David Epardo Argaiz

All Publications

• Growth hormone reduces retinal inflammation and preserves microglial morphology after optic nerve crush in male rats. Frontiers in cellular neuroscience Balderas-Márquez, J. E., Epardo, D., Siqueiros-Márquez, L., Carranza, M., Luna, M., Quintanar, J. L., Arámburo, C., Martínez-Moreno, C. G. 2025; 19: 1636399

  Abstract

  This study investigates the neuroprotective role of growth hormone (GH) in modulating retinal inflammation and microglial responses following optic nerve crush (ONC) in male rats.Retinal inflammation and microglial activation were assessed at 24 h and 14 days post-ONC, with or without GH treatment (0.5 mg/kg, subcutaneously, every 12 h). Gene and protein expression of inflammatory markers (e.g., IL-6, TNFα, Iba1, CD86, CD206) were evaluated using qPCR, ELISA, and Western blotting. Microglial morphology was quantified using skeleton and fractal analysis of Iba1-stained retinal sections. Retinal structure and function were assessed via fundus imaging and optomotor reflex testing.ONC induced significant increases in proinflammatory cytokines (IL-6, TNFα, IL-18) and microglial activation, characterized by reduced branching complexity and increased cell density. GH treatment significantly decreased proinflammatory cytokine levels, modulated microglial phenotype (CD86/CD206 expression), and preserved microglial morphology in the retina. Using the SIM-A9 microglial cell line, we further demonstrated that GH reduces NFκB pathway activation and suppresses LPS-induced proinflammatory cytokine production. At 14 days post-injury, GH-treated retinas exhibited reduced optic nerve size and improved optomotor responses, indicating both structural neuroprotection and functional recovery.Overall, GH mitigates ONC-induced retinal inflammation by reducing proinflammatory signaling and preserving microglial architecture, thereby protecting retinal integrity and function. These findings highlight the potential of GH as a therapeutic agent for retinal neurodegenerative conditions.

  View details for DOI 10.3389/fncel.2025.1636399

  View details for PubMedID 40980564

  View details for PubMedCentralID PMC12446313

• Neurotrophic Effects of GH and GnRH in a Full Sciatic Nerve Transection Model in Male Rats. Neuroendocrinology Baca-Alonso, J. J., Calderón-Vallejo, D., Hernández-Jasso, I., Epardo, D., Balderas-Márquez, J. E., Luna, M., Arámburo, C., Quintanar, J. L., Martínez-Moreno, C. G. 2025; 115 (6-7): 530-552

  Abstract

  Peripheral nerve injuries, such as sciatic nerve transection (SNT), are often associated with significant sensory and motor deficits. Growth hormone (GH) and gonadotropin-releasing hormone (GnRH) have been shown to exert neurotrophic effects that can promote nerve regeneration and functional reinnervation. However, the combined impact of these hormones on peripheral nerve repair remains poorly understood.This study aimed to analyze the individual and combined effects of GH and GnRH in a rat model of SNT, using orchiectomized male rats to prevent steroid-mediated neuroregeneration and neuroprotection. Treatments included GH, GnRH, or a combination of both, with subsequent assessments of motor and sensory function, as well as histological and molecular analyses of the nerve tissue and associated muscles.The results revealed that both GH and GnRH significantly enhanced nerve regeneration and neural function when administered individually. Treated animals exhibited improved axonal growth, myelination, and sensory and motor functional recovery. In addition, GH and GnRH reduced neuroinflammation/reactive gliosis, as evidenced by the downregulation of TNFα, IL-1β, Iba-1, and GFAP, which are typically elevated following nerve injury. These findings indicate that each hormone independently supports critical aspects of nerve repair and functional restoration after injury. Surprisingly, when GH and GnRH were administered together, their beneficial effects were not additive. Instead, the combination of the two treatments led to diminished outcomes in comparison to either treatment alone. Specifically, animals receiving the combined therapy showed reduced axonal organization, impaired myelination, and less functional improvement.GH and GnRH demonstrate considerable potential as individual therapeutic agents for promoting peripheral nerve regeneration, each providing significant benefits in terms of axonal growth, functional recovery, and reduction of neuroinflammation.

  View details for DOI 10.1159/000545129

  View details for PubMedID 40101695

  View details for PubMedCentralID PMC12060828

• Growth Hormone Neuroprotective Effects After an Optic Nerve Crush in the Male Rat. Investigative ophthalmology & visual science Epardo, D., Balderas-Márquez, J. E., Rodríguez-Arzate, C. A., Thébault, S. C., Carranza, M., Luna, M., Ávila-Mendoza, J., Calderón-Vallejo, D., Quintanar, J. L., Arámburo, C., Martínez-Moreno, C. G. 2024; 65 (13): 17

  Abstract

  Growth hormone (GH) has neuroprotective effects that have not been evaluated in the mammalian visual system. This study tested the hypothesis that GH administration can promote retinal neuroprotection in an optic nerve crush (ONC) model in male rats.The ON was compressed for 10 seconds, and bovine GH was injected concomitantly to injury for 14 days (0.5 µg/g every 12 hours). At 24 hours and 14 days after ONC, we evaluated the effects of GH upon several markers by quantitative PCR (qPCR), Western blot, and immunohistochemistry; the ON integrity was assessed using CTB Alexa 488 anterograde tracer, and retinal function was tested by full-field electroretinogram.GH partially prevented the ONC-induced death of retinal ganglion cells (RGCs), as well as the increase in gliosis marker GFAP at 14 days. Most of the ONC-induced changes in mRNA retinal levels of several neurotrophic, survival, synaptogenic, gliosis, and excitotoxicity markers were prevented by GH, both at 24 hours and 14 days, and treatment also stimulated the expression of antiapoptotic proteins Bcl-2 and Bcl-xL at 24 hours. Additionally, GH partially maintained the ON integrity and active anterograde transport, as well as retinal function by avoiding the reduced amplitude and slowing of the A- and B-waves and oscillatory potentials associated with the ONC at 14 days.GH has neuroprotective effects in the ONC model in male rats, it promoted RGC survival, gliosis reduction, and axonal transport increase, likely through the regulation of genes involved in neuroprotection, survival, and synaptogenesis. Furthermore, GH prevented functional impairment, indicating its potential as a therapeutic option for retinal neurodegenerative diseases.

  View details for DOI 10.1167/iovs.65.13.17

  View details for PubMedID 39504048

  View details for PubMedCentralID PMC11549927

• Neurotrophic and synaptic effects of GnRH and/or GH upon motor function after spinal cord injury in rats. Scientific reports Martínez-Moreno, C. G., Calderón-Vallejo, D., Díaz-Galindo, C., Hernández-Jasso, I., Olivares-Hernández, J. D., Ávila-Mendoza, J., Epardo, D., Balderas-Márquez, J. E., Urban-Sosa, V. A., Baltazar-Lara, R., Carranza, M., Luna, M., Arámburo, C., Quintanar, J. L. 2024; 14 (1): 26420

  Abstract

  Thoracic spinal cord injury (SCI) profoundly impairs motor and sensory functions, significantly reducing life quality without currently available effective treatments for neuroprotection or full functional regeneration. This study investigated the neurotrophic and synaptic recovery potential of gonadotropin-releasing hormone (GnRH) and growth hormone (GH) treatments in ovariectomized rats subjected to thoracic SCI. Employing a multidisciplinary approach, we evaluated the effects of these hormones upon gene expression of classical neurotrophins (NGF, BDNF, and NT3) as well as indicative markers of synaptic function (Nlgn1, Nxn1, SNAP25, SYP, and syntaxin-1), together with morphological assessments of myelin sheath integrity (Klüver-Barrera staining and MBP immunoreactivity) and synaptogenic proteins (PSD95, SYP) by immunohystochemistry (IHC) , and also on the neuromotor functional recovery of hindlimbs in the lesioned animals. Results demonstrated that chronic administration of GnRH and GH induced notable upregulation in the expression of several neurotrophic and synaptogenic activity genes. Additionally, the treatment showed a significant impact on the restoration of functional synaptic markers and myelin integrity. Intriguingly, while individual GnRH application induced certain recovery benefits, the combined treatment with GH appeared to inhibit neuromotor recovery, suggesting a complex interplay in hormonal regulation post-SCI. GnRH and GH are bioactive and participate in modulating neurotrophic responses and synaptic restoration under neural damage conditions, offering insights into novel therapeutic approaches for SCI. However, the intricate effects of combined hormonal treatment accentuate the necessity for further investigation that conduce to optimal and novel therapeutic strategies for patients with spinal cord lesions.

  View details for DOI 10.1038/s41598-024-78073-3

  View details for PubMedID 39488642

  View details for PubMedCentralID PMC11531546

• Gonadotropin-releasing hormone and growth hormone act as anti-inflammatory factors improving sensory recovery in female rats with thoracic spinal cord injury. Frontiers in neuroscience Martínez-Moreno, C. G., Calderón-Vallejo, D., Díaz-Galindo, C., Hernández-Jasso, I., Olivares-Hernández, J. D., Ávila-Mendoza, J., Epardo, D., Balderas-Márquez, J. E., Urban-Sosa, V. A., Baltazar-Lara, R., Carranza, M., Luna, M., Arámburo, C., Quintanar, J. L. 2023; 17: 1164044

  Abstract

  The potential for novel applications of classical hormones, such as gonadotropin-releasing hormone (GnRH) and growth hormone (GH), to counteract neural harm is based on their demonstrated neurotrophic effects in both in vitro and in vivo experimental models and a growing number of clinical trials. This study aimed to investigate the effects of chronic administration of GnRH and/or GH on the expression of several proinflammatory and glial activity markers in damaged neural tissues, as well as on sensory recovery, in animals submitted to thoracic spinal cord injury (SCI). Additionally, the effect of a combined GnRH + GH treatment was examined in comparison with single hormone administration. Spinal cord damage was induced by compression using catheter insufflation at thoracic vertebrae 10 (T10), resulting in significant motor and sensory deficits in the hindlimbs. Following SCI, treatments (GnRH, 60 μg/kg/12 h, IM; GH, 150 μg/kg/24 h, SC; the combination of both; or vehicle) were administered during either 3 or 5 weeks, beginning 24 h after injury onset and ending 24 h before sample collection. Our results indicate that a chronic treatment with GH and/or GnRH significantly reduced the expression of proinflammatory (IL6, IL1B, and iNOS) and glial activity (Iba1, CD86, CD206, vimentin, and GFAP) markers in the spinal cord tissue and improved sensory recovery in the lesioned animals. Furthermore, we found that the caudal section of the spinal cord was particularly responsive to GnRH or GH treatment, as well as to their combination. These findings provide evidence of an anti-inflammatory and glial-modulatory effect of GnRH and GH in an experimental model of SCI and suggest that these hormones can modulate the response of microglia, astrocytes, and infiltrated immune cells in the spinal cord tissue following injury.

  View details for DOI 10.3389/fnins.2023.1164044

  View details for PubMedID 37360158

  View details for PubMedCentralID PMC10288327

• Neuroprotective and Regenerative Effects of Growth Hormone (GH) in the Embryonic Chicken Cerebral Pallium Exposed to Hypoxic-Ischemic (HI) Injury. International journal of molecular sciences Olivares-Hernández, J. D., Carranza, M., Balderas-Márquez, J. E., Epardo, D., Baltazar-Lara, R., Ávila-Mendoza, J., Martínez-Moreno, C. G., Luna, M., Arámburo, C. 2022; 23 (16)

  Abstract

  Prenatal hypoxic−ischemic (HI) injury inflicts severe damage on the developing brain provoked by a pathophysiological response that leads to neural structural lesions, synaptic loss, and neuronal death, which may result in a high risk of permanent neurological deficits or even newborn decease. It is known that growth hormone (GH) can act as a neurotrophic factor inducing neuroprotection, neurite growth, and synaptogenesis after HI injury. In this study we used the chicken embryo to develop both in vitro and in vivo models of prenatal HI injury in the cerebral pallium, which is the equivalent of brain cortex in mammals, to examine whether GH exerts neuroprotective and regenerative effects in this tissue and the putative mechanisms involved in these actions. For the in vitro experiments, pallial cell cultures obtained from chick embryos were incubated under HI conditions (<5% O2, 1 g/L glucose) for 24 h and treated with 10 nM GH, and then collected for analysis. For the in vivo experiments, chicken embryos (ED14) were injected in ovo with GH (2.25 µg), exposed to hypoxia (12% O2) for 6 h, and later the pallial tissue was obtained to perform the studies. Results show that GH exerted a clear anti-apoptotic effect and promoted cell survival and proliferation in HI-injured pallial neurons, in both in vitro and in vivo models. Neuroprotective actions of GH were associated with the activation of ERK1/2 and Bcl-2 signaling pathways. Remarkably, GH protected mature neurons that were particularly harmed by HI injury, but was also capable of stimulating neural precursors. In addition, GH stimulated restorative processes such as the number and length of neurite outgrowth and branching in HI-injured pallial neurons, and these effects were blocked by a specific GH antibody, thus indicating a direct action of GH. Furthermore, it was found that the local expression of several synaptogenic markers (NRXN1, NRXN3, GAP-43, and NLG1) and neurotrophic factors (GH, BDNF, NT-3, IGF-1, and BMP4) were increased after GH treatment during HI damage. Together, these results provide novel evidence supporting that GH exerts protective and restorative effects in brain pallium during prenatal HI injury, and these actions could be the result of a joint effect between GH and endogenous neurotrophic factors. Also, they encourage further research on the potential role of GH as a therapeutic complement in HI encephalopathy treatments.

  View details for DOI 10.3390/ijms23169054

  View details for PubMedID 36012320

  View details for PubMedCentralID PMC9409292

• Growth Hormone Neuroprotection Against Kainate Excitotoxicity in the Retina is Mediated by Notch/PTEN/Akt Signaling. Investigative ophthalmology & visual science Fleming, T., Balderas-Márquez, J. E., Epardo, D., Ávila-Mendoza, J., Carranza, M., Luna, M., Harvey, S., Arámburo, C., Martínez-Moreno, C. G. 2019; 60 (14): 4532-4547

  Abstract

  In the retina, growth hormone (GH) promotes axonal growth, synaptic restoration, and protective actions against excitotoxicity. Notch signaling pathway is critical for neural development and participates in the retinal neuroregenerative process. We investigated the interaction of GH with Notch signaling pathway during its neuroprotective effect against excitotoxic damage in the chicken retina.Kainate (KA) was used as excitotoxic agent and changes in the mRNA expression of several signaling markers were determined by qPCR. Also, changes in phosphorylation and immunoreactivity were determined by Western blotting. Histology and immunohistochemistry were performed for morphometric analysis. Overexpression of GH was performed in the quail neuroretinal-derived immortalized cell line (QNR/D) cell line. Exogenous GH was administered to retinal primary cell cultures to study the activation of signaling pathways.KA disrupted the retinal cytoarchitecture and induced significant cell loss in several retinal layers, but the coaddition of GH effectively prevented these adverse effects. We showed that GH upregulates the Notch signaling pathway during neuroprotection leading to phosphorylation of the PI3K/Akt signaling pathways through downregulation of PTEN. In contrast, cotreatment of GH with the Notch signaling inhibitor, DAPT, prevented its neuroprotective effect against KA. We identified binding sites in Notch1 and Notch2 genes for STAT5. Also, GH prevented Müller cell transdifferentiation and downregulated Sox2, FGF2, and PCNA after cotreatment with KA. Additionally, GH modified TNF receptors immunoreactivity suggesting anti-inflammatory actions.Our data indicate that the neuroprotective effects of GH against KA injury in the retina are mediated through the regulation of Notch signaling. Additionally, anti-inflammatory and antiproliferative effects were observed.

  View details for DOI 10.1167/iovs.19-27473

  View details for PubMedID 31675424

• Regenerative Effect of Growth Hormone (GH) in the Retina after Kainic Acid Excitotoxic Damage. International journal of molecular sciences Martinez-Moreno, C. G., Epardo, D., Balderas-Márquez, J. E., Fleming, T., Carranza, M., Luna, M., Harvey, S., Arámburo, C. 2019; 20 (18)

  Abstract

  In addition to its role as an endocrine messenger, growth hormone (GH) also acts as a neurotrophic factor in the central nervous system (CNS), whose effects are involved in neuroprotection, axonal growth, and synaptogenic modulation. An increasing amount of clinical evidence shows a beneficial effect of GH treatment in patients with brain trauma, stroke, spinal cord injury, impaired cognitive function, and neurodegenerative processes. In response to injury, Müller cells transdifferentiate into neural progenitors and proliferate, which constitutes an early regenerative process in the chicken retina. In this work, we studied the long-term protective effect of GH after causing severe excitotoxic damage in the retina. Thus, an acute neural injury was induced via the intravitreal injection of kainic acid (KA, 20 µg), which was followed by chronic administration of GH (10 injections [300 ng] over 21 days). Damage provoked a severe disruption of several retinal layers. However, in KA-damaged retinas treated with GH, we observed a significant restoration of the inner plexiform layer (IPL, 2.4-fold) and inner nuclear layer (INL, 1.5-fold) thickness and a general improvement of the retinal structure. In addition, we also observed an increase in the expression of several genes involved in important regenerative pathways, including: synaptogenic markers (DLG1, NRXN1, GAP43); glutamate receptor subunits (NR1 and GRIK4); pro-survival factors (BDNF, Bcl-2 and TNF-R2); and Notch signaling proteins (Notch1 and Hes5). Interestingly, Müller cell transdifferentiation markers (Sox2 and FGF2) were upregulated by this long-term chronic GH treatment. These results are consistent with a significant increase in the number of BrdU-positive cells observed in the KA-damaged retina, which was induced by GH administration. Our data suggest that GH is able to facilitate the early proliferative response of the injured retina and enhance the regeneration of neurite interconnections.

  View details for DOI 10.3390/ijms20184433

  View details for PubMedID 31509934

  View details for PubMedCentralID PMC6770150