos con hiperglucemia. Históricamente se han utilizado cuatro factores para identificar esta diversidad: la edad de inicio, la gravedad de la enfermedad o grado de pérdida de la función de la célula beta, el grado de resistencia a la insulina y la presencia de autoanticuerpos asociados a la enfermedad. Actualmente, los parámetros empleados para clasificar los diferentes tipos de DM dificultan el diagnóstico y tratamiento de los pacientes. Las distintas presentaciones clínicas requieren una clasificación diagnóstica más eficaz para un abordaje terapéutico más preciso, valiéndose del avance de la inmunogenética y la bioquímica clínica. Esta guía está orientada a clasificar con precisión las presentaciones clínicas que a menudo generan incertidumbre dentro de los dos tipos principales de DM.

Abstract Diabetes mellitus (DM) is a heterogeneous disease, with diverse clinical phenotypes, all with hyperglycemia. Historically, four factors have been used to identify this diversity: the age at onset, the severity of the disease, that is, the degree of loss of beta cell function and insulin resistance, and the presence of circulating autoantibodies. Currently, the parameters used to classify the different types of DM make it difficult to diagnose and treat patients. The different clinical manifestations require an accurate diagnosis to achieve an effective therapeutic approach through the use of immunogenetics and clinical biochemistry. This practical guide aims to accurately classify the often uncertain clinical presentations within the two main types of diabetes.

The Lysine Demethylase KDM5B Regulates Islet Function and Glucose Homeostasis.

AIMS: Posttranslational modifications of histones and transcription factors regulate gene expression and are implicated in beta-cell failure and diabetes. We have recently shown that preserving H3K27 and H3K4 methylation using the lysine demethylase inhibitor GSK-J4 reduces cytokine-induced destruction of beta-cells and improves beta-cell function. Here, we investigate the therapeutic potential of GSK-J4 to prevent diabetes development and examine the importance of H3K4 methylation for islet function. MATERIALS AND METHODS: We used two mouse models of diabetes to investigate the therapeutic potential of GSK-J4. To clarify the importance of H3K4 methylation, we characterized a mouse strain with knockout (KO) of the H3K4 demethylase KDM5B. RESULTS: GSK-J4 administration failed to prevent the development of experimental diabetes induced by multiple low-dose streptozotocin or adoptive transfer of splenocytes from acutely diabetic NOD to NODscid mice. KDM5B-KO mice were growth retarded with altered body composition, had low IGF-1 levels, and exhibited reduced insulin secretion. Interestingly, despite secreting less insulin, KDM5B-KO mice were able to maintain normoglycemia following oral glucose tolerance test, likely via improved insulin sensitivity, as suggested by insulin tolerance testing and phosphorylation of proteins belonging to the insulin signaling pathway. When challenged with high-fat diet, KDM5B-deficient mice displayed similar weight gain and insulin sensitivity as wild-type mice. CONCLUSION: Our results show a novel role of KDM5B in metabolism, as KDM5B-KO mice display growth retardation and improved insulin sensitivity.

Hormonal Regulation of Follicle-Stimulating Hormone Glycosylation in Males.

The Follicle-Stimulating Hormone plays an important role in the regulation of gametogenesis. It is synthesized and secreted as a family of glycoforms with differing oligosaccharide structure, biological action, and half-life. The presence of these oligosaccharides is absolutely necessary for the full expression of hormone bioactivity at the level of the target cell. The endocrine milieu modulates the glycosylation of this hormone. During male sexual development a progressive increase in FSH sialylation and in the proportion of glycoforms bearing complex oligosaccharides are the main features in this physiological condition. In late puberty, FSH oligosaccharides are largely processed in the medial- and trans-Golgi cisternae of the gonadotrope and remain without changes throughout adult life. In experimental models, the absence of gonads severely affects FSH sialylation; androgen administration is able to restore the characteristics observed under physiological conditions. The expression of ST6 beta-galactoside alpha-2,6-sialyltransferase 1 is hormonally regulated in the male rat; it decreases after short periods of castration but increases markedly at longer periods of androgen deprivation. Although ST3 beta-galactoside alpha-2,3-sialyltransferase 3 is expressed in the male rat pituitary it is not influenced by changes in the endocrine milieu. The oligosaccharide structure of FSH has an impact on the Sertoli cell endocrine activity. In more advanced stages of Sertoli cell maturation, both sialylation and complexity of the oligosaccharides are involved in the regulation of inhibin B production; moreover, FSH glycoforms bearing incomplete oligosaccharides may enhance the stimulatory effect exerted by gonadal growth factors. In this review, we discuss available information on variation of FSH glycosylation and its hormonal regulation under different physiological and experimental conditions, as well as the effect on Sertoli cell endocrine activity.

SPARC is required for the maintenance of glucose homeostasis and insulin secretion in mice.

Obesity, metabolic syndrome, and type 2 diabetes, three strongly interrelated diseases, are associated to increased morbidity and mortality worldwide. The pathogenesis of obesity-associated disorders is still under study. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein expressed in many cell types including adipocytes, parenchymal, and non-parenchymal hepatic cells and pancreatic cells. Studies have demonstrated that SPARC inhibits adipogenesis and promotes insulin resistance; in addition, circulating SPARC levels were positively correlated with body mass index in obese individuals. Therefore, SPARC is being proposed as a key factor in the pathogenesis of obesity-associated disorders. The aim of this study is to elucidate the role of SPARC in glucose homeostasis. We show here that SPARC null (SPARC-/-) mice displayed an abnormal insulin-regulated glucose metabolism. SPARC-/- mice presented an increased adipose tissue deposition and an impaired glucose homeostasis as animals aged. In addition, the absence of SPARC worsens high-fat diet-induced diabetes in mice. Interestingly, although SPARC-/- mice on high-fat diet were sensitive to insulin they showed an impaired insulin secretion capacity. Of note, the expression of glucose transporter 2 in islets of SPARC-/- mice was dramatically reduced. The present study provides the first evidence that deleted SPARC expression causes diabetes in mice. Thus, SPARC deficient mice constitute a valuable model for studies concerning obesity and its related metabolic complications, including diabetes.

Interactions Between the Neuroendocrine System and T Lymphocytes in Diabetes.

It is well established that there is a fine-tuned bidirectional communication between the immune and neuroendocrine tissues in maintaining homeostasis. Several types of immune cells, hormones, and neurotransmitters of different chemical nature are involved as communicators between organs. Apart of being key players of the adaptive arm of the immune system, it has been recently described that T lymphocytes are involved in the modulation of metabolism of several tissues in health and disease. Diabetes may result mainly from lack of insulin production (type 1 diabetes) or insufficient insulin and insulin resistance (type 2 diabetes), both influenced by genetic and environmental components. Herein, we discuss accumulating data regarding the role of the adaptive arm of the immune system in the pathogenesis of diabetes; including the action of several hormones and neurotransmitters influencing on central and peripheral T lymphocytes development and maturation, particularly under the metabolic burden triggered by diabetes. In addition, we comment on the role of T-effector lymphocytes in adipose and liver tissues during diabetes, which together enhances pancreatic ß-cell stress aggravating the disease.

Role of FSH glycan structure in the regulation of Sertoli cell inhibin production.

Variations in follicle-stimulating hormone (FSH) carbohydrate composition and structure are associated with important structural and functional changes in Sertoli cells (SCs) during sexual maturation. The aim of the present study was to investigate the impact of FSH oligosaccharide structure and its interaction with gonadal factors on the regulation of monomeric and dimeric inhibin production at different maturation stages of the SC. Recombinant human FSH (rhFSH) glycosylation variants were isolated according to their sialylation degree (AC and BA) and complexity of oligosaccharides (CO and HY). Native rhFSH stimulated inhibin α-subunit (Pro-αC) but did not show any effect on inhibin B (INHB) production in immature SCs isolated from 8-day-old rats. Activin A stimulated INHB and had a synergistic effect on FSH to stimulate Pro-αC. The less acidic/sialylated rhFSH charge analogues, BA, were the only charge analogue mix that stimulated INHB as well as the most potent stimulus for Pro-αC production. Native rhFSH stimulated both Pro-αC and INHB in SCs at a more advanced maturation stage, isolated from 20-day-old rats. In these cells, all rhFSH glycosylation variants increased INHB and Pro-αC production, even in the presence of growth factors. The BA preparation exerted a more marked stimulatory effect on INHB and Pro-αC than the AC. Glycoforms bearing high mannose and hybrid-type oligosaccharides, HY, stimulated INHB and Pro-αC more effectively than those bearing complex oligosaccharides, CO, even in the presence of gonadal growth factors. These findings demonstrate the modulatory effect of FSH oligosaccharide structure on the regulation of inhibin production in the male gonad.

GR-independent down-modulation on GM-CSF bone marrow-derived dendritic cells by the selective glucocorticoid receptor modulator Compound A.

Dendritic cells (DC) initiate the adaptive immune response. Glucocorticoids (GCs) down-modulate the function of DC. Compound A (CpdA, (2-(4-acetoxyphenyl)-2-chloro-N-methyl-ethylammonium chloride) is a plant-derived GR-ligand with marked dissociative properties. We investigated the effects of CpdA on in vitro generated GM-CSF-conditioned bone marrow-derived DC (BMDC). CpdA-exposed BMDC exhibited low expression of cell-surface molecules and diminution of the release of proinflammatory cytokines upon LPS stimulation; processes associated with BMDC maturation and activation. CpdA-treated BMDC were inefficient at Ag capture via mannose receptor-mediated endocytosis and displayed reduced T-cell priming. CpdA prevented the LPS-induced rise in pErk1/2 and pP38, kinases involved in TLR4 signaling. CpdA fully inhibited LPS-induced pAktSer473, a marker associated with the generation of tolerogenic DC. We used pharmacological blockade and selective genetic loss-of-function tools and demonstrated GR-independent inhibitory effects of CpdA in BMDC. Mechanistically, CpdA-mediated inactivation of the NF-κB intracellular signaling pathway was associated with a short-circuiting of pErk1/2 and pP38 upstream signaling. Assessment of the in vivo function of CpdA-treated BMDC pulsed with the hapten trinitrobenzenesulfonic acid showed impaired cell-mediated contact hypersensitivity. Collectively, we provide evidence that CpdA is an effective BMDC modulator that might have a benefit for immune disorders, even when GR is not directly targeted.

Male Central Precocious Puberty: Serum Profile of Anti-Müllerian Hormone and Inhibin B before, during, and after Treatment with GnRH Analogue.

We aimed to describe the functional changes of Sertoli cells, based on the measurement of serum anti-Müllerian hormone (AMH) and inhibin B during treatment with GnRHa and after its withdrawal in boys with central precocious puberty. Six boys aged 0.8 to 5.5 yr were included. AMH was low at diagnosis in patients >1 yr but within the normal range in younger patients. AMH increased to normal prepubertal levels during treatment. After GnRHa withdrawal, AMH declined concomitantly with the rise in serum testosterone. At diagnosis, inhibin B was elevated and decreased throughout therapy, remaining in the upper normal prepubertal range. In patients with testicular volume above 4 mL AMH remained higher in spite of suppressed FSH. After treatment withdrawal, inhibin B rose towards normal pubertal levels. In conclusion, AMH did not decrease in patients <1 yr reflecting the lack of androgen receptor expression in Sertoli cells in early infancy. Serum inhibin B might result from the contribution of two sources: the mass of Sertoli cells and the stimulation exerted by FSH. Sertoli cell markers might provide additional tools for the diagnosis and treatment followup of boys with central precocious puberty.

The glycan structure in recombinant human FSH affects endocrine activity and global gene expression in human granulosa cells.

The aim of this study was to analyse the biological response to different recombinant human FSH (rhFSH) glycosylation variants on the endocrine activity and gene expression at whole-genome scale in human granulosa-like tumor cell line, KGN. The effects of differences in rhFSH sialylation and oligosaccharide complexity were determined on steroid hormone and inhibin production. A microarray approach was used to explore gene expression patterns induced by rhFSH glycosylation variants. Set enrichment analysis revealed that hormone sialylation and oligosaccharide complexity in rhFSH differentially affected the expression of genes involved in essential biological processes and molecular functions of KGN cells. The relevance of rhFSH oligosaccharide structure on steroidogenesis was confirmed assessing gene expression by real time-PCR. The results demonstrate that FSH oligosaccharide structure affects expression of genes encoding proteins, growth factors and hormones essential for granulosa cells function.

Effect of sialylation and complexity of FSH oligosaccharides on inhibin production by granulosa cells.

Granulosa cell (GC) inhibin A and B production is regulated by FSH and gonadal factors. This gonadotrophin is released as a mixture of glycoforms, which induce different biological responses in vivo and in vitro. Our aim was to determine the effect of recombinant human FSH (rhFSH) glycosylation variants on inhibin A and B production by rat GCs. Preparative isoelectro focusing was used to isolate more acidic/sialylated (pH <4.00) and less acidic/sialylated (pH >5.00) rhFSH charge analogues. Concanavalin A was used to isolate unbound and firmly bound rhFSH glycoforms on the basis of their oligosaccharide complexity. GCs, obtained from oestrogen-primed immature rats, were cultured with either native rhFSH or its glycosylation variants. Inhibin A and B were determined using specific ELISAs. Results were expressed as mean±s.e.m. Under basal conditions, inhibin A was the predominant dimer produced (inhibin A: 673±55; inhibin B: 80±4  pg/ml). More acidic/sialylated charge analogues stimulated inhibin B production when compared to inhibin A at all doses studied; by contrast, less acidic/sialylated charge analogues stimulated inhibin A production and elicited no effect on inhibin B. Glycoforms bearing complex oligosaccharides showed a potent stimulatory effect on inhibin B when compared to inhibin A production (i.e. dose 1  ng/ml: 4.9±0.5 vs 0.9±0.1-fold stimulation, P<0.001). Glycoforms bearing hybrid-type oligosaccharides favoured inhibin A production (i.e. dose 4  ng/ml 2.9±0.1 vs 1.6±0.1-fold stimulation, P<0.05). These results show that the sialylation degree as well as the complexity of oligosaccharides present in the rhFSH molecule may be considered additional factors that differentially regulate dimeric inhibin production by rat GCs.

Regulation of inhibin/activin expression in rat early antral follicles.

The aim of the present study was to determine the endocrine activity of cultured early antral follicles (EAF) isolated from prepubertal diethylstilbestrol-treated rats. The effect of steroidogenic substrates and FSH on steroid, inhibin A and B, Pro-alphaC and activin A production was evaluated. Androsterone was the predominant steroid produced by EAF. The addition of androstenedione, androstenedione+FSH and progesterone stimulated oestradiol production, whereas 25-hydroxycholesterol (25-OH-Chol) increased progesterone production. Inhibin A, B, Pro-alphaC, and activin A were produced under basal conditions. The predominance of inhibin B over inhibin A was not affected by the addition of androstenedione or progesterone. Inhibin A and activin A production was stimulated by FSH. 25-OH-Chol increased Inha, Inhba and Inhbb mRNA expression and the production of the three molecular forms of inhibins but decreased activin A production. These results show that FSH and the steroid follicular microenvironment differentially modulate the gene expression of inhibin/activin subunits, their assembly and secretion.

Seminiferous tubule function in delayed-onset X-linked adrenal hypoplasia congenita associated with incomplete hypogonadotrophic hypogonadism.

OBJECTIVE: X-linked adrenal hypoplasia congenita (AHC, OMIM 300200) due to mutations in the DAX-1 gene is frequently associated to hypogonadotrophic hypogonadism (HHG, OMIM 238320). Clinical variants with delayed-onset have been recognized. The objective of this study is to assess Sertoli cell function throughout pubertal development in patients with childhood-onset AHC due to stop mutations in the DAX-1 gene. DESIGN: Observational follow-up study of gonadotrophin pulsatility pattern, and serum levels of antimüllerian hormone and inhibin B through pubertal development in these patients. PATIENTS: Three patients belonging to two families with AHC were included in this study. MEASUREMENTS: The gonadotrophic pattern, serum inhibin B and antimüllerian hormone were determined in relation to clinical Tanner stage of pubertal development. RESULTS: One patient showed a marked elevation in serum FSH concomitantly with low inhibin B and antimüllerian hormone levels, indicating a primary testicular dysfunction. The other two patients showed a gonadotrophic pattern of HHG, and their serum levels of inhibin B and antimüllerian hormone also reflected a moderate primary testicular dysfunction. The three patients were azoospermic. CONCLUSIONS: These cases give further insight into the clinical spectrum of phenotypes of the hypothalamic-pituitary-gonadal axis in patients with variants in hypogonadism associated with childhood-onset X-linked AHC due to DAX-1 mutations.

Establishment of testicular endocrine function impairment during childhood and puberty in boys with Klinefelter syndrome.

OBJECTIVE: To precisely characterize the chronology of testicular endocrine function impairment during childhood and adolescence in patients with Klinefelter syndrome. Design Retrospective chart review. Patients A total of 29 boys with Klinefelter syndrome with up to 12.3 years follow-up. MEASUREMENTS: Clinical features and serum hormone levels were analysed during follow-up. RESULTS: Of the 29 patients, 16 were prepubertal and 13 had already entered puberty at their first visit. Fifteen patients were followed up through late puberty. Before puberty, LH, FSH, testosterone, anti-Müllerian hormone (AMH) and inhibin B were within the expected range in almost all cases. However, levels of the inhibin alpha-subunit precursor Pro-alphaC were in the lowest levels of the normal range in most cases. During puberty, FSH levels increased earlier and more markedly than LH. Inhibin B and AMH declined to abnormally low or undetectable levels in advanced pubertal stages. Although testosterone and Pro-alphaC levels were within the reference ranges in most cases, they were abnormally low for the observed LH values. CONCLUSIONS: In Klinefelter syndrome, a mild Leydig cell dysfunction is present from early childhood in most cases and persists throughout puberty. Sertoli cell function is normal until mid puberty, when a dramatic impairment is observed.

Time course of the serum gonadotropin surge, inhibins, and anti-Müllerian hormone in normal newborn males during the first month of life.

CONTEXT: Newborns with ambiguous genitalia or males with nonpalpable gonads usually require an early assessment of the presence and functional state of testicular tissue. OBJECTIVE: Our objective was to characterize the precise ontogeny of the serum patterns of gonadotropins, testosterone, anti-Müllerian hormone (AMH), and inhibins in normal newborn boys. DESIGN: We conducted a cross-sectional and longitudinal study. SUBJECTS: Serum samples were obtained in 57 boys and 13 girls on d 2 of life. A second sample was obtained on d 7, 10, 15, 20, and 30 (boys) and on d 30 (girls). MAIN OUTCOME MEASURES: Serum levels of gonadotropins, testosterone, AMH, and inhibins were measured. RESULTS: In males, LH and FSH were undetectable or very low on d 2. By d 7, LH increased to 3.94 +/- 3.19 IU/liter (mean +/- sd) and FSH to 2.04 +/- 1.67 IU/liter. LH/FSH ratios were 0.40 +/- 0.11 (d 2) and 2.02 +/- 0.20 (d 30). AMH rose from 371 +/- 168 pmol/liter (d 2) to 699 +/- 245 pmol/liter (d 30), and inhibin B rose from 214 +/- 86 ng/liter (d 2) to 361 +/- 93 ng/liter (d 30). The inhibin alpha-subunit precursor (pro-alphaC) remained stable during the first month of life. Testosterone levels were 66 +/- 42 ng/dl (d 2), 82 +/- 24 ng/dl (d 20), and 210 +/- 130 ng/dl (d 30). A sexual dimorphism was observed in AMH and inhibin B (lower in girls on d 2 and 30), in LH/FSH ratio (lower in girls on d 30) and in testosterone (lower in girls on d 30). CONCLUSIONS: Sertoli cell markers AMH and inhibin B are the earliest useful markers indicating the existence of normal testicular tissue.

Controversial role of inhibin alpha-subunit gene in the aetiology of premature ovarian failure.

BACKGROUND: Premature ovarian failure (POF) is characterized by hypergonadotropic amenorrhoea before the age of 40. Inhibin alpha-subunit (INHalpha) gene is proposed as a candidate gene due to its role in negative feedback control of FSH. METHODS: Polymorphism -16C>T of INHalpha gene was studied in 61 POF patients and 82 controls above 40 years old (C > 40). Substitution 769G>A was studied in 59 POF patients, 76 C > 40 and 73 controls below 40 years old (C < 40). RESULTS: No significant difference in risk of POF development for -16T allele was found when comparing idiopathic POF (I-POF) with C > 40 (Odds ratio = 1.46; 95% confidence interval = 0.63-3.19). Implication of -16C>T polymorphism in serum inhibin levels was analysed in 46 controls, and no significant differences (P > 0.05) were found between CC and CT + TT genotype groups when comparing either mid-follicular phase Pro-alphaC and inhibin B values or mid-luteal phase Pro-alphaC and inhibin A values. Heterozygosity for substitution 769G>A was found in 1 of 59 POF woman, 2 of 76 C > 40 and 6 of 73 C < 40. Presence of this substitution in a relevant number of control subjects is herein described for the first time. CONCLUSION: Our results indicate that -16C>T and 769G>A variants in INHalpha gene may not be associated to POF disease.

Relation between the reproductive status and somatolactin cell activity in the pituitary of pejerrey, Odontesthes bonariensis (Atheriniformes).

The aim of this study was to analyze the relationship between somatolactin (SL) expressing cells and the reproductive status in a multiple spawning fish, the pejerrey Odontesthes bonariensis. Somatolactin cells were identified in adults of both sexes by immunocytochemistry using a heterologous piscine antiserum. The area of the cells that showed immunoreactivity to SL (ir-SL) was compared in specimens with different degrees of reproductive activity as inferred from histological examination of the gonads and calculation of the gonadosomatic index (GSI %). The results showed a significant difference between the area of ir-SL cells of resting/regressing (62.9 +/- 2.1 micron 2) and sexually active/vitellogenic (76.8 +/- 2.3 micron 2) females and a significant positive correlation between the ir-SL cellular area and the GSI % (P < 0.01 in both cases). In males, the correlation between the area of ir-SL cells and the GSI % was not statistically significant. However, in those animals with the highest GSI % values, the ir-SL cells appeared more numerous and showed an increase in the immunostained area when compared to individuals with lower GSI % values. The present in morphological observations are in accordance with biochemical data obtained from other species and support the assumption that SL might be involved in the regulation of reproduction in fish.