GAL and hydrops fetalis: In the context of the transmitters of the ANS, galanin is another potential biomarker implicated in sympathovagal crosstalk, contributing to the paracrine attenuation of the cardiac cholinergic tone following adrenergic hyperactivity: cardiac parasympathetic fibers express galanin and NPY receptors, whose prolonged activation in HF reduces the acetylcholine release, which, in turn, attenuates the cholinergic neurotransmission in the heart [91,92].