With all the hormones and whatnot inside. Dopamine, adrenaline, melatonin, whatever. Also, there’s this Hunter S. Thompson bit on the… pineal gland?
If it had an effect on you, wouldn’t it be a really messed up high, all over the place? With uppers, downers etc mixed? (Not including the emotional implications of eating raw human brains.)
For whatever reason prion disease has a chance to spontaneously occur when mammals cannibalize. Especially if they are obligate herbivores. Prion disease was originally discovered in cows transmitting it to humans due to some particularly sick fuck running a slaughter factory thinking it would be a good idea to put cow meat scraps back in their feed soylent green style.