Aparicio Sara, Garau Celia, Nicolau María C, Rial Rubén V, Esteban Susana
Laboratori de Neurofisiologia, Departament de Biologia Fonamental i Ciènces de la Salut., Universitat de les Illes Balears, Spain.
Comp Biochem Physiol A Mol Integr Physiol. 2006 Jun;144(2):173-9. doi: 10.1016/j.cbpa.2006.02.028. Epub 2006 Mar 3.
The role of l-tryptophan as precursor of serotonin and melatonin synthesis on activity-rest rhythm was studied in ring doves, Streptopelia risoria, as a representative of diurnal animals and rats, Rattus norvegicus, as a typical nocturnal one. The animals were housed in cages equipped for horizontal activity recording in a thermostatized chamber and submitted to a 12/12h light/dark photoperiod (lights on at 08:00 h). After acclimatization, the animals received vehicle (methylcellulose) and l-tryptophan (240 mg/kg) by esophagic cannula 2h before the onset of either light or dark phase. Also, oral melatonin (2.5mg/kg) was tested for comparative purposes. After nocturnal l-tryptophan administration, rats showed increased activity (149%), while the opposite occurred in ring doves (39% decrease). No significant changes were found after diurnal l-tryptophan intake in either species. Melatonin produced effects similar to those of l-tryptophan. These results suggest that the effects of l-tryptophan administration are dependent on the nocturnal/diurnal habits of the studied species and, most probably, are mediated by increased melatonin synthesis.
在作为昼行性动物代表的环颈鸽（Streptopelia risoria）和作为典型夜行性动物的大鼠（Rattus norvegicus）中，研究了L-色氨酸作为血清素和褪黑素合成前体对活动-休息节律的作用。将动物饲养在配备有水平活动记录装置的笼子中，置于恒温箱内，并接受12/12小时的光照/黑暗光周期（08:00开灯）。适应环境后，在光照或黑暗阶段开始前2小时，通过食管插管给动物注射载体（甲基纤维素）和L-色氨酸（240毫克/千克）。此外，为了进行比较，还测试了口服褪黑素（2.5毫克/千克）。夜间给予L-色氨酸后，大鼠的活动增加（增加了149%），而环颈鸽则出现相反的情况（减少了39%）。两种动物在白天摄入L-色氨酸后均未发现显著变化。褪黑素产生的效果与L-色氨酸相似。这些结果表明，给予L-色氨酸的效果取决于所研究物种的夜行性/昼行性习性，而且很可能是通过增加褪黑素的合成来介导的。
