Japanese
Yamaguchi University, Joint Faculty of Veterinary Medicine

Preventive Physiology and Management

Faculty

HIROYA KADOKAWA, PhD
Associate Professor, Preventive Physiology and Management


Our Lab

 Animal food supply is very important for human in the world. In all of the animal industries, young animals will be sacrificed for meat supply, or female animals (e.g. cows) will lactate after parturition for milk production. For both style, reproduction is the most important limiting factor. It is because if reproduction is not good, number of young animals will be shortage, and female animals cannot become pregnant which is necessary for lactation of mammals. Our field, "Veterinary Preventive Medicine", aims "Advanced Animal Production and Reproduction" in domestic animals in both advanced and developing countries.
 The previous studies and concepts are not enough to clarify important mechanisms and to develop new tools in order to improve production/reproduction in food animals. We have tried to discover new physiological mechanism to suppress or stimulate productive/reproductive performance from the views of management, neuroendocrinology, new hormone and receptors, nutritional factors affecting functions of brain, pituitary and reproductive tracts.
 In recent, many papers have cited the papers of our group. Indeed, at least 25 papers have cited our papers every year, and the 74 papers have cited our papers in 2017. Especially, about 100 papers cited our papers in 2014. Such papers are not only for domestic animals but also for human medicine. Thus, our studies for domestic animals can be extended to human medicine.

Research Topics

  • Roles of newly discovered estrogen receptors to control LH and FSH secretion from gonadotroph in anterior pituitary in domestic animal
  • Clarify important mechanisms for the suppressed oviduct/uterus functions in lean and obese cows, and old cows
  • Clarify important mechanisms in "LIPID RAFT" containing GnRH receptor on the plasma membrane of gonadotroph
  • Develop new diagnose method based on blood indicator for aging of reproductive function in cows
  • Summer heat stress to suppress production and reproduction in domestic animals
  • Vomeronasal 1 pheromoen receptor family expressed in bulls, steers, and estrous and non-estrous heifers

Research Interests

We recently discovered that GnRH receptor is located on special region of plasma membrane namely "lipid raft" (as shown as light blue in the confocal microscope image of left picture). Utilizing this knowledge, we have developed a new method to purify gonadotroph cells from the heterogeneous pituitary cells as shown in the right pictures.


Furthermore, we have recently discovered that the orphan G-protein-coupled receptor (GPR) 61 colocalized with GnRH receptors on the surface of most of bovine gonadotrophs. Also we have discovered that a ligand candidate for GPR61, ethanolamine plasmalogen stimulates FSH and LH secretion from cultured bovine gonadotrophs.


We previously reported that obese heifers (body condition score on 5-point scale is 3.5) have been found to produce fewer excellent-grade embryos than lean (body condition score is 2.75) and normal heifers (body condition score is 3) due to unknown mechanisms.


In recent, we clarified that MIF and GMCSF expressed in bovine oviducts are the 2 important key proteins to cause such suppression. Left picture shows the immunohistochemistry for MIF expression in oviduct in lean, normal, and obese heifers. The primary site of MIF and GMCSF expression in the ampulla and isthmus is the tunica mucosa, the stage of fertilization and early embryogenesis. Right picture is summary of relationship between MIF and GMCSF expressions and body condition.

URL to Our HP

http://web.cc.yamaguchi-u.ac.jp/~hiroya/
(both English and Japanese)