Publicaciones por año
Publicaciones del Departamento de Histología y Embriología
Phenotypically aberrant astrocytes that promote motoneuron damage in a model of inherited amyotrophic lateral sclerosis
Proc Natl Acad Sci U S A 2011 108(44):18126-31
Pablo Díaz-Amarilla a, Silvia Olivera-Bravo a, Emiliano Trias a, Andrea Cragnolini b, Laura Martínez-Palma c, Patricia Cassina c, Joseph Beckman d e, Luis Barbeito a b
a Instituto de Investigaciones Biológicas Clemente Estable, Montevideo 11600, Uruguay; b Institut Pasteur de Montevideo, Montevideo 11600, Uruguay; c Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay; and d Department of Biochemistry and Biophysics, Environmental Health Sciences Center, and e Linus Pauling Institute, Oregon State University, Corvallis, OR 97331
DOI: 10.1073/pnas.1110689108
PMID: 22010221
Pubmed: https://pubmed.ncbi.nlm.nih.gov/22010221
Texto completo: https://www.pnas.org/doi/full/10.1073/pnas.1110689108
Abstract:
Motoneuron loss and reactive astrocytosis are pathological hallmarks of amyotrophic lateral sclerosis (ALS), a paralytic neurodegenerative disease that can be triggered by mutations in Cu-Zn superoxide dismutase (SOD1). Dysfunctional astrocytes contribute to ALS pathogenesis, inducing motoneuron damage and accelerating disease progression. However, it is unknown whether ALS progression is associated with the appearance of a specific astrocytic phenotype with neurotoxic potential. Here, we report the isolation of astrocytes with aberrant phenotype (referred as "AbA cells") from primary spinal cord cultures of symptomatic rats expressing the SOD1(G93A) mutation. Isolation was based on AbA cells' marked proliferative capacity and lack of replicative senescence, which allowed oligoclonal cell expansion for 1 y. AbA cells displayed astrocytic markers including glial fibrillary acidic protein, S100β protein, glutamine synthase, and connexin 43 but lacked glutamate transporter 1 and the glial progenitor marker NG2 glycoprotein. Notably, AbA cells secreted soluble factors that induced motoneuron death with a 10-fold higher potency than neonatal SOD1(G93A) astrocytes. AbA-like aberrant astrocytes expressing S100β and connexin 43 but lacking NG2 were identified in nearby motoneurons, and their number increased sharply after disease onset. Thus, AbA cells appear to be an as-yet unknown astrocyte population arising during ALS progression with unprecedented proliferative and neurotoxic capacity and may be potential cellular targets for slowing ALS progression.
Brain androgen receptor expression correlates with seasonal changes in the behavior of a weakly electric fish, Brachyhypopomus gauderio
Horm Behav 2010 58(5):729-36
Paula Pouso b d, Laura Quintana a, Carmen Bolatto d, Ana C. Silva b c
a Departamento de Neurofisiología, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo 11600, Uruguay b Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo 11600, Uruguay c Laboratorio de Neurociencias, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay d Departamento Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay
DOI: 10.1016/j.yhbeh.2010.07.005
PMID: 20688071
Pubmed: https://pubmed.ncbi.nlm.nih.gov/20688071
Texto completo: https://linkinghub.elsevier.com/retrieve/pii/S0018-506X(10)00201-1
Abstract:
Seasonal breeders are superb models for understanding natural relationships between reproductive behavior and its neural bases. We investigated the cellular bases of hormone effects in a weakly pulse-type electric fish with well-defined hormone-sensitive communication signals. Brachyhypopomus gauderio males emit social electric signals (SESs) consisting of rate modulations of the electric organ discharge during the breeding season. This discharge is commanded by a medullary pacemaker nucleus (PN), composed of pacemaker and relay neurons. We analyzed the contribution of androgen receptor (AR) expression to the seasonal generation of SESs, by examining the presence of ARs in the PN in different experimental groups: breeding, non-breeding, and testosterone (T)-implanted non-breeding males. AR presence and distribution in the CNS was assessed through western blotting and immunohistochemistry using the PG-21 antibody, which was raised against the human AR. We found AR immunoreactivity, for the first time in a pulse-type Gymnotiform, in several regions throughout the brain. In particular, this is the first report to reveal the presence of AR in both pacemaker and relay neurons within the Gymnotiform PN. The AR immunoreactivity was present in breeding males and could be induced in T-implanted non-breeding males. This seasonal and T-induced AR expression in the PN suggests that androgens may play an important role in the generation of SESs by modulating intrinsic electrophysiological properties of pacemaker and relay neurons.
Value of quantitative ultramorphological sperm analysis in infertile men
Reprod Biol 2010 10(2):125-39
Maria F. Skowronek 2 3, Jimena Alciaturi 3, Gabriela Casanova 2 4, Ana Capurro 5, Jose M. Montes 6, Rossana Sapiro 3
2 Transmission Electron Microscopy Unit, School of Science, Montevideo, Uruguay 3 Laboratory of Molecular Biology of Reproduction-Histology and Embryology Department, School of Medicine, Montevideo, Uruguay 4 Cellular and Molecular Biology Department, School of Science, Montevideo, Uruguay 5 Unit of Human Reproduction-Pereira-Rossell Hospital Center, Montevideo, Uruguay 6 Fertilab Montevideo, Uruguay
DOI: 10.1016/s1642-431x(12)60055-2
PMID: 20668504
Pubmed: https://pubmed.ncbi.nlm.nih.gov/20668504
Texto completo: https://linkinghub.elsevier.com/retrieve/pii/S1642-431X(12)60055-2
Abstract:
A specific cause of infertility cannot be identified in at least 25% of men referred to a specialized clinic. Diagnosis of infertile men is based mainly on standard semen analysis and the observation of sperm under light microscope. The aim of our study was to find the subcellular sperm characteristics that could explain infertility in a group of teratozoospermic infertile men. Morphological characteristics of sperm from non-teratozoospermic (control donors) and teratozoospermic infertile men were analyzed by transmission electron microscopy (TEM) and quantified. Our analysis showed that sperm cells from control donors presented a higher number of normal heads and tails than infertile men. Regarding subcellular characteristics of nucleus and tails, only the percentage of vacuolated nucleus, the absence of at least one pair of microtubules of the axoneme and the total distortion of the tail were statistically higher in infertile men than in control donors. There were no differences in the number of normal acrosomes between the groups. Although the ultrastructural sperm defects overlapped between control donors and infertile men, TEM permits the identification and differentiation of a larger amount of defects than light microscopy. Vacuolated nucleus and gross alterations of the tail are the major sperm defects that seem to have prognostic value in teratozoospermic men.
Extracellular ATP and the P2X7 receptor in astrocyte-mediated motor neuron death: implications for amyotrophic lateral sclerosis
J Neuroinflammation 2010 7:33
Mandi Gandelman 1 2, Hugo Peluffo 1 2, Joseph S Beckman 3, Patricia Cassina 2, Luis Barbeito 1 4
1 Neurodegeneration Laboratory, Institut Pasteur, Montevideo, Uruguay 2 Departamento de Histología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay 3 Linus Pauling Institute, Oregon State University, Corvallis, Oregon 97331, USA 4 Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
DOI: 10.1186/1742-2094-7-33
PMID: 20534165
Pubmed: https://pubmed.ncbi.nlm.nih.gov/20534165
Texto completo: https://jneuroinflammation.biomedcentral.com/articles/10.1186/1742-2094-7-33
Abstract:
Background: During pathology of the nervous system, increased extracellular ATP acts both as a cytotoxic factor and pro-inflammatory mediator through P2X(7) receptors. In animal models of amyotrophic lateral sclerosis (ALS), astrocytes expressing superoxide dismutase 1 (SOD1G93A) mutations display a neuroinflammatory phenotype and contribute to disease progression and motor neuron death. Here we studied the role of extracellular ATP acting through P2X(7) receptors as an initiator of a neurotoxic phenotype that leads to astrocyte-mediated motor neuron death in non-transgenic and SOD1G93A astrocytes.
Methods: We evaluated motor neuron survival after co-culture with SOD1G93A or non-transgenic astrocytes pretreated with agents known to modulate ATP release or P2X(7) receptor. We also characterized astrocyte proliferation and extracellular ATP degradation.
Results: Repeated stimulation by ATP or the P2X(7)-selective agonist BzATP caused astrocytes to become neurotoxic, inducing death of motor neurons. Involvement of P2X(7) receptor was further confirmed by Brilliant blue G inhibition of ATP and BzATP effects. In SOD1G93A astrocyte cultures, pharmacological inhibition of P2X(7) receptor or increased extracellular ATP degradation with the enzyme apyrase was sufficient to completely abolish their toxicity towards motor neurons. SOD1G93A astrocytes also displayed increased ATP-dependent proliferation and a basal increase in extracellular ATP degradation.
Conclusions: Here we found that P2X(7) receptor activation in spinal cord astrocytes initiated a neurotoxic phenotype that leads to motor neuron death. Remarkably, the neurotoxic phenotype of SOD1G93A astrocytes depended upon basal activation the P2X(7) receptor. Thus, pharmacological inhibition of P2X(7) receptor might reduce neuroinflammation in ALS through astrocytes.
Lipid peroxyl radicals mediate tyrosine dimerization and nitration in membranes
Chem Res Toxicol 2010 23(4):821-35
Silvina Bartesaghi 1 2 3, Jorge Wenzel 4 5, Madia Trujillo 6 7, Marcos López 8, Joy Joseph 9, Balaraman Kalyanaraman 10, Rafael Radi 11 12
1 Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Uruguay. Phone: +598-2-9249561, Fax: +598-2-9249563 2 Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Uruguay. Phone: +598-2-9249561, Fax: +598-2-9249563 3 Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Uruguay. Phone: +598-2-9249561, Fax: +598-2-9249563 4 Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Uruguay. Phone: +598-2-9249561, Fax: +598-2-9249563 5 Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Uruguay. Phone: +598-2-9249561, Fax: +598-2-9249563 6 Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Uruguay. Phone: +598-2-9249561, Fax: +598-2-9249563 7 Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Uruguay. Phone: +598-2-9249561, Fax: +598-2-9249563 8 Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee WI 53226, USA. Phone: + 414-456-4000, Fax: +414-456-6512 9 Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee WI 53226, USA. Phone: + 414-456-4000, Fax: +414-456-6512 10 Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee WI 53226, USA. Phone: + 414-456-4000, Fax: +414-456-6512 11 Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Uruguay 12 Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Uruguay
DOI: 10.1021/tx900446r
PMID: 20170094
Pubmed: https://pubmed.ncbi.nlm.nih.gov/20170094
Texto completo: https://doi.org/10.1021/tx900446r
Abstract:
Protein tyrosine dimerization and nitration by biologically relevant oxidants usually depend on the intermediate formation of tyrosyl radical ((*)Tyr). In the case of tyrosine oxidation in proteins associated with hydrophobic biocompartments, the participation of unsaturated fatty acids in the process must be considered since they typically constitute preferential targets for the initial oxidative attack. Thus, we postulate that lipid-derived radicals mediate the one-electron oxidation of tyrosine to (*)Tyr, which can afterward react with another (*)Tyr or with nitrogen dioxide ((*)NO(2)) to yield 3,3'-dityrosine or 3-nitrotyrosine within the hydrophobic structure, respectively. To test this hypothesis, we have studied tyrosine oxidation in saturated and unsaturated fatty acid-containing phosphatidylcholine (PC) liposomes with an incorporated hydrophobic tyrosine analogue BTBE (N-t-BOC l-tyrosine tert-butyl ester) and its relationship with lipid peroxidation promoted by three oxidation systems, namely, peroxynitrite, hemin, and 2,2'-azobis (2-amidinopropane) hydrochloride. In all cases, significant tyrosine (BTBE) oxidation was seen in unsaturated PC liposomes, in a way that was largely decreased at low oxygen concentrations. Tyrosine oxidation levels paralleled those of lipid peroxidation (i.e., malondialdehyde and lipid hydroperoxides), lipid-derived radicals and BTBE phenoxyl radicals were simultaneously detected by electron spin resonance spin trapping, supporting an association between the two processes. Indeed, alpha-tocopherol, a known reactant with lipid peroxyl radicals (LOO(*)), inhibited both tyrosine oxidation and lipid peroxidation induced by all three oxidation systems. Moreover, oxidant-stimulated liposomal oxygen consumption was dose dependently inhibited by BTBE but not by its phenylalanine analogue, BPBE (N-t-BOC l-phenylalanine tert-butyl ester), providing direct evidence for the reaction between LOO(*) and the phenol moiety in BTBE, with an estimated second-order rate constant of 4.8 x 10(3) M(-1) s(-1). In summary, the data presented herein demonstrate that LOO(*) mediates tyrosine oxidation processes in hydrophobic biocompartments and provide a new mechanistic insight to understand protein oxidation and nitration in lipoproteins and biomembranes.
Lead exposure stimulates VEGF expression in the spinal cord and extends survival in a mouse model of ALS
Neurobiol Dis 2010 37(3):574-80
Ana G Barbeito 1, Laura Martinez-Palma 1, Marcelo R Vargas 2, Mariana Pehar 2, Nelly Mañay 3, Joseph S Beckman 4, Luis Barbeito 2, Patricia Cassina 1
1 Departamento de Histología y Embriología, Facultad de Medicina, Montevideo, Uruguay 2 Laboratorio de Neurobiologia Celular y Molecular, Instituto Clemente Estable and Institut Pasteur de Montevideo, Uruguay 3 Departamento de Toxicología, Facultad de Química, Montevideo, Uruguay 4 Department of Biochemistry and Biophysics, Environmental Health Sciences Center and Linus Pauling Institute, Oregon State University, Corvallis, Oregon
DOI: 10.1016/j.nbd.2009.11.007
PMID: 19914377
Pubmed: https://pubmed.ncbi.nlm.nih.gov/19914377
Texto completo: https://linkinghub.elsevier.com/retrieve/pii/S0969-9961(09)00329-5
Abstract:
Exposure to environmental lead (Pb) is a mild risk factor for amyotrophic lateral sclerosis (ALS), a paralytic disease characterized by progressive degeneration of motor neurons. However, recent evidence has paradoxically linked higher Pb levels in ALS patients with longer survival. We investigated the effects of low-level Pb exposure on survival of mice expressing the ALS-linked superoxide dismutase-1 G93A mutation (SOD1(G93A)). SOD1(G93A) mice exposed to Pb showed longer survival and increased expression of VEGF in the ventral horn associated with reduced astrocytosis. Pretreatment of cultured SOD1(G93A) astrocytes with low, non toxic Pb concentrations upregulated VEGF expression and significantly abrogated motor neuron loss in coculture, an effect prevented by neutralizing antibodies to VEGF. The actions of Pb on astrocytes might explain its paradoxical slowing of disease progression in SOD1(G93A) mice and the improved survival of ALS patients. Understanding how Pb stimulates astrocytic VEGF production and reduces neuroinflammation may yield a new therapeutic approach for treating ALS.
Hyperpolarization of the plasma membrane potential provokes reorganization of the actin cytoskeleton and increases the stability of adherens junctions in bovine corneal endothelial cells in culture
Cell Motil Cytoskeleton 2009 66(12):1087-99
Verónica Nin 1, Julio A Hernández 2, Silvia Chifflet 3
1 Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay 2 Sección Biofísica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay 3 Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
DOI: 10.1002/cm.20416
PMID: 19753628
Pubmed: https://pubmed.ncbi.nlm.nih.gov/19753628
Texto completo: https://doi.org/10.1002/cm.20416
Abstract:
In previous works we showed that the depolarization of the plasma membrane potential (PMP) determines a reorganization of the cytoskeleton of diverse epithelia in culture, consisting mainly of a reallocation of peripheral actin toward the cell center, ultimately provoking intercellular disruption. In view of this evidence, we explored in this study the possible effects of membrane potential hyperpolarization on the cytoskeletal organization and adherens junction (AJ) morphology and the stability of confluent bovine corneal endothelial cells in culture. For this purpose, hyperpolarization was achieved by substitution of extracellular sodium by nondiffusible cations or via the incorporation of valinomycin to the control solution. Actin compactness at the cell periphery was assessed by quantitative analysis of fluorescence microscopy images. The stability of the AJ was challenged by calcium deprivation or temperature decrease. Our results showed that plasma membrane hyperpolarization provokes a compaction of AJ-associated actin filaments toward the plasma membrane and an increase in the stability of the AJs. We also observed that the hyperpolarizing procedures determined similar modifications in the actin cytoskeleton of endothelial cells in whole bovine corneas. Together with our previous work, the results of this study contribute to the idea that modifications in the PMP of nonexcitable cells participate in cellular adaptive responses involving reorganization of cytoskeletal components.
Axonal mitochondrial clusters containing mutant SOD1 in transgenic models of ALS
Antioxid Redox Signal 2009 11(7):1535-45
Jose R Sotelo-Silveira 1 2 5, Paola Lepanto 1, Victoria Elizondo 1, Sofia Horjales 2, Florencia Palacios 2, Laura Martinez-Palma 1, Monica Marin 2, Joseph S Beckman 3, Luis Barbeito 1 4
1 Department of Cell and Molecular Neurobiology, Instituto de Investigaciones Biologicas Clemente Estable, Montevideo, Uruguay. 2 Department of Cell and Molecular Biology, Facultad de Ciencias, Montevideo, Uruguay. 3 Environmental Health Sciences Center, Oregon State University, Corvallis, Oregon. 4 Institut Pasteur de Montevideo, Montevideo, Uruguay. 5 Present address of Dr. Sotelo-Silveira: Laboratory of Molecular Technology, ATP, SAIC-National Cancer Institute, Frederick, Maryland.
DOI: 10.1089/ars.2009.2614
PMID: 19344250
Pubmed: https://pubmed.ncbi.nlm.nih.gov/19344250
Texto completo: https://www.liebertpub.com/doi/10.1089/ars.2009.2614
Abstract:
We studied the subcellular distribution of mitochondria and superoxide dismutase-1 (SOD1) in whole mounts of microdissected motor axons of rats expressing the ALS-linked SOD1-G93A mutation. The rationale was to determine whether physical interactions between the enzyme and mitochondria were linked to the axonopathy of motor fibers occurring in amyotrophic lateral sclerosis (ALS). Mitochondria and SOD1 displayed a homogeneous distribution along motor axons both in nontransgenic rats and in those overexpressing wild-type SOD1. In contrast, axons from SOD1-G93A rats (older than 35 days) showed accumulation of mitochondria in discrete clusters located at regular intervals. Most of SOD1 immunoreactivity was enriched in these clusters and colocalized with mitochondria, suggesting a recruitment of SOD1-G93A to the organelle. The SOD1/mitochondrial clusters were abundant in motor axons but scarcely seen in sensory axons. Clusters also were stained for neuronal nitric oxide synthase, nitrotyrosine, and cytochrome c. The later also was detected surrounding clusters. Ubiquitin colocalized with clusters only at late stages of the disease. The cytoskeleton was not overtly altered in clusters. These results suggest that mutant SOD1 and defective mitochondria create localized dysfunctional domains in motor axons, which may lead to progressive axonopathy in ALS.
Mitochondrial calcium overload triggers complement-dependent superoxide-mediated programmed cell death in Trypanosoma cruzi
Biochem J 2009 418(3):595-604
Florencia Irigoín 1 2, Natalia M Inada 3, Mariana P Fernandes 3, Lucía Piacenza 2 4, Fernanda R Gadelha 5, Anibal E Vercesi 3, Rafael Radi 2 4
1 Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay 2 Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Avda. Gral. Flores 2125, 11800 Montevideo, Uruguay 3 Labóratorio de Bioenergética, Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Unicamp, Campinas, Brazil 4 Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay 5 Instituto de Biologia, Unicamp, Campinas, Brazil
DOI: 10.1042/BJ20081981
PMID: 19053945
Pubmed: https://pubmed.ncbi.nlm.nih.gov/19053945
Texto completo: https://portlandpress.com/biochemj/article-lookup/doi/10.1042/BJ20081981
Abstract:
The epimastigote stage of Trypanosoma cruzi undergoes PCD (programmed cell death) when exposed to FHS (fresh human serum). Although it has been known for over 30 years that complement is responsible for FHS-induced death, the link between complement activation and triggering of PCD has not been established. We have previously shown that the mitochondrion participates in the orchestration of PCD in this model. Several changes in mitochondrial function were described, and in particular it was shown that mitochondrion-derived O(2)(*-) (superoxide radical) is necessary for PCD. In the present study, we establish mitochondrial Ca(2+) overload as the link between complement deposition and the observed changes in mitochondrial physiology and the triggering of PCD. We show that complement activation ends with the assembly of the MAC (membrane attack complex), which allows influx of Ca(2+) and release of respiratory substrates to the medium. Direct consequences of these events are accumulation of Ca(2+) in the mitochondrion and decrease in cell respiration. Mitochondrial Ca(2+) causes partial dissipation of the inner membrane potential and consequent mitochondrial uncoupling. Moreover, we provide evidence that mitochondrial Ca(2+) overload is responsible for the increased O(2)(*-) production, and that if cytosolic Ca(2+) rise is not accompanied by the accumulation of the cation in the mitochondrion and consequent production of O(2)(*-), epimastigotes die by necrosis instead of PCD. Thus our results suggest a model in which MAC assembly on the parasite surface allows Ca(2+) entry and its accumulation in the mitochondrion, leading to O(2)(*-) production, which in turn constitutes a PCD signal.
Prepubertal estrogen exposure modifies neurotrophin receptor expression in celiac neurons and alters ovarian innervation
Auton Neurosci 2009 Jan 28;145(1-2):35-43
Gabriel Anesetti 1, Paula Lombide 1 2, Rebeca Chávez-Genaro 1
1 Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, General Flores 2125, CP 11800, Uruguay 2 Departamento de Morfología y Desarrollo, Facultad de Veterinaria, Lasplaces 1550, CP 11600, Universidad de la República, Montevideo, Uruguay
DOI: 10.1016/j.autneu.2008.10.021
PMID: 19036644
Pubmed: https://pubmed.ncbi.nlm.nih.gov/19036644
Texto completo: https://linkinghub.elsevier.com/retrieve/pii/S1566-0702(08)00195-1
Abstract:
Estradiol is a key hormone in the regulation of reproductive processes acting both on peripheral organs and sympathetic neurons associated to reproductive function. However, many of its regulatory effects on the development and function on the sympathetic neurons have not been completely clarified. Sympathetic neurons located in the celiac ganglion projects to visceral, vascular and glandular targets, and contribute to ovarian innervation, being the main source of sympathetic fibers. In the present study, we analyze the effects of elevated levels of exogenous estrogen during the prepubertal period in post-ganglionic sympathetic neurons. Estrogen exposure induced a significant increase in sympathetic celiac neuronal size and modified the expression of neurotrophin receptor p75. This change affected mainly small and medium size neurons. The effect of estrogens on innervation of celiac target organs was heterogeneous, inducing a significant increase in catecholaminergic innervation of the ovary, but not of the pyloric muscular layers. These findings further support the role of estrogen as a modulator of neuronal plasticity and suggest that estrogen could modify some features involved in the relation between sympathetic immature peripheral neurons and their target organs throughout a neurotrophin-dependent mechanism.