Biochemistry of the hypothalamus in Parkinson's disease.

We assayed the content of neurotransmitters (or their synthesizing enzymes) and neuropeptides in the hypothalamus of control and parkinsonian brains post mortem. Only dopamine concentrations were lower than normal in Parkinson's disease, suggesting that deficiency in hypothalamic dopamine transmission may play a role in the autonomic and endocrine abnormalities of this disorder.

Opioid receptors and neuropeptides in the CNS in rats treated chronically with amoxapine or amitriptyline.

The central mechanism responsible for the potentiation by antidepressant drugs of analgesia induced by morphine, was explored by measuring the levels of various neuropeptides (met-enkephalin, leu-enkephalin, dynorphin, substance P and cholecystokinin-like materials) and the density of delta and mu opioid binding sites in the spinal cord of rats treated for 14 days with amoxapine (10 mg/kg i.p., daily) or amitriptyline (10 mg/kg i.p., daily). Similar measurements were made in the hypothalamus and cerebral cortex for comparison. Chronic treatment with amoxapine or amitriptyline did not affect the levels of dynorphin, substance P and cholecystokinin, but markedly enhanced the levels of leu-enkephalin in the three structures examined. The levels of met-enkephalin were also increased after treatment with amitriptyline but only in the spinal cord and hypothalamus. No changes in opioid receptors were found in the cerebral cortex, but the densities of delta and mu opioid binding sites were increased in the spinal cord, and decreased in the hypothalamus of rats treated with amoxapine or amitriptyline. These changes induced by antidepressants in opioidergic markers at the spinal level might account for the potentiation of the action of morphine in amoxapine- or amitriptyline-treated rats. In addition, the observed alterations in the same markers in the hypothalamus could be associated with changes induced by antidepressants in neuroendocrine regulation.

Biochemical mapping of cholecystokinin-, substance P-, [Met]enkephalin-, [Leu]enkephalin- and dynorphin A (1-8)-like immunoreactivities in the human cerebral cortex.

The distribution of immunoreactive cholecystokinin, substance P, [Met]enkephalin, [Leu]-enkephalin and dynorphin was determined in the cerebral cortex of the human brain post mortem. Peptide radioimmunoassays in three selected zones of the cortical gray mantle (frontal, temporal, occipital) revealed significant regional differences, prompting to the development of a new dissection procedure for the complete mapping of peptide-like materials throughout the entire cerebral cortex. For this purpose, frozen cerebral hemispheres were cut rostrocaudally in 21 verticofrontal serial sections, from which the cortical gray matter was divided into 4-5 distinct zones. The peptides could be measured in each of the 93 dissected pieces of tissue, but their distribution was uneven. The most abundant was cholecystokinin, particularly in the anterior part of the frontal lobe and in the temporal cortex, where its levels reached 0.5 ng/mg of tissue. The regional distribution of cholecystokinin resembled that of substance P with a decreasing gradient from the frontal to the occipital pole, but absolute levels of substance P were hardly one tenth of cholecystokinin levels. The mean concentrations of the three opioid peptides were even less than those of substance P, and their regional distributions were markedly different. [Met]Enkephalin was concentrated in the occipital cortex, and [Leu]enkephalin in the temporal cortex. Dynorphin was the least abundant, even in the temporal cortex where the highest levels were found. The widespread and heterogeneous distribution of these peptides strongly suggests that each of them exerts specific functions in the human cerebral cortex.

Immunocytochemical evidence for calcitonin gene-related peptide-like neurons in the dorsal horn and lateral spinal nucleus of the rat cervical spinal cord.

Calcitonin gene-related peptide (CGRP) in the dorsal horn of the rat spinal cord was assumed until now to be principally of primary afferent origin. It is shown here, on the basis of both light and electron microscopic immunocytochemical evidence, that some cell bodies of the dorsal horn and lateral spinal nucleus (LSn) of the rat cervical spinal cord contain a CGRP-like immunoreactivity. At the light microscopic level, immunoreactive cell bodies were observed in animals pretreated with colchicine injected intraventricularly, CGRP-like cell bodies were morphologically heterogeneous and distributed in the three superficial layers of the dorsal horn. They were very rare in lamina I and more numerous in laminae II and III. A group of immunoreactive cell bodies was also observed in the LSn. Using electron microscopic techniques, a few immunoreactive cell bodies were observed even in control animals. In addition, relatively numerous immunoreactive dendrites were observed in lamina II. The specificity of the reaction and the physiological implications of the results are discussed.

Simultaneous determination of radio-immunoassayable methionine-enkephalin and radioreceptor-active opiate peptides in CSF of chronic pain suffering and non suffering patients.

Radio-immunoassayable methionine-enkephalin (ME) and radioreceptor-active opiate peptide levels (OP) were determined in CSF from patients, both with and without chronic pain, under investigation for vertebral disk disease. This study showed: that there was no direct correlation between ME and OP levels in CSF; OP levels were negatively correlated with the ME/OP ratio; migraine patients had higher levels of ME; ME concentrations were reduced in patients receiving anti-inflammatory drugs (nonsteroidal): patients with chronic pain (non migraine, no anti-inflammatory drug therapy) had lower ME levels than patients without pain. The data are discussed in relation to animal models of chronic pain.

Levels of Met-enkephalin, Leu-enkephalin, substance P and cholecystokinin in the brain of the common marmoset following long term 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine treatment.

Common marmosets were treated daily with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 7-9 mg/kg i.p.) for 25 days, and then kept out of drug for three months before biochemical measurements in various brain areas. This treatment induced a dramatic fall (-80%) in dopamine, homovanillic acid and dihydroxyphenylacetic acid levels in the putamen and caudate nucleus, and a significant but less pronounced reduction (less than or equal to 50%) in the levels of these compounds in the nucleus accumbens. In contrast, the concentrations of four neuropeptides: met-enkephalin, leu-enkephalin, substance P, and cholecystokinin, remained unaltered in all brain areas examined in MPTP-treated marmosets. Therefore the neuropeptide alterations previously reported in Parkinson's disease are probably not secondary to the severe lesion of dopaminergic neurones, but constitute another intrinsic feature of the disease.

Dynorphin levels in parkinsonian patients: Leu5-enkephalin production from either proenkephalin A or prodynorphin in human brain.

When measured in postmortem parkinsonian brains, dynorphin levels were unchanged, as compared to control brains, in mesencephalic, striatal and corticolimbic areas. A significant reduction in Leu5-enkephalin and Met5-enkephalin levels had been previously observed in the pallidum and putamen whereas only Met5-enkephalin concentrations were decreased in the substantia nigra of parkinsonian brains. These data suggest that L-Enk could be generated either from proenkephalin A in the striatal areas or from prodynorphin in the nigral areas.

Parkinson's disease affects differently Met5- and Leu5-enkephalin in the human brain.

When measured in post-mortem human control brains, the ratio of Met5-enkephalin levels to those of Leu5-enkephalin varied from 1 to 13 in the 11 areas examined. In parkinsonian brains a significant reduction in the levels of both peptides was found in the pallidum and putamen whereas only Met5-enkephalin levels were decreased in the substantia nigra and ventral tegmental area. Therefore, Met5-enkephalin and Leu5-enkephalin may be located (at least partly) in different neuronal populations in the human brain.

Microtopography of methionine-enkephalin, dopamine and noradrenaline in the ventral mesencephalon of human control and Parkinsonian brains.

The topographical distributions of Met-enkephalin, dopamine and noradrenaline were determined in serial frontal sections of human substantia nigra (pars compacta and pars reticulata) and ventral tegmental area. Met-enkephalin was identified by Biogel and thin layer chromatography and assayed by a specific radioimmunoassay. In the substantia nigra (pars compacta and pars reticulata), the levels of Met-enkephalin increased progressively from the rostral to the caudal part of the structure. This pattern closely resembled that of dopamine levels, particularly in the pars compacta. Noradrenaline levels in the substantia nigra and those of Met-enkephalin, dopamine, and noradrenaline in the ventral tegmental area, exhibited only limited fluctuations from the anterior to the posterior part of each structure. Highly significant decreases in Met-enkephalin, dopamine and noradrenaline levels were observed in the substantia nigra and ventral tegmental area of Parkinsonian brains. This observation, together with the close topographical association of dopamine and Met-enkephalin in the substantia nigra, further supports the likely existence of important functional relationships between dopaminergic and enkephalinergic neurons in the human brain.

Brain neuropeptides in progressive supranuclear palsy.

No significant alterations in the levels of Met-enkephalin-, Leu-enkephalin-, cholecystokinin- and substance P-like immunoreactive materials were found in 10 areas of postmortem brains from patients with progressive supranuclear palsy (PSP) when compared to controls. These results are at difference with the marked decrease in the levels of enkephalin-, cholecystokinin- and substance P-like immunoreactive materials previously reported in the basal ganglia of parkinsonian patients. Since PSP and Parkinson's disease are both characterized by a severe dopamine nigrostriatal deficit, these results suggest that the decreased brain peptide concentrations found in Parkinson's disease do not simply result from a dopaminergic neuronal loss.

Enkephalinergic markers in substantia nigra and caudate nucleus from Parkinsonian subjects.

Marked reductions in opiate receptor binding (-42%), "enkephalinase" activity (-39%), and Met5-enkephalin levels (-72%) accompanied the well-established dopamine depletion in the substantia nigra pars compacta of Parkinsonian subjects. In contrast, enkephalinergic markers were not significantly modified in caudate nucleus.

Lack of change in basal ganglia neuropeptide content following subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treatment of the common marmoset.

Treatment of common marmosets with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 1-4 mg/kg for up to 4 days) caused a profound parkinsonian state. Ten days from the start of MPTP treatment, all animals showed marked motor impairment, consisting of bradykinesia and akinesia, limb rigidity, postural abnormalities, loss of vocalisation and blink reflex, and, on occasions, postural tremor. Measurement of caudate-putamen monoamine content at this time showed a profound loss in 3,4-dihydroxyphenylethylamine, homovanillic acid, and 3,4-dihydroxyphenylacetic acid concentrations. Measurement of neuropeptide concentrations in the caudate-putamen, internal and external segments of the globus pallidus, nucleus accumbens, substantia nigra, frontal cortex, and hippocampus showed met-enkephalin, leu-enkephalin, and cholecystokinin (CCK-8) concentrations to be unaffected by MPTP treatment. There was a small decrease in the substance P content of frontal cortex, but otherwise the content of this neuropeptide was unaltered. Parkinsonism in the marmoset, induced by MPTP treatment 10 days earlier, does not alter neuropeptide concentrations in the manner observed in Parkinson's disease.

Increased calcitonin gene-related peptide- and cholecystokinin-like immunoreactivities in spinal motoneurones after dorsal rhizotomy.

Possible changes in neuropeptides within the ventral horn of the spinal cord were investigated after unilateral dorsal rhizotomy at the lumbar level (L1-L6) in adult rats. Ten days after the surgery, immunohistochemical observations and radioimmunological determinations confirmed a marked loss of calcitonin gene-related peptide (CGRP)- and substance P (SP)-like immunoreactivities within the superficial layers of the deafferented dorsal horn, as expected from the degeneration of primary afferent fibres containing these peptides. A concomitant increase in immunohistochemical staining and levels of CGRP (+296%) and CCK (+71%)-like immunoreactivities was observed in the ipsilateral ventral horn where both peptides are located in motoneurones. In contrast, substance P-like immunoreactivity that is confined to fibres and terminals within the ventral horn, was not altered by dorsal rhizotomy. These data indicate that the expression of neuropeptides in spinal motoneurones can be influenced by primary afferent inputs.

Plasma calcitonin gene-related peptide decreases in chronic congestive heart failure.

To investigate the role of calcitonin gene-related peptide (CGRP) in cardiac failure, a sensitive and specific radioimmunoassay was developed to study plasma levels of CGRP in 37 normal subjects and 41 patients with heart failure (HF). The mean plasma levels of CGRP were 294.3 pg.ml-1 (SEM: 41.4) in normal subjects and 121.2 pg.ml-1 (SEM: 21.2) in HF patients. The significant decrease observed in HF patients suggests that CGRP is involved in the pathogenesis of heart failure via a direct effect or via modulation of sympathetic nervous activity.

Regional distribution of calcitonin gene-related peptide-, substance P-, cholecystokinin-, Met5-enkephalin-, and dynorphin A (1-8)-like materials in the spinal cord and dorsal root ganglia of adult rats: effects of dorsal rhizotomy and neonatal capsaicin.

Biochemical mapping of five different peptide-like materials--calcitonin gene-related peptide (CGRP), substance P (SP), Met5-enkephalin (ME), cholecystokinin (CCK), and dynorphin A (1-8) (DYN)--was conducted in the dorsal and ventral zones of the spinal cord at the cervical, thoracic, and lumbar levels in 3-month-old rats 10 days after unilateral dorsal rhizotomy at the cervical level (C4-T2) or after neonatal administration of capsaicin (50 mg/kg s.c.). In control rats, all peptide-like materials were more abundant in the dorsal than in the ventral zone all along the spinal cord. However, in both zones, absolute concentrations of CGRP, SP, ME, and CCK were significantly higher at the lumbar than at the cervical level. Rhizotomy-induced CGRP depletion (-85%) within the ipsilateral dorsal zone of the cervical cord was more pronounced than that due to neonatal capsaicin (-60%), a finding suggesting that this peptide is contained in both capsaicin-sensitive (mostly unmyelinated) and -insensitive (myelinated) primary afferent fibers. In contrast, similar depletions of SP (-50%) were observed after dorsal rhizotomy and neonatal capsaicin treatment, as expected from the presence of SP only in the capsaicin-sensitive small-diameter primary afferent fibers. Although the other three peptides remained unaffected all along the cord by either intervention, evidence for the existence of capsaicin-insensitive CCKergic primary afferent fibers could be inferred from the increased accumulation of CCK (together with SP and CGRP) in dorsal root ganglia ipsilateral to dorsal root sections.