F. Bekhadra, Y.M. Paulet, A. Donval
Abstract:
A large number of studies have been devoted to the involvement of monoamines, serotonin (5-Hydroxytryptamine, 5-MT) and dopamine (DA), in the reproductive process of bivalves. In return, few investigations have evaluated the annual variations of these compounds in the central nervous system (CNS) and in the gonad of animals from the field throughout a year.
The aim of the present study was to quantify two monoamines in CNS cerebropedal (CPG) and visceral ganglia (VG), and gonad of Pecten maximus, and hermaphrodite Pectinidea, throughout a year using a sensitive high performance liquid chromatographic method with electrochemical detection. Three-years-old animals were collected from Bay of Brest and immediately sacrificed for analysis.
5-HT and DA levels were high in the two organs. The results showed notable fluctuations of monoamines in the CNS and gonad relative to seasons. Several important oscillations were identified. The highest annual values were measured in autumn, this period corresponding to a gamete release. The average quantities of 5-HT in the CNS were minimal in June (247 ng/CPG and 474 ng/GV) and maximal in October (1594 ng/CPG, 1372 ng/GV); those of DA were maximal between September and October (726 ng/CPG, 1020 ng/GV) and minimal in December (232 ng/CPG) and in August (523 ng/GV).
In the female part of the gonad, the average quantities measured attained maximum values of 5-HT (2676 ng) and DA (697 ng). In the male part, the average quantities attained maximum values of 7803 ng of 5-HT and 876 ng of DA. We have observed a difference between the two part of the gonad, the female part exhibited higher quantities of monoamines than the male part. This difference can be important (5127 ng of 5-HT in December and 320 ng of DA in June).
In conlusion, we demonstrated seasonal changes of monoamine levels in the CNS and in the reproductive organ, an also changes between the two part of the gonad.
(IUEM, Lab. BIOFLUX, Place Nicolas Copernic, 29280, Plouzane,
France, e-mail: Farida.Bekhadra@univ-brest.fr)