title: Protective effects of high Tryptophan diet on aging-induced passive avoidance impairment and hippocampal apoptosis.
abstract: In our previous work we have shown that L-Tryptophan (TrP) enriched diet prevents the age-induced decline of hippocampal Serotonin (5-HT) production. Considering that loss or reduction in 5-HT neurotransmission may contribute to age-related cognitive decline, here we have investigated the effect of such diet on passive avoidance (PA) behavior, cell death, pro- and anti- apoptotic molecules (BAX, Bcl-2 and Caspase-3) and an important transcription factor involved in synaptic plasticity and memory (CREB). The increase in 5-HT neurotransmission in the Hippocampus (Hp) of aged rats was induced by 1 month of high TrP administration. In the first phase of our study we found that high TrP diet improves PA behaviour of aged rats and this correlated with a decrease of TUNEL positive cells in all hippocampal regions tested (CA1, CA2, CA3, DG). Interestingly, the Hp of aged animals fed with high TrP diet showed a significant downregulation of proapoptotic proteins, caspase-3 and BAX, and an increase of antiapoptotic molecules Bcl-2 as indicated by Western Blot and immunohistochemical analyses. Also, high TrP diet partially rescued the age-induced inhibition of hippocampal CREB phosphorylation. Altogether, our data suggest that enhanced TrP intake, and in consequence a potential increase in 5-HT neurotransmission, might be beneficial in preventing age-related detrimental features by inhibition of hippocampal apoptosis.
authors.affiliation: Department of Biomedical and Biotechnological Sciences, Human Anatomy and Histology Section, University of Catania, Catania, Italy. Electronic address: giumusu@gmail.com.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Musumeci
authors.affiliation: Department of Biomedical and Biotechnological Sciences, Human Anatomy and Histology Section, University of Catania, Catania, Italy. Electronic address: pacastro@unict.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Castrogiovanni
authors.affiliation: Department of Biomedical and Biotechnological Sciences, Human Anatomy and Histology Section, University of Catania, Catania, Italy. Electronic address: marta.sz@hotmail.it.
authors.forename: Marta Anna
authors.initials: MA
authors.lastname: Szychlinska
authors.affiliation: Department of Biomedical and Biotechnological Sciences, Human Anatomy and Histology Section, University of Catania, Catania, Italy. Electronic address: roimbesi@unict.it.
authors.forename: Rosa
authors.initials: R
authors.lastname: Imbesi
authors.affiliation: Department of Biomedical and Biotechnological Sciences, Human Anatomy and Histology Section, University of Catania, Catania, Italy. Electronic address: carla.loreto@unict.it.
authors.forename: Carla
authors.initials: C
authors.lastname: Loreto
authors.affiliation: Department of Biomedical and Biotechnological Sciences, Human Anatomy and Histology Section, University of Catania, Catania, Italy. Electronic address: sergio.castorina@unict.it.
authors.forename: Sergio
authors.initials: S
authors.lastname: Castorina
authors.affiliation: Department of Biomedical and Biotechnological Sciences, Human Anatomy and Histology Section, University of Catania, Catania, Italy. Electronic address: salvatore.giunta15@virgilio.it.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Giunta
mesh_terms: D000375:Aging / Q000378:metabolism / Q000473:pathology* / Q000523:psychology*; D000821:Animal Feed; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001362:Avoidance Learning / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D019587:Dietary Supplements; D006624:Hippocampus / Q000473:pathology* / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D014364:Tryptophan / Q000008:administration & dosage*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494828:Bax protein, rat; C000617196:Bcl2 protein, rat; D017362:Cyclic AMP Response Element-Binding Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D012701:Serotonin; D014364:Tryptophan; C505410:Casp3 protein, rat; D053148:Caspase 3
keywords: Apoptotic molecules; CREB; Hippocampus; Learning; Serotonin