Inhibitory effect of somatostatin on the mechanosensitivity of articular afferents in normal and inflamed knee joints of the rat

Pain. 1997 Dec;73(3):377-382. doi: 10.1016/S0304-3959(97)00124-3.


The effect of somatostatin on the sensory activity of primary afferents was studied in normal and acutely inflamed rat knee joints. Fine afferent nerve fibers with conduction velocities of 0.9-18.0 m/s were recorded as single units. All nerve fibers tested responded to local mechanical stimulation, movements of the joint and i.a. injections of KCl (10(-4) mol, 0.1 ml) close to the joint. Somatostatin (10(-4) mol, 0.2 ml) caused no direct response of the units. In normal joints, somatostatin did not change the discharges evoked by non-noxious movements but decreased the responses to noxious movements significantly to about 63% of the responses before the application. In acutely inflamed joints, somatostatin reduced the discharges of non-noxious and of noxious movements to about 55% and 52%, respectively. Injections of somatostatin with lower concentrations (10(-6) mol, 10(-8) mol) i.a. close to inflamed joints revealed shorter and less pronounced reductions of the responses to noxious movements. In a proportion of afferents, substance P (10(-4) mol) and bradykinin (10(-4) mol) were able to increase these responses again. These data indicate that the mechanosensitivity of articular afferents in normal joints may also be regulated by several neuropeptides based on a balance of pro-inflammatory peptides such as substance P, and anti-inflammatory peptides such as somatostatin. In an inflamed joint, pro-inflammatory peptides seem to predominate resulting in a sensitization of the peripheral nerve fibers. In this case, an application of somatostatin or its analogues could be used clinically to compensate this effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Afferent Pathways / drug effects
  • Animals
  • Arthritis / chemically induced
  • Arthritis / drug therapy*
  • Bradykinin / therapeutic use
  • Knee Joint / innervation*
  • Male
  • Rats
  • Rats, Wistar
  • Reference Values
  • Somatostatin / pharmacology*
  • Stress, Mechanical
  • Substance P / therapeutic use


  • Substance P
  • Somatostatin
  • Bradykinin