Suppressing effects of short-chain fatty acids on growth hormone (GH)-releasing hormone-induced GH release in isolated anterior pituitary cells of goats.
The involvement of tetrodotoxin-sensitive Na+ channels and receptor-operated nonspecific Ca2+ channels, and the effects of short-chain fatty acids, on growth hormone (GH) release induced by GH-releasing hormone (GHRH) were investigated in cultured and freshly isolated caprine anterior pituitary cells. In 3-d cultured cells in Dulbecco's modified Eagle's medium, an increase in GH release induced by GHRH (10 nmol/l) was moderately, but significantly, reduced by a voltage-sensitive Na+ channel antagonist tetrodotoxin (1 micromol). The GHRH-induced GH increase, which was not affected by a simultaneous addition of a receptor-operated nonspecific Ca2+ channel antagonist tetramethrine (0.1 mmol/l), was significantly reduced by a voltage-sensitive L-type Ca2+ channel antagonist nifedipine (1 micromol/l). Propionate and butyrate at 10 mmol/l, however, not only suppressed basal GH release but also significantly reduced the GH increase induced by 10 nmol/l of GHRH. The inhibitory action of these acids was also reproduced by an addition of beta-hydroxy butyrate (10 mmol/l) and octanoate (10 mmol/l). In freshly isolated and perifused cells, butyrate (10 mmol/l) as well as somatostatin (100 nmol/l) significantly reduced the GH increase induced by GHRH. From these findings we conclude that tetrodotoxin-sensitive Na+ channels and voltage-dependent L-type Ca2+ channels are involved in the cellular mechanism for GHRH-induced GH release, and that short-chain fatty acids such as propionate and butyrate have a direct action on somatotrophs to reduce basal and GHRH-induced GH release, in caprine somatotrophs.
Katoh
K
K
Department of Animal Physiology, Faculty of Agriculture, Tohoku University, Tsutsumidori, Sendai, Japan. kato@bios.tohoku.ac.jp
Ohata
Y
Y
Ishiwata
H
H
D000818:Animals; D015220:Calcium Channels / Q000378:metabolism; D002478:Cells, Cultured; D005232:Fatty Acids, Volatile / Q000494:pharmacology*; D006041:Goats / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D009479:Neuropeptides / Q000378:metabolism; D009543:Nifedipine / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction; D015222:Sodium Channels / Q000378:metabolism; D013779:Tetrodotoxin / Q000378:metabolism
D015220:Calcium Channels; D005232:Fatty Acids, Volatile; D009479:Neuropeptides; D015222:Sodium Channels; D013779:Tetrodotoxin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D009543:Nifedipine