The structure of the common atrioventricular valve in hearts having isomeric atrial appendages and double inlet ventricle

The primary purpose of the study was to examine the role of the posterior cruciate ligament (PCL) in knee-joint proprioception after total knee arthroplasty (TKA). Knee-joint proprioception was measured in 10 patients with nonsacrificed PCL TKAs and 10 with sacrificed PCL TKAs. Knee-joint proprioception was evaluated through reproduction of static knee angles using a Penny and Giles electrogoniometer. The primary variable was absolute angular error (AAE). AAE was defined as the absolute value of the difference between the test angle and the patient's perceived version of the test angle. Proprioception deficit was compared to the WOMAC questionnaire which evaluates pain, stiffness, and physical function of the lower extremity. No significant difference was found between the nonsacrificed PCL TKA (4.33 degrees +/- 1.52 degrees) and sacrificed PCL TKA (4.38 degrees +/- 1.39 degrees) AAE values (P > .4). Furthermore, no significant differences were observed in the WOMAC questionnaire scores for all three parameters between the two types of knee prosthesis (P > .35). The current findings suggest that the preservation of the PCL in TKA may not improve knee-joint proprioception and subsequently may not improve TKA functional performance.     

Histopathological findings in the proprioception of the shoulder joint

Purpose of this study was the evaluation of distribution and morphology of mechanoreceptors in the glenohumeral joint capsule and rotator cuff in comparison to the coracoacromial ligament by means of specific immunfluorescence microscopy. The complemente joint capsules, rotator cuffs and coracoacromial ligaments of three fresh cadaver shoulder were harvesed. Serial cryostate sections were taken and alternately incubated with antiserum against neurofilament, lamin or myelin of peripheral nerves. The antibody-reaction was visualized with fluorescin lg-G. The nerve endings were photographed and computer-aided 3-dimensional reconstructions were performed. Three types of corpuscular and free nerve endings of different morphology were found in different distributions: whereas the Ruffini corpuscles were much more frequent in the coracoacromial ligament and rotator cuff, Pacini endings were predominantly found in the joint capsule. Generally corpuscular nerve endings were more frequent in the coracoacromial ligament and the rotator cuff than in the antero-inferior capsule and the number of corpuscles increased from medial to lateral within the anterior and inferior parts of the capsule. The dense ligamentous tissue was almost aneural whereas the periarticular fatty or loose connective tissue contained nerve fibres and nerve endings. In view of the results of other experimental and clinical studies the high frequency of Ruffini and Pacini endings in the rotator cuff and coracoacromial ligament suggest, that both are involved in the neurosensory control of glenohumeral stability and subacromial impingement. In contrast our findings in the joint capsule do not clearly prove, that those joint receptors predominantly maintain joint stability.     

Alterations in mystacial pad innervation in the aged rat

It is well established that sensory perception becomes impaired with advancing age and that, in parallel, dystrophy and degeneration of axons occur in sensory pathways. In this study, the impact of aging was examined in the mystacial pad, which receives a large variety of sensory nerve endings organized in a highly predictable pattern. Mystacial pad specimens from aged (30 months old) and young adult (2-3 months old) female Sprague-Dawley rats were processed, in parallel, for immunohistochemical analyses with antibodies against human neuronal cytoplasmic protein (protein gene product 9.5), transmitter enzymes, and several neuropeptides. Several changes in cutaneous innervation including both degenerative and regenerative processes were evident in the aged rat: (1) the Merkel endings and lanceolate endings that emanate from large-caliber afferents in the whisker follicles were reduced and showed signs of degeneration. Furthermore, a reduction of piloneural complexes at the intervibrissal hairs were evident, but only in aged rats that showed more severe behavioral sensorimotor disturbances. In contrast, Ruffini endings as well as mechanoreceptors emanating from medium-caliber axons, i.e., transverse lanceolate and reticular endings, appeared normal. (2) A reduction was evident among two sets of unmyelinated epidermal endings; however, the epidermal innervation affiliated with the intervibrissal hairs appeared normal in the aged rat. (3) A loss of sympathetic neuropeptide tyrosine (NPY) or tyrosine hydroxylase-immunoreactive (IR) and somatosensory Calcitonin gene-related peptide (CGRP)-IR perivascular axons was paralleled by an increase in presumed parasympathetic NPY/CGRP-IR axons. (4) Two "novel" networks of fine-caliber axons were observed in the outer and inner root sheaths of the whisker follicles in the aged rat. (5) NPY was present in a population of small-caliber, somatosensory CGRP-IR axons in the aged rat. This may represent a de novo synthesis, since, normally, NPY-like immunoreactivity is not observed in this set of axons. Our results suggest that the sensory impairments occurring with advancing age are part of a peripheral process instigated by changes in nerve-target interactions and/or incapacitation of the neuronal machinery to sustain the axonal integrity.     

Early, incapacitating instability of posterior cruciate ligament-retaining total knee arthroplasty

Numerous studies indicate that total knee arthroplasty (TKA) achieves excellent long-term success whether the posterior cruciate ligament (PCL) is saved or excised. In 13 patients, 16 PCL-retaining TKAs were identified with incapacitating instability secondary to early PCL deficiency. Patients with clinical PCL insufficiency present with a triad of subjective complaints: persistent swelling/effusions, anterior knee pain, and giving-way or instability episodes with activities of daily living. Of 13 patients, 12 had at least three postoperative visits with identical subjective complaints before PCL deficiency was diagnosed. On examination all patients exhibited effusion, posterior sag, positive quadriceps active test, and a visible anterior translation of the tibia on the femur while extending the leg from a seated, 90 degree flexed position. This sign has not been previously described to our knowledge but was present in all of our study patients. No patients had radiographic evidence of loosening or osteolysis. Joint aspiration was negative for infection in all patients. No patient had lateral patellofemoral maltracking. By radiographic measurement, the PCL-deficient knees had an average joint line elevation of 10.3 mm, compared with well-functioning TKAs which had an average joint line elevation of 5.0 mm. There was no correlation of PCL deficiency with excessive proximal tibial resection. Nonsurgical intervention provided no improvement in pain or instability. Six patients had improvement of pain, effusion, and stability after revision to a cruciate-substituting implant. We believe that this complication occurs more frequently than is currently being identified and should be considered in problem TKAs with normal radiographs.     

Alterations in ultrastructural localization of growth-associated protein-43 (GAP-43) in periodontal Ruffini endings of rat molars during experimental tooth movement

It is known that orthodontic forces induce discomfort and/or abnormal sensation after application of an orthodontic appliance in patients, suggesting the adaptation of periodontal neural elements to environmental changes. However, no morphological data have been provided. The present study investigated, by immunoelectron microscopy, the localization of growth-associated protein-43 (GAP-43) in periodontal Ruffini endings in rat molars during experimental tooth movement. In the untreated control group, immunoelectron microscopy demonstrated that GAP-43-like immunoreactivity in the Ruffini endings was confined to the Schwann sheaths around the axon terminals, and was in neither the cell bodies of terminal Schwann cells nor the axon terminals themselves. Immunoelectron microscopic observation revealed alterations in the localization of GAP-43-like immunoreactivity in the periodontal Ruffini endings during experimental tooth movement. After 1 day of treatment, the cell bodies of the terminal Schwann cells associated with Ruffini endings appeared to contain immunoreaction products for GAP-43, and retained GAP-43-like immunoreactivity during tooth movement. From 5 to 7 days, a major population of the axoplasm of the periodontal Ruffini endings, which was immunonegative in control, filled the GAP-43 immunoreactions, showing a tendency to decrease in number later, and disappeared completely at 14 days. These findings suggest that orthodontic forces easily induce the remodeling of the mechanoreceptive Ruffini endings as well as the active tissue remodeling in a close relationship. Since the ultrastructural localization of GAP-43-like immunoreactivity was drastically changed in the Ruffini endings during tooth movement, GAP-43 functions as one of the key molecules in the remodeling of mechanoreceptive Ruffini endings during tooth movement.     

Factors associated with copper T IUD removal for bleeding/pain: a multivariate analysis

The retractor penis muscle originates from the vertebrae in pigs, horses, cattle and goats; it arises from the rectum in sheep. In all the species considered, sensitive innervation was found. This was represented by encapsulated receptors. Nervous vegetative supply, made up of isolated or assembled ganglion cells, was also present. Among the numerous sensory nerve endings found in pigs, goats and sheep were Pacinian, Pacinian-like, Golgi-Mazzoni corpuscles and Krause's end bulbs (genital corpuscles). Few Pacinian and Pacinian-like corpuscles were found in cattle and horses. A hypothesis on the probable functional role of the observed receptorial apparatus was formulated.     

Effect of anxiety on the rate of gastric emptying of liquids

We studied the morphology and distribution of nerve endings in the human triangular fibrocartilage complex using both silver staining and immunohistochemical staining using a protein specific to nerve fibres. Free nerve endings were found in the ulnar side of the triangular fibrocartilage complex, especially in the ulnar collateral ligament, meniscus homologue and the adjacent collagen fibre area of the peripheral part of the ulnar side of the articular disc. Meissner's and Krause's corpuscles were observed in the ulnar collateral ligament and meniscus homologue. The fact that free nerve endings were observed in the meniscus homologue and adjacent collagen fibre area of the peripheral part of the ulnar side of the articular disc suggests that this disc may be a source of wrist pain. The presence of nerve end bulbs in the triangular fibrocartilage complex also suggests a possible role for corpuscles as mechanoreceptors.     

Overexpression of glucagon-like peptide-1 receptor in an insulin-secreting cell line enhances glucose responsiveness

Pituitary adenylate cyclase-activating polypeptide (PACAP), a member of the VIP (vasoactive intestinal polypeptide) family of peptides, has been demonstrated in neurons of the sensory system. PACAP expression of these neurons is sensitive to nerve damages such as nerve crush or axotomy. In the present study, PACAP expression in the mesencephalic trigeminal nucleus of the rat was examined after transsection of the main trunk of the masseteric nerve. The primary sensory neurons of the nucleus are considered to have purely proprioceptive functions. By quantitative in situ hybridization using a PACAP [35S]cRNA probe, an increase in PACAP mRNA was observed on the side ipsilateral to transsection already after 3 h and the expression reached a peak 24 h after surgery after which the levels gradually decreased during the next 14 days. A low and constant expression of PACAP mRNA could be seen on the side contralateral to transsection. PACAP immunoreactivity was demonstrated on the ipsilateral side after 18 h, using a specific monoclonal PACAP antibody. Co-existence of PACAP with NPY and galanin was demonstrated 7 days after transsection. Analysis of the masseteric nerve by radioimmunoassay on transsected and normal nerve stumps revealed an increase of PACAP-38 immunoreactivity in the nerve proximal to the transsection compared to the normal side (15.3 vs. 6.1 pmol/g wt). The results suggest that PACAP has a role in the early phase of adaptation to nerve injury in the proprioceptive neurons.     

Proprioceptive deficits of the knee joint after rupture of the medial meniscus

We assessed knee joint proprioception in 23 patients with an isolated lesion of the medial meniscus. Thirteen patients were tested prior to their arthroscopic operation, and 10 patients were examined after partial arthroscopic resection of the injured meniscus. As a control group we evaluated 30 healthy volunteers with clinically inconspicious knee joints. For documentation of the proprioceptive capabilities we performed an angle reproduction test. Additionally the subjects were tested with and without an elastic knee bandage, to test the influence of such a bandage on knee joint proprioception. Our results showed that preoperatively proprioception was significantly less good than in the control group. We found no influence of the knee bandage on the proprioception of the injured knee. The postoperative group of patients showed significantly better proprioceptive capability than the preoperative patients. The postoperative results did not differ significantly from those of the control group.     

Differential dependency of cutaneous mechanoreceptors on neurotrophins, trk receptors, and P75 LNGFR

The impact of null mutations of the genes for the NGF family of neurotrophins and their receptors was examined among the wide variety of medium to large caliber myelinated mechanoreceptors which have a highly specific predictable organization in the mystacial pad of mice. Immunofluorescence with anti-protein gene product 9.5, anti-200-kDa neurofilament protein (RT97), and anti-calcitonin gene-related product was used to label innervation in mystacial pads from mice with homozygous null mutations for nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin-4 (NT-4), the three tyrosine kinase receptors (trkA, trkB, trkC), and the low-affinity nerve growth factor receptor p75. Specimens were sacrificed at birth and at 1, 2, and 4 weeks for each type of mutation as well as at 11 weeks and 1 year for p75 and trkC mutations, respectively. Our results demonstrate several major concepts about the role of neurotrophins in the development of cutaneous mechanoreceptors that are supplied by medium to large caliber myelinated afferents. First, each of the high-affinity tyrosine kinase receptors, trkA, trkB, and trkC, as well as the low-affinity p75 receptor has an impact on at least one type of mechanoreceptor. Second, consistent with the various affinities for particular trk receptors, the elimination of NGF, BDNF, and NT-3 has an impact comparable to or more complex than the absence of their most specific high-affinity receptors: trkA, trkB, and trkC, respectively. These complexities include potential NT-3 signaling through trkA and trkB to support some neuronal survival. Third, most types of afferents are dependent on a different combination of neurotrophins and receptors for their survival: reticular and transverse lanceolate afferents are dependent upon NT-3, NGF, and trkA; Ruffini afferents upon BDNF and trkB; longitudinal lanceolate afferents upon NGF, trkA, BDNF, and trkB; and Merkel afferents on NGF, trkA, NT-3, trkC, and p75. NT-4 has no obvious detrimental impact on the mechanoreceptor development in the presence of BDNF. Fourth, NT-4 and BDNF signaling through trkB may suppress Merkel innervation and NT-3 signaling through trkC may suppress Ruffini innervation. Finally, regardless of the neurotrophin/receptor dependency for afferent survival and neurite outgrowth, NT-3 has an impact on the formation of all the sensory endings. In the context of these findings, indications of competitive and suppressive interactions that appear to regulate the balance of innervation density among the various sets of innervation were evident.     

The nature and distribution of the innervation of human supraspinal and interspinal ligaments

STUDY DESIGN: To use fresh, human supraspinal and interspinal ligaments and document their innervation. OBJECTIVES: To characterize the innervation of the human supraspinal and interspinal ligaments. SUMMARY OF BACKGROUND DATA: The nature and distribution of the innervation of spinal ligaments remains unknown. METHODS: Sections of spinal ligaments were labeled with a fluorescent antibody against neurofilament proteins and observed with a confocal microscope. RESULTS: The ligaments were found to be well innervated. Innervation was equally distributed along the ligament, symmetrically distributed between left and right sides, and more densely distributed in the periphery. Pacinian corpuscles were scattered randomly, close to blood vessels, whereas Ruffini corpuscles were in the periphery, close to the collagen bundles. CONCLUSIONS: Human supraspinal and interspinal ligaments are well innervated. This innervation might form the basis of neurologic feedback mechanisms for the protection and stability of the spine. These mechanisms might also be important in the development of diseases such as scoliosis.     

Motor illusions: What do they reveal about proprioception?

Five illusions involving distortions in the perception of limb position, movement, and weight are described in the context of their contribution to understanding the sensory processes involved in proprioception. In particular, these illusions demonstrate that the position sense representation of the body and the awareness of limb movement result from the cross-calibration of visual and proprioceptive signals. Studies of the vibration illusion and phantom-limb phenomenon indicate that the perception of limb movement and position are encoded independently and can be dissociated. Postural aftereffects and the illusions of movement induced by vibration highlight the remarkable lability of this sense of limb position, which is a necessary feature for congruence between the spatial senses. Finally, I discuss the role of corollary discharges in the central processing of afferent information with respect to the size-weight and vibration illusions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parietal lobe syndrome and schizophrenia: Comparison of neuropsychological deficits.

Investigated reported communalities in the perceptual impairments and body image distortions found after parietal lobe lesions and in schizophrenia. To compare these 2 syndromes, 15 patients with lesions of the parietal lobe and 15 patients with schizophrenia were tested on a neuropsychological battery designed to assess deficits in proprioception, tactile functions, and body image experience. Control groups consisted of 15 normal persons and of a series of 15 brain-injured cases in which the parietal lobe had been spared. Results indicate that both schizophrenic and parietally damaged Ss showed significant impairments in weight-discrimination measures of proprioceptive acuity when compared to the control brain-injured and normal Ss. No significant differences among groups were found on a comparable tactile size-estimation task, but the group with parietal injury exhibited a significant deficit in tactile sensory perception on the Finger Agnosia Test. Only the schizophrenic group showed evidence of disturbed body image when reality factors of body dysfunction were taken into account in the brain-injured patients. It is concluded that persons with schizophrenia and parietal lobe damage share a deficit in proprioception that may be based on different neurological substrates leading to (a) tactile impairments in cases with parietal damage, and (b) body-image disturbance in schizophrenia. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of proprioception in normal and clumsy children

This study investigates the relation between performance on simple tasks dependent on proprioception, and performance of complex perceptual-motor skills in clumsy children and age-matched control children. One hundred and forty-six right-handed children aged between 5 and 8 years were tested on non-visual aiming, non-visual posture matching, the Kinaesthetic Sensitivity Test (KST), and the Movement Assessment Battery for Children (ABC). Half of the children had scores below the 15th centile on the Movement ABC and were classed into the developmental coordination disorder (clumsiness) group. Scores on the proprioceptive tasks were used to predict performance on complex tasks of the subscales of the Movement ABC (manual dexterity, ball skills, and balance). Specific relations were found between the proprioceptive tasks and the subscales of the Movement ABC, but the KST did not predict differences in motor skills, and no relation was found between tasks carried out without vision. Simple non-visual movement tasks do predict performance in more complex skilled tasks but this is affected by many task features rather than simply the reliance on proprioception for information about movement.     

Kinematics of posterior cruciate ligament-retaining and -sacrificing mobile bearing total knee arthroplasties. An in vitro comparison of the New Jersey LCS meniscal bearing and rotating platform prostheses

The posterior cruciate ligament (PCL)-retaining, meniscal bearing and the PCL-sacrificing rotating platform designs of the LCS prosthesis (DePuy, Warsaw, IN) were designed to minimally constrain knee kinematics while minimizing bone-cement-prosthesis interface stresses and polyethylene wear. The kinematics and stability of the knee following arthroplasty with these devices rely on adequate tensioning of the remaining soft tissues by management of the flexion/extension gaps at the time of surgery. In this in vitro study, the knee kinematics of the function of the quadriceps mechanism for 8 cadaveric knees were measured quantitatively before and after implantation of these 2 prosthesis designs. Following implantation of the PCL-retaining, meniscal bearing prosthesis, anterior translations during anterior drawer testing were significantly greater (P < .05) than those seen in the intact knee. Implantation of the PCL-retaining, meniscal bearing prosthesis resulted in an increase in the extension gap of 2 mm. Quadriceps force needed to achieve full extension was increased by 30% over that needed in the intact knee. The PCL-sacrificing, rotating platform prosthesis constrained anterior translation such that nearly normal anterior knee stability was reestablished; however, the extension gap was increased by 4 mm and the quadriceps force needed to achieve full extension was 50% greater than that needed in the intact knee. Attempts to achieve joint stability by increases in the thickness of the tibial component to widen the flexion/extension gaps results in compromises of quadriceps efficiency, particularly in the absence of a functioning PCL, as demonstrated in this in vitro model. Patients receiving the PCL-sacrificing prosthesis may experience difficulty in those activities requiring quadriceps power near full extension, such as rising from a chair or ascending or descending stairs.     

Proprioceptive capacities of patients with retropatellar knee pain with special reference to effectiveness of an elastic knee bandage

In the presented study, knee joint proprioception of 43 patients with a patellar pain syndrome of the knee joint was evaluated. In a control group, the proprioception of 30 healthy volunteers with clinical and an-amnestic inconspicous knee joints was examined. We tested the proprioceptive capability of the subjects with a passive angle reproduction test. Additionally, all knee joints were measured with and without an elastic knee bandage. The patient group showed significant deterioration of angle reproduction capability (13.2 degrees +/- 6.1 degrees) compared to the control group (7.8 degrees +/- 2.8 degrees). After applying an elastic knee bandage, the angle reproduction capability significantly improved to 9.2 degrees +/- 4.5 degrees. Proprioception of the contralateral, noninvolved knee joint in the patients (11.6 degrees +/- 6.3 degrees) was worse compared to the control group. Applying an elastic knee bandage did not significantly improve the proprioception of the uninjured knee joint.     

Is knee joint proprioception worse in the arthritic knee versus the unaffected knee in unilateral knee osteoarthritis?

OBJECTIVE: Neuromuscular joint protection requires proprioceptive input and motor output. Impairment of proprioception in knee osteoarthritis (OA) may contribute to, and/or result from, the disease. If this impairment was exclusively a local result of OA, a between-knee difference would be expected in patients with unilateral OA (UOA). To explore causal directions, 2 hypotheses were tested: 1) proprioception is worse in UOA patients versus elderly controls; 2) proprioception is worse in the arthritic knee versus the unaffected knee in UOA patients. METHODS: Twenty-eight UOA patients (Kellgren-Lawrence grade > or =2 in 1 knee and <2 in the other knee) and 29 elderly controls were enrolled. The unaffected knee of each UOA patient and both knees of the elderly controls were required to meet symptom, examination, and radiographic criteria. Proprioception (detection threshold of joint displacement after slow, passive, automated knee motion), body mass index, pain, functional status, range of motion, and laxity were measured. RESULTS: UOA patients had worse proprioception than did elderly controls, in either knee. A between-knee difference was not found in UOA patients. CONCLUSION: Impaired proprioception is not exclusively a local result of disease in knee OA. The relative importance of impaired proprioception in the development and progression of knee OA will require longitudinal study.     

The manipulation of informational feedback and its effects upon prism adaptation.

Supplied 88 volunteers, primarily college students, in 4 groups, with varying amounts and types of information regarding the nature of their visual fields, which in 3 cases were laterally displaced by means of a 20-diopter wedge prism. Ss who experienced (a) target-pointing error, (b) proprioception-vision discrepancy, and (c) reafference-reafference discrepancy during the prism-exposure period (target group) adapted more than Ss exposed to only the latter 2 sources of information (no-target group). This difference in adaptation was seen in both negative aftereffect (NA) and proprioceptive shift (PS). In a 3rd condition (no-error group) Ss were induced to experience their target pointing as accurate, while at the same time being exposed to discrepancies between proprioception and vision and between "old" and "new" reafference. This experimental condition resulted in 0 NA but a significant PS. In a 4th condition (no-prism group), in which target-pointing errors were experienced but the 2 sensory discrepancies did not exist, a significant NA resulted, but no PS. Because NA and PS were not highly correlated with each other and were differentially affected by the experimental manipulations, it is suggested that they represent qualitatively different forms of adaptation. (French summary) (44 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of systemic resiniferatoxin treatment on substance P mRNA in rat dorsal root ganglia and substance P receptor mRNA in the spinal dorsal horn

We have investigated the expression, using immunohistochemical and Western blot methods, of some cytoskeletal proteins including desmin, vimentin, actin, alpha-actinin, and ubiquitin in hereditary myopathy of the diaphragmatic muscles in Holstein-Friesian cattle (the histochemical and electron microscopical aspects have been previously reported). Immunohistochemically, the expression of desmin was observed strongly in the subsarcolemmal regions, but was lacking or faint in the area corresponding to the core-like structures. Vimentin showed almost the same localization as desmin, but no activity could be observed in the core-like structures. In addition, the core-like structures showed strong immunoreactivity for actin and ubiquitin, but no immunoreactivity for alpha-actinin. F-actin stained with phalloidin-tetramethyl-rhodamine was strongly positive in irregular spots that corresponded to the core-like structures, but was negative for desmin-positive regions. Western blot analysis of the diseased muscles revealed a significant increase in the amount of desmin and vimentin immunoreactivities and similar amounts of actin and alpha-actinin compared with the control muscles. Two-dimensional electrophoresis revealed no isoforms of desmin, suggesting the absence of abnormal phosphorylated forms of desmin. Since the co-localization of desmin and vimentin and the absence of phosphorylated desmin suggest that the overexpression of desmin may be reflected in the reactive change or regenerating process, the present myopathy should be regarded as an entity separate from desmin-storage myopathy or desmin-related myopathies. We also discuss the possibility that the present myopathy could be considered as myofibrillar myopathy, a recently proposed nosological entity.     

Occurrence of heat shock response in deafferented neurons in the substantia nigra of rats

The substantia nigra is innervated by massive inhibitory GABAergic projections from the striatum and globus pallidus, deafferentation of which is supposed to lead to anterograde trans-synaptic degeneration of the nigral neurons. An immunohistochemical method was used to examine the induction of 72,000 mol. wt heat shock protein in the substantia nigra following cerebral hemitransection or transient middle cerebral artery occlusion. At three and four days post-transection, strong immunoreactivity for 72,000 mol. wt heat shock protein was found in the ipsilateral substantia nigra pars reticulata. Light microscopic observation revealed a number of pars reticulata neurons showing strong immunoreactivity for 72,000 mol. wt heat shock protein in their perikarya and proximal processes. In addition, Golgi-like stained neurons with dystrophic features were occasionally observed in the ipsilateral substantia nigra pars reticulata. The immunoreactivity for 72,000 mol. wt heat shock protein in the ipsilateral pars reticulata gradually declined and almost disappeared by 15 days after transection. No apparent induction of 72,000 mol. wt heat shock protein was found in the substantia nigra pars compacta throughout the time period examined. Massive striatal ischemic injury produced by transient middle cerebral artery occlusion also induced expression of 72,000 mol. wt heat shock protein in the pars reticulata neurons three and four days postoperatively. These findings suggest that deafferentation of the striatal or striatopallidal inputs per se is a harmful stress for the substantia nigra pars reticulata neurons, inducing 72,000 mol. wt heat shock protein synthesis. The present data may contribute to our understanding of the molecular basis of the pathomechanism of the transneuronal regression of substantia nigra pars reticulata neurons, which may occur after removal of inhibitory GABAergic inputs.