RESUMO
The review concerns morpho-functional characteristics of orexin receptors. The data on their structure, signal transduction pathways, biological effects of orexin receptors 1 or 2 depending on association with different G-proteins are presented. Localisation of orexin receptors in various CNS structures as well as in peripheral organs mediates regulation of different physiological functions by orexins. Low concentration of orexins in peripheral blood and orexin-containing cells in ganglions and internal organs suggests a possibility to activate orexin-sensitive cells distantly, paracrinely or autocrinely. The data on effects of selective or non-selective orexin receptor antagonists is analysed.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Neuropeptídeos/metabolismo , Receptores Acoplados a Proteínas G/química , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropeptídeos/química , Receptores de Neuropeptídeos/metabolismo , Animais , Encéfalo/citologia , Encéfalo/metabolismo , Sistema Nervoso Central/citologia , Sistema Nervoso Central/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Camundongos , Neuropeptídeos/genética , Receptores de Orexina , Orexinas , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/fisiologia , Receptores de Neuropeptídeos/genética , Receptores de Neuropeptídeos/fisiologia , Transdução de SinaisRESUMO
Hypothalamic orexin neurons are involved in the regulation of many physiological functions. The immunoreactivity of these neurons is shown to be altered after LPS injection. This phenomenon is characterized by definite time-space pattern and depends on dose of antigen applied. The expression level ofpreproorexin gene in rat hypothalamus was investigated in 2, 4 and 6 hours after injection of 25 and 500 mkg/kg b. w. LPS. Both injections of higher and lower doses resulted in the increase of expression level of preproorexin gene after 2 hours that could suggest an enhancement of orexin synthesis in neurons. There were no significant changes in 4 and 6 hours after injection. The comparative analysis of the data obtained earlier with immunohistochemistry, and the data shown in the present study suggest the mechanisms of orexin neurons reaction to injection of LPS in different doses, i. e. the more considerable prevalence of orexin utilization over its synthesis in hypothalamic cells after injection of subseptic (500 mkg/kg) dose of LPS.
Assuntos
Regulação da Expressão Gênica , Hipotálamo/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Lipopolissacarídeos/imunologia , Neurônios/imunologia , Neuropeptídeos/genética , Animais , Relação Dose-Resposta Imunológica , Hipotálamo/citologia , Lipopolissacarídeos/administração & dosagem , Masculino , Orexinas , RatosRESUMO
Orexin is a hypothalamic peptide, a neurotransmitter described in 1998. Orexinergic neurons are localized in hypothalamic structures and play a significant role in regulation of various physiological functions. The localization oforexin-containing neurons and their projections in hypothalamus of Wistar rats and other structures of CNS are presented. The participation of orexinergic neurons in the regulation of feeding behavior and in the sleep/wake cycle as well as their involvement in the regulation of immune functions is discussed. There are experimental data, containing comparative analysis oforexin-containing neurons responses to stimuli of antigenic and non-antigenic nature, which suggest functional heterogeneity of orexin-containing neurons of hypothalamus that leads, particularly, to involvement of different neurons in the realization of brain reaction to antigen and non-antigen stimuli. Both analyses ofpreproorexin gene expression level and morphofunctional characteristics of orecxin-containing neurons of hypothalamus after antigen challenge suggest the possibility of their participation in the mechanisms of realization of brain reaction to antigen challenge.
Assuntos
Antígenos/imunologia , Hipotálamo/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Neurônios/imunologia , Neuropeptídeos/imunologia , Animais , Antígenos/farmacologia , Ritmo Circadiano/efeitos dos fármacos , Ritmo Circadiano/imunologia , Comportamento Alimentar/efeitos dos fármacos , Comportamento Alimentar/fisiologia , Hipotálamo/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Neurônios/metabolismo , Neuropeptídeos/metabolismo , Orexinas , Ratos , Ratos WistarRESUMO
Studying of immunereactivity of orexin-containing neurons after restraint and cold stress has allowed to reveal a selective change of a degree ofimmunereactivity ofhypothalamic orexin-containing neurons. Orexin-containing neurons are located in structures 28, 29, 31 levels of brain slices and have the different degree of immunereactivity that indicates functional heterogeneity of a population of hypothalamic orexin-containing neurons. Structures and zones of hypothalamus involved in development of complex brain responses to restraint or cold stress applications were identified. Changes of immunereactivity of orexin-containing neurons located in the areas involved in system of regulation ofthermogenesis (DMH, PH and some zones LHA) suggest a possibility of orexin-containing neurons participation in thermoregulation.
