ABSTRACT
In a preliminary report, Crim (1981) reported that some catacholamines inhibited GtH release from cultured pituitaries of rainbow trout. Further work has shown that GnRIF is probably a dopamine. Injections of dopamine into mature female goldfish suppressed GtH secretion. But injections of either pimozide, domperidone, spiperone or haloperidol, any one of these dopamine antagonists, followed by LH-RH injections 12 hours later induced virtually 100% ovulation and very high plasma GtH levels. Injections of LH-RH alone are far less effective (Chang et al., 1983, Peter et al., 1983). Taking advantage of this investigation in recent years, the Linpe method which involves the combination of a GnRH analogue (LHRH-A or GnRH-A) and dopamine antagonist for induced ovulation and spawning has proven to be successful with common carp, mud carp, bream, grass carp, bighead, black carp and leach (Peter et al., 1988, Peter and Yu, 1997). However, Atlantic croaker (Micropogonias undulates) has been demonstrated to be an exception in that no evidence of DA inhibition of GtH secretion has been found, in spite of a thorough search (Copeland and Thomas, 1989).
