New Zealand Journal of Marine and Freshwater Research abstracts

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Changes in vertebrate-type steroids and 5-hydroxytryptamine during ovarian recrudescence in the Indian spiny lobster, Panulirus homarus

Ramalingam Kirubagaran
Dassiah M. Peter
Gopal Dharani
Nambali V. Vinithkumar
Gopinathapillai Sreeraj
Muthukamatchi Ravindran

National Institute of Ocean Technology
Velachery-Tambaram Main Road
Pallikaranai
Chennai 601 302
Tamil Nadu, India
email: kiruba@niot.res.in

Abstract  Vertebrate-type steroids (estradiol-17b and progesterone) and 5-hydroxytryptamine (5-HT) were examined during the different stages of ovarian maturation in the Indian spiny lobster Panulirus homarus. Estradiol-17b and progesterone in the haemolymph and ovary were quantified by radioimmunoassay. Estradiol-17b was not detectable in the haemolymph when the oocytes were in stage I. It appeared in the haemolymph only as the oocytes attained stage II. Subsequently, a sharp increase in the level of estradiol-17b was observed in the haemolymph of lobsters with stage III oocytes; it then showed a significant fall when the ovary was full of stage IV oocytes. Although progesterone was also not detectable in the haemolymph when the oocytes were in stage I, it gradually increased during stages II and III and reached a peak level during stage IV. Surprisingly, both estradiol-17b and progesterone were detectable in the ovary from stage I onwards. In the ovary, estradiol-17b and progesterone showed peak levels during stages III and IV, respectively. A stage-dependent change in the activity and distribution of 5-hydroxytryptaminergic neurons in the brain and thoracic ganglia was also observed immunocytochemically in relation to ovarian recrudescence. Furthermore, HPLC-EC conducted on the level of 5-HT in the brain and thoracic ganglia indicated similar changes in relation to ovarian maturation. These results strongly suggest that 5-HT is involved in ovarian development through certain inhibitory/stimulatory factors present in the X-organ-sinus gland complex of the eye-stalk in the spiny lobster P. homarus.

Keywords  estradiol-17b; progesterone; 5-hydroxytryptamine; ovary; brain ganglia; thoracic ganglia; Panulirus homarus

M04013; Online publication date 8 June 2005 Received 8 February 2004; accepted 1 September 2004
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39: 527-537
0028-8330/05/3903-0527 © The Royal Society of New Zealand 2005

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