In Eisenia fetida, during the period of genital activity, the synthesis of androgen by testicular tissues is under the control of a neurohormone elaborated by cerebral ganglia (CG). These ganglia also have a trophic effect on ovarian protein synthesis. Present results confirm that incorporation in vitro of l3H1-leucine by ovaries is stimulated by a cerebral neurohormone. Furthermore, fractions of brain homogenate, obtained by gel filtration on Sephadex G 25, have the same action on ovaries in organ culture as CG. Two specific fractions (fractions 3 and 4) stimulate protein synthesis in the ovary. In the ovarian oocytes, the rate of vitellogenesis is low, since in cultured isolated ovaries the amount of radioactive precursor incorporated is only 0.06% of the amount added and this percentage remains low in the ovaries cultured with fractions 3 and 4 (0.15% and 0.21%, respectively) or with CG (0.24%). Further research is necessary to obtain and characterize the biologically active material. 0 1993 Wiley-Liss, IncIn the earthwormEisenia fetida, the cerebral ganglia (CG) are responsible for several endocrine effects.They induce gametogenetic activity (HerlantMeewis, '59, '67; Saussey, '63) as well as the secretion, by testicular tissues, of an androgen necessary for the differentiation of spermatogonia (Lattaud, '75, '80, '82). It is now known that ovogenesis is an example of autodifferentiation (Lattaud, '73). Cerebral ganglia also control the external sexual characteristics, in particular the maintenance of turgescence of the clitellum (Berjon, '68, and they control the mechanisms of regeneration by the action of an inhibitory factor (Marcel, '67). Several of these effects can be attributed to a neurohormone, a peptide with a relative mass (Mr) of around 2,000 (Marcel and Cardon, '79, '82; Lattaud and Marcel, '83). This cerebral hormone is being purified and its action is either stimulatory or inhibitory according to the timing of its action and the stage of the target cells. In order to study the hormonal control of female gametogenesis, a simple biological test had been devised exploiting organ culture of ovaries in vitro (Lattaud and Marcel, '89). This test evaluates the intraovarian synthesis of proteins by measuring the incorporation of [3H]-leucine, by ovaries that are associated or not with different ganglia of the central nervous system (CNS). As a result, the stimulatory action of the CNS on the 0 1993 WILEY-LISS. INC. metabolism of protein in the ovaries has been clearly revealed, and among the different ganglia of the CNS, only the CG are effective.We attempted to determine whether the brain substance responsible for this stimulation could be isolated and eventually identified as a cerebral hormone. Therefore, a brain homogenate was purified under the same conditions as those chosen for the studies described above. The different fractions obtained were tested in cultures of isolated ovaries in vitro, and ovarian protein synthesis was evaluated by measuring the radioactivity of ovaries after incorp...
