No abstract

All living organisms; from single-celled microorganisms to humans, they have to adapt to changing environmental conditions to maintain their survival processes. Circadian rhythm is one of the most important mechanism that associated with this adaptation processes. There are biological clocks in the body, which are related to the circadian rhythm and have a hierarchical organization. The master circadian clock is located in the suprachiasmatic nucleus (SCN) of hypothalamus. SCN maintain body rhythms in synchronous with the light-dark cycle in the external environment. There are also peripheral oscillators that work in coordination with SCN. Neurological, endocrinological, and immunological functions in the body are under the influence of circadian and seasonal rhythms. Melatonin and cortisol (corticosterone in animals) are among the most important hormones that show circadian rhythm in the body. The body adapts to daily and seasonal changes with biological rhythms regulated by biological clocks. It is well known that the immune system is affected by the external environment. Changes in endocrine system, hypothalaomo-pituitary adrenal (HPA) axis, and immune system are marked, especially depending on the seasonal changes. Therefore, the immune system has close relationship with the circadian rhythm. Understanding relationship between physiological regulation of the circadian rhythm, HPA axis and immune activity is important for to keep our body in healthy conditions and struggle with the diseases as well. In current review, the interaction and relationship of genes and proteins related to the circadian rhythm with HPA axis and immune system parameters are discussed with both physiological and pathological examples.

No abstract

Sosyal özellikleri en gelişmiş canlı olan insanlarda gülme davranışı önemli bir etkileşim ve iletişim aracıdır. Gülmenin ayrıca sağlık için de önemli katkıları olduğu düşünülmektedir. Beynin entelektüel bir fonksiyonu olarak ortaya çıkan gülme davranışında özellikle broca alanı, motor korteks, bazal nükleuslar ve anterior singulat korteks ve diğer limbik sistem yapılarının yanı sıra beyin sapı önemli rol oynamaktadır. İlginç bir husus olarak bu bölgelerin gülme ile ilişkisi genellikle beyin lezyonlarıyla ilişkili araştırmalarda tanımlanmıştır. Yazımızda gülme ile ilgili beyin bölgeleri ve gülmenin sağlık üzerine etkileri ele alınmaktadır. Gülme ile ilgili beyin bölgelerinin karakterizasyonunda bu alanlardaki lezyon inceleme çalışmalarındaki bulgular esas alınmaktadır. Bu sayede patofizyolojik değişikliklerden gülmenin fizyolojik regülasyonuna yönelik çıkarımlar hedeflenmektedir.

Circadian rhythms in the body affect physiological functions and behaviors and therefore have important roles on health. These rhythms mainly regulate important physiological processes such as the sleep-wake cycle, autonomic activity, endocrine function and immune system. Regarding biological rhythm, the master structure is the suprachiasmatic nucleus (SCN) in the hypothalamus. Furthermore, many circadian oscillators are present in the central nervous system and peripheral body tissues. These oscillators exhibit their function under the coordination of SCN for the functional integrity of the circadian rhythms. Daily retinal light-dependent stimuli are essential for the rhythm of day and night and the synchronization of circadian clocks. In this synchronization, melatonin hormone has a major role as an endocrine factor. The expression of melatonin is regulated by light signals reaching to the SCN. In many blind people without light perception, circadian rhythm synchronization is impaired due to the inability of the SCN to receive light information. In such cases, serious sleep disorders can be seen. This condition is called non-24-Sleep-Wake Rhythm Disorder. This disorder can be treated with behavioral therapy and medial therapy. Moreover, melatonin or its agonists are used in medical treatment.