vasoactive intestinal polypeptide female 52 Vasoactive Intestinal Peptide 50 priority journal 48 Female 46 controlled study 46 article 34 Pregnancy 32 mouse 32 Animals 30 human 30 nonhuman 30 protein expression 30 Humans 28 Mice 28 animal experiment 28 animal model 28 Mice, Inbred NOD 26 interleukin 10 26 trophoblast 26 Mice, Inbred BALB C 24 Sjoegren syndrome 22 Trophoblasts 22 animal tissue 22 VIP 20 human cell 20 metabolism 20 pregnancy 20 enzyme activity 18 first trimester pregnancy 18