N-methyl-D,L-aspartate modulation of luteinizing hormone and growth hormone secretion from pig pituitary cells in culture.
Administration of n-methyl-d, l-aspartate (NMA) to pigs in vivo increased GH and suppressed LH secretion. Cultures of anterior pituitary cells from pigs in the follicular phase (FOL; n = 3) and luteal phase (LUT; n = 3) of the estrous cycle, and ovariectomized (OVX; n = 10) pigs were treated with NMA (10(-4), 10(-6) or 10(-8) M) or the NMA antagonist, 2-amino-5-phosphonopentanoic acid (AP5; 10(-4), 10(-6) or 10(-8) M), to determine if NMA affects the pituitary directly. Secreted LH and GH were measured at 4 h after treatment. Basal LH and GH secretion (control; C) were 1.1 +/- 0.6, 4.4 +/- 2.1 and 5.6 +/- 1.3 ng/well and 5.2 +/- 1.2, 7.5 +/- 1.2 and 5.2 +/- 1.7 ng/well for FOL, LUT and OVX, respectively. Relative to C, 10(-4) M NMA increased (P < 0.001) LH secretion 2.4-, 2.2- and 5.1-fold in FOL, LUT and OVX cultures, respectively. The effect of 10(-4) M NMA was inhibited by 10(-4) M AP5 (P < 0.05) in FOL cultures, but not in OVX cultures. GnRH increased (P < 0.001) LH levels 3.1-, 2.3- and 3.8-fold in FOL, LUT and OVX cultures, respectively. Relative to C, 10(-4), 10(-6) and 10(-8) M NMA increased (P < 0.03) GH secretion 1.5-, 1.5- and 2.3-fold in LUT and 1.7-, 2.3- 2.0-fold in OVX cultures, respectively. AP5 alone or in combination with NMA failed to alter basal GH secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
Barb
C R
CR
United States Department of Agriculture, Agricultural Research Service, Athens, GA 30613.
Barrett
J B
JB
Rampacek
G B
GB
Kraeling
R R
RR
D000818:Animals; D002478:Cells, Cultured; D004971:Estrus / Q000502:physiology; D005260:Female; D013006:Growth Hormone / Q000187:drug effects* / Q000378:metabolism; D007986:Luteinizing Hormone / Q000187:drug effects* / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology*; D010052:Ovariectomy; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013552:Swine
D016202:N-Methylaspartate; D007986:Luteinizing Hormone; D013006:Growth Hormone