Both pre- and postsynaptic mechanisms have been proposed as an explanation of the depressive effects of opioids on the activity of nociceptive dorsal horn neurons. In order to gauge the importance of the two mechanisms, we studied the effect of morphine on the spontaneous hyperactivity of nociceptive dorsal horn neurons in the spinalized decerebrated deafferented rat (C5-Th1). In this preparation, intravenous morphine was shown to depress spontaneous firing rate in a dose-dependent fashion. A comparative analysis of the effect of the same dose of morphine (2 mg/kg i.v.) in the intact spinalized decerebrated arthritic rat, in which dorsal horn convergent neurons also display high spontaneous activity, revealed that systemic morphine is twice as potent when primary afferent fibers are left intact. These results can explain why the analgesic effect of morphine is more marked against pains due to an excess of nociception than against pains arising from deafferentation.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/0304-3959(89)90199-1 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The effects of weight- and non-weight-bearing exercise on corticospinal axon sprouting, regeneration-related proteins and functional recovery after spinal cord contusion.
J Exerc Rehabil
December 2024
Department of Kinesiology, College of Natural Science, Jeju National University, Jeju, Korea.
The purpose of this study was to investigate the effects of weight- and non-weight-bearing exercises on the Basso-Beattie-Bresnahan (BBB) locomotor rating scale, corticospinal axon regrowth and regeneration-related proteins following spinal cord injury (SCI). Twenty-four male Sprague-Dawley rats were randomly divided into four groups: control group (n=6), SCI+sedentary group (SED, n=6), SCI+treadmill exercise group (TREAD, n=6), and SCI+swimming exercise group (SWIM, n=6). All rats in the SCI group were given the rest for 2 weeks after SCI, and then they were allowed to engage in low-intensity exercise for 6 weeks on treadmill device.
View Article and Find Full Text PDF-related gene C (MrgC) receptor activation induced inhibition of neurochemical alterations in the spinal dorsal horn and dorsal root ganglia in a rat model of bone cancer pain.
Sheng Li Xue Bao
December 2024
College of Life Sciences, Fujian Normal University; Fujian Key Laboratory of Developmental and Neuro Biology, Fuzhou 350117, China.
Cancer pain is one of the most common symptoms in patients with advanced cancer. In this study, we aimed to investigate the effects of the -related gene C (MrgC) receptors on bone cancer pain. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured after the inoculation of Walker 256 mammary gland carcinoma cells into the tibia of adult Sprague-Dawley rats.
View Article and Find Full Text PDFBrainstem serotonin amplifies nociceptive transmission in a mouse model of Parkinson's disease.
NPJ Parkinsons Dis
January 2025
Université de Bordeaux, Institut des Maladies Neurodégénératives, Bordeaux, France.
Parkinson's disease arises from the degeneration of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms such as akinesia, rigidity, and tremor at rest. The non-motor component of Parkinson's disease includes increased neuropathic pain, the prevalence of which is 4 to 5 times higher than the general rate. By studying a mouse model of Parkinson's disease induced by 6-hydroxydopamine, we assessed the impact of dopamine depletion on pain modulation.
View Article and Find Full Text PDFIvabradine reduces neuropathic pain after spinal cord injury by inhibiting excitatory synaptic transmission in the spinal dorsal horn.
Neurosci Lett
January 2025
Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi Dori, Chuo-Ku, Niigata City, Niigata 951-8510, Japan. Electronic address:
Spinal cord injuries (SCIs) can lead to severe neuropathic pain and increased risk of myocardial infarction and heart failure; therefore, the use of analgesics against SCI-induced pain should be minimized because of their adverse effects on the cardiovascular system. Ivabradine, a blocker of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels, is used as a bradycardic agent, but recent studies focused on it as an analgesic agent for peripheral neuropathic pain. However, the analgesic effects of ivabradine on central neuropathic pain, such as SCI-induced pain, have not been examined.
View Article and Find Full Text PDFVisualization of primary afferent-evoked excitation of spinal dorsal horn neurons using an intracellular Ca imaging technique in adult rat spinal cord slices.
J Anesth
January 2025
Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Science, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510, Japan.
Article Synopsis
- This study developed a method for intracellular calcium imaging in adult rat spinal cord slices to understand neuronal activity better.
- The research found that the type of stimulation used (A-fiber vs. C-fiber) affected the calcium responses, with different intensity levels leading to distinct response patterns.
- Results showed that certain drugs, like morphine, significantly suppressed calcium responses, while others, like bicuculline and high doses of tranexamic acid, enhanced them, allowing for insights into pain transmission and modulation in the spinal cord.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!