[reverett123]

It is easy to fall into the trap of thinking it is a neurotransmitter only if it is made by a neuron. If we say, however, that it is a neuroransmitter if it makes a neuron fire the field broadens greatly. There's cytokines from the immune system as noted below and as Ron's tooth demonstrated for us and there are hormones from the endocrine system and there are mysterious little chains of proteins floating up from our gut and gosh knows what else.

It is all semantics but serious too because those are in many ways artificial divisions of scientific turf. You have a problem with your brain chemistry you have four different specialties there, most of whom are somewhat vague in their understanding of the others. That is one reason we are stuck in a cul-de-sac.


1: Biol Psychiatry. 2008 Jun 1;63(11):1022-9. Epub 2008 Feb 1.

Peripheral inflammation is associated with altered substantia nigra activity and
psychomotor slowing in humans.

Brydon L, Harrison NA, Walker C, Steptoe A, Critchley HD.

Department of Epidemiology and Public Health, Institute of Neurology at
University College London, London, United Kingdom. l.brydon@ucl.ac.uk

BACKGROUND: Systemic infections commonly cause sickness symptoms including
psychomotor retardation. Inflammatory cytokines released during the innate immune
response are implicated in the communication of peripheral inflammatory signals
to the brain. METHODS: We used functional magnetic resonance brain imaging (fMRI)
to investigate neural effects of peripheral inflammation following typhoid
vaccination in 16 healthy men, using a double-blind, randomized,
crossover-controlled design. RESULTS: Vaccination had no global effect on
neurovascular coupling but markedly perturbed neural reactivity within substantia
nigra during low-level visual stimulation. During a cognitive task, individuals
in whom typhoid vaccination engendered higher levels of circulating interleukin-6
had significantly slower reaction time responses. Prolonged reaction times and
larger interleukin-6 responses were associated with evoked neural activity within
substantia nigra. CONCLUSIONS: Our findings provide mechanistic insights into the
interaction between inflammation and neurocognitive performance, specifically
implicating circulating cytokines and midbrain dopaminergic nuclei in mediating
the psychomotor consequences of systemic infection.


PMID: 18242584 [PubMed - indexed for MEDLINE]