Among catecholamines, serotonin, as well as serotonergic agonists have been shown to regulate protein, amino acid, glycogen and cyclic nucleotide metabolism in rat skeletal musculature. To a better understanding of the role of tryptophan (L-Tp) itself, and its amine serotonin (5-HT), it is proposed an animal model consisting of young male L-Tp-deprived rats, namely rats fed a diet containing all the essential amino acids with exception of L-Tp, throughout sixty days. After onset of L-Tp-free feeding, both control and L-Tp-free rats have been sacrificed at intervals of ten days for sixty days, in order to investigate the changes on the neuroendocrine system and skeletal musculature. In L-Tp-free rats, soon after (3-5 days) the withdrawal of L-Tp from daily feeding, blood 5-HT and its metabolite 3-5-hydroxyindolacetic acid (5-HIAA) paradoxically showed a significant (P < 0.05) rise, followed by a rapid drop until disappearance within the fifteenth day. Therefore, L-Tp-free rats are at the same time also 5-HT-free rats. As compared with the controls. 5-HT-free animals showed, throughout the sixty days of the experiment, a zero body weight gain, that fell significantly below zero at the approaching of the fiftieth and, further on, the sixtieth day. The skeletal musculature showed marked signs of hypotrophy or frank atrophy. When compared with the controls, in the L-Tp-free fed rats plasma GH, TSH, T3 and T4 levels already collapsed after 20 days of L-Tp-deprivation. Plasma values of testosterone markedly dropped almost to the lowest range of the sensitivity of the assay after thirty days L-Tp-free-feeding. Submicroscopically the muscles showed striking signs of cellular damage and degeneration. These data indicate that the skeletal muscles of L-Tp-free fed rats are markedly damaged not only by an impaired protein synthesis,but also through an involvement of the central and peripheral neuroendocrine system.
L-tryptophan and serotonin influence either direcly or indirect trophism and contractility of the skeletal musculature. Neuroendocrinological observations in young adult, serotonin-free male rats
IMBESI, Rosa;
1996-01-01
Abstract
Among catecholamines, serotonin, as well as serotonergic agonists have been shown to regulate protein, amino acid, glycogen and cyclic nucleotide metabolism in rat skeletal musculature. To a better understanding of the role of tryptophan (L-Tp) itself, and its amine serotonin (5-HT), it is proposed an animal model consisting of young male L-Tp-deprived rats, namely rats fed a diet containing all the essential amino acids with exception of L-Tp, throughout sixty days. After onset of L-Tp-free feeding, both control and L-Tp-free rats have been sacrificed at intervals of ten days for sixty days, in order to investigate the changes on the neuroendocrine system and skeletal musculature. In L-Tp-free rats, soon after (3-5 days) the withdrawal of L-Tp from daily feeding, blood 5-HT and its metabolite 3-5-hydroxyindolacetic acid (5-HIAA) paradoxically showed a significant (P < 0.05) rise, followed by a rapid drop until disappearance within the fifteenth day. Therefore, L-Tp-free rats are at the same time also 5-HT-free rats. As compared with the controls. 5-HT-free animals showed, throughout the sixty days of the experiment, a zero body weight gain, that fell significantly below zero at the approaching of the fiftieth and, further on, the sixtieth day. The skeletal musculature showed marked signs of hypotrophy or frank atrophy. When compared with the controls, in the L-Tp-free fed rats plasma GH, TSH, T3 and T4 levels already collapsed after 20 days of L-Tp-deprivation. Plasma values of testosterone markedly dropped almost to the lowest range of the sensitivity of the assay after thirty days L-Tp-free-feeding. Submicroscopically the muscles showed striking signs of cellular damage and degeneration. These data indicate that the skeletal muscles of L-Tp-free fed rats are markedly damaged not only by an impaired protein synthesis,but also through an involvement of the central and peripheral neuroendocrine system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
