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

Abstract

The study was designed to determine the effect of endotoxin-induced inflammation on luteinizing hormone (LH) synthesis and gonadotropin-releasing hormone (GnRH) receptor expression in the pars tuberalis (PT) of ewes during anestrous season and follicular phase taking into account the time of the day. Moreover, the effect of inflammation on the release of melatonin and its type I receptor gene expression in the PT was also determined. Lipopolysaccharide administration reduced nocturnal release of melatonin only during anestrous season, but it did not influence the gene expression of melatonin type I receptor in the PT. Inflammation inhibited nocturnal increase in the gene and protein expression of LH in the PT during the follicular phase. Since in day-active species nocturnal accumulation of LH protein in the pituitary precedes the LH surge, this lowering of LH content may delay or disturb the surge occurrence. Suppression of LH secretion could have resulted from the decreased sensitivity of the PT on the action of GnRH because inflammation reduced GnRH receptor expression. The study suggests that the ability of endotoxin to suppress LH synthesis in the PT may be another mechanism by which inflammation disturbs reproductive neuroendocrine axis in seasonal breeders.

Effect of Acute and Prolonged Inflammation on the Gene Expression of Proinflammatory Cytokines and Their Receptors in the Anterior Pituitary Gland of Ewes

“…The amount of GnRHR determining the ability and storage strength of the pituitary gonadotropes in response to GnRH [ 48 ]. It was previously found that during inflammation the pituitary sensitivity to GnRH stimulation [ 9 ] and the expression of GnRHR in ewes were suppressed [ 49 , 50 ]. It is believed that the lower GnRHR gene expression in the pituitary during an immune/inflammatory challenge is mainly due to the lower secretion of the hypothalamic GnRH [ 1 , 45 , 46 , 47 ], which is one of the most important regulator of its own receptor expression.…”

Anandamide Influences Interleukin-1β Synthesis and IL-1 System Gene Expressions in the Ovine Hypothalamus during Endo-Toxin-Induced Inflammation

“…Real-time RT-PCR analysis 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) in line with the method described elsewhere [ 34 ]. Specific primers to determine the expression of the genes of interest and housekeeping genes were chosen on the basis of our previous experience (see Table 2 ).…”