Biochemical Factors Involved in the FSH Action on Amino Acid Transport in Immature Rat Testes

Summary

Testes of 15-day-old rats preincubated and incubated during different times with various doses of FSH (0.2; 2.0 and 20.0 mU/ml) in Krebs-Ringer bicarbonate (KRb) buffer increase the uptake of [¹⁴C] methylaminoisobutyric acid and [¹⁴C] aminoisobutyric acid. The basal and FSH stimulated amino acid transport occurs at absolute lower levels when the protein or glycoprotein synthesis is inhibited by cycloheximide (350 μmol/l) or tunicamycin (12 μmol/l) or when the microtubules are depolimerized with colchicine (1.2 μmol/l). However, the proportional increase of amino acid transport produced by FSH was maintained. The blockage of the voltage-dependent Ca⁺⁺ channels with verapamil or the competitive inhibition of the bivalent ion channels by Co⁺⁺ or Ni⁺⁺ nullified the stimulatory action of FSH on the amino acid transport. Also quinine, that blocks the ATP dependent K⁺ channels, abolished the FSH action. It was concluded that in immature rat testes FSH stimulates amino acid transport through a mechanism involving voltage-dependent Ca⁺⁺ channels and ATP-sensitive K⁺ channel.

Key words

FSH in Amino Acid Transport - Sertoli Cells and FSH - Amino Acid Transport in Sertoli Cells