Biomedical subjects

P R Murphy

Publications and source records attributed to P R Murphy.

At least 37 records · Page 2Linked to original sources

PubMed1996

The basic fibroblast growth factor (FGF-2) antisense RNA (GFG) is translated into a MutT-related protein in vivo.

The basic fibroblast growth factor (FGF-2) gene is transcribed bidirectionally to yield multiple sense (coding) transcripts and a unique 1.5 kb antisense transcript which may regulate sense RNA stability. The antisense RNA also contains a long open reading frame that predicts a hypothetical protein with homology to the prokaryotic MutT antimutator proteins. However, translation of this protein has not previously been demonstrated. We employed antibodies against the conserved MutT-domain of the deduced human FGF-2 antisense protein (GFG) to demonstrate expression of an immunoreactive 24 kDa protein in liver extracts from Xenopus laevis, and two proteins of 28 and 35 kDa in rat liver. In rats, GFG protein expression detected by western blot was tissue-specific and correlated with the level of FGF-2 antisense mRNA expression. These findings demonstrate that, in addition to its possible RNA regulatory function, the FGF-2 antisense transcript is translated into a conserved MutT-related protein.

Amino Acid Sequence↗

PubMed1996

Expression of the rat BFGF antisense RNA transcript is tissue-specific and developmentally regulated.

The basic fibroblast growth factor (bFGF) gene locus is transcribed into a number of mRNA transcripts including an antisense mRNA derived from the opposite DNA strand of the bFGF gene. Expression of this natural antisense RNA has been implicated in regulation of the bFGF sense mRNA expression and turnover. In the present study we examined the developmental pattern of expression of the bFGF antisense transcript in fetal and postnatal rat tissues. Northern hybridization with a strand-specific cRNA probe detected a 1.5-kb polyadenylated antisense RNA in all tissues examined except brain, in which two transcripts were detected as a doublet of approximately 1.3-1.5 kb in size. The level of antisense transcript expression was markedly tissue- and age-dependent. In the developing brain, both sense and antisense transcripts were detected by Northern hybridization, but the pattern of their expression was inversely related. The 6.0-kb bFGF sense transcript increased in an age-dependent manner from days 3-30 of postnatal development while the antisense transcript decreased to nearly undetectable levels over the same period. In embryonic (days 15-19) liver, kidney, heart and intestine bFGF antisense RNA expression was low but increased dramatically at parturition, rising 5-10-fold over fetal levels by 10 days of age, then declined slowly to a new steady-state level in adult tissues. The level of antisense RNA in these tissues was much higher than that of bFGF sense mRNA, which was undetectable by Northern analysis. Sense and antisense trancripts were also detected in midgestational (11.5 days) embryos by RT-PCR. Antisense expression did not increase when embryos were explanted and cultured for 48 h (9.5-11.5 days). The apparent reciprocal relationship between the abundance of sense and antisense bFGF transcripts in developing brain supports the possibility of a regulatory role for the antisense transcript in this tissue. There was no evidence for a reciprocal relationship between sense and antisense expression in the other tissues examined, indicating that the relationship between sense and antisense RNA expression may be tissue-specific.

Adrenal Glands↗

PubMed1995

Basic fibroblast growth factor binding and processing by human glioma cells.

Tumor cells of glial origin express high levels of basic fibroblast growth factor (bFGF) which stimulates their proliferation in an autocrine manner. In the present study we examined bFGF receptor (FGFR) expression and 125I-bFGF binding and processing in a human glioma cell line. RT-PCR demonstrated the co-expression of bFGF and FGFR mRNAs in five glioma cell lines examined. The high-affinity FGFR was visualized in U87-MG glioma cells by crosslinking with 125I-bFGF and by Western blotting with anti-receptor antisera. Both techniques identified a discrete 110-kDa moiety associated with the cell membrane, consistent with the reported size of one of the FGFR-1 isoforms. Western blotting also identified an intracellular receptor pool which was not accessible with exogenous 125I-bFGF. Suramin treatment induced a 2-fold increase in immunoreactive FGFR and a 1.5-fold increase in 125I-bFGF binding sites, indicating that FGFRs are chronically down-regulated by endogenous bFGF in U87-MG cells. Removal of extracellular bFGF with heparin resulted in a rapid, cycloheximide-sensitive increase in high-affinity bFGF binding sites. At 37 degrees C, receptor-bound 125I-bFGF was internalized and subjected to limited proteolytic cleavage over 12 h. U87-MG cells also contained abundant low-affinity bFGF binding sites which were removed by digestion with heparinase III but not by chondroitinase ABC. The presence of heparin (25 micrograms/ml) in the binding reaction eliminated the association of 125I-bFGF with the heparin-like sites but did not prevent binding to the high-affinity receptor. Scatchard binding analysis in the presence of heparin revealed a single class of high-affinity sites in U87-MG cells (Kd = 4.9 +/- 0.9 pM; 10-12 x 10(3) sites per cell). Neither heparin nor heparinase digestion prevented the binding of 125I-bFGF to the detergent-extractable high-affinity receptor, although both treatments significantly reduced the extent of 125I-bFGF association with the receptor. These findings indicate that in U87-MG cells, heparan sulfate proteoglycans may be involved in presentation of bFGF to the high-affinity receptor, but are not essential for high-affinity binding to occur.

Animals↗

PubMed1995

Fusimotor neurone responses to medial plantar nerve stimulation in the decerebrate cat.

1. The effect of single shock electrical stimulation, up to 20 x threshold (T), of the medial plantar nerve on the discharges of single medial gastrocnemius static and dynamic gamma-efferents has been investigated in the decerebrate cat. 2. The neurones were classified as static (15) or dynamic (8) indirectly on the basis of their locomotor and/or resting discharge characteristics. 3. All gamma-efferents were affected by stimulation of the medial plantar nerve. Dynamic units showed net inhibition while facilitation dominated the responses of static neurones. 4. The responses of dynamic units consisted of powerful short latency (15 +/- 1.2 ms, mean +/- S.D.) spinal inhibition followed by weaker facilitation that was difficult to characterize due to concomitant rephasing of neuronal discharge. 5. Static neurones showed two patterns of response. Some units (7 of 15) were facilitated at medium latency (39.9 +/- 12.2 ms) while the remainder showed mixed effects in which short latency (18 +/- 3.6 ms) spinal inhibition was followed by stronger facilitation (latency, 38.1 +/- 5.3 ms). 6. Fusimotor facilitation and inhibition were generally present at 2T. The inhibition of dynamic and static gamma-efferents, and the facilitation of the latter type, increased with stimulus intensity. Thus low and high threshold afferents contributed to the effects without changing their qualitative nature. 7. We conclude that low threshold cutaneous mechanoreceptors in the plantar surface of the foot are capable of influencing the discharges of medial gastrocnemius static and dynamic gamma-efferents. Further, the cutaneous responses of fusimotor neurones appear to vary according to both the source of the afferent input and the type of unit involved. 8. The results are discussed in relation to the control and function of fusimotor neurones and the possible existence of subdivisions within the static system.

Animals↗

PubMed1995

Hormonal responses of male gerbils to stimuli from their mate and pups.

Following copulation and cohabitation with a pregnant female, male gerbils show high levels of parental behavior toward their pups. The initiation of male parental behavior may be the result of neuroendocrine changes induced by cohabiting with the pregnant female or by pup stimuli. Experiment 1 examines the changes in androgen and prolactin levels in male gerbils cohabiting with females over the reproductive cycle. Gerbils were mated and blood samples taken from males for hormone analysis 1, 10, and 20 days after pairing and 3, 10, and 20 days after pups were born. A group of unmated male gerbils served as controls. Plasma prolactin levels of males were elevated throughout the female's pregnancy and lactation periods, but were only statistically significantly higher than those of unmated males 20 days after pups were born. Androgen levels rose during pregnancy and dropped significantly after the birth of the pups. These hormonal changes are similar to those found in males of monogamous birds and differ from those found in males of polygynous rodents such as the rat. Experiment 2 examined the hormonal responses of male and female gerbils to pup replacement after 4 hr of parent-pup separation. Female gerbils showed a significant elevation of prolactin levels 1 hr after pup replacement, but males did not. Males with pups returned showed no difference in androgen levels from males who did not have pups returned. Thus, male gerbils show neuroendocrine changes following long-term cohabitation with their mate and pups, but do not show acute hormone responses to pup removal and replacement. These results indicate that parental males have neuroendocrine changes associated with parental behavior and these differ from the neuroendocrine changes underlying female parental behavior.

Androgens↗

PubMed1995

Interleukin-2 activates a sub-population of cutaneous C-fibre polymodal nociceptors in the rat hairy skin.

We have investigated the effects of interleukin-2 on identified cutaneous C- and A delta- fibre nociceptors in an in vivo rat saphenous nerve preparation. A fraction of C-polymodal (33%), A delta- (22%) and C- (7.5%) mechanical nociceptors were activated by intradermal injection of interleukin-2. For C-fibre polymodal nociceptors, concentration thresholds were < or = 0.12 unit/3 microliters and the percentage of interleukin-2-activated nociceptors did not increase with concentrations above 0.06 unit/3 microliters. Responses were dose-dependent and characterized by potent tachyphylaxis for subsequent injections of the same dose. C-fibre polymodal nociceptors activated by interleukin-2 were also activated by subsequent chemical stimuli as follows: 81% were activated by histamine (300 ng/3 microliters), 87% by bradykinin (75 ng/3 microliters), 100% by topical acetic acid and 87% by capsaicin (3 micrograms/3 microliters). In contrast, C-fibre polymodal nociceptors that could not be activated by interleukin-2 responded less frequently to histamine (17%) and bradykinin (24%) but were generally activated by noxious chemicals, including acetic acid (82%) and capsaicin (70%). In conclusion, this study demonstrates that interleukin-2 is a potent activator of a discrete population of cutaneous C-polymodal nociceptors, which are chemosensitive to endogenous inflammatory mediators. The fact that these nociceptors respond to a variety of endogenous mediators is consistent with the concept of multiple humoral mechanisms of itch and, consequently, the difficulties in reducing itch associated with inflammation.

Animals↗

PubMed1994

Basic fibroblast growth factor sense (FGF) and antisense (gfg) RNA transcripts are expressed in unfertilized human oocytes and in differentiated adult tissues.

Basic fibroblast growth factor (bFGF) is a highly conserved and ubiquitously distributed mitogen. In amphibian oocytes bFGF mRNA is regulated post-transcriptionally by interaction with an antisense RNA transcript. We used reverse transcription-polymerase chain reaction (RT-PCR) and Northern hybridization to determine the presence of bFGF and its antisense RNA (gfg) in unfertilized human oocytes and postnatal differentiated tissues. BFGF and gfg transcripts were co-expressed in many tissues, with bFGF transcripts (7, 3.7 and 1.8 kb) being more abundant than the gfg transcript (1.5 kb) in 8 of 16 tissues examined. Sense and antisense expression was approximately equal in kidney and colon, while in heart, liver, skeletal muscle and testis gfg transcripts predominated. RT-PCR demonstrated the presence of bFGF and gfg transcripts in unfertilized oocytes where the antisense transcript was present in excess of the sense transcript. These findings suggest a role for gfg in regulation of bFGF expression.

Adult↗

PubMed1994

Western blotting of formaldehyde-fixed neuropeptides as small as 400 daltons on gelatin-coated nitrocellulose paper.

A method is described for Western blotting of peptides as small as 400 daltons (Da). Peptides were separated by tricine-sodium dodecyl sulfate electrophoresis and electroblotted to gelatin-coated PH79 nitrocellulose paper (0.1 micron). The electroblotted peptides were fixed to the nitrocellulose paper for 5-10 min in 4% paraformaldehyde solution. Using anti-rabbit FMRF-amide (Phe-Met-Arg-Phe-NH2) as primary antibody, positive immunoreactivity was detected with an amplified alkaline phosphatase assay which was sensitive to at least 0.5 microgram FMRFamide/lane. When immunoreactivity was determined with 125I-protein A, it was possible to amplify and detect weak signals by increasing the autoradiography time. Therefore, using the 125I-protein A detection method, Western blot analysis of brain extracts from Lymnaea stagnalis (pond snail) and Poecilia reticulata (guppy) indicated the presence of four FMRFamide immunoreactive bands after a 7-day exposure to X-ray film. The most abundant peptide coelectrophoresed with the FMRFamide standard (M(r) 598.8 Da). In addition, this Western blotting procedure also detected APGWamide (Ala-Pro-Gly-Try-NH2; 428.5 Da) and [D-Ala2]-Leu-enkephalinamide (568.7 Da) with their respective specific antibodies.

Animals↗

PubMed1994

The application of antisense oligonucleotide technology to the brain: some pitfalls.

1. Amphetamine-induced c-fos and egr-1 expression in the striatum was used as a model in which to study the effects of antisense oligodeoxynucleotides (ODNs) directed at c-fos. Using direct infusions of ODNs into the striata of animals we have demonstrated that c-fos antisense ODNs retain most of their biological activity with 2- or 3-base substitutions. The c-fos antisense and mismatch ODNs attenuated Fos immunoreactivity but had little effect on Egr-1 immunoreactivity. 2. In another group of studies examining the role of c-fos in amygdala kindling, we have demonstrated that ODNs cause neurotoxic damage following repeated daily infusions into the amygdala. The damage observed was greatly diminished when the time interval between infusions was extended.

Amygdala↗

PubMed1994

Identification and characterization of an antisense RNA transcript (gfg) from the human basic fibroblast growth factor gene.

Basic fibroblast growth factor (bFGF) is an autocrine growth factor that is overexpressed in glial tumor cells and promotes their unregulated proliferation. We have previously reported that increased messenger RNA (mRNA) stability contributes to the elevated steady state levels of bFGF mRNA in human U87-MG glioma cells. Stability of bFGF mRNA is regulated by a natural antisense transcript in Xenopus oocytes, but the mammalian equivalent of this transcript has not previously been described. We were interested in identifying the human equivalent of this antisense transcript in order to study its role in bFGF mRNA stability. Analysis of the 3'-untranslated region of the 6.7-kilobase human bFGF mRNA revealed two areas of greater than 75% homology to exons 3 and 4 of the Xenopus antisense transcript, separated by 4300 basepairs of nonhomologous sequence. We used reverse transcription-polymerase chain reaction to amplify, clone, and sequence a 301-basepair fragment of the antisense splice variant from U87-MG cells. The clone (gfg-1) is 73% identical to the Xenopus sequence, with a conserved splice junction and an open reading frame. Strand-specific gfg-1 complementary RNA probes detect a 1.5-kilobase mRNA transcript in normal rat tissues and human T47D breast cancer cells, which contain very low levels of bFGF mRNA. In contrast, antisense transcript expression was undetectable by Northern hybridization in U87-MG cells, which overexpress the bFGF sense mRNA. The reciprocal relationship between bFGF sense and antisense expression suggests that antisense transcripts may regulate bFGF expression in mammalian cells, and that disruption of normal sense/antisense mRNA ratios may lead to overexpression of bFGF in some tumors.

Animals↗

PubMed1993

Fusimotor discharge patterns during rhythmic movements.

Sensory information from muscle is a major factor in the control of posture and movement. The central nervous system can greatly vary this proprioceptive feedback via the fusimotor (gamma) system that innervates the muscle spindle, a length receptor. Despite 50 years of intensive research, the role of the fusimotor system still remains controversial. One of the major reasons for this state of affairs is, because of technical difficulties, the complete lack of direct recordings from classified gamma-motoneurones (that is, static or dynamic) in intact animals. However, such recordings have been achieved in reduced feline preparations during three types of rhythmic movement: respiration, jaw movements and locomotion. The recordings indicate that the patterns of discharge of static and dynamic fusimotor neurones can vary in different types of movement, or in different muscles during the same behaviour. Notwithstanding such variation, a generalization has emerged in which it is proposed that, for rhythmic movements, extrafusal muscle contraction is accompanied by coactivity in static and dynamic gamma-efferents. Such coactivity serves to optimize spindle afferent feedback for reflex contributions to muscle contraction.

Animals↗

PubMed1993

The locomotor discharge characteristics of ankle flexor gamma-motoneurones in the decerebrate cat.

1. The discharge patterns of ankle flexor, tibialis anterior (TA), gamma-motoneurones were recorded during locomotion in the decerebrate cat. 2. At rest gamma-efferents had no background discharge. During locomotion two patterns of gamma activity could be distinguished. Most units (16) were phasically recruited with homonymous electroneurogram (ENG) activity, while the remainder (5) were tonically active throughout the step cycle. 3. The modulation of phasic units was greater (P < 0.01) than tonic neurones. Phasic units had lower (P < 0.02) mean, but higher (P < 0.01) peak, rates during the step cycle. 4. The discharge rate of both types of efferent increased around the onset of ENG activity and peaked during ENG activity, or shortly after its cessation. The conduction velocities of phasic and tonic units overlapped widely. 5. It is proposed, on the basis of muscle spindle afferent recordings during locomotion, that TA phasic and tonic units correspond to static and dynamic gamma-motoneurones, respectively. This correspondence is functionally advantageous for the role of ankle flexor muscles during locomotion. Thus phasic static gamma discharge during flexion would aid muscle contraction via increased Ia afferent activity, while tonic dynamic gamma firing would enhance Ia afferent stretch sensitivity throughout the step cycle. Such enhancement during flexion would oppose unexpected muscle lengthening while, during extension, it would contribute to reciprocal inhibition of ankle extensor muscles. 6. The results are discussed in relation to strategies of gamma usage during rhythmic movements. It is postulated that, for such behaviour, muscle contraction is accompanied by coactivity in static and dynamic gamma-motoneurones. A functional rationale is suggested for this strategy.

Action Potentials↗

PubMed1992

Antisense oligonucleotide eliminates in vivo expression of c-fos in mammalian brain.

Immediate-early genes such as c-fos and NGFI-A are rapidly and transiently expressed in the striatum following amphetamine administration in vivo. Here we show that direct infusion of an antisense oligodeoxynucleotide to c-fos into striatum will reduce amphetamine-induced production of Fos-like immunoreactivity without affecting NGFI-A expression. These results suggest that it is possible to use antisense technology to study the role of immediate-early genes in specific sites in the brain in vivo.

Animals↗

PubMed1992

Short latency cutaneous reflex responses of gamma-efferents in the decerebrate cat.

The effect of single shock stimulation, up to 20 x threshold (T), of the sural nerve on the discharges of triceps surae gamma-efferents was investigated in decerebrate cats. Units were classified as static (12) or dynamic (7) on the basis of their resting discharge rates (Murphy et al. 1984). All neurones were excited at short latency by sural nerve stimulation and response size was graded with stimulus intensity. Short latency mixed or inhibitory responses were not evident. Although reflex effects first occurred at low stimulus strengths (less than or equal to 1.5T) in both types of efferent, most responses appeared at higher intensities (greater than 1.5T). The estimated central delays of the responses of static (3.0 +/- 1.1 ms, mean +/- SD) and dynamic (3.4 +/- 1.0 ms) gamma-motoneurones were not significantly different and are consistent with spinal oligosynaptic pathways. The present results differ from those of the only previous study (Johansson and Sojka 1985) of the short latency responses of triceps surae static and dynamic gamma-motoneurones to sural nerve stimulation, in which mixed and inhibitory effects were common in anaesthetised cats. Although differences in recording techniques and gamma sampling may account for the apparent disparity between these studies, it is also feasible that a difference in the setting of interneuronal pathways in the two types of preparation is responsible. The results are discussed in relation to the control of gamma-motoneurones with particular reference to the "final common input" hypothesis (Johansson 1981; Appelberg et al. 1983).

Animals↗

PubMed1992

Phosphorothioate antisense oligonucleotides against basic fibroblast growth factor inhibit anchorage-dependent and anchorage-independent growth of a malignant glioblastoma cell line.

Basic fibroblast growth factor (bFGF) is a broad spectrum mitogen for many cells of neuroectodermal origin, including glial cells. The human malignant glioblastoma cell line U87-MG expresses high steady state levels of the bFGF mRNA and contains abundant stores of biologically active bFGF protein. In the present study we have examined the contribution of endogenous bFGF to the autocrine growth of these cells. Using reverse transcription-polymerase chain reaction, U87-MG cells were shown to express the mRNAs for both bFGF and the bFGF receptor, confirming the existence of the basic requirements for an autocrine loop. Addition of 5 microM bFGF-specific antisense oligonucleotide to U87-MG cultures significantly inhibited the growth rate of these cells within 48 h and blocked proliferation beyond 2 days. The corresponding bFGF-specific sense oligonucleotide did not significantly inhibit cell proliferation over the course of these experiments. Similarly, antisense oligonucleotides significantly inhibited colony formation in soft agar, while the sense sequence was without effect. Western blotting with antihuman bFGF revealed that U87-MG cells synthesize three isoforms of bFGF, approximately 18, 23, and 25 kilodaltons (kDa) in size. The 23- and 25-kDa isoforms together comprise approximately 80% of the total cellular stores of bFGF. Antisense treatment for 4 days reduced the abundance of the 23- and 25-kDa isoforms by 64-74%, but had little effect on the 18-kDa isoform. The inhibitory effect of the antisense oligonucleotides on anchorage-dependent proliferation was reversed by the addition of recombinant 18-kDa human bFGF.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

PubMed1991

The role of cutaneous afferents in the control of gamma-motoneurones during locomotion in the decerebrate cat.

1. The effect of electrical stimulation, up to 20x threshold (T), of the sural nerve on the discharges of single medial gastrocnemius static and dynamic gamma-motoneurones has been investigated at rest and during locomotion in the decerebrate cat. 2. A total of twenty-three gamma-motoneurones were recorded. The neurones were identified as static (15) or dynamic (8) on the basis of their discharge characteristics (Murphy, Stein & Taylor, 1984). 3. Low intensity stimulation (less than or equal to 1.5T) had no effect on the discharges of most (22 of 23) gamma-efferents at rest or during locomotion. Hence the largest afferents in the sural nerve had little influence on the discharges of static or dynamic gamma-motoneurones in either condition. 4. Higher intensity stimulation (greater than 1.5T) excited both types of gamma-efferent in the resting state and response size was graded with stimulus intensity. For most neurones (20 of 23) excitatory effects appeared in the range 1.5-2T. 5. Stimulation at intensities greater than 1.5T also excited dynamic and some static gamma-motoneurones during locomotion. The responses of dynamic gamma-motoneurones were unchanged during locomotion compared to the resting state. In contrast, the responses of static neurones were significantly reduced, or even abolished, during locomotion and stimuli less than or equal to 3T generally (12 of 13) had no effect. Thus the responses of static, but not dynamic, gamma-efferents were task dependent. Further, the thresholds of responses indicate that activation of low threshold mechanoreceptors in the sural receptive field excites both types of gamma-efferent at rest, and dynamic neurones during locomotion. In contrast, it is proposed that the same peripheral input does not affect static gamma-efferents during locomotion. 6. The responses of static and dynamic gamma-motoneurones during locomotion were not obviously related to step cycle phase, or gamma rate, and responses occurring during or between homonymous electromyogram (EMG) bursts were not significantly different. Thus gamma responses during locomotion were not phase dependent. 7. Stimulation at intensities greater than 3T excited dynamic and some static gamma-motoneurones during locomotion but simultaneously inhibited on-going EMG activity. Peripheral inputs are therefore capable of influencing alpha- and gamma-motoneurones independently during locomotion. 8. The significance of the results is discussed in relation to the control and function of gamma-motoneurones.

Animals↗

PubMed1990

In-gel ligand blotting with 125I-heparin for detection of heparin-binding growth factors.

125I-labeled heparin was used to detect basic fibroblast growth factor (bFGF) in crude tumor cell extracts after separation by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. 125I-labeled heparin bound avidly to native recombinant bFGF immobilized on nitrocellulose and eluted with 1.5-2.0 M NaCl. However, Western transfer of bFGF to nitrocellulose after SDS-polyacrylamide gel electrophoresis destroyed heparin-binding ability. In contrast, bFGF was detected by incubation of the polyacrylamide gels directly with 125I-labeled heparin in a gel overly technique. Heparin affinity and NaCl elution pattern from bFGF in gel were similar to those observed for native bFGF spotted on nitrocellulose. This procedure permitted detection of bFGF in crude extracts of a human astrocytoma cell line. In view of the rapid growth of the heparin-binding fibroblast growth factor gene family, this technique should prove useful for the rapid and sensitive detection of other heparin-binding growth factors.

Blotting, Western↗

PubMed1990

Gamma-motoneurone discharge patterns during fictive locomotion in the decerebrate cat.

Triceps surae gamma-motoneurones were recorded during fictive locomotion in the paralysed high decerebrate cat. Two distinctive patterns of discharge were observed which were similar to those reported for static and dynamic gamma-motoneurones during locomotion in the same preparation, but without paralysis (Murphy, Stein & Taylor, 1984). These results suggest that movement-related afferent feedback is not essential for the generation of the basic patterns of static and dynamic gamma-motoneurone activity during locomotion. The results are discussed in relation to the generation of alpha and gamma locomotor rhythms.

Action Potentials↗