There are many studies on this on pubmed. Unfortunately most are from the 70's and early 80's but hey, B6 is still B6. Curious Mutt if you happen to know where your E2 is running at? Many people on even that low a dosage still need a minimal amount of AI. Don't judge your AI level only by nip sensitivity as that would be a mistake.
Remember also high doses can cause numbness like I believe you stated, and a loss of coordination (picking up that little bugger may become a biatch)
http://www.ncbi.nlm.nih.gov/pubmed/562688
Easy to find list here:
Primary Prolactin Inhibitor Supplements:
1) Vitamin B6
2) Vitamin E
3) SAM-e
Secondary Prolactin Inhibitor Supplements:
1) Ginseng extract
2) Maca powder
3) Ashwagandha
4) Mucuna pruriens
5) Zinc
6) Ginkgo Biloba
Possibly add calcium d-Glucarate to this but I have to dig a little deeper..
Good post Mutt!