The relationships of neurotransmitter and neuromodulatory systems, especially serotonergic, noradrenergic and glutamatergic, were studied on animal models of pain, stress, anxiety and schizophrenia. N-feruloylserotonin influenced the nociception in rats with higher pain threshold only.
These animals were also more anxious. This serotonin-like substance exhibited selective anxiolytic effects in more anxious animals.
Medetomidine - an alpha2 adrenergic agonist - potentiated ketamine-induced analgesia. Ketamine is selective blockader of NMDA receptors.
Ketamine- blockade of NMDA receptors suppressed the development of neuropathic pain in the model of the brachial plexus avulsion. The CNS lesion induced by quinolinic acid in early postnatal period increased the perception of both acute and neuropathic pain in adulthood.
The same lesion decelerated the learning processes and worsened memory ability. Both anxious behavior and pain modulation are hierarchically organized.
Interaction of stimulus intensity and phenotype or genotype of behavior is decisive which system of antinociception will be activated and therefore which type of behavior will be realized.