Pinch Test Research Articles

Nerve regeneration and serum levels of insulin-like growth factor-I in rats with streptozotocin-induced insulin deficiency

Peripheral nerve regeneration was studied in female Sprague-Dawley rats with streptozotocin-induced insulin deficiency. Nerve regeneration was provoked by a crush lesion on the sciatic nerve 21 days after the streptozotocin injection. The regeneration was assessed by a pinch test at different time-points after injury. The rate ofregeneration in insulin-deficient animals, 2.5 mm/day, was significantly lower than in control animals, 2.9 mm/day(P < 0.05). There was no difference in the initial delay, i.e. the period before regeneration attains a constant velocity. One group of insulin-deficient rats was treated with insulin during the regeneration period by means of implanted osmotic mini-pumps. This treatment prevented the decrease in regenerationsw. After 6 days the sciatic nerves of insulin-deficient rats had regenerated 12.3 ±0.3mm(mean±S.E.M.), while the corresponding value for insulin-treated rats was 15.7 ±0.6 mm (P > 0.01). The streptozotocin-treated rats were found to have a 39% reduction in the serum level of insulin-like 1 growth factor-I (IGF-I)_compared to control rats (0.33 ± 0.22 μg/ml and 0.54 ± ml respectively, (P < 0.001). Insulin treatment 1830 1732 during the regeneration period completely restored the IGF-I level back to normal.

Effects of chronic haloperidol on stress-induced oral behaviour in rats

Rats received daily injections of haloperidol (HAL, 5 mg/kg SC, or IP) or tartaric acid vehicle for 14-21 days. Four to six days after discontinuation of the daily injections, rats were given a single 5-min tail pinch (TP) test. HAL-treated rats showed significantly shorter latencies to display oral behaviours (OB: licking, gnawing, or drinking) compared to controls in five separate replications. Food consumption per se was not consistently affected. Shorter OB latencies were significantly correlated both with increased striatal 3H-spiperone binding and with apomorphine stereotypy scores. In a final experiment, this effect of HAL on OB latencies was blocked by a systemic injection of naloxone (2 mg/kg IP) prior to the TP test. Naloxone did not affect OB latency in control rats, suggesting the possibility of endogenous opiate involvement in the chronic HAL effects. The overall results suggest that OB latencies following mildly activating stimulation may provide a useful behavioural assay for neuroleptic-induced oral abnormalities as well as a functional index of striatal dopamine D-2 receptor sensitivity.

Prevention of Lower Lid Retraction and Ectropion in Lower Lid Blepharoplasty

At the recent fall meeting of the American Academy of Facial Plastic and Reconstructive Surgery in Washington, DC, Bruce B. Becker, Encino, Calif, noted ectropions to be one of the most common complications after lower lid blepharoplasty. He feels that the incidence of this complication can be reduced by a thorough preoperative evaluation and careful surgical technique. He felt that the major causes of postblepharoplasty ectropions were uncorrected horizontal lid laxity, excessive skin excision, and vertical retraction of the lid from scarring or orbicularis muscle shortening. Careful preoperative evaluation was felt to be very important, with special attention directed at evaluation of lower lid laxity. Two tests were recommended for evaluation of lower lid laxity: the snap test, in which the lower lid is pulled away from the globe and allowed to snap back, and the pinch test, where the distance the lower lid can be pulled from the globe

Insulin-like growth factor (IGF-1) as a stimulator of regeneration in the freeze-injured rat sciatic nerve

The effect of insulin-like growth factor (IGF-1) on the ability of the rat sciatic nerve to regenerate into a freeze-injured nerve segment was investigated. The freeze-injured segment was perfused for 6 days with Ringer solution and different concentrations of IGF-1, dispensed by a subcutaneously implanted osmotic minipump. At a pump concentration of 50, 100 and 200 μg IGF-1/ml the regeneration length increased with 14, 25 and 26%, respectively, as measured by the pinch test and by immunocytochemical staining for neurofilaments (NF) in the growing neurites. Schwann cells invading the freeze-injured segment were visualized by immunostaining for S-100 protein. In nerves perfused with Ringer solution alone the Schwann cells were present as far as the neurites had regenerated, while neurites seemed to grow slightly ahead of the Schwann cells in the nerves perfused with IGF-1. Incorporation of [ 3H]thymidine increased in IGF-1 treated nerves. However, IGF-1 perfusion did not increase thymidine incorporation when outgrowth of neurites was detained by a transection proximal to the freeze-injured area. The results suggest that IGF-1 affects regeneration by local stimulation of the growing neurites and that IGF-1 stimulates the proliferation of non-neuronal cells indirectly.

Regeneration of the rat sciatic nerve after different conditioning lesions: effects of the conditioning interval.

Regeneration of the rat sciatic nerve was studied after a crush lesion (test lesion) on nerves previously subjected to a conditioning lesion. The test lesion was made approximately 30 mm proximal to the conditioning lesion. The period between the conditioning lesion and the test lesion was varied. Regeneration was measured by the pinch test. The conditioning procedure increased the rate of axonal elongation and decreased the initial delay. Conditioning intervals between 14 hours and 4 days were sufficient to increase the regeneration distance significantly, but only until day 4. If the conditioning interval was prolonged to 7 or 14 days, the conditioning effect persisted until day 6. A conditioning effect also was produced by transection of the sciatic nerve and by local compression produced with a silicone tube. The results of this study demonstrate that the type of injury and the conditioning intervals are important determinants in producing the conditioning effect in the rat.

Facial and Neck Contouring Using Liposuction and Lipoinjection

Speaking at the annual meeting of the Triological Society in Palm Beach, Fla, Dr John Dmytryshyn, Vancouver, British Columbia, Canada, discussed his techniques for contouring five major facial zones using liposuction or lipoinjection. Those zones include the submental, submandibular, midlateral neck, preparotid, and nasolabial zones. Depending on the area to be contoured, he recommended the submental and nasolabial stab-incision approach and the open-facelift approach. Liposuction was performed before rhytidectomy. Pinch testing was advocated before operation and after suctioning to determine the need for and the result of liposuction, respectively. Dr Dmytryshyn did not advocate the use of liposuction in the lateral mandibular area, and he cautioned that the technique was not a substitute for weight loss. Lipoinjection was much less predictable than liposuction, due to the 50% resorption of injected material. Lipoinjection was advocated only for placement under facial creases, wrinkles, and scars, not as augmentation for chin and cheek

Non-opioid analgesia of the neuropeptide, neo-kyotorphin and possible mediation by inhibition of GABA release in the mouse brain

The novel neuropeptide, neo-kyotorphin, produced a naloxone-resistant analgesia in the tail pinch test when given (IC) to mice. Pretreatments with implantation of a morphine pellet or with phentolamine (10 μg IT) or with reserpine (10 mg/kg SC) did not attenuate this analgesia, yet the analgesia was antagonized by GABA mimetics, such as muscimol (0.1 μg IC), nipecotic acid (100 mg/kg IP). Neo-kyotorphin inhibited the Ca 2+-dependent and depolarization-evoked release of 3H-GABA, from crude synaptosomes of the lower brain stem of rats. These findings suggest that inhibition of GABA in the brain may in part be involved in neo-kyotorphin-induced analgesia.

Alterations in nociception following adrenal medullary transplants into the rat periaqueductal gray.

Adrenal medullary chromaffin cells were transplanted to the midbrain periaqueductal gray, a region known to play a primary role in the modulation of nociception. Chromaffin cells were chosen for transplantation since they contain several neuroactive substances (e.g. catecholamines, opioid peptides, other neuropeptides) whose release can be stimulated by pharmacological agents such as nicotine. Both dissected adult rat adrenal medullary tissue and bovine chromaffin cells served as graft tissue in the periaqueductal gray region of adult rats. When stimulated with a low dose of nicotine, potent analgesia was induced in these animals as assessed by tail flick, paw pinch and hot plate tests. The bovine chromaffin cell implants were more effective in inducing this response. The analgesia induced by nicotine stimulation in rats with adrenal medullary implants was partially attenuated by both opiate antagonist naloxone, and adrenergic antagonist phentolamine. These results suggest that the implantation of cells which release neuroactive substances can produce reductions in pain sensitivity.

Subconvulsive doses of intracisternal bicuculline methiodide, a GABA A receptor antagonist, produce potent analgesia as measured in the tail pinch test in mice

Bicuculline methiodide, a GABA A antagonist produced potent analgesia in the tail pinch test when it was given intracisternally (i.c.) but not intrathecally (i.t.). The ED 50 was ng/mouse. This analgesia was antagonized by i.c. muscimol, a GABA A agonist. On the contrary, muscimol (i.t.) produced bicuculline-reversible analgesia. These findings suggest that brain GABA may transmit the nociceptive information while GABA in the spinal cord may inhibit it.

Morphological and functional effects of triiodothyronine on regenerating peripheral nerve

The functional and morphologic consequences of treatment of peripheral nerve lesions with exogenous 3,3′,5-triiodo- l-thyronine (T 3) are unclear. In this study adult wistar rats with sciatic nerve crush lesions were treated with 20 μg/kg/day of T 3. The treated animals gained weight though more slowly than vehicle-treated rats. Ten control and 10 experimental animals assessed 4 days postoperatively for sensory axon regeneration by the “pinch test” showed no significant difference in distance regenerated. Motor function recovery was monitored for 21 days after nerve crush lesions by the vestibular placing response and also showed no significant difference. Light microscopy of transverse epoxy sections of the sciatic nerve 5 mm distal to the lesion showed no significant difference in whole nerve area or myelinated fiber density but quantitative electron microscopy revealed a significant increase in axolemma, myelin spiral length, whole nerve fiber area, and nerve fiber perimeter in T 3-treated rats. Statistically non-significant increases in axonal area and myelin periodicity were also noted. These results are interpreted as indicating that although T 3 treatment is not functionally beneficial in the regeneration of adult mammalian peripheral nerve it nonetheless has subtle morphologic effects that indicate a stimulating effect on membrane synthesis.

Analgesic effects of dynorphin-A and morphine in mice

To investigate whether or not dynorphin-A is analgesic, the effect of this peptide was tested in comparison with that of morphine in mice. Dynorphin-A produced a potent analgesic effect in the acetic acid writhing and tail pinch tests, but a weak effect in the tail flick test when given by intracerebroventricular injection. In contrast, morphine caused a potent analgesia in all the tests. Dynorphin-A was more effective when given by intrathecal injection than by intracerebroventricular injection, whereas morphine was equipotent by both injection routes. The results suggest that dynorphin-A is analgesic and that its analgesia may be differentiated from that of morphine.

Role of nerve growth factor in the adult dorsal root ganglia neuron and its response to injury.

The response of dorsal root ganglia (DRG) neurons to NGF deprivation and to axotomy was examined in adult guinea pigs. The success of NGF deprivation by means of an autoimmune approach was monitored by the measurement of serum antibody titer levels against guinea pig NGF with the standard bioassay for NGF activity. That the antibody produced NGF deprivation was confirmed by histologic evidence of neuronal atrophy and apparent cell loss in sections of the superior cervical ganglia (SCG) and by marked decreases (65-80%) of SCG neurotransmitter-synthesizing enzyme activity levels. By using the autoimmune approach a new source of guinea pigs was found which consistently produced high titers of cross-reacting anti-NGF antibodies. Experiments were designed to examine the response of the sensory neuron to injury while chronically deprived of NGF. Total neuronal counts in the sixth lumbar DRG 98 days after sciatic nerve crush showed no difference between NGF-deprived and control ganglia. Measurement of the size spectrum of DRG neurons showed evidence of atrophy of the NGF-deprived neurons in both the uninjured and axotomized side compared to respective controls. The mean volume of uninjured sensory neurons measured in the NGF-deprived guinea pigs was decreased 27.7% (P less than .05) compared with that of control guinea pigs. The degree of regeneration 6 days following a nerve crush was the same in NGF-deprived sensory neurons and in controls when measured by the "pinch test" and by isotope-labeled axonal transport studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilateral lesions of the dorsolateral funiculus of the cat spinal cord: Effects on basal nociceptive reflexes and nociceptive suppression produced by cholinergic activation of the pontine parabrachial region

In cats, bilateral microinjections of the cholinergic agonist, carbachol (0.6 μg in 0.2 μl), into an area surrounding the lateral half of the brachium conjunctivum (BC) produces a non-narcotic suppression of nociceptive responses, as assessed by flexion reflexes (tail-flick and calibrated pinch tests). Bilateral lesions of the dorsolateral funiculi (DLF) of the thoracic spinal cord (T2) significantly reduced the magnitude of this nociceptive suppression. Nociceptive suppression following carbachol microinjections into sites along the dorsal aspect of BC was reduced by DLF lesions to a greater degree than nociceptive suppression following injections into sites within or ventral to BC. Relatively superficial DLF lesions produced reductions in nociceptive suppression which were equivalent to reductions induced by deeper lesions. DLF lesions, either superficial or deep, produced equivalent, reliable decreases in tail-flick test assessments of baseline nociceptive thresholds. The magnitude of decreases in baseline nociceptive thresholds produced by DLF lesions was not correlated with the magnitude of reduction of carbachol-induced suppression of nociceptive responses, indicating that DLF lesions suppress anti-nociception independent of baseline alterations. These data suggest that non-narcotic analgesia produced by cholinergic activation of cells along the dorsal aspect of BC may be predominantly mediated by fibers descending within the DLF. However, results of the retrograde peroxidase (HRP) tracing studies reported in the present investigation indicate that this pain suppression is probably mediated by polysynaptic pathways since this region dorsal to BC projects neither through DLF nor extra-DLF pathways. Retrograde HRP data show that areas ventral to and including BC project to the cord via both DLF and extra-DLF pathways. Since DLF lesions were less effective in reducing analgesia attained from ventral compared to dorsal sites, spinal pathways other than DLF may mediate reflex suppression following carbachol microinjection into these more ventral sites. Possible cholinergic contributions to endogenous, non-opiate forms of analgesia are discussed.

Potentiation of physical dependence by conjugation at the 6-position of nalorphine.

The experiments concerned the effects of glucuronate or sulfate conjugation at the 6-position of nalorphine on the analgesic and antagonistic activities and also on the development of tolerance and physical dependence. Nalorphine-3-and 6-sulfate ester were synthesized for the first time. The analgesic effect of nalorphine-6-sulfate and -glucuronide was higher than that of nalorphine when assessed in the acetic acid writhing test. However, these 6-conjugates exhibited less potent agonistic activity in the test with guinea-pig ileum muscle strip and revealed no analgesic effect in the tail pinch test. The antagonistic activity of these 6-conjugates to morphine analgesia was lower on their s.c. injection, but higher on i.c.v. injection than that of nalorphine. The development of tolerance to the analgesia caused by nalorphine was not affected by the 6-modifications. Frequent withdrawal signs were seen in mice treated chronically with anlorphine-6-conjugates by challenging with naloxone while mice treated with nalorphine showed no such signs. This potent enhancing effect of 6-conjugation on the development of physical dependence was suggested to be also the case with morphine. These changes of potency due to conjugation were interpreted as due to the altered interaction with multiple opioid receptors.

Antinociception following microinjection of dibutyryl cyclic nucleotides into the caudal reticular formation and periaqueductal gray of the rat brain

The tail flick, paw pinch, and hot plate tests were used to assess changes in nociceptive threshold following microinjection of dibutyryl derivatives of cyclic nucleotides into areas of the central nervous system previously shown to be involved in modulation of nociceptive threshold and mediation of morphine analgesia. An elevation in the nociceptive threshold was observed on all three tests following administration of 10 μg dibutyryl cyclic 3':5' adenosine monophosphate (db cAMP) into the caudal brainstem reticular formation (CRF) and periaqueductal gray (PAG). Two μg db cAMP produced the same magnitude of analgesia but had a shorter duration of action. Twenty μg dibutyryl cyclic 3':5' guanosine monophosphate (db cGMP) produced analgesia on all three tests following microinjection at CRF sites but not at PAG sites. These data indicate that morphine analgesia and the antinociception produced by cyclic nucleotides may involve, at least in part, common neuronal substrates. However, the observed capacity of db cAMP to elevate nociceptive threshold does not support the hypothesis that the mechanism of morphine's analgesic action involves inhibition of adenylate cyclase.

Does neurotoxic conditioning accelerate nerve regeneration?

The prototype environmental neurotoxin, 2,5-hexanedione(2,5-HD), induces changes in somata of sensory ganglia that are morphologically similar to chromatolysis; this study assessed the functional significance of neuronal alterations. Experimental rats were exposed 6 weeks to 2,5-HD, and after 1 week without treatment were then subjected to experimental crush of the sciatic nerve (paired controls were unintoxicated). Nerve regeneration was assayed by the pinch test 4 to 13 days after crush. These preliminary results did not show an accelerated rate of axonal outgrowth; however, there was a small but significant ( P < 0.05) decrease in the initial delay.

Is Fleming's lysozyme an analgesic agent? Experiments on mice.

1. Antinociceptive activity of hen egg white lysozyme (Fleming's lysozyme) was determined against abdominal contractions provoked by irritants injected intraperitoneally into mice. Carrageenan (2 mg) (CA) injected with arachidonic acid (15 micrograms) (AA) or prostaglandins PGE1 or PGF2 alpha (0.04 ng), brewer's yeast (10 mg), caolin (10 mg), mepartricin (80 U) and phenylquinone (50 micrograms) were used as irritants. 2. Lysozyme was active at 400-800 mg/kg i.v. against CA + AA, CA + PG, brewer's yeast and caolin nociceptive stimulation. The compound was more effective against CA + AA than against CA + PG. Acetylsalicylic acid at 50-100-200 mg/kg p.o. was equally active against CA + AA and CA + PG. 3. Lysozyme was inactive in the tail pinch and hot plate tests that mainly detect central analgesics. 4. The results are discussed in relation to the claim advanced years ago that lysozyme is an effective analgesic agent in humans. The compound was found active against herpes zoster or cancer pain but did not find use despite the favourable reports presented. 5. The experimental results obtained on laboratory animals do not contradict the conclusions drawn after the clinical use of the compound.

Isolation from bovine brain of a novel analgesic pentapeptide, neo-kyotorphin, containing The Tyr-Arg (kyotorphin) unit

A novel analgesic peptide, isolated from the bovine brain, was found to contain the Tyr-Arg (kyotorphin) unit at the C-terminal portion. This peptide, in the methanol-soluble fraction, was isolated by gel filtration and cation exchange chromatography. This peptide was termed “neo-kyotorphin” and the amino acid sequence is Thr-Ser-Lys-Tyr-Arg. The synthetically prepared neo-kyotorphin proved to have a dose-dependent analgesic effect in mice. The median analgesic dose, ED 50 of neo-kyotorphin was 195 nmol/mouse (intracisternal injection), with the tail pinch test, and the potency was approximately equal that of Leu-enkephalin.

Analgesie activity and opioid receptor binding of dynorphin

Analgesic activity and binding characteristics of dynorphin (DYN) were studied. The analgesic activities were studied on the mouse tail pinch test. The ED50 values(nmol/mouse) by intracerebroventricular(i.c.v.) injection of DYN,morphine and ethylketocyclazocine(EKC) were 3.8,0.17 and 0.87,respectively. Those by intraspinal(i.s.) injection were 0.61,0.18 and 0.65, respectively.

Comparison of adenylate cyclase activity in segments of rat sciatic nerve with a condition/test or test lesion

A prior “conditioning” lesion enhances the rate of nerve regeneration after a subsequent “test” lesion made proximal to the first injury. This effect has been observed in several species and in both peripheral and central neurons. Nonetheless, the molecular basis of the conditioning effect remains uncertain. The initiation of regeneration and its progress appear to depend on separate processes, and either or both may be affected in different species. This investigation focused on rat sciatic nerve, where only the rate of elongation appears to be consistently enhanced. I investigated the distribution of adenylate cyclase activity in various segments of the injured nerves to determine if cyclic AMP might modulate some aspect of the regeneration process. Adenylate cyclase activity accumulated at the point of injury and was significantly increased in regenerating nerve tips, as determined by the pinch test, in both condition/test- and test-lesion nerves. The sole significant difference between these experimental groups was an increase in adenylate cyclase activity immediately distal to the test lesion and immediately distal to the regeneration point in the condition-lesion nerves. I suggest that an increase in cyclic AMP concentration in nerve segments distal to a lesion may condition the local environment to enhance axon sprouting or elongation. Nerve growth stimulated by a local increase in cyclic AMP, however, may require additional cell body-supplied material to be sustained.