IGF-1 Receptor Antagonist JB-1 Research Articles

GPER and IGF-1R mediate the anti-inflammatory effect of genistein against lipopolysaccharide (LPS)-induced nigrostriatal injury in rats

Neuroinflammation plays an important role in the pathogenesis of Parkinson's disease (PD). Genistein is an estrogen-like phytoestrogen that can exert biological effects via the crosstalk of estrogen receptor and insulin-like growth factor 1 receptor (IGF-1R). The present study aimed to evaluate the involvement of G protein-coupled estrogen receptor (GPER) and IGF-1R in the anti-inflammatory effects of genistein against lipopolysaccharide (LPS)-induced nigrostriatal injury in ovariectomized rats. Our results showed that genistein treatment could ameliorate the apomorphine-induced rotational behavior in LPS-induced inflammatory PD rat model. Genistein attenuated LPS-induced decrease of the contents of dopamine (DA) and its metabolites in striatum as well as the loss of tyrosine hydroxylase-immunoreactive (TH-IR) neurons in the substantia nigra (SN) of the lesioned side, which could be blocked by GPER antagonist G15 or IGF-1R antagonist JB1. Meanwhile, G15 or JB1 could attenuate the anti-inflammatory effects of genistein in LPS-induced microglial activation and production of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, genistein could inhibit the LPS-induced phosphorylation of p38, JNK, ERK and IκB in the lesioned side of SN and these effects could also be blocked by G15 or JB1. Taken together, our data provide the first evidence that genistein can inhibit the increase of microglia and protect dopaminergic neurons at least in part via GPER and IGF-1R signaling pathways in ovariectomized PD rat model.

IGF-1 receptor is involved in the regulatory effects of icariin and icaritin in astrocytes under basal conditions and after an inflammatory challenge

Icariin and icaritin, the major active components of Epimedii Genus, are considered as promising drugs with anti-inflammatory, anti-aging and neuroprotective effects. Our previous studies have demonstrated that icariin and icaritin can protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)/1-methyl-4-phenylpyridinium (MPP+)-induced neurotoxicity on dopaminergic neurons via insulin-like growth factor-1 receptor (IGF-1 receptor) signaling. In the present study, we aimed to evaluate the role of IGF-1 receptor signaling in mediating the anti-inflammatory effects of icariin and icaritin against lipopolysaccharide (LPS)-induced neuroinflammation as well as their biological regulation effects in midbrain primary astrocytes. Our results showed that both icariin and icaritin significantly inhibited LPS-induced mRNA expressions of tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β). Pre-treatment with IGF-1 receptor antagonist JB-1 could significantly block the anti-inflammatory effects of icariin and icaritin on LPS-induced up-regulations of TNF-α, IL-1β, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Under basal conditions of astrocytes, icariin and icaritin treatment alone increased the phosphorylation of ERK1/2 and AKT, which could be blocked by JB-1. Moreover, the mRNA expressions of glutamate transptor-1 (GLT-1) and glutamate-aspartate transporter (GLAST) could be up-regulated by icariin and icaritin in a time-dependent manner via IGF-1 receptor. Taken together, our results suggest for the first time that both icariin and icaritin exert regulatory effects in astrocytes under basal conditions and after an inflammatory challenge via IGF-1 receptor signaling pathway.

Anti-inflammatory effect of IGF-1 is mediated by IGF-1R cross talk with GPER in MPTP/MPP+-induced astrocyte activation

Insulin-like growth factor-1 (IGF-1) is a potent neuroprotective polypeptide that exerts neuroprotective effects via the IGF-1 receptor (IGF-1R). Our previous study reported that G protein-coupled estrogen receptor (GPER) was involved in the anti-apoptotic effect of IGF-1. The present study was designed to investigate the anti-inflammatory effect of IGF-1 in association with astrocyte activation and the molecular details of the interaction between IGF-1R and GPER. We showed that IGF-1 could improve 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor deficits and attenuate the upregulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) both in vivo and in vitro. The IGF-1R antagonist JB-1 and the GPER antagonist G15 could antagonize the anti-inflammatory effect of IGF-1. Silencing GPER abrogated the inhibitory effect of IGF-1 on 1-methyl-4-phenylpyridinium (MPP+)-induced upregulation of COX-2 and iNOS in primary astrocytes. Moreover, the MPP + -induced inflammatory response was related to the activation of mitogen-activated protein kinases (MAPKs) and NF-κB signaling pathways. The inhibitory effects of IGF-1 on the phosphorylation of p38, JNK and IκB could be blocked by JB-1. G15 antagonized the inhibitory effects of IGF-1 on p-JNK and p-IκB, but not p-p38. Furthermore, IGF-1 treatment alone increased the expression of GPER, which was blocked by JB-1, the phosphatidylinositol 3-kinase (PI3–K) antagonist LY294002 and the MEK antagonist PD98059 in primary astrocytes. Overall, we show for the first time that GPER may contribute to the anti-inflammatory effect of IGF-1 against MPTP/MPP + -induced astrocyte activation. IGF-1 could regulate the expression of GPER via the IGF-1R/PI3-K/MAPK signaling pathway in primary astrocytes.

Antidepressant-like effects of insulin and IGF-1 are mediated by IGF-1 receptors in the brain

Depression is associated with uncontrolled diabetes, which indicates a lack of insulin effect, yet the role of the insulin receptor in mediating depression is not clearly established because insulin receptors are not required for glucose entry into the brain. However, insulin receptors are important for brain function since insulin receptor knockout mice have depressive-like activity. Depression and cognitive problems are also associated with low insulin-like growth factor-1 (IGF-1) in the elderly. Rodent studies showed chronic IGF-1 administration had antidepressant-like (AD) activity. We asked if insulin in the brain might act through the IGF-1 receptor, as it does in some tissues. We used acute insulin or IGF-1 infusions into the 3rd ventricle (icv) in rats and tested animals in a forced swim test. We found that antidepressive-like behavior is mediated by insulin and IGF-1. Further, administration of the IGF-1 receptor antagonist JB-1 blocked the antidepressive-like activity of the insulin and IGF-1, indicating a strong relationship between insulin, IGF-1 and depression. Insulin acts at least partially through the IGF-1 receptor and is responsive to receptor antagonism. The model offers promise for future studies of the mechanism of depression, and therapy to increase insulin sensitivity and IGF-1 action including exercise and nutrition.

IGFBP2 Produces Rapid-Acting and Long-Lasting Effects in Rat Models of Posttraumatic Stress Disorder via a Novel Mechanism Associated with Structural Plasticity.

Background:Posttraumatic stress disorder is an anxiety disorder characterized by deficits in the extinction of aversive memories. Insulin-like growth factor 1 (IGF1) is the only growth factor that has shown anxiolytic and antidepressant properties in human clinical trials. In animal studies, insulin-like growth factor binding protein 2 (IGFBP2) shows both IGF1-dependent and IGF1-independent pharmacological effects, and IGFBP2 expression is upregulated by rough-and-tumble play that induces resilience to stress.Methods:IGFBP2 was evaluated in Porsolt, contextual fear conditioning, and chronic unpredictable stress models of posttraumatic stress disorder. The dependence of IGFBP2 effects on IGF1- and AMPA-receptor activation was tested using selective receptor antagonists. Dendritic spine morphology was measured in the dentate gyrus and the medial prefrontal cortex 24 hours after in vivo dosing.Results:IGFBP2 was 100 times more potent than IGF1 in the Porsolt test. Unlike IGF1, effects of IGFBP2 were not blocked by the IGF1-receptor antagonist JB1, or by the AMPA-receptor antagonist 2,3-Dioxo-6-nitro-1,2,3,4 tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX) in the Porsolt test. IGFBP2 (1 µg/kg) and IGF1 (100 µg/kg i.v.) each facilitated contextual fear extinction and consolidation. Using a chronic unpredictable stress paradigm, IGFBP2 reversed stress-induced effects in the Porsolt, novelty-induced hypophagia, sucrose preference, and ultrasonic vocalization assays. IGFBP2 also increased mature dendritic spine densities in the medial prefrontal cortex and hippocampus 24 hours postdosing.Conclusions:These data suggest that IGFBP2 has therapeutic-like effects in multiple rat models of posttraumatic stress disorder via a novel IGF1 receptor-independent mechanism. These data also suggest that the long-lasting effects of IGFBP2 may be due to facilitation of structural plasticity at the dendritic spine level. IGFBP2 and mimetics may have therapeutic potential for the treatment of posttraumatic stress disorder.

Involvement of IGF-1 receptor signaling pathway in the neuroprotective effects of Icaritin against MPP+-induced toxicity in MES23.5 cells

Icaritin, a natural derivative of Icariin, is the major bioactive component of Epimedium Genus. The present study tested the hypothesis that the neuroprotective effects of Icaritin against 1-Methyl-4-phenylpyridinium ion (MPP+)-induced toxicity involved activation of the insulin-like growth factor-1 receptor (IGF-1R) signaling pathway in MES23.5 cells. Our results revealed that Icaritin pretreatment attenuated the MPP+-induced decrease of cell viability in a dose-dependent fashion. Co-pretreatment with phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002, mitogen-activated protein kinase (MEK) inhibitor PD98059 or IGF-1 receptor antagonist JB-1 could completely block the protective effects of Icaritin. Moreover, Icaritin pretreatment down-regulated MPP+-induced increase of Bax/Bcl-2 ratio transcriptionally and post-transcriptionally. Further study revealed that Icaritin pretreatment could restore the decreased protein expression of Akt and extracellular signal-regulated kinase 1/2 (ERK1/2) induced by MPP+ and these effects could be completely abolished by LY294002, PD98059 or JB-1. Additionally, Icaritin treatment alone time-dependently enhanced the phosphorylation of Akt and ERK1/2 in MES23.5 cells. The activation of Akt and ERK1/2 by Icaritin could be completely blocked by JB-1, LY294002 or PD98059. Taken together, our data demonstrate that IGF-1 receptor mediated activation of PI3K/Akt and MEK/ERK1/2 signaling pathways are involved in the protective effects of Icaritin against MPP+-induced toxicity in MES23.5 cells.

Early IGF-1 primes visual cortex maturation and accelerates developmental switch between NKCC1 and KCC2 chloride transporters in enriched animals

Environmental enrichment (EE) has a remarkable impact on brain development. Continuous exposure to EE from birth determines a significant acceleration of visual system maturation both at retinal and cortical levels. A pre-weaning enriched experience is sufficient to trigger the accelerated maturation of the visual system, suggesting that factors affected by EE during the first days of life might prime visual circuits towards a faster development. The search for such factors is crucial not only to gain a better understanding of the molecular hierarchy of brain development but also to identify molecular pathways amenable to be targeted to correct atypical brain developmental trajectories. Here, we showed that IGF-1 levels are increased in the visual cortex of EE rats as early as P6 and this is a crucial event for setting in motion the developmental program induced by EE. Early intracerebroventricular (i.c.v.) infusion of IGF-1 in standard rats was sufficient to mimic the action of EE on visual acuity development, whereas blocking IGF-1 signaling by i.c.v. injections of the IGF-1 receptor antagonist JB1 prevented the deployment of EE effects. Early IGF-1 decreased the ratio between the expression of NKCC1 and KCC2 cation/chloride transporters, and the reversal potential for GABAAR-driven Cl− currents (ECl) was shifted toward more negative potentials, indicating that IGF-1 is a crucial factor in accelerating the maturation of GABAergic neurotransmission and promoting the developmental switch of GABA polarity from excitation to inhibition. In addition, early IGF-1 promoted a later occurring increase in its own expression, suggesting a priming effect of early IGF-1 in driving post-weaning cortical maturation.

IGF-1 as an Important Endogenous Growth Factor for Recovery from Impaired Urethral Continence Function in Rats with Simulated Childbirth Injury

We examined the functional role of endogenous IGF-1 (insulin-like growth factor-1) in the recovery phase of stress urinary incontinence induced by simulated childbirth trauma using an IGF-1 receptor inhibitor. Simulated birth trauma was induced by vaginal distension in female Sprague Dawley® rats. The IGF-1 receptor antagonist JB-1 (10 and 100 μg/kg per day) or vehicle was continuously delivered from 1 day before vaginal distension for 7 days using subcutaneous osmotic pumps. Seven, 14 and 21 days after vaginal distension the effect of JB-1 treatment was examined by functional analyses, including leak point and urethral baseline pressure, and urethral responses during passive increments in intravesical pressure, as well as molecular analyses in urethral tissues, including phosphorylation of Akt, apoptotic changes and peripheral nerve density using Western blot and immunohistochemistry. On functional analyses vehicle treated rats with vaginal distension had significantly decreased leak point and urethral baseline pressure, and urethral responses at 7 days, which recovered to the normal level 14 and 21 days after vaginal distension. In the JB-1 treated vaginal distension group leak point and urethral baseline pressure, and urethral responses were still significantly reduced 21 days after vaginal distension. On molecular analyses JB-1 treatment increased apoptotic cells, induced a significant decrease in phosphorylated Akt and prolonged the decrease of peripheral nerve density in urethral tissues. Suppression of endogenous IGF-1 activity delayed recovery from stress urinary incontinence induced by simulated childbirth trauma in rats. Thus, IGF-1 is likely to be an important endogenous mediator for functional recovery from childbirth related stress urinary incontinence. This suggests that IGF-1 could be an effective target for treating stress urinary incontinence in women.

Galantamine promotes adult hippocampal neurogenesis via M₁ muscarinic and α7 nicotinic receptors in mice.

Galantamine, an inhibitor of acetylcholinesterase, promotes hippocampal neurogenesis, but the exact mechanism for this is not known. In the present study, we examined the mechanisms underlying the effects of acute galantamine on neurogenesis in the mouse hippocampus. Galantamine (3 mg/kg) increased the number of 5-bromo-2'-deoxyuridine (BrdU)-positive cells in the subgranular zone of the dentate gyrus. This effect was blocked by the muscarinic receptor antagonist scopolamine and the preferential M1 muscarinic receptor antagonist telenzepine, but not by the nicotinic receptor antagonists mecamylamine and methyllycaconitine. Galantamine did not alter the ratio of neuronal nuclei (NeuN)- or glial fibrillary acidic protein (GFAP)-positive cells to BrdU-labeled cells in the subgranular zone and granule cell layer. Galantamine (1, 3 mg/kg) promoted the survival of 2-wk-old newly divided cells in mice in the granule cell layer of the dentate gyrus, whereas it did not affect the survival of newly divided cells at 1 and 4 wk. Galantamine-induced increases in cell survival were blocked by the α7 nicotinic receptor antagonist methyllycaconitine, but not by scopolamine. Bilateral injection of recombinant IGF2 into the dentate gyrus of the hippocampus mimicked the effects of galantamine. The effects of galantamine were blocked by direct injection of the IGF1 receptor antagonist JB1. These findings suggest that galantamine promotes neurogenesis via activation of the M1 muscarinic and α7 nicotinic acetylcholine receptors. The present study also suggests that IGF2 is involved in the effects of galantamine on the survival of 2-wk-old immature cells in the granule cell layer.

IGF-1 restores visual cortex plasticity in adult life by reducing local GABA levels.

The central nervous system architecture is markedly modified by sensory experience during early life, but a decline of plasticity occurs with age. Recent studies have challenged this dogma providing evidence that both pharmacological treatments and paradigms based on the manipulation of environmental stimulation levels can be successfully employed as strategies for enhancing plasticity in the adult nervous system. Insulin-like growth factor 1 (IGF-1) is a peptide implicated in prenatal and postnatal phases of brain development such as neurogenesis, neuronal differentiation, synaptogenesis, and experience-dependent plasticity. Here, using the visual system as a paradigmatic model, we report that IGF-1 reactivates neural plasticity in the adult brain. Exogenous administration of IGF-1 in the adult visual cortex, indeed, restores the susceptibility of cortical neurons to monocular deprivation and promotes the recovery of normal visual functions in adult amblyopic animals. These effects were accompanied by a marked reduction of intracortical GABA levels. Moreover, we show that a transitory increase of IGF-1 expression is associated to the plasticity reinstatement induced by environmental enrichment (EE) and that blocking IGF-1 action by means of the IGF-1 receptor antagonist JB1 prevents EE effects on plasticity processes.

The Neurotoxic Effects of Estrogen on Ischemic Stroke in Older Female Rats Is Associated with Age-Dependent Loss of Insulin-Like Growth Factor-1

Hormone therapy to postmenopausal females increases the risk and severity of ischemic stroke. Our previous work using an animal model of menopause (reproductive senescence) shows that middle cerebral artery occlusion (MCAo) causes a larger cortical-striatal infarct in this older acyclic group compared with younger females. Moreover, although estrogen treatment is neuroprotective in younger females, estrogen paradoxically increases infarct volume in acyclic females. We hypothesized that the neurotoxic effects of estrogen in older females occurs because of decreased availability of IGF-1, a neuroprotectant that decreases with advancing age and is downregulated by estrogen treatment. Our data show that plasma IGF-1 levels are significantly reduced in reproductive senescent females and further reduced by estrogen at all ages. The neuroprotective effect of estrogen on MCAo-induced cortical infarct volume in mature adult female is reversed by intracerebroventricular injections of IGF-1 receptor antagonist JB-1. Similarly, estrogens neurotoxic effects on cortical infarct volume in senescent females is attenuated by concurrent IGF-1 treatment, and reversed when IGF-1 is infused 4 h after the onset of ischemia (delayed IGF-1 treatment). Delayed IGF-1/estrogen treatment also suppressed ischemia-induced ERK1 phosphorylation, reduced protein oxidation, and stimulated an early increase in prostaglandin E(2) at the infarct site. IGF-1 treatment was only protective in senescent females that received estrogen, indicating that the neuroprotective actions of this peptide require interaction with the steroid hormone receptor. These data support the hypothesis that stroke severity in older females is associated with decreased IGF-1 and further indicate that short-term postischemic IGF-1 therapy may be beneficial for stroke.

Setting the Pace for Retinal Development: Environmental Enrichment Acts Through Insulin-Like Growth Factor 1 and Brain-Derived Neurotrophic Factor

Environmental enrichment strongly affects visual system maturation both at retinal and cortical levels. Which molecular pathways are activated by an enriched environment (EE) to regulate visual system development has not been clarified. Here, we show that early [postnatal day 1 (P1) to P7] insulin-like growth factor 1 (IGF-1) injections in the eyes of non-EE rat pups mimic EE effects both in increasing BDNF levels in the retinal ganglion cell layer at P10 and in determining a more adult-like retinal acuity, assessed with pattern electroretinogram at P25. Blocking IGF-1 action in EE animals during the same early postnatal time window by injecting the IGF-1 receptor antagonist JB1 prevents EE effects both on BDNF expression and on retinal acuity maturation. Reducing BDNF expression in the retina of IGF-1-treated rats prevents IGF-1 effects on retinal acuity development. Finally, we show that tyrosine hydroxylase (TH) expression is increased in the retina of P10 EE and IGF-1-treated rats and that blocking TH expression in EE animals prevents EE from affecting retinal acuity development. Thus, early levels of IGF-1 play a key role in mediating EE effects on retinal development through an action that requires BDNF and involves dopaminergic amacrine cell network.

Mechanism involved in genistein activation of insulin-like growth factor 1 receptor expression in human breast cancer cells

Our previous studies have shown that genistein can enhance the insulin-like growth factor (IGF)-1 receptor signalling pathway via an oestrogen receptor (ER) in human breast cancer MCF-7 cells. The present study aims to investigate how genistein regulates IGF-1 receptor expression in human MCF-7 cells. Genistein at 1 microm stimulated the growth of MCF-7 cells and this effect could be completely blocked by the IGF-1 receptor antagonist JB-1, suggesting that IGF-1 receptor is essential for mediating the proliferative effects of genistein in MCF-7 cells. Genistein increased IGF-1 receptor promoter activity. This effect could be completely abolished by co-treatment of MCF-7 cells with ICI 182,780 (10- 6 m). Genistein increased IGF-1 receptor gene expression and this effect could be completely blocked by the IGF-1 receptor antagonist JB-1. Co-treatment of MCF-7 cells with cycloheximide (5 microg/ml) completely blocked the induction of IGF-1 receptor protein and mRNA expression by genistein. The results indicated that the induction of IGF-1 receptor promoter activity by genistein required the action of ER while the stimulatory actions of genistein on IGF-1 receptor expression required the activity of the IGF-1 receptor and de novo protein synthesis. These data provide evidence to support the hypothesis that the inductive effects of genistein on IGF-1 receptor expression require the cross-talk between IGF-1 receptor and the ER-dependent pathways.

Insulin-Like Growth Factor 1 (IGF-1) Mediates the Effects of Enriched Environment (EE) on Visual Cortical Development

Enriched environment (EE) has been recently shown to affect visual cortex development and plasticity, and to prevent dark rearing effects. The factors mediating EE effects on visual cortical development and plasticity are still unclear. We have investigated whether IGF-1 is involved in mediating EE effects on the developing visual cortex. We show that EE increases the number of IGF-1 positive neurons in the visual cortex at P18. Increasing IGF-1 in the visual cortex of non-EE rats by means of osmotic minipumps implanted at P18 mimics EE effects, accelerating visual acuity development, assessed with Visual Evoked Potentials (VEPs). Blocking IGF-1 action in the visual cortex of EE rats by means of the IGF-1 receptor antagonist JB1 from P18 completely blocks EE action on visual acuity development. These results show that IGF-1 is a key factor mediating EE effects on visual cortical development. We then show that IGF-1 affects GAD65 immunoreactivity in perisomatic innervation and the condensation of Chondroitin Sulphate Proteoglycans (CSPGs) in perineuronal nets (PNNs) in the visual cortex. This suggests that IGF-1 action in mediating EE effects could be exerted through the modulation of intracortical inhibitory circuitry and PNN development.