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EN
We aimed to quantify the gene expression changes of the potent orexigenic melanin-concentrating hormone (MCH) in chicken (Gallus gallus) hypothalamus with quantitative real-time polymerase chain reaction (qPCR), and for the first time determine peptide concentrations with a novel radioimmunoassay (RIA) under different feeding status. Three different experimental conditions, namely ad libitum feeding; fasting for 24 h; fasting for 24 h and then refeeding for 2 h, were applied to study changes of the aforementioned target and its receptor (MCHR4) gene expression under different nutritional status. The relative changes of MCH and MCHR4 were also studied from 7 to 35 days of age. Expression of PMCH and MCHR4 along the gastrointestinal tract (GIT) was also investigated. We found that expression of both targets was significant in the hypothalamus, while only weak expression was detected along the GIT. Different nutritional states did not affect the PMCH and MCHR4 mRNA levels. However, fasting for 24 h had significantly increased the MCH-like immunoreactivity by 25.65%. Fasting for 24 h and then refeeding for 2 h had further significantly increased the MCH peptide concentration by 32.51%, as compared to the ad libitum state. A decreasing trend with age was observable for both, the PMCH and MCHR4 mRNA levels, and also for the MCH-like immunoreactivity. Correlation analysis did not result in a significant correlation between MCH peptide concentration and abdominal fat mass in ad libitum fed birds. In conclusion, MCH peptide concentration altered in response to 24 h fasting, which indicated that this peptide may take part in feed intake regulation of broiler chickens.
EN
In this review we present infl uences of the neuropeptide Y (NPY), a 36-amino acid peptide which belongs to the pancreatic polypeptide family, on the central and peripheral cardiovascular regulation. NPY has been detected in many central nervous system areas, including arcuate and paraventricular nuclei of the hypothalamus, nucleus of the solitary tract (NTS) and rostral ventral-lateral medulla (RVLM). Moreover, it is released from postganglionic neurons of the sympathetic nervous system and platelets. Both at the central and peripheral level, NPY acts as a peptide neuromodulator secreted together with classical neurotransmitters. It infl uences the cardiovascular center function acting directly on RVLM and hypothalamic neurons and indirectly – via regulation of the baroreceptor refl ex sensitivity at NTS level. Interestingly, the activation of diff erent types of NPY receptors in diff erent central nervous system areas can cause various, even opposite, eff ects in the cardiovascular regulation. There is an increase in NPY synthesis and release in conditions of disturbed circulatory homeostasis, for instance in haemorrhagic shock. In critical haemorrhagic hypotension, NPY probably activates compensatory mechanisms leading to maintenance of blood pressure values necessary to survive. Thus, we conclude that further studies are needed to clarify NPY functions in conditions of hyper- and hypotension.
PL
W niniejszej pracy przedstawiono wpływ neuropeptydu Y (NPY), peptydu zbudowanego z 36 aminokwasów, należącego do rodziny polipeptydów trzustkowych, na ośrodkową oraz obwodową regulację układu krążenia. NPY jest obecny w wielu obszarach ośrodkowego układu nerwowego, takich jak jądra łukowate, przykomorowe podwzgórza, jądro pasma samotnego (NTS) czy też przednia brzuszno-boczna część rdzenia przedłużonego (RVLM). Ponadto jest on uwalniany z pozazwojowych neuronów układu współczulnego oraz z płytek krwi. NPY działa zarówno w ośrodkowym, jak i obwodowym układzie nerwowym jako neuromodulator uwalniany łącznie z klasycznymi neurotransmiterami. Wpływa on na funkcje ośrodka sercowo-naczynioruchowego w sposób bezpośredni, działając na RVLM oraz neurony podwzgórza, jak również pośrednio, poprzez wpływ na czułość odruchu z baroreceptorów tętniczych na poziomie NTS. Co ciekawe, aktywacja różnych typów receptorów NPY w ośrodkowym układzie nerwowym może powodować różne, a nawet przeciwstawne efekty w regulacji czynności układu krążenia. W stanie zaburzonej homeostazy krążeniowej, np. podczas wstrząsu krwotocznego, dochodzi do wzrostu syntezy i uwalniania NPY, który prawdopodobnie aktywuje mechanizmy kompensacyjne prowadzące do utrzymania niezbędnych do przeżycia wartości ciśnienia krwi. Przedstawiona analiza wskazuje na konieczność prowadzenia dalszych badań nad rolą NPY w stanie hiper- i hipotensji.
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