An in vitro study on catecholamine modulation of ovarian steroidogenic activity in the catfish Heteropneustes fossilis

作者：Joy K P^*; Singh V; Chaube R

来源：General and Comparative Endocrinology, 2014, 196: 91-99.

DOI：10.1016/j.ygcen.2013.11.019

• alpha-Methylparatyrosine
• Catecholamines
• Catfish
• L-DOPA
• Ovarian steroids

In the present study, alpha-methylparatyrosine (alpha-MPT), a tyrosine hydroxylase inhibitor was used to impair ovarian catecholaminergic activity in vitro. The consequent effects on catecholamine (CA) levels were correlated with follicular steroid production. L-dihdroxyphenylalanine (L-DOPA, the precursor of CA) and human gonadotropin (hCG) were supplemented to reverse the effect of alpha-MPT. The experiments were conducted in two reproductive phases, namely preparatory and pre-spawning phases in female catfish Heteropneustes fossilis. The incubation with alpha-MPT inhibited ovarian L-DOPA, dopamine (DA), norepinephrine (NE) and epinephrine (EP) levels and the L-DOPA supplementation compensated the inhibitory effect. The level of tyramine (TR) was increased by the alpha-MPT treatment but inhibited by the L-DOPA supplementation. alpha-MPT produced stage-specific (seasonal) effects on ovarian estradiol-17 beta (E-2); in the preparatory phase, E-2 was decreased significantly at both 12 and 24 h and in the pre-spawning phase, the level was stimulated over the respective control groups. The changes were higher at 24 h in both phases. L-DOPA and hCG increased the E-2 level significantly in the preparatory phase and reversed the inhibitory effect of alpha-MPT in the co-incubation groups. In the pre-spawning phase, alpha-MPT-stimulated the E-2 level compared to the control groups, which was reversed by L-DOPA, hCG, or by both, in co-incubations. In contrast, the alpha-MPT treatment decreased progesterone (P-4), 17-hydroxyprogesterone and 17,20 beta-dihydroxy-4-prenen-3-one (17,20 beta-DP) in a duration-dependent manner while the co-incubations with L-DOPA, hCG, or by both, significantly reversed the inhibitory effect. These results suggest that ovarian CAs (DA, NE and EP) may exert differential and stage-specific effects on E-2, inhibition in the preparative phase and stimulation in the pre-spawning phase. The progestin steroids appear to be stimulated by CAs. In conclusion, this study highlights a possible direct/causal functional interaction between CA activity and gonadotropin on steroidogenic activity, and that CAs may be involved in regulating temporal secretion of the hormones through causing the shift in steroidogenic pattern.

• 出版日期2014-1-15