Anti-Müllerian hormone and its receptor are detected in most gonadotropin-releasing-hormone cell bodies and fibers in heifer brains

Abstract

Circulating concentrations of Anti-Müllerian hormone (AMH) can indicate fertility in various animals, but the physiological mechanisms underlying the effect of AMH on fertility remain unknown. We recently discovered that AMH has extragonadal functions via its main receptor, AMH receptor type 2 (AMHR2). Specifically, AMH stimulates the secretion of luteinizing hormone and follicle stimulating hormone from bovine gonadotrophs. Moreover, gonadotrophs themselves express AMH to exert paracrine/autocrine functions, and AMH can activate gonadotropin-releasing-hormone (GnRH) neurons in mice. This study aimed to evaluate whether AMH and AMHR2 are detected in areas of the brain relevant to neuroendocrine control of reproduction: the preoptic area (POA), arcuate nucleus (ARC), and median eminence (ME), and in particular within GnRH neurons. Reverse transcription-polymerase chain reaction detected both AMH and AMHR2 mRNA in tissues containing POA as well as in those containing both ARC and ME, collected from post-pubertal heifers. Western blotting detected AMH and AMHR2 protein in the collected tissues. Triple fluorescence immunohistochemistry revealed that the majority of cell bodies or fibers of GnRH neurons were AMHR2-positive and AMH-positive, although some were negative.Immunohistochemistry revealed that 75 to 85% of cell bodies and fibers of GnRH neurons were positive for both AMH and AMHR2 in the POA, ARC, and both the internal and external zones of ME. The cell bodies of GnRH neurons were situated around other AMHpositive cell bodies or fibers of GnRH and non-GNRH neurons. Our findings thus indicate that AMH and AMHR2 are detected in the majority of cell bodies or fibers of GnRH neurons in POA, ARC, or ME of heifer brains. These data support the need for further study as to how AMH and AMHR2 act within the hypothalamus to influence GnRH and gonadotropin secretion.

Discovery of new receptors regulating luteinizing hormone and follicle-stimulating hormone secretion by bovine gonadotrophs to explore a new paradigm for mechanisms regulating reproduction

“…Interestingly, I recently reported that most cell bodies or fibers of GnRH-secreting neurons in the preoptic area, arcuate nucleus, and internal and external zones of the median eminence in the heifer hypothalamus express AMH [ 56 ]. Therefore, my recent data provide a new hypothesis ( Fig.…”

Decreased Anti-Müllerian hormone and Anti-Müllerian hormone receptor type 2 in hypothalami of old Japanese Black cows

“…Moreover, recently, GnRH neurons in the areas of the brain relevant to neuroendocrine control of reproduction [the preoptic area (POA), arcuate nucleus (ARC), and median eminence (ME)] in humans and rodents were reported to express AMHR2 [ 2 ]. Additionally, we recently reported that 75–85% of cell bodies and fibers of bovine GnRH neurons are positive for both AMH and AMHR2 in the POA, ARC, and the internal and external zones of the ME [ 6 ]. Furthermore, AMH strongly activates GnRH neurons in adult female mice both in vivo and in vitro [ 2 ], and AMHR2-deficient mice showed abnormal development and function of GnRH neurons, which resulted in reduced fertility [ 11 ].…”

“…We obtained POA and ARC&ME tissue samples based on the bovine brain atlas [ 10 , 14 ] using methods detailed in previous studies [ 3 , 6 ] and in Fig. 1.…”

“…1. Schematic illustration of brain tissue sampling according to a previous study [ 6 ]. Briefly, brain tissues were dissected as per the dotted line on the ventral side (A) with the following margins: rostrally-rostral border of the optic chiasm; caudally-rostral to the mammillary bodies; lateral to the optic chiasm; and 0.5 cm dorsal to the third ventricle.…”

“…We then split the block into two parts by cutting rostral to the median eminence (ME), yielding an anterior part containing the preoptic area (POA block) and a posterior part containing the arcuate nucleus and median eminence (ARC&ME block) according to a method reported by Hassaneen et al [ 3 ]. The blocks were further cut using a previously reported method [ 6 ]. Both the POA and ARC&ME blocks were cut at the midlines to obtain left and right sides.…”