Seasonality and role of SCN in entrainment of lizard circadian rhythms to daily melatonin injections

被引:16
作者
Bertolucci, C [1 ]
Foà, A [1 ]
机构
[1] Univ Ferrara, Dipartimento Biol, Sez Biol Evolut, I-44100 Ferrara, Italy
关键词
suprachiasmatic nuclei; pineal gland; electrolytic lesions;
D O I
10.1152/ajpregu.1998.274.4.R1004
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
To establish whether the capability of daily melatonin injections to entrain circadian rhythms varies with season, we examined in constant conditions the locomotor behavior of lizards Podarcis sicula collected and subjected to daily melatonin injections at different times of the year. Although in summer locomotor rhythms of both pineal-intact and pinealectomized lizards became entrained to the 24-h injection period, in the other seasons their rhythms did not entrain to the injection period. To establish whether the suprachiasmatic nuclei (SCN) mediate summer entrainment of locomotor rhythms to melatonin, we examined the behavioral effects of daily melatonin injections in lizards subjected to either bilateral (SCN-X) or unilateral (USCN-X) ablation of the SCN. SCN-X lizards became behaviorally arrhythmic, and daily melatonin injections did not restore rhythmicity. USCN-X lizards remained rhythmic, and their locomotor rhythms did entrain to the injections. Besides demonstrating for the first time in a vertebrate that daily melatonin injections are capable of entraining circadian rhythmicity in only one season (summer), the present results support the view that the SCN (and not the pineal gland) are the primary target sites of melatonin in the circadian system of P. sicula.
引用
收藏
页码:R1004 / R1014
页数:11
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