Seasonal changes in the hypothalamo-pituitary-testes axis of the Japanese wood mouse (Apodemus speciosus).
Seasonal changes in the hypothalamo-pituitary-testes axis of the Japanese wood mice (Apodemus speciosus) were studied. The testes, epididymis, pituitary and hypothalamus were compared between mice in the breeding season (July) and non-breeding season (October) using morphological techniques, and the plasma testosterone level was evaluated by enzyme immunoassay. Significant differences in these tissues were observed between the breeding season and the non-breeding season. Specifically, differences in the non-breeding season included 1) a decline in testicular and epididymal weights, arrest of spermatogenesis and decrease of serum testosterone concentration; 2) a decrease in the number of luteinizing hormone (LH)-, follicle stimulating hormone (FSH)-, prolactin (PRL)-, and growth hormone (GH)-immunoreactive cells, and decrease in the size of FSH, PRL, and GH-immunoreactive cells; and 3) an increase in the size of gonadotropin-releasing hormone (GnRH)-immunoreactive neurons. Our findings indicate that the male adult Japanese wood mouse exhibits unique seasonal changes in the hypothalamo-pituitary-testes axis which are not found in laboratory mice.
Kuwahara
S
S
Department of Veterinary Anatomy, Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, Osaka, Japan.
Mizukami
T
T
Omura
M
M
Hagihara
M
M
Iinuma
Y
Y
Shimizu
Y
Y
Tamada
H
H
Tsukamoto
Y
Y
Nishida
T
T
Sasaki
F
F
D000818:Animals; D001947:Breeding; D004822:Epididymis / Q000737:chemistry / Q000166:cytology / Q000502:physiology; D005640:Follicle Stimulating Hormone / Q000032:analysis; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis; D013006:Growth Hormone / Q000032:analysis; D007030:Hypothalamo-Hypophyseal System / Q000166:cytology / Q000502:physiology*; D007118:Immunoassay; D007986:Luteinizing Hormone / Q000032:analysis; D008297:Male; D051379:Mice; D009929:Organ Size; D010903:Pituitary Gland, Anterior / Q000737:chemistry / Q000166:cytology / Q000502:physiology; D011388:Prolactin / Q000032:analysis; D012621:Seasons; D013737:Testis / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D013739:Testosterone / Q000097:blood
D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone