Colocalization of GPR120 and anterior pituitary hormone-producing cells in female Japanese Black cattle

Abstract

Negative energy balance in domestic animals suppresses their reproductive function. These animals commonly use long-chain fatty acids (LCFAs) from adipocytes as an energy source under states of malnutrition. The G-protein coupled receptor, GPR120, is a specific receptor for LCFAs, but its role in reproductive function remains unknown in domestic animals. The purpose of this study was to examine whether GPR120 is involved in the reproductive system of cattle. GPR120 mRNA expression was evaluated in brain, pituitary, and ovarian tissue samples by RT-PCR. GPR120 gene expression was detected with high intensity only in the anterior pituitary sample, and GPR120-immunoreactive cells were found in the anterior pituitary gland. Double immunohistochemistry of GPR120 in the anterior pituitary hormone-producing cells, such as gonadotropes, thyrotropes, lactotropes, somatotropes, and corticotropes, was performed to clarify the distribution of GPR120 in the anterior pituitary gland of ovariectomized heifers. Luteinizing hormone β subunit (LHβ)-and folliclestimulating hormone β subunit (FSHβ)-immunoreactive cells demonstrated GPR120 immunoreactivity at 80.7% and 85.9%, respectively. Thyrotropes, lactotropes, somatotropes, and corticotropes coexpressed GPR120 at 21.1%, 5.4%, 13.6%, and 14.5%, respectively. In conclusion, the present study suggests that GPR120 in the anterior pituitary gland might mediate LCFA signaling to regulate gonadotrope functions, such as hormone secretion or production, in cattle.

<i>Gpr120</i> mRNA expression in gonadotropes in the mouse pituitary gland is regulated by free fatty acids

“…The anterior pituitary gland contains non-endocrine cells and five types of endocrine cells. In our histological studies, GPR120 expression was observed only in gonadotropes in mice [9], but it was observed in more than 80% of gonadotropes and less than 20% of four other types of endocrine cells in cattle [10]. These results suggest that GPR120 is involved in the mechanism of gonadotropic hormone synthesis and/or secretion and in the regulation of gonadal function.…”

“…GPR120 has been reported to interact with extracellular signal-regulated kinases 1/2 (ERK1/2) [2,4]. Furthermore, the expression of GPR120 has been observed in various organs and tissues, including the taste buds [5], muscles [6], pancreas [7], liver [8], intestines [2], and pituitary gland [9,10]. The anterior pituitary gland contains non-endocrine cells and five types of endocrine cells.…”

Ethanolamine plasmalogens derived from whale brain stimulate both follicle‐stimulating hormone and luteinizing hormone secretion by bovine gonadotrophs

“…We obtained AP cells from six healthy, post-pubertal Japanese Black heifers (2.2 ± 0.0 years old; n = 6). The size of the whole bovine pituitary gland (at least 4 cm along the rostrocaudal axis, 3 cm along the lateral axis, and 4 cm along the vertical axis) facilitates easy differentiation of the anterior lobe (the hard, light brown, or pink portion) from the posterior and intermediate lobes (soft, brown portion) following sagittal dissection along the midline (Nakamura et al, 2020). Enzymatic dispersal of AP cells was performed using a previously described method (Kadokawa et al, 2014), and confirmation of cell viability of >90% was confirmed via trypan blue exclusion.…”