Serotonin increases the phase shift of the circadian locomotor activity rhythm in mice after dark pulses in constant light conditions.
نویسندگان
چکیده
Investigations on the effects of the 5-HT agonists and antagonists on the phase of the circadian locomotor activity rhythm of animals kept in constant light conditions (LL) are rare. Therefore the influence of R-(+)-OH-DPAT (5-HT1A receptors agonist) and metergoline (5-HT1/2/7 receptors antagonist) on the phase shift of the locomotor-activity rhythm alone and when combined with dark pulses in mice kept in LL are examined. The results indicate that 8-OH-DPAT administered independently at 12.00CT (Circadian Time) shifted the phase of the circadian rhythm and reinforced the effect of dark pulses on this parameter. 12.00CT was defined arbitrarily as the onset of locomotor activity in constant conditions. Metergoline diminished the phase shifts after dark pulses compared to 8-OH-DPAT. The influence of the serotonin agonist showed that serotonin can reinforce the phase shifting effect of the locomotor activity rhythm after dark pulses in LL condition.
منابع مشابه
Effect of Eight Weeks of Endurance Training in Light and Dark Phases of Circadian Rhythm on the Oxidative Stress Index in Pancreas of Diabetic Mice
Introduction: Chronic hyperglycemia is associated with an increase in cellular damage due to oxidative stress in pancreatic tissue. The effect of exercise in different phases of the circadian cycle on protecting pancreatic tissue from oxidative stress in diabetic patients is unknown. The aim of this study was to investigate the effect of eight weeks of endurance training in light and dark phase...
متن کاملDark adaptation in the circadian system of the mouse.
Entrainment of circadian rhythms by zeitgebers is generally believed to conform to the principles of the so-called nonparametric theory of entrainment. Although seldom recognized, this theory presupposes that the response of the circadian system to photic stimulation is dependent on previous photic stimulation. The process of dark adaptation in the circadian system has been investigated previou...
متن کاملCIRCADIAN VARIATION OF THE ACUTE TOXICITY AND NOCICEPTIVE ACTIVITY OF AMINOPHYLLINE IN MICE
The circadian variation of the toxicity and nociceptive actIvity of aminophylline as an important methylxanthine was studied in mice. The animals were housed under controlled light-dark cycles for at least 2 weeks. Acute toxicity was determined by LD50. Hot-plate test was used for determination of thermal pain threshold. Doses of 200, 250, 280 and 340 mg/kg of aminophylline were injected i...
متن کاملResetting of the hamster circadian system by dark pulses.
Circadian rhythms of animals are reset by exposure to light as well as dark; however, although the parameters of photic entrainment are well characterized, the phase-shifting actions of dark pulses are poorly understood. Here, we determined the tonic and phasic effects of short (0.25 h), moderate (3 h), and long (6-9 h) duration dark pulses on the wheel-running rhythms of hamsters in constant l...
متن کاملEffects of light, food, and methamphetamine on the circadian activity rhythm in mice.
The circadian rhythm of locomotor activity in mice is synchronized to environmental factors such as light and food availability. It is well-known that entrainment of the activity rhythm to the light-dark cycle is attained by the circadian pacemaker in the suprachiasmatic nucleus (SCN). Locomotor activity is also controlled by two extra-SCN oscillators; periodic food availability entrains the fo...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Folia biologica
دوره 55 3-4 شماره
صفحات -
تاریخ انتشار 2007