Glucocorticoids and corticotropin-releasing hormone (CRH) are key regulators of stress responses. Different types of stress activate the CRH system; in hypothalamus, CRH expression and release are increased by physical or psychological stressors while in amygdala, preferentially by psychological stress. Learning and memory processes are modulated by glucocorticoids and stress at different levels. To characterize the kind of stress provoked by a hippocampal-dependent task such as spatial learning, we compared the expression profile of glucocorticoid receptor (GR), pro-CRH and CRH-R1 mRNAs (analyzed by RT-PCR), in amygdala, hippocampus and hypothalamus and quantified serum corticosterone levels by radioimmunoassay at different stages of training. mRNA levels of brain-derived neurotrophic factor (BDNF) were also quantified due to its prominent role in learning and memory processes. Male Wistar rats trained for 1, 3 or 5 days in the Morris water-maze (10 trials/day) were sacrificed 5–60 min the after last trial. A strong stress response occurred at day one in both yoked and trained animals (increased corticosterone and hypothalamic pro-CRH and CRH-R1 mRNA levels); changes gradually diminished as the test progressed. In amygdala, pro-CRH mRNA levels decreased while those of BDNF augmented when stress was highest, in yoked and trained animals. Hippocampi, of both yoked and trained groups, had decreased levels of GR mRNA on days 1 and 3, normalizing by day 5, while those of pro-CRH and CRH-R1 increased after the 3rd day. Increased gene expression, specifically due to spatial learning, occurred only for hippocampal BDNF since day 3. These results show that the Morris water-maze paradigm induces a strong stress response that is gradually attenuated. Inhibition of CRH expression in amygdala suggests that the stress inflicted is of physical but not of psychological nature and could lead to reduced fear or anxiety.

Sandi C: Stress, cognitive impairment and cell adhesion molecules. Nat Rev Neurosci 2004;5:917–930.
Roozendaal B: Systems mediating acute glucocorticoid effects on memory consolidation and retrieval. Prog Neuropsychopharmacol Biol Psychiatry 2003;27:1213–1223.
Conrad CD, Lupien SJ, McEwen BS: Support for a bimodal role for type II adrenal steroid receptors in spatial memory. Neurobiol Learn Mem 1999;72:39–46.
Sapolsky RM: Stress and plasticity in the limbic system. Neurochem Res 2003;28:1735–1742.
Oitzl MS, Reichardt HM, Joëls M, de Kloet ER: Point mutation in the mouse glucocorticoid receptor preventing DNA binding impairs spatial memory. Proc Natl Acad Sci USA 2001;98:12790–12795.
Turnbull AV, Rivier C: Corticotropin-releasing factor and endocrine responses to stress: CRF receptors, binding protein, and related peptides. Proc Soc Exp Biol Med 1997;215:1–10.
Imaki, J, Onodera H, Demura H, Vale W: Corticotropin-releasing factor up-regulates its own receptor mRNA in the paraventricular nucleus of the hypothalamus. Mol Brain Res 1996;38:166–170.
Herman P, Ostrander MM, Mueller NK, Figuereido H: Limbic system mechanisms of stress regulation: hypothalamo-pituitary-adrenocortical axis. Progr Neuropsychopharmacol Biol Psychiatr 2005;29:1201–1213.
Sawchenko PE, Brown ER, Kovacs KJ: The paraventricular nucleus of hypothalamus and the functional neuroanatomy of visceromotor responses to stress. Prog Brain Res 1996;107:201–222.
Heinrichs SC, Koob, GF: Corticotropin-releasing factor in brain: a role in activation, arousal and affect regulation. J Pharmacol Exp Ther 2004;311:427–440.
Steckler T, Holsboer F: Corticotropin-releasing hormone receptor subtypes and emotion. Biol Psychiatr 1999;46:1480–1508.
Makino S, Hashimoto K, Gold PW: Multiple feedback mechanisms activating corticotropin-releasing hormone mRNA systems in the brain during stress. Pharmacol Biochem Behav 2002;73:147–158.
Schulkin J, Morgan MA, Rosen JB: A neuroendocrine mechanism for sustaining fear. Trends Neurosci 2005;28:629–635.
Givalois L, Arancibia S, Tapia-Arancibia L: Concomitant changes in CRH mRNA levels in rat hippocampus and hypothalamus following immobilization stress. Brain Res Mol Brain Res 2000;75:166–171.
Lee EH, Huang AM, Tsuei KS, Lee WY: Enhanced hippocampal corticotropin-releasing factor gene expression associated with memory consolidation and memory storage in rats. Chin J Physiol 1996;39:197–203.
Blank T, Nijholt I, Eckart K, Spiess J: Priming of long-term potentiation in mouse hippocampus by corticotropin-releasing factor and acute stress: implications for hippocampus-dependent learning. J Neurosci 2002;22:3788–3794.
Radulovic J, Rühmann A, Liepold T, Spiess J: Modulation of learning and anxiety by corticotropin-releasing factor (CRF) and stress: differential roles of CRF receptors 1 and 2. J Neurosci 1999;19:5016–5025.
Morris R: Developments of a water-maze procedure for studying spatial learning in the rat. J Neurosci Meth 1984;11:47–60.
Schaaf MJ, Sibug RM, Duurland R, Fluttert MF, Oitzl MS, De Kloet ER, Vreugdenhil E: Corticosterone effects on BDNF expression in the hippocampus. Implications on memory formation. Stress 2000;3:201–208.
Ramírez-Amaya V, Balderas I, Sandoval J, Escobar ML, Bermúdez-Rattoni F: Spatial long-term memory is related to mossy fiber synaptogenesis. J Neurosci 2001;21:7340–7348.
Yamada K, Nabeshima T: Brain-derived neurotrophic factor/TrkB signaling in memory processes. J Pharmacol Sci 2003;91:267–270.
Kesslak JP, So V, Choi J, Cotman CW, Gómez-Pinilla F: Learning upregulates brain-derived neurotrophic factor messenger ribonucleic acid: a mechanism to facilitate encoding and circuit maintenance? Behav Neurosci 1998;112:1012–1019.
Paxinos G, Watson C: The Rat Brain in Stereotaxic Coordinates, ed 2. Orlando, Academic Press, 1986.
Chomczynski P, Sacchi N: Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem 1987;162:156–159.
Pérez-Martínez L, Carreón-Rodríguez A, González-Alzati ME, Morales C, Charli JL, Joseph-Bravo P: Dexamethasone rapidly regulates TRH mRNA levels in hypothalamic cell cultures: interaction with the cAMP pathway. Neuroendocrinology 1998;68:345–354.
Timmusk T, Persson H, Metsis M: Analysis of transcriptional initiation and translatability of brain-derived neurotrophic factor mRNAs in the rat brain. Neurosci Lett 1994;177:27–31.
Perrin MH, Donaldson CJ, Chen R, Lewis KA, Vale WW: Cloning and functional expression of a rat brain corticotropin releasing factor receptor. Endocrinology 1993;133:3058–3061.
Danielson PE, Forss-Petter S, Brow MA, Calaveta L, Douglass J, Milner RJ, Sutcliffe JG: p1B15: a cDNA clone of the rat mRNA encoding cyclophilin. DNA 1988;7:261–267.
Tso JY, Sun XH, Kao TH, Reece KS, Wu R: Isolation and characterization of rat and human glyceraldehyde-3-phosphate dehydrogenase cDNAs: genomic complexity and molecular evolution of the gene. Nucleic Acids Res 1985;13:2485–2502.
Miesfeld R, Rusconi S, Godowski PJ, Maler BA, Okret S, Wikstrom AC, Gustafsson JA, Yamamoto KR: Genetic complementation of a glucocorticoid receptor deficiency by expression of cloned receptor cDNA. Cell 1986;46:389–399.
Jingami H, Mizuno N, Takahashi H, Shibahara S, Furutani Y, Imura H, Numa S: Cloning and sequence analysis of cDNA for rat corticotropin-releasing factor precursor. FEBS Lett 1985;191:63–66.
De Gortari P, Uribe RM, García-Vázquez A, Aguilar-Valles A, Martínez M, Valdés A, Charli JL, Fernández-Guardiola F, Joseph-Bravo P: Amygdala kindling differentially regulates the expression of the elements involved in TRH transmission. Neurochem Int 2006;48:31–42
Parkes D, Rivest S, Lee S, Rivier C, Vale W: Corticotropin-releasing factor activates c-fos, NGFI-B, and corticotropin-releasing factor gene expression within the paraventricular nucleus of the rat hypothalamus. Mol Endocrinol 1993;7:1357–1367.
Sánchez E, Charli JL, Morales C, Corkidi G, Seidah NG, Joseph-Bravo P, Uribe RM: Expression of the proprotein convertases PC1 and PC2 mRNAs in thyrotropin-releasing hormone neurons of the rat paraventricular nucleus of hypothalamus. Brain Res 1997;76:77–86.
Kalsbeek A, van Heerikhuize JJ, Wortel J, Buijs RM: A diurnal rhythm of stimulatory input to the hypothalamo-pituitary-adrenal system as revealed by timed intrahypothalamic administration of the vasopressin V1 antagonist. J Neurosci 1996;16:5555–5565.
Watts AG: Glucocorticoid regulation of peptide genes in neuroendocrine CRH neurons: a complexity beyond negative feedback. Front Neuroendocrinol 2005;26:109–130.
Cote-Vélez A, Pérez-Martínez L, Díaz-Gallardo M, Pérez-Monter C, Carreón A, Charli JL, Joseph-Bravo P: Dexamethasone repressed cAMP rapid upregulation of TRH gene transcription. Identification of a composite GRE and a CRE in TRH promoter. J Mol Endocrinol 2005;34:177–197.
Herman JP, Adams D, Prewitt C: Regulatory changes in neuroendocrine states. Integrative circuitry produced by a variable stress paradigm. Neuroendocrinology 1995;61:180–190.
Fernandes GA, Perks P, Cox NKM, Lightman SL, Ingram CD, Shanks N: Habituation and cross-sensitization of stress induced hypothalamic-pituitary-adrenal activity: effects of lesions in the paraventricular nucleus of the thalamus or bed nuclei of the stria terminalis. J Neuroendocrinol 2002;14:593–602.
Tapia-Arancibia L, Rage F, Givalois L, Arancibia S: Physiology of BDNF: focus on hypothalamic function. Front Neuroendocrinol 2004;25:77–107.
McGaugh JL: Memory consolidation and the amygdala: a systems perspective. Trends Neurosci 2002;25:456–461.
Kim JJ, Koo JW, Lee HJ, Han JS: Amygdalar inactivation blocks stress-induced impairments in hippocampal long-term potentiation and spatial memory. J Neurosci 2005;25:1532–1539.
Kavushansky A, Vouimba RM, Cohen H, Richter-Levin G: Activity and plasticity in the CA1, dentate gyrus, and the amygdala following controllable vs. uncontrollable water stress. Hippocampus 2006;16:35–42.
Merali Z, Michaud D, McIntosh J, Kent P, Anisman H: Differential involvement of amygdaloid CRH system(s) in the salience and valence of the stimuli. Prog Neuropsychopharmacol Biol Psychiatry 2003;27:1201–1212.
Rattiner LM, Davis M, Ressler KJ: Brain-derived neurotrophic factor in amygdala dependent learning. Neuroscientist 2005;11:323–333.
Conner JM, Lauterborn JC, Yan Q, Gall CM, Varon S: Distribution of brain-derived neurotrophic factor protein and mRNA in the normal adult rat CNS: evidence for anterograde axonal transport. J Neurosci 1997;17:2295–2313.
Koponen E, Voikar V, Riekki R, Saarelainen T, Rauramaa T, Rauvala H, Taira T, Castren E: Transgenic mice overexpressing the full-length neurotrophin receptor TrkB exhibit increased activation of the TrkB-PLC-γ pathway, reduced anxiety, and facilitated learning. Mol Cell Neurosci 2004;26:166–181.
Bannerman DM, Grubb M, Deacon RM, Yee BK, Feldon J, Rawlins JN: Ventral hippocampal lesions affect anxiety but not spatial learning. Behav Brain Res 2003;139:197–213.
Paskitti ME, Creary BJ, Hermann JP: Stress regulation of adrenocorticosteroid receptor gene transcription and mRNA expression in rat hippocampus: time-course analysis. Mol Brain Res 2000;80:142–152.
Fujikawa T, Soya H, Fukuoka H, Alam KS, Yoshizato H, McEwen BS, Nakashima K: A biphasic regulation of receptor mRNA expressions for growth hormone, glucocorticoid and mineralocorticoid in the rat dentate gyrus during acute stress. Brain Res 2000;874:186–193.
Tritos N, Kitraki E, Philippidis H, Stylianopoulou F: Neurotransmitter modulation of glucocorticoid receptor mRNA levels in the rat hippocampus. Neuroendocrinology 1999;69:324–330.
Hogan JB, Hodges DB Jr, Lelas S, Gilligan PJ, McElroy JF, Lindner MD: Effects of CRF1 receptor antagonists and benzodiazepines in the Morris water maze and delayed non-matching to position tests. Psychopharmacology 2005;178:410–419.
Van Gaalen MM, Stenzel-Poore M, Holsboer F, Steckler T: Reduced attention in mice overproducing corticotropin-releasing hormone. Behav Brain Res 2003;142:69–79.
Smith MA, Weiss SR, Berry RL, Zhang LX, Clark M, Massenburg G, Post RM: Amygdala-kindled seizures increase the expression of corticotropin-releasing factor (CRF) and CRF-binding protein in GABAergic interneurons of the dentate hilus. Brain Res 1997;745:248–256.
Brunson KL, Grigoriadis DE, Lorang MT, Baram TZ: Corticotropin-releasing hormone (CRH) downregulates the function of its receptor (CRF1) and induces CRF1 expression in hippocampal and cortical regions of immature rat brain. Exp Neurol 2002;176:75–86.
Bannerman DM, Rawlins JN, McHugh SB, Deacon RM, Yee BK, Bast T, Zhang WN, Pothuizen HH, Feldon J: Regional dissociations within the hippocampus-memory and anxiety. Neurosci Biobehav Rev 2004;28:273–283.
Vaidya VAA, Marek GJ, Aghajanian GK, Duman RS: 5-HT2A receptor-mediated regulation of brain-derived neurotrophic factor mRNA in the hippocampus and neocortex. J Neurosci 1997;17:2785–2795.
Cotman CW, Berchtold NC: Exercise: a behavioral intervention to enhance brain health and plasticity. Trends Neurosci 2002;25:295–301.
Marmigère F, Givalois L, Rage F, Arancibia S, Tapia-Arancibia S: Rapid induction of BDNF expression in the hippocampus during immobilization stress challenge in adult rats. Hippocampus 2003;13:646–655.
Moser E, Moser MB, Andersen P: Spatial learning impairment parallels the magnitude of dorsal hippocampal lesions, but is hardly present following ventral lesions. J Neurosci 1993;13:3916–3925.
De Hoz L, Knox J, Morris RG: Longitudinal axis of the hippocampus: both septal and temporal poles of the hippocampus support water maze spatial learning depending on the training protocol. Hippocampus 2003;13:587–603.
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