Author(s): Kakizawa S, Kaneko T, Hirano T
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Abstract The profile of daily release of somatolactin (SL) and effects of hypothalamic factors on SL secretion from the organ-cultured pituitary of rainbow trout were examined. The daily release of SL was relatively high (340-380 ng/pituitary/day) for the first 2 days and then decreased. After Day 5, the SL release was maintained at a low level (30-50 ng/pituitary/day) until the end of the experiment at Day 7. The secretory patterns of SL differed from those of growth hormone (GH) and prolactin (PRL); GH secretion was consistently high (15-20 microg/pituitary/day), whereas PRL secretion was low (10 ng/pituitary/day) during the experiment. SL release was not stimulated by calcium ionophore on Days 2 and 6, suggesting that SL release was maximal. Dopamine and epinephrine, added separately to the medium, inhibited SL release. In contrast, serotonin, corticotropin-releasing factor, and gonadotropin-releasing hormone stimulated the dopamine-inhibited SL release. Thus, SL secretion is concluded to be under hypothalamic control and regulated by mechanisms different from those affecting PRL and GH secretion.
This article was published in Gen Comp Endocrinol
and referenced in Biochemistry & Pharmacology: Open Access