Different endogenous analgesia systems are activated by noxious stimulation of different body regions

Fleischmann, Amos; Urca, Gideon

doi:10.1016/0006-8993(88)90113-8

Cited by 14 publications

(3 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This lack of effect was particularly striking in connections can lead to long-term potentiation (LTP) or the anesthetized, obex-transected preparation where the long-term depression (LTD) of synaptic transmission (Bliss C-fiber responses were remarkably stable and identical to the and Lomo 1973;Collingridge and Singer 1990;Ito 1989; controls after high-intensity conditioning. This observation Linden and Connor 1995;Malenka 1994). Little is known suggests that intrinsic spinal mechanisms that were reported about synaptic plasticity at primary afferent synapses with to decrease the spinal transmission of nociceptive signals dorsal horn neurons.…”

Section: Emg Signals and Preparationsmentioning

confidence: 83%

Temporal Summation of C-Fiber Afferent Inputs: Competition Between Facilitatory and Inhibitory Effects on C-Fiber Reflex in the Rat

Gozariu¹,

Bragard

Willer³

et al. 1997

Journal of Neurophysiology

View full text Add to dashboard Buy / Rent full text

Long-lasting facilitations of spinal nociceptive reflexes resulting from temporal summation of nociceptive inputs have been described on many occasions in spinal, nonanesthetized rats. Because noxious inputs also trigger powerful descending inhibitory controls, we investigated this phenomenon in intact, halothane-anesthetized rats and compared our results with those obtained in other preparations. The effects of temporal summation of nociceptive inputs were found to be very much dependent on the type of preparation. Electromyographic responses elicited by single square-wave electrical shocks (2 ms, 0.16 Hz) applied within the territory of the sural nerve were recorded in the rat from the ipsilateral biceps femoris. The excitability of the C-fiber reflex recorded at 1.5 times the threshold (T) was tested after 20 s of electrical conditioning stimuli (2 ms, 1 Hz) within the sural nerve territory. During the conditioning procedure, the C-fiber reflex was facilitated (wind-up) in a stimulus-dependent fashion in intact, anesthetized animals during the application of the first seven conditioning stimuli; thereafter, the magnitude of the responses reached a plateau and then decreased. Such a wind-up phenomenon was seen only when the frequency of stimulation was 0.5 Hz or higher. In spinal, unanesthetized rats, the wind-up phenomenon occurred as a monotonic accelerating function that was obvious during the whole conditioning period. An intermediate picture was observed in the nonanesthetized rat whose brain was transected at the level of the obex, but the effects of conditioning were profoundly attenuated when such a preparation was anesthetized. In intact, anesthetized animals the reflex was inhibited in a stimulus-dependent manner during the postconditioning period. These effects were not dependent on the frequency of the conditioning stimulus. Such inhibitions were blocked completely by transection at the level of the obex, and in nonanesthetized rats were then replaced by a facilitation. A similar long-lasting facilitation was seen in nonanesthetized, spinal rats. It is concluded that, in intact rats, an inhibitory mechanism counteracts the long-lasting increase of excitability of the flexor reflex seen in spinal animals after high-intensity, repetitive stimulation of C-fibers. It is suggested that supraspinally mediated inhibitions also participate in long term changes in spinal cord excitability after noxious stimulation.

show abstract

Section: Emg Signals and Preparationsmentioning

confidence: 83%

Temporal Summation of C-Fiber Afferent Inputs: Competition Between Facilitatory and Inhibitory Effects on C-Fiber Reflex in the Rat

Gozariu¹,

Bragard

Willer³

et al. 1997

Journal of Neurophysiology

View full text Add to dashboard Buy / Rent full text

show abstract

“…All experiments were initiated after an additional 30 minutes of habituation of the animals to the experimenter. Noxious stimuli were delivered with an artery clamp (Dieffenbach BH 27; Aesculap, Federal Republic Germany; 650-750 g; the pinch was mildly painful when tested on the experimenter's skin) placed on the base of the tail in one rat and on the nape of the neck in the second rat (Fleischmann and Urca, 1988) for 20 seconds every 5 minutes during 90 minutes. For a control of nonspecific effects, we used innocuous cutaneous stimulation (brush) of the base of the tail.…”

Section: Noxious Mechanical Stimulationmentioning

confidence: 99%

Subnuclear localization of FOS-like immunoreactivity in the rat parabrachial nucleus after nociceptive stimulation

Hermanson

Blomqvist

1996

J. Comp. Neurol.

View full text Add to dashboard Buy / Rent full text

The effect of noxious stimulation on the expression of FOS-like immunoreactivity (FOS-LI) in neurons of the parabrachial nucleus (PB) was studied in awake, freely moving rats. In one series of experiments, the rats were subjected to noxious mechanical stimulation (pinch) of either the nape of the neck or the base of the tail for 20 seconds every 5 minutes for 90 minutes, and then they were killed by transcardial perfusion after 45-210 minutes. Control animals received innocuous mechanical stimulation (brush) of the tail. Noxious stimuli resulted in FOS-LI in neurons in the dorsal part of the lateral PB, with heavy labeling in the superior lateral (PBsl) and the dorsal lateral (PBdl) subnuclei. FOS-LI was also elicited in the central lateral subnucleus (PBcl) and, although much more sparsely, in the external lateral subnucleus and the Kölliker-Fuse nucleus. Tail and neck stimulation resulted in similar labeling patterns, but more neurons, particularly in PBsl, expressed FOS-LI after pinch of the tail than of the neck. In another series of experiments, rats received injection of 5% formalin into one hindpaw. After 75-90 minutes, FOS-LI was seen in the same parts of PB as after noxious mechanical stimulation. The heaviest labeling was seen on the side contralateral to the injection side, with statistically significant (P < 0.05) side differences present in PBsl and PBdl. In a third series of experiments, rats were hemisected at low cervical-upper thoracic segments, allowed 2 weeks to recover, and then given formalin injections in both hindpaws. Significantly more neurons were FOS-labeled in PBdl, PBsl, and PBcl on the side contralateral to the hemisection than on the ipsilateral side. These observations are discussed in relation to the organization of the spinal afferent input and the efferent connections of PB. It is concluded that the FOS-LI expression in PBdl and PBsl and probably also in PBcl, to a large extent, is evoked by the ascending spinal nociceptive input to PB. Because these subnuclei project to several hypothalamic regions, it is suggested that neurons in PB that express FOS after noxious mechanical and chemical stimulation primarily are involved in autonomic and homeostatic responses to behavioral situations that involve tissue-damaging stimuli.

show abstract

“…These complexities are not limited to isolated paradigms but instead appear to pervade our behavioral paradigms, with a wide range of aversive stimuli paradoxically engaging opposing pain modulatory systems (cf. Amir, 1986; Fleischmann & Urca, 1988; Hendrie, 1989; Jorum, 1988; Kelly, 1982; Netto, Siegfried, & Izquierdo, 1987; Simone & Bodnar, 1982; Vidal & Jacob, 1982a, 1982b, 1986; Wiertelak, Furness, Watkins, & Maier, 1994).…”

mentioning

confidence: 99%

Shock-induced hyperalgesia: II. Role of the dorsolateral periaqueductal gray.

McLemore¹,

Crown²,

Meagher³

et al. 1999

Behavioral Neuroscience

View full text Add to dashboard Buy / Rent full text

Exposure to 3 moderately intense (1-mA) tailshocks has been shown to lower vocalization thresholds to both heat and shock. Previous shock exposure also facilitates the acquisition of conditioned fear as measured by freezing. These observations suggest that shock induces hyperalgesia (enhanced pain). This study explored whether shock-induced hyperalgesia depends on neurons within rostral or caudal portions of the dorsolateral periaqueductal gray (dlPAG). Experiment 1 examined the impact of dlPAG lesions on the acquisition of conditioned fear. Sham-operated rats demonstrated enhanced acquisition after shock exposure; both rostral and caudal lesions eliminated this effect. Experiment 2 showed that tailshock lowered vocalization thresholds to heat in sham-operated but not lesioned subjects. These results suggest that the dlPAG plays a critical role in the production of shock-induced hyperalgesia.

show abstract

Different endogenous analgesia systems are activated by noxious stimulation of different body regions

Cited by 14 publications

References 13 publications

Temporal Summation of C-Fiber Afferent Inputs: Competition Between Facilitatory and Inhibitory Effects on C-Fiber Reflex in the Rat

Temporal Summation of C-Fiber Afferent Inputs: Competition Between Facilitatory and Inhibitory Effects on C-Fiber Reflex in the Rat

Subnuclear localization of FOS-like immunoreactivity in the rat parabrachial nucleus after nociceptive stimulation

Shock-induced hyperalgesia: II. Role of the dorsolateral periaqueductal gray.

Contact Info

Product

Resources

About