Purinergic P2X receptors (P2X) are ATP-gated ion channels that are broadly expressed in the brain, particularly in the hypothalamus. As ionic channels with high permeability to calcium, P2X play an important and active role in neural functions. The hypothalamus contains a number of small nuclei with many molecularly defined types of peptidergic neurons that affect a wide range of physiological functions, including water balance, blood pressure, metabolism, food intake, circadian rhythm, childbirth and breastfeeding, growth, stress, body temperature, and multiple behaviors. P2X are expressed in hypothalamic neurons, astrocytes, tanycytes, and microvessels. This review focuses on cell-type specific expression of P2X in the most important hypothalamic nuclei, such as the supraoptic nucleus (SON), paraventricular nucleus (PVN), suprachiasmatic nucleus (SCN), anteroventral periventricular nucleus (AVPV), anterior hypothalamic nucleus (AHN), arcuate nucleus (ARC), ventromedial hypothalamic nucleus (VMH), dorsomedial hypothalamic nucleus (DMH), tuberomammillary nucleus (TMN), and lateral hypothalamic area (LHA).> The review also notes the possible role of P2X and extracellular ATP in specific hypothalamic functions. The literature summarized here shows that purinergic signaling is involved in the control of the hypothalamic-pituitary endocrine system, the hypothalamic-neurohypophysial system, the circadian systems and nonendocrine hypothalamic functions.

• Keywords
• P2X, arcuate nucleus (ARC), extracellular ATP, hypothalamus, paraventricular nucleus (PVN), suprachiasmatic nucleus (SCN), supraoptic nucleus (SON),
• MeSH
• Adenosine Triphosphate metabolism   MeSH
• Astrocytes metabolism   MeSH
• Hypothalamus * metabolism   cytology   MeSH
• Humans MeSH
• Neurons metabolism   MeSH
• Receptors, Purinergic P2X * metabolism   genetics   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Adenosine Triphosphate MeSH
• Receptors, Purinergic P2X * MeSH

The Institute of Physiology of the Czech Academy of Sciences (CAS) has been involved in the field of chronobiology, i.e., in research on temporal regulation of physiological processes, since 1970. The review describes the first 35 years of the research mostly on the effect of light and daylength, i.e., photoperiod, on entrainment or resetting of the pineal rhythm in melatonin production and of intrinsic rhythms in the central biological clock. This clock controls pineal and other circadian rhythms and is located in the suprachiasmatic nuclei (SCN) of the hypothalamus. During the early chronobiological research, many original findings have been reported, e.g. on mechanisms of resetting of the pineal rhythm in melatonin production by short light pulses or by long exposures of animals to light at night, on modulation of the nocturnal melatonin production by the photoperiod or on the presence of high affinity melatonin binding sites in the SCN. The first evidence was given that the photoperiod modulates functional properties of the SCN and hence the SCN not only controls the daily programme of the organism but it may serve also as a calendar measuring the time of a year. During all the years, the chronobiological community has started to talk about "the Czech school of chronobiology". At present, the today´s Laboratory of Biological Rhythms of the Institute of Physiology CAS continues in the chronobiological research and the studies have been extended to the entire circadian timekeeping system in mammals with focus on its ontogenesis, entrainment mechanisms and circadian regulation of physiological functions. Key words: Pineal, Melatonin, AA-NAT rhythm, Light entrainment, Photoperiod, SCN clock.

• MeSH
• Academies and Institutes MeSH
• Biological Clocks physiology   MeSH
• Circadian Clocks physiology   MeSH
• Circadian Rhythm * physiology   MeSH
• History, 20th Century MeSH
• History, 21st Century MeSH
• Pineal Gland * metabolism   physiology   MeSH
• Photoperiod MeSH
• Humans MeSH
• Melatonin metabolism   MeSH
• Brain metabolism   physiology   MeSH
• Suprachiasmatic Nucleus physiology   metabolism   MeSH
• Animals MeSH
• Check Tag
• History, 20th Century MeSH
• History, 21st Century MeSH
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Historical Article MeSH
• Review MeSH
• Names of Substances
• Melatonin MeSH