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Adenosine inhibition of synaptic transmission in the substantia gelatinosa. ganglia (DRG) and trigeminal ganglia (Woolf and Ma, 2007). For nearly fifty years, it was known that many small-diameter DRG neurons expressed a histochemically identifiable acid phosphatase (Colmant, 1959), commonly referred to as Fluoride-Resistant Acid Phosphatase (FRAP) or Thiamine Monophosphatase (TMPase) (Dodd et al., 1983; Knyihar-Csillik et al., 1986). TMPase dephosphorylates diverse substrates, including the Vitamin B1 derivative thiamine monophosphate (TMP) and 5-nucleotide monophosphates (Dodd et al., 1983; Sanyal and Rustioni, 1974; Silverman and Kruger, 1988a). TMPase was intensively studied in the 1980s in an effort to determine its molecular identity and function. TMPase marks most nonpeptidergic DRG neurons, a subset of peptidergic DRG neurons and unmyelinated axon terminals in lamina II of the dorsal spinal cord (Carr et al., 1990; Dalsgaard et al., 1984; Dodd et al., 1983; Hunt and Rossi, Banoxantrone dihydrochloride 1985; Knyihar-Csillik et al., 1986; Nagy and Hunt, 1982; Silverman and Kruger, 1988a). Since peptidergic and nonpeptidergic neurons are generally considered to be nociceptive (Woolf and Ma, 2007), these anatomical studies suggested TMPase might function in nociception. Moreover, TMPase staining in lamina II of spinal cord is reduced or eliminated when peripheral nerves are damaged (Colmant, 1959; Csillik and Knyihar-Csillik, 1986; Shields et al., 2003; Tenser, 1985; Tenser et al., 1991). Ultimately, studies of TMPase waned when it was found that isolectin B4 (IB4) co-localized with TMPase and was an easier-to-use marker of nonpeptidergic neurons (Silverman and Kruger, 1988b; Silverman and Kruger, 1990). More importantly, the gene encoding TMPase was never identified, making it impossible to study the molecular and physiological function of TMPase in sensory neurons. In an attempt to identify the TMPase gene, Dodd and co-workers partially purified TMPase protein from rat DRG using chromatography (Dodd et al., 1983). The partially purified rat protein was inhibited by the nonselective acid phosphatase inhibitor L(+)-tartrate and was similar in molecular weight to the secretory isoform of human prostatic acid phosphatase (PAP, also known as ACPP), the only known isoform of PAP at the time (Ostrowski and Kuciel, 1994). These biochemical experiments hinted that TMPase might be secretory PAP (Dodd et al., 1983). However, subsequent studies using anti-PAP antibodies failed to immunostain small-diameter DRG neurons and their axon terminals in lamina II (i.e. the neurons and axons that contain TMPase) (Dodd et al., 1983; Silverman and Kruger, 1988a). As summarized by Silverman and Kruger in 1988, these data made it impossible to determine if TMPase was PAP or some other enzyme. In light of this unsolved question regarding the molecular nature of TMPase and the historical use of TMPase as a nociceptive neuron marker, we sought to definitively identify the TMPase gene and ascertain its function in nociception. Our experiments revealed that TMPase was a recently-discovered transmembrane (TM) isoform of PAP (TM-PAP) (Quintero et al., 2007) and was not the secretory isoform of PAP. This molecular identification then allowed us to use modern molecular and genetic approaches to rigorously study the function of PAP/TMPase in nociceptive circuits. Using our PAP knockout mice, we found that deletion of PAP increased thermal hyperalgesia (increased pain sensitivity) and mechanical allodynia in animal models of chronic pain. Conversely, a single intraspinal injection of PAP protein had anti-nociceptive, anti-hyperalgesic and anti-allodynic effects that lasted for up to three days, much longer than a single injection of the commonly used opioid analgesic morphine. Mechanistically, we found that PAP is an ectonucleotidase that dephosphorylates extracellular AMP to adenosine and requires A1-adenosine receptors (A1Rs) for anti-nociception. PAP has been intensively studied for seventy years in the prostate cancer field (Gutman and Gutman, 1938). Despite decades of research, the molecular and physiological functions for PAP remained unknown. Our studies with pain-sensing neurons are the first to identify the substrate, the molecular mechanism and the physiological function for this medically-relevant protein. Moreover, we are the first to show that PAP functions in nociception. Considering that TM-PAP is expressed throughout the body (Quintero et al., 2007), PAP could regulate diverse physiological processes that are dependent on adenosine (Jacobson and Gao,.Moreover, central injection of PAP can rescue behavioral deficits caused by deletion of PAP throughout the animal (Figure 6). Although our data clearly support a central mechanism of action, we cannot exclude the possibility that PAP might also generate adenosine peripherally to mediate anti-nociception. monophosphate (AMP) to adenosine and activates A1-adenosine receptors in dorsal spinal cord. Our studies reveal molecular and physiological functions for PAP in purine nucleotide metabolism and nociception and suggest a novel use for PAP in the treatment of chronic pain. INTRODUCTION tissue-damaging and Unpleasant stimuli are sensed by small-diameter nociceptive neurons, situated in the dorsal main ganglia (DRG) and trigeminal ganglia (Woolf and Ma, 2007). For pretty much fifty years, it had been known that lots of small-diameter DRG neurons portrayed a histochemically identifiable acidity phosphatase (Colmant, 1959), typically known as Fluoride-Resistant Acidity Phosphatase (FRAP) or Thiamine Monophosphatase (TMPase) (Dodd et al., 1983; Knyihar-Csillik et al., 1986). TMPase dephosphorylates different substrates, like the Supplement B1 derivative thiamine monophosphate (TMP) and 5-nucleotide monophosphates (Dodd et al., 1983; Sanyal and Rustioni, 1974; Silverman and Kruger, 1988a). TMPase was intensively examined in the 1980s in order to determine its molecular identification and function. TMPase marks most nonpeptidergic DRG neurons, a subset of peptidergic DRG neurons and unmyelinated axon Banoxantrone dihydrochloride terminals in lamina II from the dorsal spinal-cord (Carr et al., 1990; Dalsgaard et al., 1984; Dodd et al., 1983; Hunt and Rossi, 1985; Knyihar-Csillik et al., 1986; Nagy and Hunt, 1982; Silverman and Kruger, 1988a). Since peptidergic and nonpeptidergic neurons are usually regarded as nociceptive (Woolf and Ma, 2007), these anatomical research recommended TMPase might function in nociception. Furthermore, TMPase staining in lamina II of spinal-cord is decreased or removed when peripheral nerves are broken (Colmant, 1959; Csillik and Knyihar-Csillik, 1986; Shields et al., 2003; Tenser, 1985; Tenser Banoxantrone dihydrochloride et al., 1991). Eventually, research of TMPase waned when it had been discovered that isolectin B4 (IB4) co-localized with TMPase and was an easier-to-use marker of nonpeptidergic neurons (Silverman and Kruger, Banoxantrone dihydrochloride 1988b; Silverman and Kruger, 1990). Moreover, PP2Abeta the gene encoding TMPase was hardly ever identified, rendering it impossible to review the molecular and physiological function of TMPase in sensory neurons. So that they can recognize the TMPase gene, Dodd and co-workers partly purified TMPase proteins from rat DRG using chromatography (Dodd et al., 1983). The partly purified rat proteins was inhibited with the nonselective acid solution phosphatase inhibitor L(+)-tartrate and was very similar in molecular fat towards the secretory isoform of individual prostatic acidity phosphatase (PAP, also called ACPP), the just known isoform of PAP at that time (Ostrowski and Kuciel, 1994). These biochemical tests hinted that TMPase may be secretory PAP (Dodd et al., 1983). Nevertheless, subsequent research using anti-PAP antibodies didn’t immunostain small-diameter DRG neurons and their axon terminals in lamina II (i.e. the neurons and axons which contain TMPase) (Dodd et al., 1983; Silverman and Kruger, 1988a). As summarized by Silverman and Kruger in 1988, these data managed to get impossible to see whether TMPase was PAP or various other enzyme. In light of the unsolved question about the molecular character of TMPase as well as the historical usage of TMPase being a nociceptive neuron marker, we sought to definitively recognize the TMPase gene and ascertain its function in nociception. Our tests uncovered that TMPase was a recently-discovered transmembrane (TM) isoform of PAP (TM-PAP) (Quintero et al., 2007) and had not been the secretory isoform of PAP. This molecular id after that allowed us to make use of contemporary molecular and hereditary methods to rigorously research the function of PAP/TMPase in nociceptive circuits. Using our PAP knockout mice, we discovered that deletion of PAP elevated thermal hyperalgesia (elevated discomfort awareness) and mechanised allodynia in pet types of chronic discomfort. Conversely, an individual intraspinal shot of PAP proteins acquired anti-nociceptive, anti-hyperalgesic and anti-allodynic results that lasted for three days, a lot longer than a one injection.