Monoaminergic regulation of Sonic hedgehog signaling cascade expression in the adult rat hippocampus

Article (PDF Available)inNeuroscience Letters 453(3):190-4 · May 2009with43 Reads
DOI: 10.1016/j.neulet.2009.02.034 · Source: PubMed
Abstract
Monoamines are implicated in the modulation of adult hippocampal neurogenesis in depression models and following chronic antidepressant treatment. Given the key role of Sonic hedgehog (Shh) in adult neurogenesis, we examined whether monoaminergic perturbations regulate the expression of Shh or its co-receptors Smoothened (Smo) and Patched (Ptc). Combined depletion of both serotonin and norepinephrine with para-chlorophenylalanine (PCPA) resulted in a significant decrease in Smo and Ptc mRNA within the dentate gyrus subfield of the hippocampus. However, selective depletion of serotonin, using the serotonergic neurotoxin 5,7-dihyrdroxytryptamine (5,7-DHT), or norepinephrine, using the noradrenergic neurotoxin DSP-4, did not alter expression of Shh and its co-receptors, Smo and Ptc. Acute treatment with the monoamine releasing agent, para-chloroamphetamine (PCA) significantly upregulated Smo mRNA within the dentate gyrus. However, acute or chronic treatment with pharmacological antidepressants that modulate monoaminergic neurotransmission did not regulate Shh cascade expression. These results indicate that robust changes in monoamine levels can regulate the expression of the Shh signaling cascade in the adult rodent brain.

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    • "For example, human keratinocytes from healthy controls and patients with bipolar depression have been reprogrammed into cortical neurons. When compared with control cells, neurons derived from patients with bipolar depression showed an alteration in the expression of transcripts that regulate Hedgehog signaling (Cheung et al. 2009), as well as modulations in key components of the mTOR pathway (O'Shea and McInnis 2015), which have both been shown to be among the mechanisms involved in the development of depressive disorders (Rajendran et al. 2009; Ignacio et al. 2015). Using iPSC-derived forebrain neurons, we showed that ketamine, known to have fast-acting antidepressant efficacy in treatment-resistant patients, was able to rescue the detrimental effects produced by treatment with IL-1? and to increase the number of presynaptic and postsynaptic proteins. "
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    • "These results thus indicate that robust changes in monoamine levels may be needed to alter the expression of the Shh signaling cascade in the adult rodent brain (Rajendran et al. 2009). Acute and chronic treatments with pharmacological antidepressants that modulate monoaminergic neurotransmission do not regulate Shh cascade expression (Rajendran et al. 2009). In contrast electroconvulsive seizures, a potent treatment for major depressive disorders, induce a rapid upregulation of the transcriptional target Ptc, but also a rapid and robust reduction in Smo transcription in the dentate gyrus (Banerjee et al. 2005). "
    [Show abstract] [Hide abstract] ABSTRACT: The discovery of a Sonic Hedgehog (Shh) signaling pathway in the mature vertebrate CNS has paved the way to the characterization of the functional roles of Shh signals in normal and diseased brain. Shh is proposed to participate in the establishment and maintenance of adult neurogenic niches and to regulate the proliferation of neuronal or glial precursors in several brain areas. Consistent with its role during brain development, misregulation of Shh signaling is associated with tumorigenesis while its recruitement in damaged neural tissue might be part of the regenerating process. This review focuses on the most recent data of the Hedgehog pathway in the adult brain and its relevance as a novel therapeutic approach for brain diseases including brain tumors.
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    • "More recently, Shh was found to be a crucial signal for adult neurogenesis, particularly in maintaining stem cell selfrenewal and acting as a mitogen in the SVZ and SGZ (Palma et al., 2005; Ahn and Joyner, 2005; Wang et al., 2007; Han et al., 2008). Changes in monoamine levels in vivo through chemical depletion have been shown to regulate the expression of the Shh signaling cascade in the adult rodent brain measured with in situ hybridization (Rajendran et al., 2009). The same group also reported that electroconvulsive seizures upregulated Shh signaling pathways at the mRNA level in the SGZ (Banerjee et al., 2005 ). "
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