Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome
Non-associative learning is a basic neuroadaptive behavior exhibited in almost all animal species and sensory modalities but its functions and mechanisms in the mammalian brain are poorly understood. Previous studies have identified two distinct forms of non-associative learning in the classic Herin...
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| Format: | Article |
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Frontiers Research Foundation
2011
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| Online Access: | http://hdl.handle.net/1721.1/66199 |
| _version_ | 1826198332176859136 |
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| author | Song, Gang Tin, Chung Giacometti, Emanuela Poon, Chi-Sang |
| author2 | Harvard University--MIT Division of Health Sciences and Technology |
| author_facet | Harvard University--MIT Division of Health Sciences and Technology Song, Gang Tin, Chung Giacometti, Emanuela Poon, Chi-Sang |
| author_sort | Song, Gang |
| collection | MIT |
| description | Non-associative learning is a basic neuroadaptive behavior exhibited in almost all animal species and sensory modalities but its functions and mechanisms in the mammalian brain are poorly understood. Previous studies have identified two distinct forms of non-associative learning in the classic Hering–Breuer inflation reflex (HBIR) induced apnea in rats: NMDA receptor (NMDAR)-independent habituation in a primary vagal pathway and NMDAR-dependent desensitization in a secondary pontine pathway. Here, we show that abnormal non-associative learning of the HBIR may underlie the endophenotypic tachypnea in an animal model of Rett syndrome (RTT), an autism-spectrum disorder caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MECP2). Mecp2+/− [Mecp2 superscript + / -] symptomatic mice on a mixed-strain background demonstrated significantly increased resting respiratory frequency with shortened expiration and normal inspiratory duration compared with asymptomatic mutants and wild-type controls, a phenotype that is characteristic of girls with RTT. Low-intensity electrical stimulation of the vagus nerve elicited fictive HBIR with time-dependent habituation in both Mecp2+/− [Mecp2 superscript + / -] and wild-type mice. However, time-dependent desensitization of the HBIR was evidenced only in wild-type controls and asymptomatic mutant mice but was absent or suppressed in Mecp2+/− [Mecp2 superscript + / -] symptomatic mice or in wild-type mice after blockade of NMDAR with dizocilpine. Remarkably, ∼50% of the Mecp2+/− [Mecp2 superscript + / -] mice developed these X-linked phenotypes despite somatic mosaicism. Such RTT-like respiratory endophenotypes in mixed-strain Mecp2+/− [Mecp2 superscript + / -] mice differed from those previously reported in Mecp2-/y [Mecp2 superscript - / y] mice on pure C57BL/6J background. These findings provide the first evidence indicating that impaired NMDAR-dependent desensitization of the HBIR may contribute to the endophenotypic tachypnea in RTT. |
| first_indexed | 2024-09-23T11:03:11Z |
| format | Article |
| id | mit-1721.1/66199 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:03:11Z |
| publishDate | 2011 |
| publisher | Frontiers Research Foundation |
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| spelling | mit-1721.1/661992022-09-27T16:46:58Z Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome Song, Gang Tin, Chung Giacometti, Emanuela Poon, Chi-Sang Harvard University--MIT Division of Health Sciences and Technology Massachusetts Institute of Technology. Department of Biology Whitehead Institute for Biomedical Research Poon, Chi-Sang Song, Gang Tin, Chung Giacometti, Emanuela Poon, Chi-Sang Non-associative learning is a basic neuroadaptive behavior exhibited in almost all animal species and sensory modalities but its functions and mechanisms in the mammalian brain are poorly understood. Previous studies have identified two distinct forms of non-associative learning in the classic Hering–Breuer inflation reflex (HBIR) induced apnea in rats: NMDA receptor (NMDAR)-independent habituation in a primary vagal pathway and NMDAR-dependent desensitization in a secondary pontine pathway. Here, we show that abnormal non-associative learning of the HBIR may underlie the endophenotypic tachypnea in an animal model of Rett syndrome (RTT), an autism-spectrum disorder caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MECP2). Mecp2+/− [Mecp2 superscript + / -] symptomatic mice on a mixed-strain background demonstrated significantly increased resting respiratory frequency with shortened expiration and normal inspiratory duration compared with asymptomatic mutants and wild-type controls, a phenotype that is characteristic of girls with RTT. Low-intensity electrical stimulation of the vagus nerve elicited fictive HBIR with time-dependent habituation in both Mecp2+/− [Mecp2 superscript + / -] and wild-type mice. However, time-dependent desensitization of the HBIR was evidenced only in wild-type controls and asymptomatic mutant mice but was absent or suppressed in Mecp2+/− [Mecp2 superscript + / -] symptomatic mice or in wild-type mice after blockade of NMDAR with dizocilpine. Remarkably, ∼50% of the Mecp2+/− [Mecp2 superscript + / -] mice developed these X-linked phenotypes despite somatic mosaicism. Such RTT-like respiratory endophenotypes in mixed-strain Mecp2+/− [Mecp2 superscript + / -] mice differed from those previously reported in Mecp2-/y [Mecp2 superscript - / y] mice on pure C57BL/6J background. These findings provide the first evidence indicating that impaired NMDAR-dependent desensitization of the HBIR may contribute to the endophenotypic tachypnea in RTT. National Institutes of Health (U.S.) (Grant HL093225) National Institutes of Health (U.S.) (Grant HL067966) National Institutes of Health (U.S.) (Grant HL072849) National Institutes of Health (U.S.) (Grant HL079503) National Institutes of Health (U.S.) (Grant RR028241) 2011-10-06T22:16:14Z 2011-10-06T22:16:14Z 2011-05 2011-01 Article http://purl.org/eprint/type/JournalArticle 1662-5145 http://hdl.handle.net/1721.1/66199 Song, Gang et al. “Habituation without NMDA Receptor-Dependent Desensitization of Hering–Breuer Apnea Reflex in a Mecp2+/− Mutant Mouse Model of Rett Syndrome.” Frontiers in Integrative Neuroscience 5:6 (2011): n. pag. © 2011 Song, Tin, Giacometti and Poon en_US http://dx.doi.org/10.3389/fnint.2011.00006 Frontiers in Integrative Neuroscience Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Frontiers Research Foundation Frontiers |
| spellingShingle | Song, Gang Tin, Chung Giacometti, Emanuela Poon, Chi-Sang Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome |
| title | Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome |
| title_full | Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome |
| title_fullStr | Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome |
| title_full_unstemmed | Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome |
| title_short | Habituation without NMDA Receptor-Dependent Desensitization of Hering- Apnea Reflex in a Mecp2 [superscript + / -] Mutant Mouse Model of Rett Syndrome |
| title_sort | habituation without nmda receptor dependent desensitization of hering apnea reflex in a mecp2 superscript mutant mouse model of rett syndrome |
| url | http://hdl.handle.net/1721.1/66199 |
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