Fish Physiology and Biochemistry

, Volume 20, Issue 3, pp 219–229

Cellular distribution of insulin-like growth factor II (IGF-II) mRNA and hormonal regulation of IGF-I and IGF-II mRNA expression in rainbow trout testis (Oncorhynchus mykiss)

  • V. Perrot
  • B. Funkenstein

DOI: 10.1023/A:1007735314871

Cite this article as:
Perrot, V. & Funkenstein, B. Fish Physiology and Biochemistry (1999) 20: 219. doi:10.1023/A:1007735314871


In this study, Northern blot analysis of RNA from trout testis revealed a single transcript of insulin-like growth factor II (IGF-II) around 4.7 kb. The cellular distribution of IGF-II mRNA was studied and quantified in different testicular cells enriched populations by RT-PCR. IGF-II mRNA appears to be expressed in all cellular types tested: spermatogonia A and B, primary spermatocytes, spermatids and secondary spermatocytes and Sertoli cells. A significantly higher expression of IGF-II was found in premeiotic germ cells. The levels of IGF-II mRNA appear to be higher than those of IGF-I in immature trout testis, as judged from the semi-quantitative RT-PCR results. These data suggest that in addition to IGF-I, IGF-II may play a role in testicular physiology in fish.

The hormonal regulation of IGF-I and IGF-II gene expression was investigated both in vitro and in vivo using RT-PCR approach. Gonadotropin (GtH) added to testicular explants increased IGF-II mRNA levels but had no effect on IGF-I. No statistically significant effect was observed with androgens. In vivo, GH and pituitary extracts resulted in an 8 fold and 2-3 fold increase in both IGF-I and IGF-II mRNA levels, respectively.

Taken together, our study suggests that IGF-I and IGF-II may act as local mediators of GH and GtHs in fish testis. Moreover, our results imply that in fish testicular cells, IGFs are potential paracrine/autocrine regulators inside the spermatogenic compartment and can act directly on germ cells to stimulate their proliferation.

fish gene expression GH GtH gonad growth factors RT-PCR salmonid 

Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • V. Perrot
    • 1
  • B. Funkenstein
    • 2
  1. 1.Institut National de la Recherche AgronomiqueLaboratoire de Physiologie des PoissonsRennes CedexFrance
  2. 2.Israel Oceanographic & Limnological ResearchHaifaIsrael

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