Expression and distribution of GnRH, LH, and FSH and their receptors in gastrointestinal tract of man and rat

Abstract

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Gonadotropin-Releasing Hormone and Its Physiological and Pathophysiological Roles in Relation to the Structure and Function of the Gastrointestinal Tract

“…Although GnRH receptors have not been found in the gastrointestinal tract in all studies [7], they may still be present, as has been described by others [11,12,13,14,15]. GnRH analogs stimulate the anterior pituitary, resulting in elevated LH secretion along with the stimulation of LH receptors and elevated steroidal sex hormone secretion [1,2,3,50].…”

“…GnRH analogs stimulate the anterior pituitary, resulting in elevated LH secretion along with the stimulation of LH receptors and elevated steroidal sex hormone secretion [1,2,3,50]. The harmful effects evoked in the gastrointestinal tract could be mediated by this route because LH receptors are found in the gastrointestinal tract in humans and rats [7,10,16,17], and they are downregulated following GnRH stimulation [10]. Elevated serum levels of estradiol following buserelin treatment along with the secondary synchronization of hormonal cycles and a thickened uterine muscle layer [50] confirm the presence of elevated FSH and LH secretion in a rat model [10].…”

“…In contrast, other groups have observed GnRH and GnRH receptor immunoreactivity in rat enteric neurons, smooth muscle cells, and epithelial parietal cells [11,12,13,14], and still more have found GnRH receptor mRNA in enteric neurons [15]. LH receptors have been described on enteric neurons in both rats and humans [7,10,16,17] (table 1). The LH receptor belongs to the rhodopsin/β 2 -adrenergic receptor-like family A of the G-protein-coupled receptor group and is predominantly expressed in the gonads [18].…”

“…mRNA for both GnRH1 and GnRH2 can be detected via polymerase chain reaction analysis in the human gastrointestinal tract [7]. The cellular localization of GnRH has been described in about half of the submucosal and myenteric neurons along the human gastrointestinal tract [8,9] (table 1).…”

“…The cellular localization of GnRH has been described in about half of the submucosal and myenteric neurons along the human gastrointestinal tract [8,9] (table 1). In one study, GnRH was not detected via immunocytochemistry in the rat gastrointestinal tract in vivo [10], and neither the GnRH receptor, FSH, the FSH receptor, or LH were detected via polymerase chain reaction or immunocytochemistry in rat or human gastrointestinal tracts [7]. In contrast, other groups have observed GnRH and GnRH receptor immunoreactivity in rat enteric neurons, smooth muscle cells, and epithelial parietal cells [11,12,13,14], and still more have found GnRH receptor mRNA in enteric neurons [15].…”