Kisspeptin modulation of nonapeptide and cytochrome P450 aromatase mRNA expression in the brain and ovary of the catfish Heteropneustes fossilis: in vivo and in vitro studies

Abstract

Abstract In the catfish Heteropneustes fossilis, Kisspeptins (Kiss) and nonapeptide (NP) hormones (vasotocin, Vt; isotocin, Itb; the Val8 isotocin paralog, Ita) stimulate the brain-pituitary-gonadal (BPG) axis. The present study investigated the functional interactions between these two systems, and that between Kiss and P450 aromatase (P450 arom) in the catfish brain and ovary. Human Kiss1 and catfish Kiss2 produced dosage-dependent effects on vt, itb and ita expression in vivo: 1 ng/g body weight (BW) and 2 ng/g BW inhibited, and 3 ng/g BW stimulated the expressions. The Kiss peptides (5, 10 and 15 nM) for 24 h produced a concentration - dependent stimulation of the gene expression in vitro. Kiss2 was more effective than Kiss1, both in vivo and in vitro. The Kiss1 administration stimulated ovarian vt, itb and ita expression at 2 and 3 ng/g BW and the Kiss2 treatment inhibited the expression at 1 ng/g BW and stimulated it at 2 and 3 ng/g BW. The Kiss receptor antagonist peptide 234 inhibited the NP mRNA expressions in a dosage/concentration-dependent manner. The Kiss peptide administration stimulated brain-specific cyp19a1b and ovary-specific cyp19a1a P450 arom expression dosage-dependently, both in vivo and in vitro. Peptide 234 inhibited the enzyme gene expression significantly, both in vivo and in vitro. The results show that Kiss peptides modulate functional targets like NP and E2 in the brain and ovary to influence reproductive functions.