Purification and Properties of Interstitial Cell-stimulating Hormone from Sheep Pituitary Glands

The brain–pituitary–gonad axis in male teleosts, with special emphasis on flatfish (Pleuronectiformes)

The key component regulating vertebrate puberty and sexual maturation is the endocrine system primarily effectuated along the brain-pituitary-gonad (BPG) axis. By far most investigations on the teleost BPG axis have been performed on salmonids, carps, catfish and eels. Accordingly, earlier reviews on the BPG axis in teleosts have focused on these species, and mainly on females (e.g. 'Fish Physiology, vol. IXA. Reproduction (1983) pp. 97'; 'Proceedings of the Fourth International Symposium on the Reproductive Physiology of Fish. FishSymp91, Sheffield, UK, 1991, pp. 2'; 'Curr. Top. Dev. Biol. 30 (1995) pp. 103'; 'Rev. Fish Biol. Fish. 7 (1997) pp. 173'; 'Proceedings of the Sixth International Symposium on the Reproductive Physiology of Fish. John Grieg A/S, Bergen, Norway, 2000, pp. 211'). However, in recent years new data have emerged on the BPG axis in flatfish, especially at the level of the brain and pituitary. The evolutionarily advanced flatfishes are important model species both from an evolutionary point of view and also because many are candidates for aquaculture. The scope of this paper is to review the present status on the male teleost BPG axis, with an emphasis on flatfish. In doing so, we will first discuss the present understanding of the individual constituents of the axis in the best studied teleost models, and thereafter discuss available data on flatfish. Of the three constituents of the BPG axis, we will focus especially on the pituitary and gonadotropins. In addition to reviewing recent information on flatfish, we present some entirely new information on the phylogeny and molecular structure of teleost gonadotropins.

Isolation and characterization of FSH and LH from pituitary glands of Atlantic halibut (Hippoglossus hippoglossus L.)

Two gonadotropins (GtH), follicle-stimulating hormone (FSH) and luteinizing hormone (LH), were isolated and characterized from pituitary glands of Atlantic halibut (Hippoglossus hippoglossus L.). Glycoproteins were extracted in 40% ethanol followed by precipitation in 85% ethanol. Subsequently, glycoproteins were fractionated by ion-exchange chromatography on a Whatman DE-52 column using a stepwise gradient of ammonium bicarbonate (50-1000 mM). Intact FSH and LH were finally purified on rpHPLC using an AsahiPak C4P-50 column with an acetonitrile gradient (10-60%). SDS-PAGE showed a molecular mass of 33 and 32 kDa for intact FSH and LH, respectively. Final purification of subunits was performed by a subsequent purification step on rpHPLC using a Phenomenex Jupiter C18 column with an acetonitrile gradient (10-60%). FSHbeta, LHbeta, and the common alpha subunit showed molecular masses of 25, 24, and 19 kDa, respectively. Subunit identity was confirmed by N-terminal amino acid sequencing. Intact FSH and LH showed gonadotropic activity by stimulating release of 11-ketotestosterone from turbot (Scophthalmus maximus L.) testicular tissue in vitro. This provides the first purification of two distinct GtHs from an evolutionary advanced pleuronectiform teleost.

Ovulation in hamster: induction by subunit of ovine interstitial cell stimulating hormone

As little as 5 micrograms of interstitial cell stimulating hormone (ICSH) or 20 micrograms of ICSH-beta is effective for the induction of ovulation in 100 percent of hamsters treated at 0500 hours on day 4 after lordosis, whereas as much as 800 micrograms of ICSH-alpha is ineffective. Both ICSH and ICSH-beta are also effective for induction of ovulation in hypophysectomized animals. Thus, the ovulation-inducing activity of the ICSH molecule resides in its beta subunit.