What neurotransmitter is most associated with haptic perception?

In the nervous system, tactile signals are transmitted using glutamate as a principal neurotransmitter at the first sensory synapses in the dorsal horn of the spinal cord and brainstem^[1]. Additionally, research indicates that norepinephrine acts as a neurotransmitter for synaptic transmission from Merkel cells to secondary sensory neurons during gentle touch^[2], while specific neuropeptides such as prokineticin 2 (PROK2) transmit pleasant touch signals^[3].