Kisspeptin signaling in the brain is involved in the control of the onset of puberty
in vertebrates. In this study, we present novel evidence indicating that kisspeptin
may link energy balance and reproduction. For that purpose, we determined the complete
gene structure of kisspeptin in a teleost fish, the Senegalese sole (Ss). In contrast
to the situation evident in several fish, in this species only Kiss2 was found. Yet,
two Ss Kiss2 isoforms generated by alternative splicing through intronic retention
were detected: Ss Kiss2_v1, producing the functional protein, and Ss Kiss2_v2, coding
for a truncated, non-functional protein. Specific qPCRs showed that the expression
of these two isoforms varied differently in brain and gonads throughout maturation.
In addition, and in contrast to what has been observed in mammals, fasting increased
hypothalamic mRNA levels of Ss Kiss2_v1, which also caused a concomitant rise in pituitary
Ss LH and Ss FSH mRNA. Together, these data indicate the impact of the nutritional
status on Kiss mRNA expression as a potential regulatory mechanism for the metabolic
control of reproduction in non-mammalian species, albeit with some significant differences
with respect to the situation described in mammals.
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