Health-Related Quality of Life in Adrenocortical Carcinoma: Development of the Disease-Specific Questionnaire ACC-QOL and Results from the PROFILES Registry.

We aimed to develop a disease-specific adrenocortical carcinoma (ACC) health-related quality of life (HRQoL) questionnaire (ACC-QOL) and assess HRQoL in a population-based cohort of patients with ACC. Development was in line with European Organization for Research and Treatment of Cancer (EORTC) guidelines, though not an EORTC product. In phase I and II, we identified 90 potential HRQoL issues using literature and focus groups, which were reduced to 39 by healthcare professionals. Pilot testing resulted in 28 questions, to be used alongside the EORTC QLQ-C30. In Phase III, 100 patients with ACC were asked to complete the questionnaires twice in the PROFILES registry (3-month interval, respondents: first 67, second 51). Confirmatory factor analysis demonstrated the structural validity of 26 questions with their scale structure (mitotane side-effects, hypercortisolism/hydrocortisone effects, emotional effects). Internal consistency and reliability were good (Cronbach's alpha 0.897, Interclass correlation coefficient 0.860). Responsiveness analysis showed good discriminative ability (AUC 0.788). Patients diagnosed more than 5 years ago reported a good HRQoL compared with the Dutch reference population, but experienced residual fatigue and emotional problems. Patients who underwent recent treatment reported a lower HRQoL and problems in several domains. In conclusion, we developed an ACC-specific HRQoL questionnaire with good psychometric properties.

Sex difference in the number of the sympathetic neurons in the spinal cord of the cat.

Counts of preganglionic sympathetic neurons in the spinal cords of four male and four female cats were obtained. The number of these neurons in males was significantly greater than that in females. These data suggest that the numbers of neurons in the mammalian central nervous system are different in the two sexes.

Sensory neuron and substance P involvement in symptoms of a zymosan-induced rat model of acute bowel inflammation.

Intestinal inflammation is a painful syndrome with multiple symptoms, including chronic pain. This study examined the possible role of sensory neurons and substance P in symptoms of an animal model of acute intestinal inflammation. The model was induced by injecting ethanol and zymosan into the colon of anesthetized male rats. Three hours later, sections of the colon were stained with hematoxylin and eosin. To determine the role of substance P, 5 mg/kg of the neurokinin-1 receptor (NK-1r) antagonist, CP-96,345, or 300 microg/kg of an antisense oligonucleotide targeted at NK-1r mRNA was administered. Spinal cord sections were examined for internalization of NK-1r, as an indicator of substance P release. Sections of colon revealed infiltration of inflammatory cells following ethanol and zymosan treatment. Plasma extravasation in rats given ethanol and zymosan was significantly greater than in controls given saline only (P<0.0001) or saline and ethanol (P<0.001). In ethanol- and zymosan-treated rats given CP-96,345, plasma extravasation was significantly less than in rats given ethanol and zymosan without the antagonist (P<0.0001). Administration of the antisense oligonucleotide also resulted in lower levels of plasma extravasation compared with controls (P<0.01). Internalization of the NK-1r was observed in neurons of lamina I in the T13-L2 and L6-S2 regions of the spinal cord, as well as in sympathetic preganglionic neurons at the L1 level. This internalization was observed in the absence of any other stimulus besides the inflammation itself. This study implicates substance P and its receptor, the NK-1r, in acute inflammation of the colon.

Bigeminal rhythms, common and uncommon mechanisms.

Bigeminy is an often encountered arrhythmia in clinical practice. There are common and uncommon mechanisms for bigeminy. Typical examples are illustrated with their salient electrocardiographic and clinical features. When one encounters a bigeminal rhythm, an awareness of these numerous possibilities will facilitate arriving at the correct diagnosis, which is where quality patient care begins.

High-level expression of the ribosomal protein L19 in human breast tumors that overexpress erbB-2.

The erbB-2 (or HER-2 or neu) gene is amplified and overexpressed in approximately one-third of cancers of the breast, stomach, and ovary. Evidence is accumulating that erbB-2 overexpression is associated with decreased survival of breast cancer patients. In an effort to understand how erbB-2 overexpression might impart a more malignant potential to breast cancer cells, we have searched for evidence of changes in gene expression associated with erbB-2 overexpression. Using differential screening of a complementary DNA library we identified several complementary DNAs that represent mRNAs the expression of which may vary according to erbB-2 level. One complementary DNA was studied in detail. The mRNA encoding the ribosomal protein L19 (1.9 kilobases) was more abundant in breast cancer samples that express high levels of erbB-2 (P < 6 x 10(-7)). The level of L19 mRNA expression varied over a 1- to 64-fold range among the tumor samples. No evidence of gene amplification for L19 was identified. The L19 overexpression in these breast tumor samples was not associated with the increased expression of the mRNAs for other ribosomal proteins (S16 and L26).

Circulating opioids: possible physiological roles in central nervous function.

Evidence is reviewed regarding the release of endorphins by such diverse conditions as stress, long distance running, acupuncture, sexual activity, suggestion and ritualistic dancing ceremonies. Additional evidence is cited regarding possible physiological roles of endorphins in antinociception, socialization, euphoria, some mental disorders, drive states and vegetative functions. The concentration of this latter type of evidence is on conditions during which endorphins seem to be exerting effects on a number of different systems together (for example, euphoria is almost always accompanied by analgesia), and the possibility is suggested that the activation of a number of functions together may be due to a global activation of opiate receptors throughout the CNS. A possible basis for this global activation arises from results from this laboratory indicating the presence of a blood-borne opioid hormone, secreted by the pituitary or by an endocrine gland under pituitary control, which is capable of passing from the blood into the CNS. This diffuse endorphinergic system, which is complementary to the well-established endorphinergic neuronal systems in the CNS, thus derives its property of global action on opiate receptors by the diffuse means by which the hormone reaches its target sites, i.e., by passing through the blood brain barrier. Thus, while each specific endorphin-mediated function can be activated by the activation of its respective neural pathway, it is proposed that the hormonal endorphinergic mechanism is activated to produce a global response provoked by conditions to which a more generalized response, including physiological and behavioural changes, is most appropriate.

Quantitative analysis of substance P-immunoreactive boutons on physiologically characterized dorsal horn neurons in the cat lumbar spinal cord.

A quantitative analysis of substance P (SP)-immunoreactive (IR) terminals contacting physiologically characterized dorsal horn neurons was performed. Three types of neuron were studied: nociceptive specific (NS) from lamina I (n = 3), wide dynamic range (WDR) from laminae II-IV (n = 3), and nonnociceptive (NN) from lamina IV (n = 3). The nociceptive response of focus was a slow, prolonged depolarization to noxious stimuli, because this response was previously shown to be blocked by selective neurokinin-1 (NK-1) receptor antagonists. Ultrastructural immunocytochemistry was used to quantify the relative number of SP-IR boutons apposed to the intracellularly labeled cell per unit of length (density). Densities of the total population (SP immunoreactive+nonimmunoreactive) of apposed boutons were similar in all three regions (cell body, proximal and distal dendrites) for the three functional types of neuron. NS neurons received a significantly higher density of appositions from SP-IR boutons than NN cells in all three regions. However, compared to WDR cells, NS cells possessed a significantly higher density of appositions from SP-IR boutons only in the cell body and proximal dendrites. WDR cells had a higher density of appositions from SP-IR boutons than NN cells, but only in the proximal and distal dendrites. On average, 33.5% of the SP-IR boutons apposed to the cells displayed a synaptic contact. Finally, 30-45% of the SP-IR boutons apposed to the cells colocalized calcitonin gene-related protein (CGRP) immunoreactivity, indicating their primary sensory origin. The data indicate a direct correlation between the amount of SP-IR input and the nociceptive nature of the cells and suggest that SP acts on NK-1 receptors at a short distance from its release site.

Relationship between mechano-receptive fields of dorsal horn convergent neurons and the response to noxious immersion of the ipsilateral hindpaw in rats.

This study examines the relationship between mechano-receptive fields (inhibitory and excitatory, located on the ipsilateral hindpaw) of convergent dorsal horn neurons, and the responses of the neurons to noxious immersion of an entire paw in noxious hot water. In pentobarbital anesthetized rats with intact spinal cords and in unanesthetized decerebrate-spinalized rats, rat hindpaws were immersed in 50 degrees C water for 10 s after the mechano-receptive fields had been delineated using 5-s noxious pinches. Convergent neurons were either excited or inhibited by noxious immersion of the hindpaw. In both groups, a significant association (chi2, P < 0.01) was found between the make-up of the mechano-receptive field and the response of the neuron to immersion. Immersion-inhibited neurons (intact = 27, spinalized = 13), always had both an excitatory and an inhibitory mechano-receptive field on the same hindpaw. Additionally, when the hindpaw was removed from the noxious water, these immersion-inhibited cells displayed a strong afterdischarge which was immediately inhibited once the paw was reimmersed. Pinch-induced and immersion-induced inhibition were found in both spinalized and intact rats suggesting spinal mechanisms were sufficient to mediate this effect. The majority of immersion-excited cells showed only an excitatory mechano-receptive field on the hindpaw (intact rats = 18/23 or 78.3%, spinalized rats = 24/36 or 66.7%). However, other immersion-excited cells had both an inhibitory and an excitatory mechano-receptive field on the hindpaw (intact rats = 5/23 or 21.7%, spinalized rats = 12/36 or 33.3%). The response of a convergent neuron, which has its excitatory receptive field located on a paw, to noxious immersion of the entire paw can be predicted by the make-up of the mechano-receptive fields. Additionally, since noxious paw immersion affects ipsilateral convergent neurons in two opposite manners, it suggests that other effects, such as heterotopic actions, might also not be uniform.

Differential responses of nociceptive vs. non-nociceptive spinal dorsal horn neurones to cutaneously applied vibration in the cat.

Extracellular single-unit recordings were made from dorsal horn neurones in the lumbar spinal cord of cats which were anaesthetized or were anaemically decerebrated. Each neurone was classified functionally as wide dynamic range (WDR), non-nociceptive, nociceptive specific or proprioceptive. Vibration was then applied to the hind limb using a feedback-controlled mechanical stimulator. WDR neurones had 3 distinct types of response to vibration (80 Hz: 0.3-1.0 mm): excitation, depression and a biphasic response consisting of excitation followed by depression. The type of response depended upon the location of the stimulator probe. With the stimulator probe placed inside that part of the receptive field from which low intensity, non-vibrational cutaneous stimuli elicited excitation, 35 neurones were excited by the vibratory stimulation, none was depressed and 4 showed the biphasic response. On the other hand, when the probe was positioned outside the receptive field for low intensity stimuli, 7 WDR neurones were excited, 164 showed depression or the biphasic response and 7 were unaffected. On-going activity and activity evoked by iontophoretic application of glutamate were decreased during the depressant response and during the depressant phase of the biphasic response. In terms of non-nociceptive neurones, all (n = 30) were excited by vibration; depressant or biphasic responses were not observed. Excitation was elicited by placing the probe either inside or outside the receptive field for non-vibrational stimuli. All nociceptive specific neurones (n = 3) were depressed by vibration regardless of the position of the stimulus. All proprioceptive neurones (n = 12) were excited by vibration. The predominantly depressant effect of vibration on nociceptive neurones vs. the predominantly excitatory effect on non-nociceptive neurones prompts us to suggest that the increase in pain threshold and the clinical analgesia elicited by vibration may be mediated at the spinal level by a decrease in the rate of firing of nociceptive neurones and/or by excitation of non-nociceptive neurones.

Substance P reduces tail-flick latency: implications for chronic pain syndromes.

In the awake restrained rat the intrathecal administration of substance P or the partial substance P homologue eledoisin-related peptide (ERP) reduced reaction time to a noxious radiant heat stimulus and, at high doses, produced additional behavioural responses suggesting that the animals had reacted to what they perceived as a painful stimulus. The reduction in tail-flick latency was observed as early as 30 sec following peptide administration peaked at 1 min and persisted for 5-10 min, after which an overshoot of the response (i.e., an increase in reaction time) was observed. The responses varied in their magnitude with the amount of peptide given, substance P being approximately 4 times more potent on a molar basis than ERP. Intrathecal administration of an equal volume of vehicle (artificial cerebrospinal fluid) had no effect on tail-flick latency and failed to produce any of the other behavioural changes. The following interpretations are made. The decrease in tail-flick latency suggests that pain threshold was decreased, and the dramatic behavioural effects seen at high doses suggest that an excess of substance P in the spinal cord is capable of producing a painful sensation. The rapid onset of the response suggests rapid penetration of substance P and ERP to the appropriate receptors, and the rapid decay of the response suggests rapid removal. Taken together, these results are consistent with the earlier suggestion that substance P plays a role as an excitatory agent in sensory pathways subserving pain. It is proposed that some conditions of chronic pain in man may therefore be due to an overabundant amount of substance P. This is complementary to a second proposal that other cases of chronic pain may be due to a supersensitivity of substance P receptors. The former is more likely to be associated with organic disorders, the latter with nerve damage, e.g. with causalgia, the neuralgias and perhaps some cases of phantom limb pain.

Nerve constriction in the rat: model of neuropathic, surgical and central pain.

In preparation for a series of electrophysiological experiments in a model of neuropathic pain, the present spinal reflex study was done to determine the optimal time after sciatic nerve constriction in the rat for tactile allodynia and to determine also the appropriate 'control' for the nerve constriction model. Therefore, this study focused on the magnitude and time course of change in paw withdrawal threshold following unilateral sciatic nerve constriction in the rat. Male Sprague-Dawley rats (375-425g) were used. Nerve constriction was done by placing a 2 mm polyethylene cuff (PE-90) around the left sciatic nerve (n=8). A second group of rats (n=8) received unilateral sham surgery and a third group (n=8) was unoperated. The ipsi- and contralateral hind paw withdrawal thresholds in each of the 3 groups were measured using von Frey hairs. In unoperated rats, the withdrawal threshold of each of the hind paws remained unchanged at approximately 50 g throughout the entire time course of the study, which lasted 145 days. However, in cuff-implanted rats, the withdrawal threshold of the nerve-injured hind paw decreased as soon as 1 day after surgery, reached as low as 1 to 2 g by 5 days and remained low throughout the test period. Threshold in sham-operated rats showed a bilateral decrease starting on days 1-3, which stabilised at about 30 g until about day 40, after which values returned gradually toward the unoperated withdrawal thresholds. In nerve-constricted rats the withdrawal threshold of the hind paw contralateral to the cuff followed the same change seen in sham-operated rats until about day 37, after which the withdrawal threshold matched that of the cuff-implanted hind paw. The data show that the cuff-induced sciatic nerve constriction produces a sustained hypersensitivity to normally innocuous tactile sensory input and that a relatively constant ipsilateral mechanical hyperalgesia can be found from days 5-27. It is also demonstrated that the contralateral hind paw and either hind paw in sham-operated rats are inappropriate as 'controls'. The data in this study suggest that three distinct types of allodynia are expressed. Ipsilateral allodynia may be representative of a model of neuropathic pain. The contralateral allodynia may be a model of central pain, as it likely arises from changes in central sensory processing. Allodynia in sham-operated rats was also expressed bilaterally and may be a model of long-term postoperative pain.

Effects of intravenously administered enantiomers of baclofen on functionally identified units in lumbar dorsal horn of the spinal cat.

The present study investigated the effects of intravenous administration of the d- and l-enantiomers of baclofen on extracellular single unit spikes recorded from the lumbar dorsal horn of the spinalized cat, either anaesthetized with chloralose or decerebrated. Both enantiomers had two types of depressant effect. One was a transient (complete within 2 min), non-specific depression of the discharge of synaptically-elicited responses and of the postsynaptic glutamate-evoked excitation; it is reasoned that this effect was due to a postsynaptic action of baclofen and its antagonism by bicuculline suggests it is via classical GABA receptors. The other type of depression was more prolonged, lasting usually for more than 1 hr. It was observed as a preferential blocking of spontaneous activity, as well as of evoked responses to noxious stimuli or innocuous thermal stimuli applied to the skin, with little or no effect on responses to hair movement or to the iontophoretic application of glutamate. In addition, baclofen preferentially reduced the late, higher threshold component of evoked responses of wide dynamic range neurones to electrical stimulation of the cutaneous receptive field. Thus, whether tested on naturally- or electrically-evoked responses, baclofen had a preferential effect on those mediated by small diameter afferents. Doses giving approximately equal effects were 0.1 mg/kg for l-baclofen and 10 mg/kg for d-baclofen. The results of the present study support recent evidence of a prolonged antinociceptive effect of baclofen, indicate that at least some of this effect is mediated by an action at the spinal level and support the possibility that the action is presynaptic, perhaps on the terminals of primary afferent fibres. In addition, a similar mechanism may account for the depression of spinal polysynaptic reflexes and thus, perhaps, additionally for some of the antispastic properties of baclofen.

Responses of functionally identified neurones in the dorsal horn of the cat spinal cord to substance P, neurokinin A and physalaemin.

The mammalian tachykinins, substance P and neurokinin A, and the non-mammalian tachykinin, physalaemin, were tested on functionally identified dorsal horn neurones in vivo. The experiments were done on cats which were anaesthetized with sodium pentobarbital or were anaemically decerebrated. Extracellular single-unit recordings were made in the lumbar spinal cord and the tachykinins were applied by iontophoresis. Each neurone was classified functionally as wide dynamic range, non-nociceptive, nociceptive specific or proprioceptive. The response to tachykinin application was determined for each neurone. Application of each of the tachykinins evoked a characteristic excitatory response which was delayed in onset, slow in developing and prolonged: physalaemin excited 99/131 neurones tested, neurokinin A excited 45/63 neurones and substance P excited 32/49 neurones. With two neurones physalaemin evoked a depression of the rate of firing, which may have been caused indirectly by excitation of a neighbouring neurone. Such depression was not elicited by either substance P or by neurokinin A. Physalaemin had a preferential excitatory effect on nociceptive neurones evoking excitation of 76/94 nociceptive neurones compared with 12/23 non-nociceptive neurones (chi 2 = 7.9, 1 d.f., P = 0.005). Substance P also caused a preferential excitation, with 30/40 nociceptive neurones being excited while all of the non-nociceptive neurones (n = 7) were unaffected (chi 2 = 11.5, 1 d.f., P = 0.0007). In contrast, neurokinin A failed to have a preferential effect; 32/46 nociceptive and 9/10 non-nociceptive neurones were excited (chi 2 = 1.0, 1 d.f., P = 0.40). Comparing the proportions of nociceptive neurones excited by the different tachykinins indicated that this type of neurone was not differently sensitive to any of the three peptides (chi 2 = 3.2, 2 d.f., P = 0.20). On the other hand, non-nociceptive neurones were preferentially excited by neurokinin A and physalaemin compared with substance P (chi 2 = 13.4, 2 d.f., P = 0.001). With regard to the endogenous tachykinins the results of this study may be interpreted in the following ways. The differential excitatory effect of substance P on nociceptive neurones supports the proposed role for this peptide in the transmission specifically of nociceptive inputs at the first afferent synapse. On the other hand, as neurokinin A excited non-nociceptive as well as nociceptive neurones, there may be a functional role for neurokinin A distinct from that of substance P.

Mediation and modulation by eicosanoids of responses of spinal dorsal horn neurons to glutamate and substance P receptor agonists: results with indomethacin in the rat in vivo.

In view of the widespread use of non-steroidal anti-inflammatory drugs for treatment of inflammatory pain, we determined the effects of the non-steroidal anti-inflammatory drug, indomethacin, on dorsal horn neurons in the rat spinal cord in vivo. At 2.0-12.0 mg/kg (i.v.), indomethacin depressed the responses of spinal dorsal horn neurons to the effects of iontophoretic application of substance P, N-methyl-D-aspartate, quisqualate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate. As indomethacin inhibits cyclo-oxygenase, these are the first data linking prostanoids and possibly arachidonic acid and other eicosanoids to the effects of substance P and glutamate in the spinal dorsal horn. As responses to iontophoretic application can be assumed to have been postsynaptic and as indomethacin had an effect generalized to all excitatory responses, we suggest a postsynaptic site for cyclo-oxygenase. We also suggest that elements in the cyclo-oxygenase signal transduction pathway may thus mediate at least some of the effects of substance P and glutamate receptor activation. Activation of the cyclo-oxygenase pathway in CNS neurons is Ca2- dependent, and activation of both N-methyl-D-aspartate and substance P receptors increases intracellular Ca2+. This led to the expectation that indomethacin would have a greater effect on responses to N-methyl-D-aspartate than to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate, but the reverse was observed. Thus, in addition to a mediator role, we hypothesize that an element(s) of the cyclo-oxygenase pathway may regulate the efficacy of excitation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors and perhaps other membrane-bound receptors. The cyclo-oxygenase signal transduction pathway thus appears to play at least two major roles in regulation of sensory processing in the spinal cord. Therefore, non-steroidal anti-inflammatory drugs, via cyclo-oxygenase inhibition, may have multiple actions in control of spinal sensory mechanisms.

Purine-induced depression of dorsal horn neurons in the cat spinal cord: enhancement by tachykinins.

The neurokinins, physalaemin, substance P, neurokinin A and bradykinin, were tested on the responses of single spinal neurons to the purines, adenosine 5'-triphosphate (ATP) and adenosine 5'-monophosphate and to GABA. Experiments were done on anaesthetized cats, recording extracellularly from functionally identified sensory neurons in the lumbar dorsal horn. All compounds were administered by iontophoresis. Neurokinins caused a slow, prolonged excitation which outlasted the period of application. Physalaemin was tested on responses to ATP in 24 units. In each case application of ATP caused either depression, excitation or a biphasic response when the application was not pre-conditioned by ejection of physalaemin. For 11 units, with ATP applications subthreshold to alter the on-going firing rate, such applications caused depression when they were preceded by administration of physalaemin. Three units were tested with ATP applications which caused the excitatory response; when the applications of ATP were preceded by ejection of physalaemin, there was then a depressant component in the response. In these 14 cases, the magnitude of the depression or of the depressant component of the response, was measured using currents which failed to produce depression in the absence of physalaemin ejection; the mean magnitude of this depression was 34.7 +/- 1.6% (+/- S.E.M.). With the 10 remaining units, responses to ATP were unaffected by application of physalaemin. The early components of the biphasic and excitatory responses were unaffected by physalaemin and hence it appeared to have a differential effect, enhancing only the depressant effects of ATP. The enhancement of depression was reversible, lasting up to 30 min following a single ejection. Neither control current nor glutamate mimicked the effect of physalaemin in the responses to application of ATP. The depressant response to adenosine 5'-monophosphate was also enhanced by physalaemin: ejections of adenosine 5'-monophosphate subthreshold to affect the on-going firing rate caused depression after physalaemin application in 3 of 8 units (average depression: 35.0 +/- 3.3%). On the other hand, depression induced by GABA was unaffected by physalaemin in every case (n = 8); in 4 of these cases GABA was tested on units for which purine-induced depression was enhanced by physalaemin. Thus, physalaemin preferentially affected depressant responses to ATP and to adenosine 5'-monophosphate.(ABSTRACT TRUNCATED AT 400 WORDS)

Antagonism of nociceptive responses of cat spinal dorsal horn neurons in vivo by the NK-1 receptor antagonists CP-96,345 and CP-99,994, but not by CP-96,344.

Extracellular and intracellular studies were undertaken to test the effects of the non-peptide, substance P (NK-1) receptor antagonists CP-96,345 and CP-99,994, and of CP-96,344, the inactive enantiomer of CP-96,345, on the responses of spinal dorsal horn neurons to peripheral noxious and non-noxious cutaneous stimuli in spinalized cats anesthetized with alpha-chloralose. The effect of these agents on the response of dorsal horn neurons to iontophoretic application of substance P was also tested in extracellular studies. The substance P-induced slow, prolonged discharge of dorsal horn neurons was blocked by administration (0.5 mg/kg, i.v.) of CP-96,345 (n = 10) or CP-99,994 (n = 9), but was unaffected by CP-96,344 (n = 9). The response of substance P-sensitive neurons to noxious thermal stimulation of the cutaneous receptive field, especially the late afterdischarge phase, was also significantly inhibited by CP-96,345 (n = 10) and by CP-99,994 (n = 7). The response of such neurons to noxious pinch stimulation of the receptive field was also significantly inhibited by CP-96,345 (n = 7) and CP-99,994 (n = 8), but the response of three other substance P-sensitive neurons to pinch was unaffected by CP-96,345. CP-96,344 did not affect the response of any neuron tested to either of these noxious stimuli (noxious thermal, n = 7; pinch, n = 6). The response to hair afferent stimulation was unaffected by any of these compounds (CP-96,345, n = 16; CP-96,344, n = 5; CP-99,994, n = 6). In intracellular studies, the effect of these antagonists was tested on responses of dorsal horn neurons to noxious pinch stimulation or to a train of high intensity electrical stimulation of the superficial peroneal nerve. Both stimuli produced an initial fast depolarization followed by a slow and prolonged depolarization with corresponding discharge patterns. CP-96,345 (n = 3) and CP-99,994 (n = 6) selectively blocked the late, slow components of the stimulus-evoked response without affecting the early components. Responses to single electrical pulses of the same intensity and duration were not affected. CP-96,344 did not affect any of the responses tested (n = 5). The data indicate that nociceptive responses of a subset of spinal dorsal horn cells are selectively blocked by the NK-1 receptor antagonists, CP-96,345 and CP-99,994, thus confirming the involvement of NK-1 receptors in these responses.(ABSTRACT TRUNCATED AT 400 WORDS)

Peripheral vibration causes an adenosine-mediated postsynaptic inhibitory potential in dorsal horn neurons of the cat spinal cord.

We have previously reported a vibration-induced, adenosine-mediated inhibition of nociceptive dorsal horn neurons in the cat spinal cord. The present study was conducted to investigate the mechanisms of this inhibition. In vivo intracellular recording was obtained from dorsal horn neurons in the lower lumbar segments of the anaesthetized cat. Vibration (80-250 Hz for 2-3 s every 15-20 s) was applied to the glabrous skin of the toes of the hind foot using a feedback-controlled mechanical stimulator. In 32 of 43 neurons tested, vibration produced a pronounced hyperpolarization of the membrane potential. This hyperpolarization peaked at -10 mV and decayed throughout the period of the application of vibration. It was associated with a decrease in membrane resistance, had a reversal potential negative to the resting membrane potential and was Cl(-)-independent, suggesting that it was due to an increase in a K+ conductance, properties typical of the response to adenosine. This inhibitory postsynaptic potential was unaffected by intravenous administration of bicuculline, strychnine and naloxone but was blocked by iontophoretic administration of 8-sulphophenyltheophylline, a P1-purinergic receptor antagonist. These results confirm our previous finding that vibration-induced inhibition of nociceptive dorsal horn neurons is mediated via the release of an endogenous purine compound and further suggests that this inhibition involves a postsynaptic inhibitory mechanism.

Effects of adenosine 5'-monophosphate and adenosine 5'-triphosphate on functionally identified units in the cat spinal dorsal horn. Evidence for a differential effect of adenosine 5'-triphosphate on nociceptive vs non-nociceptive units.

A study was done of the effects of iontophoretic application of adenosine 5'-monophosphate (AMP) and adenosine 5'-triphosphate (ATP) on functionally identified neurones in the spinal dorsal horn of the cat. AMP depressed nearly two-thirds of the 32 neurones tested regardless of functional type; the remainder were unaffected. ATP, on the other hand, had three types of effect: depression, excitation and a biphasic effect which consisted of excitation followed by depression. A significant difference was found when a comparison was made of the frequency of occurrence of each of these three types of effect in the samples of non-nociceptive (n = 18) and of wide dynamic range neurones (n = 42): of non-nociceptive neurones 61% were excited, 11% were depressed, 6% had a biphasic response and 22% were unaffected; of wide dynamic range neurones 45% had a biphasic response, 19% were depressed, 14% were excited and 21% were unaffected (chi 2 = 16.2, P less than 0.005). The depressant effects of both AMP and ATP and the depressant phase of the biphasic effect of ATP seem to be mediated through activation of P1-purinergic receptors because these effects were blocked by theophylline, a P1-purinergic antagonist [Burnstock (1978) In Cell Membrane Receptors for Drugs and Hormones: A Multidisciplinary Approach, pp. 107-118]. Thus the biphasic effect appears to consist of excitatory and depressant responses in the same neurone. The differential effects of ATP on non-nociceptive vs wide dynamic-range neurones are similar to the differential effects on these neurones observed during activation of low-threshold primary afferents. This similarity, together with evidence that ATP can be released from primary afferent neurones [Holton and Holton (1954) J. Physiol., Lond. 126, 124-140; Holton (1959) J. Physiol., Lond. 145, 494-504], prompts us to suggest that ATP may be a chemical mediator of effects of low-threshold primary afferent inputs in the spinal dorsal horn.

Tachykinins enhance the depression of spinal nociceptive neurons caused by cutaneously applied vibration in the cat.

The present investigation was prompted by previous studies in our laboratory which have indicated that tachykinins enhance depressant effects of purines and that the purine adenosine mediates a vibration-induced depression of nociceptive dorsal horn neurons. Extracellular recordings were made from single nociceptive neurons in the lower lumbar segments of anaesthetized cats. Vibration (80 Hz; 2.5-3.5 s every 20-25 s) was applied to the hindlimb using a feedback-controlled mechanical stimulator. The tachykinins physalaemin, substance P and neurokinin A were administered by iontophoresis. Physalaemin was tested on vibration-induced responses of 29 neurons; each neuron was excited by this tachykinin. To control for possible changes in the response to vibration caused by the excitation per se, statistical comparisons were made of the vibration-induced responses during excitation by tachykinins and during excitation by glutamate. In 16 cases the magnitude of the vibration-induced depression was significantly greater during the excitation caused by physalaemin. With the remaining neurons the response to vibration failed to differ during the excitation by physalaemin compared with the excitation by glutamate. In four of the 16 cases subthreshold applications of vibration caused depression after administration of physalaemin. The P1-purinergic (adenosine) antagonist, caffeine, was administered in three cases where vibration caused depression only with application of physalaemin. In each of these cases the depression was reversibly blocked by caffeine (10 or 40 mg kg-1 i.v.). The magnitude of vibration-induced depression was significantly increased during excitation by neurokinin A (5/14 neurons) or by substance P (1/9 neurons). From the results of the present study we suggest that tachykinins enhance the vibration-induced depression. This enhancement may be due to enhanced depression by adenosine.(ABSTRACT TRUNCATED AT 250 WORDS)

An adrenal-mediated, naloxone-reversible increase in reaction time in the tail-flick test following intrathecal administration of substance P at the lower thoracic spinal level in the rat.

We have shown previously that intrathecal administration of substance P to the lower thoracic vertebral level increases sympathetic output and increases the adrenal output of catecholamines. As opioid peptides are co-released with catecholamines from the adrenal medullae, experiments were done to determine whether the intrathecal administration of substance P to the eighth thoracic vertebral level would alter reaction time in the tail-flick test. Intrathecal administration of substance P (6.5 nmoles in artificial cerebrospinal fluid) in the awake restrained rat increased the reaction time at 1 and 6 min after injection to about 130-140% of the preadministration values; reaction time returned to preadministration values by 11 min. Similar administration of cerebrospinal fluid was without effect. Administration of 6.5 nmoles of thyrotropin-releasing hormone or oxytocin, peptides which also increase sympathetic output, failed to mimic the effects of substance P. The substance P-induced increase in reaction time was absent in rats which had been medullectomized and in rats pretreated with naloxone (10 mg/kg). Pretreatment with 10 mg/kg of either phentolamine or the quaternary opiate antagonists, nalorphine methochloride and naloxone methobromide, had no effect on the substance P-induced increase in reaction time. These results suggest that substance P given intrathecally to the eighth thoracic vertebral level may activate spinal sympathetic neurons to the adrenal medullae to cause the release of an opioid into the circulation. This circulating opioid may in turn play a role in the regulation of the tail-flick reflex by a centrally-mediated depression.