Archives

  • 2018-07
  • 2018-10
  • 2018-11
  • 2019-04
  • 2019-05
  • 2019-06
  • 2019-07
  • 2019-08
  • 2019-09
  • 2019-10
  • 2019-11
  • 2019-12
  • 2020-01
  • 2020-02
  • 2020-03
  • 2020-04
  • 2020-05
  • 2020-06
  • 2020-07
  • 2020-08
  • 2020-09
  • 2020-10
  • 2020-11
  • 2020-12
  • 2021-01
  • 2021-02
  • 2021-03
  • 2021-04
  • 2021-05
  • 2021-06
  • 2021-07
  • 2021-08
  • 2021-09
  • 2021-10
  • 2021-11
  • 2021-12
  • 2022-01
  • 2022-02
  • 2022-03
  • 2022-04
  • 2022-05
  • 2022-06
  • 2022-07
  • 2022-08
  • 2022-09
  • 2022-10
  • 2022-11
  • 2022-12
  • 2023-01
  • 2023-02
  • 2023-03
  • 2023-04
  • 2023-05
  • 2023-06
  • 2023-07
  • 2023-08
  • 2023-09
  • 2023-10
  • 2023-11
  • 2023-12
  • 2024-01
  • 2024-02
  • 2024-03
  • 2024-04
  • 2024-05

    • Since the circadian timekeeping system interacts with

    2018-11-09

    Since the circadian timekeeping system interacts with both the effectiveness of the cyclophosphamide and primary learning faculties11, [29], we find it necessary to study the effect of cyclophosphamide on immunosupression using a conditioning paradigm that incorporates the concept of diurnal variation. Despite the lack of exact comparative literature on diurnal variations in conditioned immunomodulation, we expected performance of nocturnal rodents (such as mice) to be better only during their active phase (i.e. the dark phase during LD cycle). The behavioral literature provides vast evidence for diurnal and circadian modulation in learned behaviors [7,8,30]. For instance, Chaudhury and Colwell [9] found intriguing results in a fear conditioning task and suggested that this apparent phase dependency may be a special feature of aversive (or fear) conditioning. Moreover, they concluded that the light phase was a fearful time for nocturnal animals and this phase dependency could lead to improved performance in aversive conditioning. However, other studies have shown better performance in nocturnal animals during the dark phase of the LD ginsenoside rh2 in different protocols learning [31,32]. These findings demonstrated possible species–specific differences and variation in training protocol and behavioral paradigms, possibly explaining our results and the conflicting reports and lack of consensus in the literature. Therefore, contrary to our expectations, the results indicated that mice could benefit from the conditioning task performed either in the light phase or in the dark phase of the LD cycle, being the success represented by an increased lifespan. Concerning the interaction between the progression of an autoimmune disease and the circadian timekeeping system, the disruption of the circadian system may occur in tumor tissue, tumor-bearing animals, and terminal cancer patients. Such rhythmic disruption includes decrease in amplitude, phase shifts, period changes, and erratic peaks and troughs in endocrine, metabolic, immunological, and rest-activity cycles [33]. Experimental challenging of the circadian timekeeping system leading to Chronodisruption due to chronic phase shifts of the light-dark (LD) cycle [34] or short 20-h LD cycle [35] have also been proved to adversely affects immune function. Additionally, changes in daily rhythms of heart rate, heart rate variability and blood pressure [36], as well as rhythmic expression of corticosterone, leptin and clock genes [37] were detected during the course of autoimmune disease progression in an animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). Finally, to keep the proper functioning of the circadian system throughout life seems to be imperative for the ordinary physiological expression of multiple functions, from lifespan to memory acquisition and consolidation. Disruption of rhythmicity reduces lifespan and suprachiasmatic implants from young animals restores higher amplitude rhythms in old rodents [38]. Moreover, animals exposed to chronic phase shifts, which has been previously to lead to circadian dysfunction, exhibit learning and memory dysfunction [39]. In conclusion, our results indicate that mice could benefit from the conditioning task performed either in the light phase or in the dark phase of the LD cycle, as expressed by an increased lifespan. Concerning the rhythmic parameters, there was evidence of association between the stability of the signal from the circadian timekeeping system and the evolution of SLE, demonstrated by the maintenance of healthy levels of amplitude and spectral power density of the 24h rhythm in animals exposed to the conditioning paradigm.
    Introduction Parkinson’s disease (PD) is the second most common neurodegenerative disease, afflicting about 1% of people over 65 years old and 4–5% of people over 85 years old [1]. It is characterized by major cardinal motor disturbances, namely rigidity, rest tremor and bradykinesia [2,3]. These alterations are the result of the progressive dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc) and consequently reductions in the striatal levels of dopamine [4]. In addition to the motor dysfunction, PD patients usually display non-motor features of the disease [2], such as sleep disorders, autonomic dysfunctions, olfactory deficits, and neuropsychiatric symptoms particularly depression, anxiety and apathy [2,5].