Photoperiod-dependent effect of inflammation on nocturnal gene expression of proinflammatory cytokines and their receptors in <i>pars tuberalis</i> of ewe

Endotoxin-Induced Inflammation Suppresses the Effect of Melatonin on the Release of LH from the Ovine Pars Tuberalis Explants—Ex Vivo Study

“…This suggests that inflammation may more strongly impair the secretory activity of the PT than the AP. The increased sensitivity of the PT cells to the inflammatory condition may result from the occurrence of a number of pro-inflammatory cytokine receptors with relatively high transcription, which was found in our previous study [ 20 ]. Moreover, our study showed that the secretory activity of the PT explants may be modulated by the locally synthesized pro-inflammatory cytokines, by which transcription was found in the explants even a few hours after the disappearance of the inflammatory stimuli.…”

“…As a starting material for cDNA reversed transcription reaction synthesis, 2 μg of total RNA was used. Real-Time PCR was carried out with the use of the HOT FIREPol EvaGreen ® qPCR Mix Plus (Solis BioDyne, Tartu, Estonia) and HPLC-grade oligonucleotide primers (Genomed, Warszawa, Poland) according to the protocol described elsewhere [ 20 ]. The primer sequences were designed using Primer 3 software ( Table 2 ).…”

“…This direct action of inflammatory mediators may occur due to the existence of their corresponding receptors in the AP [ 14 , 18 , 19 ]. Also, in our previous study it was revealed that mRNAs encoding pro-inflammatory cytokine receptors are expressed in the PT [ 20 ]. This suggests that the secretory activity of PT cells may be influenced by immune/inflammatory challenge.…”

The effect of inflammation on the synthesis of luteinizing hormone and gonadotropin-releasing hormone receptor expression in thepars tuberalisof ewe during different photoperiodic conditions

“…In vertebrates, melatonin is a hormone predominantly synthesized by pinealocytes of the pineal gland, and the secretion occurs after dark and rapidly stops after the sunrise (Todini et al 2010). Studies on sheep showed that the highest level and the longest period of melatonin secretion occur in winter during the short day photoperiod (breeding season), whereas the lowest concentration and the shortest duration of melatonin are found in the summer during long day photoperiod (seasonal anestrus) (Reiter et al 2009;Herman et al 2016aHerman et al , 2017Król et al 2016). Although the impact of melatonin on the reproductive function is undeniable, till now the main mechanism by which this hormone affects the HPG axis activity has not been clearly defined.…”

“…It was found that an immune/inflammatory challenge may influence the secretion of gonadotropins, particularly LH, via suppression of GnRH secretion in the hypothalamus (Daniel et al 2003), and that inflammatory mediators may directly influence LH secretion from the AP explants (Herman et al 2013a). We (Król et al 2016) recently reported that the cells of PT may be a target, as well as the source of proinflammatory cytokines, during endotoxin-induced inflammation. Therefore, it could be hypothesized that an immune/ inflammatory challenge affects the local secretion of LH and GnRHR expression in the PT, and that, at least partially, these changes may be related to the inflammatorydependent changes in the melatonin release and the melatonin type I receptor (MT1) gene expression in the PT.…”