Qualitative grading of disc degeneration by magnetic resonance in the lumbar and cervical spine: lack of correlation with histology in surgical cases

BACKGROUND

Clinically, magnetic resonance (MR) imaging is the most effective non-invasive tool for assessing IVD degeneration. Histological examination of the IVD provides a more detailed assessment of the pathological changes at a tissue level. However, very few reports have studied the relationship between these techniques. Identifying a relationship may allow more detailed staging of IVD degeneration, of importance in targeting future regenerative therapies.

OBJECTIVES

To investigate the relationship between MR and histological grading of IVD degeneration in the cervical and lumbar spine in patients undergoing discectomy.

METHODS

Lumbar (N = 99) and cervical (N = 106) IVD samples were obtained from adult patients undergoing discectomy surgery for symptomatic IVD herniation and graded to ascertain a histological grade of degeneration. The pre-operative MR images from these patients were graded for the degree of IVD (MR grade) and vertebral end-plate degeneration (Modic Changes, MC). The relationship between histological and MR grades of degeneration were studied.

RESULTS

In lumbar and cervical IVD the majority of samples (93%) exhibited moderate levels of degeneration (ie MR grades 3-4) on pre-operative MR scans. Histologically, most specimens displayed moderate to severe grades of degeneration in lumbar (99%) and cervical spine (93%). MR grade was weakly correlated with patient age in lumbar and cervical study groups. MR and histological grades of IVD degeneration did not correlate in lumbar or cervical study groups. MC were more common in the lumbar than cervical spine (e.g. 39 versus 20% grade 2 changes; p < 0.05), but failed to correlate with MR or histological grades for degeneration.

CONCLUSIONS

In this surgical series, the resected IVD tissue displayed moderate to severe degeneration, but there is no correlation between MR and histological grades using a qualitative classification system. There remains a need for a quantitative, non-invasive, pre-clinical measure of IVD degeneration that correlates with histological changes seen in the IVD.

Minimally invasive decompression and stabilisation for extensive haemangiomas of lumbar spine

INTRODUCTION

Vertebral haemangiomas are a common incidental finding and are largely asymptomatic. Extensive haemangiomas of the spine causing neurological deficits are exceedingly rare. Traditional open surgical approaches in these cases can be complicated by life-threatening blood loss.

PATIENT CASE HISTORY

We describe 2 patients (ages 27 and 53 years) who presented with severe back pain and lower limb weakness. Radiological investigations revealed very extensive lesions of the L1 and L4 vertebral bodies, respectively, with severe narrowing of the lumbar canal. After selective embolisation of the spinal arterial feeders, both patients underwent a posterior decompression, vertebroplasty, and bilateral pedicle screw fixation in a minimally invasive fashion. Blood loss was minimal and a rapid clinical recovery was seen.

CONCLUSIONS

Combinations of embolisation, vertebroplasty and minimally invasive posterolateral instrumentation are treatment strategies that can be used to treat extensive vertebral haemangiomas presenting with neurological deficits.

Melanoma of the sellar region

Metastatic melanoma has a propensity for multiple intra cranial deposits. Rarely, metastatic melanoma to the pituitary gland has been reported, usually in conjunction with widespread systemic metastases. We describe a patient with metastatic melanoma to the pituitary gland as the first clinical presentation of widespread metastatic disease and review the relevant literature.

Haemangioblastoma: a rare cause of a cerebellar mass in the elderly

In the elderly, cerebellar lesions are commonly metastatic tumours with poor prognosis. We describe two octogenarians who presented with obstructive hydrocephalus, secondary to posterior fossa tumours that, on computed tomography, were thought to be cerebellar metastases. Both lesions were excised and the histology proved them to be cerebellar haemangioblastomas, primary benign tumours of the posterior fossa, which are rare in the elderly.

Delayed postoperative intracerebral abscess caused byProprionibacterium acnes: case report and review of the literature

A case of delayed intracerebral abscess due to Proprionibacterium acnes (P. acnes), 18 months after an uneventful excision of a parasagittal haemangiopericytoma in a 61-year-old female is reported. This is highly unusual as cerebral abscess by P. acnes is rare and it occurred so late postoperatively in the absence of known risk factors. We propose the inclusion of cerebral abscess by P. acnes in the differential diagnosis of lesions that mimic tumour recurrences, after clean craniotomies.

MRI study of the natural history and risk factors for pseudomeningocoele formation following postfossa surgery in children

Surgical approaches to the posterior fossa may be complicated by pseudomeningocoele formation. We report on its natural history and risk factors for its formation, as seen on serial MRI postoperatively in children with posterior fossa tumours. In a retrospective study of 84 children undergoing surgery for posterior fossa tumours, 13 (16%) developed clinically apparent pseudomeningocoeles. On postoperative MRI, pseudomeningocoeles were apparent in 34 (41%) patients at 1-5 days, but in only four patients at 10-15 months postsurgery. There was a progressive decrease in the mean depth of pseudomeningocoele measured from the MRI scans postoperatively. Patients with pseudomeningocoeles were more likely to have a postoperative CSF leak from the wound (39 v. 13%), lumbar punctures or lumbar drains (54 v. 25%), wound re-closures (23 v. 1%) and prolonged hospital stay (19.9 v. 14.5 days). On multivariate analysis, patients with pseudomeningocoeles were also more likely to have undergone a suboccipital craniectomy than those without pseudomeningocoeles (69 v. 38%). Postoperative pseudomeningocoele formation following posterior fossa surgery is more apparent radiologically than clinically, but there is clinical and radiological evidence that pseudomeningocoeles gradually resolve over the postoperative period. The risk of pseudomeningocoele formation is increased by performing a suboccipital craniectomy and there is an association with increased CSF leaks, needing re-closure of the wounds.

Unilateral avulsion fracture of the transverse atlantal ligament: successful treatment in a rigid cervical collar

A 34-year-old male sustained a unilateral avulsion fracture through the origin of the transverse atlantal ligament following a road traffic accident. This was successfully treated in a rigid neck collar for 8 weeks. Injuries to the transverse atlantal ligament are often associated with significant bony injury and atlanto-axial instability. Isolated injuries to the transverse ligament are extremely rare and the present case suggests that a trial of conservative management may be worth pursuing.

The role of parenteral nutrition as a supplement to enteral nutrition in patients with severe brain injury

Enteral nutrition (EN) is the preferred and safe route of feeding in surgical patients incapable of self-nutrition. We describe three patients with severe brain insult and recurrent sepsis, who despite the early introduction of EN, remained hypoalbuminaemic, hypoproteinaemic and developed peripheral oedema. This state persisted, despite increasing the caloric and protein intake via the enteral route. However, after a short course of supplemental parenteral nutrition (PN), albumin and total protein levels improved, with resolution of peripheral oedema. We hypothesize that, in certain critically ill neurosurgical patients on EN, gastrointestinal malabsorption may underlie a persistently low serum albumin, total protein and peripheral oedema. A short course of supplemental PN may help to reverse this and a normal regimen of EN can then be continued.

Blindness from multiple cerebral gliomas mimicking metastatic brain disease

Multiple brain lesions are usually due to metastatic spread. The authors describe an unusual case of a 56-year-old male presenting with visual loss secondary to multiple intracranial lesions, with infiltration of the optic chiasm and an incidental renal lesion. Open biopsy of the brain lesion confirmed glioblastoma multiforme.

A 30 year perspective of the quality of evidence published in 25 clinical journals: signs of change?

METHODS

The quality of clinical studies published in five different specialties, over three decades was evaluated. Computerised search of the Medline database was undertaken to evaluate the articles published in 25 clinical journals in 1983, 1993, and 2003 from five different specialties (medicine, surgery, paediatrics, anaesthesia, and psychiatry). The number of randomised controlled trials (RCTs), meta-analyses, and other clinical trials (non-RCT) were noted.

RESULTS

From the 27,030 articles evaluated, there were 2283 (8.4%) RCTs, 166 (0.6%) meta-analyses, and 4153 (15.4%) other clinical trials. For the proportion of RCTs, the rank order of the specialties was; anaesthesia (503; 18%), psychiatry (294; 9.6%), medicine (899; 8.1%), paediatrics (326; 6.4%), and surgery (261; 5.3%) (p<0.001). For the proportion of meta-analysis, the rank order of the specialties was; psychiatry (36; 1.2%), medicine (105; 0.9%), paediatrics (15; 0.3%), anaesthesia (6; 0.2%), and surgery (4; 0.1%) (p<0.001). Overall, from 1983 to 2003, there were increases in the proportion of RCTs (449, 5.9% to 1027, 9.6%), meta-analysis (0, 0% to 127, 1.2%), and other clinical trials (897, 12% to 1983, 19%) (p<0.001). This trend was apparent in each clinical specialty (p<0.001).

CONCLUSIONS

Over the three decades evaluated, clinical trials, notably RCTs and meta-analysis form only a small proportion of articles published in prominent journals from five clinical specialties. This is notwithstanding the modest increases in the proportions of RCTs and meta-analysis over the same period.

A case of familial third ventricular colloid cyst

Colloid cyst of the third ventricle is a rare benign intracranial lesion, and familial cases are rarer still. They may be asymptomatic or present with symptoms of raised intracranial pressure, including sudden death. Surgical excision is curative. We report a 24 year old pregnant woman with familial colloid cyst, who presented with headaches and suffered a cardiorespiratory arrest. Early computed tomography scan of the brain is advised in patients with a family history of third ventricular colloid cyst presenting to the accident and emergency department with headache.

Use of quantitative assessment scales in cervical spondylotic myelopathy--survey of clinician's attitudes

BACKGROUND

There is considerable uncertainty regarding the selection criteria of patients and timing of surgery for cervical spondylotic myelopathy (CSM). Attempts have been made to quantify CSM severity using various assessment scales to provide an adjunct to clinical decision-making. The aim of the present study was to determine, by means of a 7-item questionnaire the attitudes of clinicians regarding the importance of quantitative assessment scales in the management of CSM, their actual use in clinical practice and how current scales fall short of the ideal.

FINDINGS

Clinical history, examination, radiological imaging and quantitative functional assessment were regarded by 117 clinicians as being almost equally important in the management of CSM. However, only 22 (19%) of clinicians admitted to using an assessment scale in clinical practice and 4 (3%) believed there was a 'gold-standard' assessment scale. These clinicians also considered 'ease of use' to be the most important attribute of an ideal assessment scale, followed by 'reproducibility', 'sensitivity to change' and 'validity'.

CONCLUSIONS

The discrepancy between the importance attached to quantitative measurement and its actual use suggests that current scales are under-utilised or unsuitable for clinical practice. A new easy-to use scale may be required that better reflects clinical requirements.

The time course of visual field recovery following transphenoidal surgery for pituitary adenomas: predictive factors for a good outcome

OBJECTIVE

To report the quantitative assessment of visual fields (VF) in patients with pituitary macroadenomas, and the time course and predictive factors for recovery of vision.

METHODS

Retrospective study of 41 patients with pituitary adenomas and visual disturbance. Patients underwent pre- and postoperative VF assessment at one week, three to six months, one year, two years, and five years using the Humphrey field analyser, which gives a quantitative measure of VF in each quadrant.

RESULTS

36/41 patients (88%) presented with a visual disturbance. Mean (SEM) duration of symptoms was 94 (50) weeks (range 0.5 to 1500); 12 (29%) had optic atrophy at presentation. Impairment of VF was greatest in the upper temporal quadrant, followed by the lower temporal. VF recovery was progressive and apparent even at the five year follow up (p<0.001). Overall, VF returned to normal in 35% of eyes, improved in 60%, and remained unchanged in 5%. Patients whose VF returned to normal had a shorter duration of symptoms (16 (5) v 137 (56) weeks; p<0.05), better preoperative visual acuity (p<0.05), and a smaller degree of impairment in preoperative lateral quadrant VF (p<0.01) than those whose VF only improved. On multivariate analysis, the only predictive factor for VF recovery was the degree of impairment in VF preoperatively.

CONCLUSIONS

Transphenoidal surgery for pituitary macroadenoma results in a progressive recovery of VF in 95% of patients. The extent of the VF recovery is mainly dependent on the preoperative VF deficit, which emphasises the need for early intervention in these patients.

Intradural metastatic spinal cord compression from ACTH-secreting pituitary carcinoma

Pituitary carcinomas are uncommon and intradural metastatic spread to the spine is rarer still. We describe a 27-year old man with metastatic spinal cord compression from an adrenocorticotrophic hormone (ACTH) cell pituitary carcinoma, 16 years following the initial presentation. He had three previous resections of the pituitary tumour and post-operative radiotherapy. The intradural, extramedullary spinal metastases causing thoracic and lumbar cord compression were excised, with neurological improvement. Spinal metastases in pituitary carcinoma are uncommon, but aggressive surgical resection of the spinal metastases produces good symptomatic relief.

14 mmHg: a case of raised intracranial pressure?

A 40-year-old woman presented with chronic headaches. She had undergone ventriculo-peritoneal (VP) shunt 7 years previously for treatment of hydrocephalus secondary to aqueduct stenosis. Intracranial pressure (ICP) monitoring revealed a resting ICP of less than 5 mmHg. Headaches were thought to be due to low ICP and the shunt tubing was ligated. Over the next 4 h there was an increase in ICP to 14 mmHg, decrease in GCS to 13 and ventriculomegaly on CT. These changes were reversed by the removal of the ligature. This unusual case highlights the fact that, in some shunted patients with over drainage of ventricles and a low resting ICP, small increases in ICP are poorly tolerated. This may be due to altered visco-elastic properties of the ventricles and the brain parenchyma.

Unifocal amyloidosis: a rare cause of spinal cord compression

A 75-year-old man presented with a 3-month history of progressive paraparesis due to an extradural mass causing cord compression at the T7 level of the thoracic spine. He underwent decompressive surgery, and later vertebrectomy and cage fixation. Histologically, the lesion was a localized mass of amyloid associated with a clonal plasma cell infiltrate. Localized 'amyloidomas' of the spine are rare, evolve slowly and often have a good prognosis following surgery.

An audit of audits: are we completing the cycle?

Clinical audit plays an important part in the drive to improve quality of patient care and thus forms a cornerstone of clinical governance. We evaluated the standard of clinical audits conducted by all departments in a teaching hospital between 1996 and 1997. Of a total of 213 audits carried out, 102 (48%) were 'partial' and only 29 (14%) were 'full'. Recommendations for improvement emerged from 134 (63%) of the audits performed. In only 51 audits (24%) was the cycle completed by re-auditing, during the subsequent 3 years. Most departments undertake clinical audits but failure to close the loop undermines their effectiveness and wastes resources.

Synchronous and metachronous gastric adenocarcinoma: case report and literature review

Whilst synchronous adenocarcinoma of the stomach is well documented, metachronous primary disease is exceedingly rare. We report a man with a family history of colonic and gastric cancer, who underwent a resection of a Duke's C adenocarcinoma of the rectum, aged 56 years, and a proximal partial gastrectomy for synchronous stage 1 gastric adenocarcinomas of the lesser curve, aged 61 years. Nine years later, a metachronous gastric primary was discovered in the gastric remnant, necessitating total gastrectomy. Total gastrectomy is the operation of choice for synchronous gastric primaries as it ensures clearance and prevents metachronous growth. However, it may not be appropriate for all gastric cancer as operative morbidity and mortality are increased, and because synchronicity and metachronicity of gastric cancer are uncommon. Moreover, there are no consistent data to demonstrate a survival advantage for total compared with partial gastrectomy for operable gastric cancer. If, after partial gastrectomy, synchronous disease is detected in the resected specimen (as in this reported case), endoscopic surveillance for metachronous disease is advised, since this may be amenable to surgical cure.

Motor and cognitive function in Lewy body dementia: comparison with Alzheimer's and Parkinson's diseases

OBJECTIVE

Motor and cognitive function were compared in patients with Lewy body dementia, Parkinson's disease, or Alzheimer's disease, to identify features that may be clinically useful in differentiating Lewy body dementia from Alzheimer's disease and Parkinson's disease.

METHODS

A range of neuropsychological function and extrapyrimidal signs (EPS) was assessed in 16 patients with Lewy body dementia, 15 with Parkinson's disease, 25 with Alzheimer's disease, and 22 control subjects.

RESULTS

The severity of total motor disability scores increased in the following order: controls approximately = Alzheimer's disease << Parkinson's disease < Lewy body dementia. Compared with patients with Parkinson's disease, patients with Lewy body dementia had greater scores for rigidity and deficits in the finger tapping test, but rest tremor and left/right asymmetry in EPS were more evident in Parkinson's disease. Patients with Lewy body dementia were also less likely to present with left/right asymmetry in EPS at the onset of their parkinsonism. "Sensitivity" to neuroleptic drugs was noted in 33% of patients with Lewy body dementia. Alzheimer's disease and Lewy body dementia groups had greater severity of dementia compared with the Parkinson's disease group and controls. Neuropsychological evaluation disclosed severe but similar degrees of impaired performances in tests of attention (digit span), frontal lobe function (verbal fluency, category, and Nelson card sort test) and motor sequencing in both Lewy body dementia and Alzheimer's disease groups, than Parkinson's disease and controls. In the clock face test, improved performance was noted in the "copy" compared to "draw" part of the test in controls, patients with Alzheimer's disease, and those with Parkinson's disease, but not in the patients with Lewy body dementia, who achieved equally poor scores in both parts of the test.

CONCLUSIONS

EPS in Lewy body dementia resemble those seen in idiopathic Parkinson's disease, although less rest tremor and left/right asymmetry but more severe rigidity favours a diagnosis of Lewy body dementia. The unique profile of patients with Lewy body dementia seen in the clock face test suggests that this simple and easy to administer test may be useful in the clinical setting to differentiate Lewy body dementia and Alzheimer's disease.

Stimulation of adenylate cyclase activity by benzazepine D-1 dopamine agonists with varying efficacies in the 6-hydroxydopamine lesioned rat--relationship to circling behaviour

The ability of benzazepine D-1 dopamine agonists with varying efficacies in stimulating adenylate cyclase and to induce contralateral circling was investigated in rats with unilateral 6-hydroxydopamine lesions of the medial forebrain bundle. In the 6-hydroxydopamine lesioned rats, the benzazepines SKF 38393 (7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine), SKF 75670 (3-CH3 analogue), SKF 80723 (6-Br analogue), SKF 83959 (6-Cl, 3-CH3, 3'-CH3 analogue), SKF 83565 (6-Cl, 3-CH3, 3'-Cl analogue) and SKF 82958 (6-Cl, 3-C3H5 analogue), all produced contralateral circling. The rank order of efficacies (maximal effect, Emax) being, SKF 83565 = SKF 75670 = SKF 83959 = SKF 80723 > SKF 38393 >> SKF 82958. In striatal slices from the intact hemisphere, dopamine, SKF 82958, SKF 80723 and SKF 75670 stimulated adenylate cyclase activity. The rank order of efficacies being SKF 82958 (109%) = dopamine (100%) = SKF 80723 (98%) > SKF 75670 (72%). Although, SKF 38393 (67%), SKF 83565 (64%) and SKF 83959 (59%) tended to stimulate adenylate cyclase activity, this effect did not reach statistical significance. In the 6-hydroxydopamine lesioned hemisphere, basal levels of adenylate cyclase activity were lower (-25%) than in the intact hemisphere. The maximal stimulation of adenylate cyclase activity (expressed as % basal levels) produced by dopamine and the benzazepines in the denervated striatum was greater than observed in the intact striatum. The rank order of efficacies in the dopamine denervated striatum being SKF 82958 (124%) > SKF 80723 (109%) = dopamine (100%) > SKF 38393 (82%) = SKF 83959 (77%) = SKF 83565 (70%) > SKF 75670 (55%). Moreover, dopamine stimulated adenylate cyclase activity in the denervated striatum with greater potency than in the intact side. The ability of the benzazepine derivatives to induce circling in the 6-hydroxydopamine lesioned rat is consistent with the general increase in the efficacies of dopamine and benzazepine stimulated adenylate cyclase activity in the dopamine denervated striatum. However, the maximal effects for inducing circling and stimulating adenylate cyclase activity do not correspond (e.g. SKF 82958 and SKF 75670). This discrepancy may reflect the involvement of other factors including a behavioural role for extrastriatal D-1 dopamine receptors and/or transduction systems other than adenylate cyclase.

Short- and long-term changes in striatal and extrastriatal dopamine uptake sites in the MPTP-treated common marmoset

The 'short-term' (15-30 days) and 'long-term' (18-42 months) effects of the systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on [3H]mazindol binding to dopamine uptake sites was investigated in the common marmoset. In the 'short-term' MPTP-treated group, [3H]mazindol binding was reduced in the caudate-putamen (by -82 to -98% with respect to controls), substantia nigra pars compacta (-71 to -84%), ventral tegmental area (-72%) and nucleus accumbens (-54%). [3H]Mazindol binding in the globus pallidus, frontal cortex and substantia nigra pars reticulata was much lower and was unaffected by MPTP treatment. In the 'long-term' MPTP-treated group [3H]mazindol binding was still greatly reduced in the substantia nigra pars compacta (by -76 to -89%), ventral tegmental area (-71%) and most of the caudate-putamen (-69 to -98%), although the reduction in [3H]mazindol binding in the nucleus accumbens (-27%) and rostroventral caudate nucleus (-69%) was less than in the 'short-term' MPTP-treated group. The motor deficits induced by MPTP treatment in the common marmoset are largely reversible with increasing survival times (Ueki et al., 1989, Neuropharmacology 28, 1089). In the present study, the apparent 'recovery' in [3H]mazindol binding in the rostroventral caudate nucleus and nucleus accumbens may indicate regeneration of dopamine neurone terminals in these regions and this may contribute to the behavioural recovery seen in this primate model of Parkinson's disease.

Selective dopamine antagonist pretreatment on the antiparkinsonian effects of benzazepine D1 dopamine agonists in rodent and primate models of Parkinson's disease--the differential effects of D1 dopamine antagonists in the primate

In rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the medial forebrain bundle, pretreatment with the D1 DA antagonists, SCH 23390 (7-chloro-8-hydroxy-2,3,4,5-tetrahydro-3-methyl-1-phenyl-1H-3-benzazepin e) and A66359 (1- 2-bromo-4,5-dimethoxybenzyl]-7-hydroxy-6-methoxy-2-methyl- 1,2,3,4 tetrahydroisoquinoline), but not the D2 DA antagonist raclopride inhibited the contralateral circling induced by the benzazepine D1 DA agonists SKF 38393 (7-H, 3-H analogue of SCH 23390), SKF 80723 (7-H, 3-H, 6-Br analogue) and SKF 83959 (7-H, 6-Cl, 3'-CH3 analogue). In MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) treated common marmosets, administration of SKF 80723 and SKF 83959 increased locomotor activity and reversed the motor disability. Grooming and oral activities were also increased. Pretreatment with SCH 23390 and A66359 inhibited all the behavioural changes induced by both D1 DA agonists. In general, higher doses of A66359 and more especially SCH 23390 were needed to inhibit SKF 83959 and SKF 80723 induced increases in oral activity and grooming than locomotor activity. Raclopride pretreatment did not affect SKF 83959 and SKF 80723 induced oral activity and grooming, though it reduced the duration of the locomotor changes induced by the D1 DA agonists. These findings demonstrate that the behavioural effects of benzazepine D1 DA agonists in the 6-OHDA lesioned rat and MPTP-treated marmoset are mediated by D1 DA receptor sites, although in the primate, stimulation of D2 DA receptors by endogenous DA may be necessary in facilitating the antiparkinsonian effects of D1 DA agonists. The differential sensitivities of locomotor/motor disability and oral/grooming behaviours to antagonism by D1 DA antagonists may indicate the involvement of multiple D1 DA receptor subtypes in mediating benzazepine D1 DA agonist induced behaviours in the MPTP-treated marmoset.

Short and long-term changes in cerebral [14C]-2-deoxyglucose uptake in the MPTP-treated marmoset: relationship to locomotor activity

The "short-term" (0.7 +/- 0.1 months post-MPTP) and "long-term" effects (36.7 +/- 4.4 months) of MPTP treatment on motor behaviour and [14C]-2DG uptake were investigated in the common marmoset. The subcutaneous administration of MPTP greatly reduced locomotor activity (-94% with respect to controls) and induced motor disability in the "short-term" MPTP-treated marmoset group. In the "long-term" MPTP group, MPTP treatment did not significantly affect locomotor activity (-27% with respect to controls) and there was partial recovery of motor disability. In the "short-term" MPTP group, there were increases in [14C]-2DG uptake in the GPl (+31 to +37%), SNc (+34 to +42%), VTA (+35%), LC (+23%), PPN (+19%) and in the VA (+19%), VL (+20%) and AM (+17%) thalamic nuclei. [14C]-2DG uptake was decreased in the STN (-15%). In the "long-term" MPTP group, [14C]-2DG uptake was increased in the GPl (+18%), SNc (+27%), VTA (+25%), PPN (+19%), ventral caudate nucleus (+18 to +23%), NAc (+22%), F.Ctx (+18%) and in the VA (+34%), VL (+28%), AV (+33%) and AM (+24%) thalamic nuclei. [14C]-2DG uptake was unchanged in the STN. The increase in metabolic activity of the surviving DA neurones and/or the reactive gliosis may account for the initial increase in [14C]-2DG uptake in the SNc and VTA. On the other hand, in the "long-term" MPTP-treated animals the increase in [14C]-2DG uptake in the SNc (though less than in the "short-term" MPTP group), ventral caudate and NAc may reflect the regenerative changes in the dopaminergic system in these areas. Despite the behavioural recovery, [14C]-2DG uptake remained elevated in the target areas for medial pallidal output (the thalamic nuclei and PPN). However, the attenuation of the changes in [14C]-2DG uptake in the GPl and STN of "long-term" MPTP-treated marmosets suggest that the striato-GPl and GPl-STN outputs closely reflect motor function in this primate model of Parkinson's disease.

The differential behavioural effects of benzazepine D1 dopamine agonists with varying efficacies, co-administered with quinpirole in primate and rodent models of Parkinson's disease

The effects of co-administration of quinpirole with benzazepine D1 dopamine (DA) agonists possessing full/supramaximal (SKF 80723 and SKF 82958), partial (SKF 38393 and SKF 75670) and no efficacies (SKF 83959) in stimulating adenylate cyclase (AC) were investigated in rodent and primate models of Parkinson's disease (PD). In rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion of the medial forebrain bundle, co-administration of SKF 38393 (7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine), SKF 75670 (3-CH3 analogue), SKF 80723 (6-Br analogue), SKF 83959 (6-Cl, 3-CH3, 3'-CH3 analogue) and SKF 82958 (6-Cl, 3-C3H5 analogue) strongly potentiated the contralateral circling induced by quinpirole. In MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) treated common marmosets, administration of quinpirole alone increased locomotor activity and reversed motor deficits. Grooming and oral activity were unaltered. Co-administration of SKF 38393 and SKF 75670 inhibited the quinpirole-induced changes in locomotor activity and motor disability. The combined treatment of SKF 80723 or SKF 82958 with quinpirole had no overall effect on locomotor activity or motor disability. In contrast, SKF 83959 extended the duration of the quinpirole-induced increase in locomotor activity with corresponding decreases in motor disability. Co-administration of high doses of SKF 82958 and more especially SKF 83959 and SKF 80723, with quinpirole induced hyperexcitability and seizures. Oral activity and grooming were unaltered following the co-administration of benzazepine derivatives with quinpirole. The ability of some benzazepine D1 DA agonists to prolong the antiparkinsonian effects of quinpirole in the MPTP-treated marmoset may indicate a role for certain D1 DA agonists in the clinical treatment of PD. In general, the behavioural responses to the combined administration of benzazepines with quinpirole in the 6-OHDA lesioned rat and more especially the MPTP-treated marmoset failed to correlate with their ability to stimulate AC. These observations further implicate a behavioural role for D1 DA receptors not linked to AC.

Differential anti-parkinsonian effects of benzazepine D1 dopamine agonists with varying efficacies in the MPTP-treated common marmoset

In common marmosets systemically treated with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), the behavioural effects of benzazepine D1 dopamine (DA) agonists with full/supramaximal (SKF 80723 and SKF 82958), partial (SKF 38393, SKF 75670 and SKF 83565) and no efficacies (SKF 83959) in stimulating adenylate cyclase (AC) activity were investigated. The benzazepine derivatives, with the exception of SKF 82958 (8 fold D1 DA receptor selectivity), demonstrated high D1 DA receptor affinity and selectivity (approximately 100 fold or more) in rat striatal homogenates. Administration of MPTP in marmosets induced locomotor hypoactivity, rigidity and motor disability. SKF 38393 (7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3- benzazepine) and SKF 75670 (3-CH3 analogue) further reduced locomotor activity (by -70 to -80%) and increased motor disability (by +22 to +67%) in these animals. SKF 83565 (6-Cl, 3-CH3, 3'-Cl analogue) and SKF 82958 (6-Cl, 3-C3H5 analogue) had only a slight effect on locomotor activity but decreased motor disability at high doses (-46 to -60%). In contrast, SKF 83959 (6-Cl, 3-CH3, 3'-CH3 analogue) and SKF 80723 (6-Br analogue) produced pronounced increases in locomotion (6-10 fold) and a reversal in motor disability (by -64 to -77%). Oral activity, consisting largely of abnormal, 'dyskinetic' tongue protrusions and vacuous chews, was increased in animals treated with SKF 38393, SKF 83565, SKF 82958 and more especially with SKF 80723 and SKF 83959. Grooming was increased with SKF 82958 and more especially with SKF 80723 and SKF 83959. In contrast, quinpirole (D2 DA agonist), reversed the MPTP-induced motor deficits in the marmoset, with no effect on grooming and oral activity. The present findings further demonstrate the antiparkinsonian actions of some D1 DA agonists in MPTP-treated primates. However, in general the behavioural effects of benzazepines failed to correlate with either their D1 DA receptor affinity/selectivity or their efficacy in stimulating adenylate cyclase (AC) activity. These observations further implicate a behavioural role for D1 DA receptors uncoupled to AC and/or a role for extrastriatal D1 DA receptors in mediating the behavioural response to D1 DA agonists.

An autoradiographic study of the differential effects of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) on striatal and extrastriatal D-1 and D-2 dopamine receptors in the rat

The effect of in vivo administration of the alkylating agent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) on striatal and extrastriatal D-1 and D-2 dopamine (DA) receptors was investigated in the rat. N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline treatment reduced specific [3H]SCH 23390 (7-chloro-8-hydroxy-2,3,4,5-tetrahydro-3-methyl-1-phenyl-1H-3-benzaze pin e) binding to D-1 DA receptors in the striatum (42-46% of saline-treated controls), entopeduncular nucleus (20%) and substantia nigra pars reticulata (23%). Similarly, specific [3H]spiperone binding to D-2 DA receptors was decreased in the striatum (28-37% of saline-treated controls). However, [3H]spiperone binding in the substantia nigra pars compacta (67%) was much less affected. In vivo pretreatment with the D-1 DA antagonist SCH 23390 selectively and dose dependently protected [3H]SCH 23390 binding against the effects of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline in the striatal/extrastriatal regions. Pretreatment with the D-2 DA antagonist raclopride or the D-2 DA agonist quinpirole selectively protected [3H]spiperone binding. In contrast, pretreatment with the D-1 DA agonist SKF 38393 (7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) not only protected [3H]-SCH 23390 binding but at very high doses protected striatal [3H]spiperone binding. The differential alkylating effects of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline on striatal vs extrastriatal D-1 and D-2 DA receptors may be related to their post- (striatal DA receptors) and pre-synaptic (extrastriatal DA receptors) localizations, respectively. The present results further demonstrate that in vivo, SCH 23390 and raclopride/quinpirole retain their D-1 and D-2 DA receptor selectivity.

The effects of chronic continuous versus intermittent levodopa treatments on striatal and extrastriatal D1 and D2 dopamine receptors and dopamine uptake sites in the 6-hydroxydopamine lesioned rat--an autoradiographic study

The effects of chronic 'continuous' infusion and 'intermittent' modes of levodopa/carbidopa administration on apomorphine induced circling behaviour, DA uptake sites (labelled with [3H]mazindol) and D1 and D2 DA receptor binding (labelled with [3H]SCH 23390 and [3H]sulpiride, respectively) were investigated in rats with unilateral 6-OHDA lesions of the medial forebrain bundle. The circling behaviour in response to apomorphine was greatly enhanced following chronic 'intermittent' but not 'continuous' levodopa treatments. Following the 'intermittent' regime, the lower dose of apomorphine induced a period of intense circling with delayed onset and rapid offset, than in rats given either 'continuous' infusion of levodopa or saline. The 6-OHDA lesion itself induced gross depletion of [3H]mazindol binding in all striatal subregions, NAc and OT, but not frontal cortex. [3H]Sulpiride binding in the ventrolateral striatal quadrant was increased on the denervated side and this correlated with the peak contralateral turns in response to 0.5 mg/kg apomorphine challenge. This asymmetry in striatal [3H]sulpiride binding was reduced in both groups of rats receiving levodopa. [3H]sulpiride binding in the NAc and OT and [3H]SCH 23390 binding in the striatum, NAc, OT and SNr were unaffected by DA denervation or either regime of levodopa treatments. 'Continuous' infusion and not 'intermittent' injections of levodopa reduced [3H]mazindol binding in the striatal subregions and the frontal cortex on both the denervated and intact sides. The potentiation of the behavioural response to apomorphine by chronic 'intermittent' levodopa treatment does not correspond with the levodopa induced alterations in striatal or extrastriatal DA receptors. In the same group of animals the narrowing of the duration of response to the lower dose of apomorphine may mimic the fluctuations in response to levodopa, seen clinically in long-term levodopa treated parkinsonian patients.

Chronic continuous and intermittent L-3,4-dihydroxyphenylalanine treatments differentially affect basal ganglia function in 6-hydroxydopamine lesioned rats--an autoradiographic study using [3H]flunitrazepam

The effects of chronic 'continuous' and 'intermittent' L-3,4-dihydroxyphenylalanine treatments on GABA receptor function in the basal ganglia of rats with unilateral 6-hydroxydopamine lesions of the medial forebrain bundle was investigated, by autoradiography with [3H]flunitrazepam. The 6-hydroxydopamine lesion itself, increased [3H]flunitrazepam binding in the substantia nigra pars reticulata (+17%, with respect to intact side) and entopeduncular nucleus (+44%), but decreased binding in the globus pallidus of the denervated hemisphere (-20%). 'Intermittent' L-3,4-dihydroxyphenylalanine treatment reduced the [3H]flunitrazepam binding changes observed in the substantia nigra pars reticulata (-13%) and entopeduncular nucleus (-4%), whereas 'continuous' infusion of the same daily dose of L-3,4-dihydroxyphenylalanine had less effect (+14%, substantia nigra pars reticulata; +26%, entopeduncular nucleus). In contrast, the [3H]flunitrazepam binding decrease in the globus pallidus of the 6-hydroxydopamine lesioned animals was unaffected by either regime of chronic L-3,4-dihydroxyphenylalanine treatment. The changes in GABA receptor function implied by these results provide further insight into the pathophysiological effects of L-3,4-dihydroxyphenylalanine treatment on basal ganglia function, following dopamine denervation. In accordance with existing electrophysiological and biochemical evidence on this subject, the main implications of these results include reduced GABA sensitivity of neurons in the entopeduncular nucleus and substantia nigra pars reticulata, following chronic 'intermittent', but not chronic 'continuous' L-3,4-dihydroxyphenylalanine treatment; this may be due to a reversal of the 6-hydroxydopamine induced decrease in the GABA-mediated neurotransmission in the striatoentopeduncular and striatonigral pathways. In contrast, the regulation of GABA receptors in the globus pallidus does not appear to be subject to modulation by chronic L-3,4-dihydroxyphenylalanine administration, suggesting that dopamine replacement in this manner does not modify the 6-hydroxydopamine induced increase in GABA-mediated neurotransmission in the stratopallidal pathway.

Alterations in striatal and extrastriatal D-1 and D-2 dopamine receptors in the MPTP-treated common marmoset: an autoradiographic study

In adult common marmosets (Callithrix jacchus), MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) treatment induced almost total depletion of cells in the substantia nigra pars compacts (SNc) but partial cell loss in the ventral tegmental area (VTA). There was severe depletion of [3H]-mazindol binding to dopamine (DA) uptake sites in the caudate, putamen, and SNc. The loss of [3H]-mazindol binding in the nucleus accumbens (NAc) and olfactory tubercle (OT) was less marked. [3H]-mazindol binding in the body of caudate nucleus showed a small but significant recovery with increasing post-lesion survival times. The specific binding of [3H]-SCH 23390 to D-1 DA receptor sites was increased after MPTP treatment in all subregions of both caudate and putamen but was unaltered in the NAc and OT. Substantia nigra pars reticulata (SNr), frontal cortex, and medial segment of globus pallidus (GPm) all demonstrated moderate levels of [3H]-SCH 23390 binding in control animals, which were unaffected by MPTP treatment. Specific [3H]-spiperone binding to D-2 DA receptor sites was not altered by MPTP treatment in the subregions of caudate-putamen. Moderate levels of [3H]-spiperone binding were observed in control animals in the NAc, OT, SNc, and the lateral segment of globus pallidus (GP1). [3H]-spiperone binding in the SNc and OT was partially decreased in MPTP-treated animals. The changes in specific [3H]-spiperone and [3H]-SCH 23390 binding induced by MPTP-treatment did not alter with post-lesion survival times. These results demonstrate that MPTP treatment causes greater dopaminergic denervation of the caudate-putamen than in NAc/OT. This resulted in an increase in postsynaptic D-1 DA receptor sites in the caudate-putamen but not in the NAc/OT. Also, there appeared to be loss of presynaptic D-2 DA receptor sites in the SNc and OT. In the caudate-putamen, the loss of presynaptic D-2 DA receptor sites may have masked postsynaptic D-2 DA receptor upregulation.