Effects of Cyclic AMP and Dibutyryl Cyclic AMP on Amino Acid Transport in the Isolated Rat Ovary

Abstract

Prepubertal rat ovaries were incubated in medium containing the non-utilizable amino acids α-aminoisobutyric acid (AIB-¹⁴C) or 1-aminocyclo-pentane-carboxylic acid (cycloleucine-¹⁴C). The rate of uptake of the two amino acids was studied in the isolated ovaries after different incubation periods. Addition of 5 mM cyclic AMP (cAMP) caused a slight stimulation of the AIB-transport but in higher concentrations (10-25 mM) an inhibition was noted. With dibutyryl cyclic AMP (dbcAMP) a dose-dependent increase was seen with 0.5-5 mM concentrations with no further effect of higher concentrations. Time course studies were performed with both AIB and cycloleucine in presence of 10 mM dbcAMP and increased uptake values were noted at each time studied (30-240 min). The phosphodiesterase inhibitor aminophylline in lower concentrations did not influence AIB-transport but 5-10 mM caused increased uptake values in the ovaries. The stimulatory action of dbcAMP on amino acid transport was augmented by a low concentration of aminophylline (0.5 mM). Experiments were in addition carried out in the presence of puromycin and under these circumstances it was still possible to enhance amino acid transport by addition of dbcAMP. The results are discussed in relation to earlier reported effects of gonadotrophins on ovarian amino acid transport.

Key words

Ovary - Cyclic AMP - Amino Acid Transport