Effects of neonatal capsaicin treatment on nociceptive thresholds in the rat.

نویسندگان

  • J I Nagy
  • D van der Kooy
چکیده

The responsiveness to noxious thermal, mechanical, and chemical stimuli was examined in adult rats that had been treated neonatally with capsaicin. A range of capsaicin doses was employed to determine whether the neurotoxicity of capsaicin to primary afferent fibers would be manifested behaviorally in a selective effect on nociceptive thresholds to specific stimuli. Animals were given 5 to 100 mg/kg of capsaicin at 2 days of age and were examined 2 to 4 months later using the tail flick and hot plate tests to determine thermal thresholds, the paw pressure test to determine mechanical thresholds, and the formalin test to determine chemical thresholds. Significant impairments of treated animals' responses to all three types of stimuli were found at high doses of capsaicin and at doses which seem to lead to the depletion of only unmyelinated primary afferent fibers. Slightly higher doses of capsaicin were required to increase thermal nociceptive thresholds in the tail flick test as compared with the other tests, and mechanical nociception seemed to be the most sensitive to the effects of capsaicin. At any particular dose of capsaicin, considerable variability was found in the responsiveness of animals to noxious stimuli. This may partly explain the inconsistencies in studies of nociceptive thresholds in capsaicin-treated animals. The results also demonstrate the difficulty of correlating the degree of analgesia exhibited by these animals with the extent of loss of primary afferent fibers or with the depletion of afferent putative peptide transmitters.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Effects of intra-fourth ventricle injection of crocin on capsaicin-induced orofacial pain in rats

Objectives: Crocin, a constituent of saffron and yellow gardenia, possesses anti-nociceptive effects. In the present study, we investigated the effects of intra-fourth ventricle injection of crocin in a rat model of orofacial pain. The contribution of opioid system was assessed using intra-fourth ventricle injection of naloxone, an opioid receptor antagonist. Materials and Methods: A guide cann...

متن کامل

Effects of Neonatal C-Fiber Depletion on Interaction between Neocortical Short-Term and Long-Term Plasticity

Introduction: The primary somatosensory cortex has an important role in nociceptive sensory-discriminative processing. Altered peripheral inputs produced by deafferentation or by long-term changes in levels of afferent stimulation can result in plasticity of cortex. Capsaicin-induced depletion of C-fiber afferents results in plasticity of the somatosensory system. Plasticity includes short-term...

متن کامل

Dependence of Nociceptive Detection Thresholds on Physiological Parameters and Capsaicin-Induced Neuroplasticity: A Computational Study

Physiological properties of peripheral and central nociceptive subsystems can be altered over time due to medical interventions. The effective change for the whole nociceptive system can be reflected in changes of psychophysical characteristics, e.g., detection thresholds. However, it is challenging to separate contributions of distinct altered mechanisms with measurements of thresholds only. H...

متن کامل

A Study on the Effect of Concurrent Administraon of Hydroalcoholic Extract of Cannabis Sava and Capsaicin on PTZ-Induced Seizure in Neonatal Rats

Introducon: Concurrent acvity of a set of neurons, due to their severity and extent, causes different seizure behaviors. More than three percent of the world's populaon has epilepsy and convenonal medicaons have undesirable side effects if taken, so access to substances with fewer side effects is essenal. The Cannabis sava is adapted to the Iranian climate and has an-seizure effects due to its ...

متن کامل

Capsaicin (8%) Patch Increases Multiple Electrical Nociceptive Perception Thresholds in Healthy Human Subjects

Background: Pre-operative nociceptive thresholds are able to predict patients susceptible to developing post-operative chronic pain. Thresholds are dependent on stimulus properties (i.e. pulsewidth (PW), number of pulses (NoP), and inter-pulse interval (IPI)) and are related to different mechanisms in the nociceptive system. Measuring multiple thresholds enables a detailed observation of periph...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • The Journal of neuroscience : the official journal of the Society for Neuroscience

دوره 3 6  شماره 

صفحات  -

تاریخ انتشار 1983