Long-term antidepressant administration alters corticotropin-releasing hormone, tyrosine hydroxylase, and mineralocorticoid receptor gene expression in rat brain. Therapeutic implications (original) (raw)
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Brain Research, 2008
Although glucocorticoid feedback sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis is frequently impaired in depression, atypical depression may exhibit increased feedback sensitivity. Because monoamine oxidase inhibitors (MAOI) are often more effective than tricyclic antidepressants (TCA) for atypical depression, we hypothesized that to normalize HPA function in atypical depression, MAOI would differ from TCA in decreasing rather than increasing feedback sensitivity. Consistent with this hypothesis and prior evidence for opposing effects on HPA feedback in mice, we report contrasting effects of chronic MAOI (phenelzine) and TCA (imipramine) treatment on neural corticosteroid receptor gene expression in adrenalectomized male C57BL/6 mice with fixed glucocorticoid levels. Our findings corroborate prior reports of antidepressant-induced increases in hippocampal mineralocorticoid (MR) and glucocorticoid receptor (GR) expression.
Identification of Hypothalamic Transcripts Upregulated by Antidepressants
Biochemical and Biophysical Research Communications, 1996
Identification of quantitative changes in gene expression that occur in the brain after antidepressant treatment can yield novel molecular markers that may be useful in the diagnosis and treatment of major depression. Using a modification of the differential display polymerase chain reaction, we describe the isolation of two transcripts that are differentially expressed in the brain after an 8-week course of antidepressant administration, compared to saline-treated control animals. ᭧ 1996 Academic Press, Inc.
2009
The hypercortisolism of melancholic depression is thought to reflect hypothalamic hypersecretion of CRH and may be related to the hyperarousal associated with this syndrome. Although chronic administration of imipramine to experimental animals significantly decreases CRH messenger RNA levels in the paraventricular nucleus, it is generally thought that resolution of hypercortisolism following recovery from depression is related to the improvement in mood and decrease in anxiety that accompanies recovery rather than an intrinsic effect of imipramine. The present study was designed to explore whether chronic imipramine administration to healthy, nondepressed volunteers is associated with effects on hypothalamic-pitu-
The International Journal of Neuropsychopharmacology, 1999
The effect of antidepressants is the culmination of a series of molecular actions occurring in the brain. These events are thought to lead to changes in the expression level of numerous, but as yet unknown genes that result in different cellular functions. In our present study we addressed this issue by establishing gene expression profiles of the rat brain after treatment with imipramine and citalopram at therapeutic doses. After 96 h and 4 wk, fronto-temporal cortices from controls and each treated strain were prepared and total RNA was isolated, and assessed using a cDNA microarray system containing 3200 clones. The expression of 6 genes was decreased and 8 were over-expressed by imipramine, whereas 27 were repressed and 7 were up-regulated by citalopram. Members of signal transduction (e.g. phosphatidylinositol transfer protein), structural elements (e.g. tubulin, fibronectin), factors related to protein metabolism in general (e.g. proteasomal subunits, ubiquitin-like proteins, polyadenylation sites), components involved in cell survival (e.g. midkine, stress-inducible protein), and determinants of membrane conductance and ion transport (e.g. vacuolar H + -ATPase), and basics of nuclear functions (e.g. translin, basal transcription factor 3), were some of the genes with altered expression. These data demonstrate that antidepressants interfere with the expression of a large array of genes involved in signalling, survival and protein metabolism. Our results demonstrate for the first time that antidepressants specifically regulate neuronal plasticity through induction of a highly specific transcriptional programme in brain cells.
European Journal of Pharmacology, 2013
To gain insight into the possible immune targets of antidepressant, we evaluated the expression of several inflammatory mediators in the hypothalamus of rats chronically (28 days) treated with the serotonin selective reuptake inhibitor fluoxetine (5 mg/kg, i.p.) or the tricyclic compound imipramine (15 mg/kg, i.p.). We focused our attention on the hypothalamus as it plays a key role in determining many of the somatic symptoms experienced by depressed patients. This brain region, critical also for expression of motivated behaviours, participates in the control of the hypothalamic-pituitary-adrenal axis activity and in stress response as well as coordinates physiological functions such as sleep and food intake that have been found altered in a high percentage of depressed patients. Notably, hypothalamus is a key structure for brain cytokine expression and function as it integrates signals from the neuro, immune, endocrine systems. By means of quantitative Real Time PCR experiments we demonstrated that a chronic treatment with either fluoxetine or imipramine resulted in a reduction of IL-6 and IFN-γ mRNAs and increased IL-4 mRNA expression in the rat hypothalamus. Moreover, we demonstrated that hypothalamic expression of members of IL-18 system was differentially affected by chronic antidepressant treatments. Chronically administered fluoxetine decreased IL-8 and CX3CL1 hypothalamic expression, while a chronic treatment with imipramine decreased p11 mRNA. Our data suggest that a shift in the balance of the inflammation toward an anti-inflammatory state in the hypothalamus may represent a common mechanism of action of both the chronic treatments with fluoxetine and imipramine.
Endocrinology, 2004
Abnormal hypothalamic-pituitary-adrenocortical (HPA) activity may provide clues to the neurochemistry of depression. Psychotic depression has one of the highest rates of elevated HPA activity and is most often responsive to the tricyclic class of antidepressants. Because successful treatment resolves HPA as well as psychiatric symptoms, we hypothesized, in light of evidence that tricyclic antidepressants can affect glucocorticoid receptor function, that these drugs would mimic glucocorticoid feedback inhibition of HPA activity. To test this hypothesis, we measured circadian nadir (morning) and peak (evening) as well as restraint stress-induced levels of plasma ACTH and corticosterone in adrenalectomized (ADX) and sham-ADX (Sham) male C57BL/6 mice after 8 wk of imipramine (20 mg/kg/d, ip) or saline treatment. Antidepressant efficacy was confirmed by decreased immobility in forcedswim testing. When glucocorticoids were low or absent, imip
Antidepressants and their neuroendocrine mechanisms in depression
Previously, we have shown that in vitro antidepressants modulate glucocorticoid receptor (GR) function and expression, and have suggested that these effects could be relevant for the mechanism of action of antidepressants. To further clarify the interaction between antidepressants and glucocorticoids, we evaluated the in vitro effect of the tricyclic antidepressant, clomipramine (CMI), on the GR function in 15 treatment-resistant depressed inpatients and 28 healthy controls. Diluted whole-blood cells were incubated for 24 h in the presence or absence of CMI (10 mM). Glucocorticoid function was measured by glucocorticoid inhibition of lypopolysaccharide (LPS)stimulated interleukin-6 (IL-6) levels. The results show that glucocorticoids (dexamethasone, prednisolone, cortisol and corticosterone) caused a concentration-dependent inhibition of LPS-stimulated IL-6 levels. In healthy controls, CMI decreased glucocorticoid inhibition of LPS-stimulated IL-6 levels, while this effect was not present in depressed patients. Therefore, depressed patients, who were clinically treatment resistant, also showed a lack of effect of the antidepressant in vitro. Upcoming studies shall test whether assessing the effects of antidepressants in vitro on GR function could predict future treatment response in a clinical setting.
Polish journal of …, 2002
In order to test if antidepressant drugs can directly influence corticotropin-releasing hormone (CRH) gene expression, their effect on CRH gene promoter activity was evaluated in neuro-2A cells stably transfected with a human CRH-chloramphenicol acetyltransferase plasmid. Forskolin (an activator of adenylate cyclase), but not phorbol 12-myristate 13-acetate (an activator of protein kinase C), ca. 3-fold increased reporter gene activity, which confirms the critical role of the cAMP-responsive element in regulation of the CRH gene. Imipramine and fluoxetine present in the medium for 5 days, in a concentration-dependent manner (3-30 mM) inhibited the basal activity of CRH gene promoter, while tianeptine was inactive. The obtained results indicate that inhibition of the human CRH gene promoter activity by imipramine and fluoxetine, but not tianeptine, may play a role in a mechanism by which the former drugs attenuate HPA axis activity.
Depression and antidepressants: molecular and cellular aspects
Cellular and Molecular Life Sciences, 2009
Clinical depression is viewed as a physical and psychic disease process having a neuropathological basis, although a clear understanding of its ethiopathology is still missing. The observation that depressive symptoms are influenced by pharmacological manipulation of monoamines led to the hypothesis that depression results from reduced availability or functional deficiency of monoaminergic transmitters in some cerebral regions. However, there are limitations to current monoamine theories related to mood disorders. Recently, a growing body of experimental data has showed that other classes of endogenous compounds, such as neuropeptides and amino acids, may play a significant role in the pathophysiology of affective disorders. With the development of neuroscience, neuronal networks and intracellular pathways have been identified and characterized, describing the existence of the interaction between monoamines and receptors in turn able to modulate the expression of intracellular proteins and neurotrophic factors, suggesting that depression/ antidepressants may be intermingled with neurogenesis/ neurodegenerative processes.