Maria Concetta Altavista

Aging is associated with a diffuse impairment of forebrain cholinergic neurons

The study evaluates whether any degenerative changes affect forebrain cholinergic systems during natural aging. The medial septal nucleus, the nuclei of the diagonal band, the neostriatum, and the basal nucleus were studied in adult and aged Wistar rats. Butchers technique for acetylcholinesterase allowed us to identify neurons located in these forebrain nuclei, which stained intensely or moderately for the enzyme and were putatively cholinergic. The size of forebrain regions containing stained neurons, and the number and size of stained perikarya located therein, were measured. In aged rats, the size of forebrain cholinergic nuclei was reduced by an average of 26%. The density of neurons located in these regions was also significantly lower in aged rats than in controls; intensely stained neurons displayed a mean reduction of 27.81%, while intensely and moderately stained perikarya together were reduced by 25.43%. Cross-sectional area of the stained perikarya was also reduced in aged rats by 32.87%. These data show that the number of forebrain acetylcholinesterase-containing neurons is reduced in aged rats. They are consistent with the hypothesis that natural aging brings about a diffuse and homogeneous depletion of forebrain cholinergic perikarya. Neurons which are viable, and can be selectively stained, show morphological alterations, which are likely to be related to a degenerative process.

PINK1 heterozygous rare variants: prevalence, significance and phenotypic spectrum†‡

Heterozygous rare variants in the PINK1 gene, as well as in other genes causing autosomal recessive parkinsonism, have been reported both in patients and healthy controls. Their pathogenic significance is uncertain, but they have been suggested to represent risk factors to develop Parkinson disease (PD). The few large studies that assessed the frequency of PINK1 heterozygotes in cases and controls yielded controversial results, and the phenotypic spectrum is largely unknown. We retrospectively analyzed the occurrence of PINK1 heterozygous rare variants in over 1100 sporadic and familial patients of all onset ages and in 400 controls. Twenty patients and 6 controls were heterozygous, with frequencies (1.8% vs. 1.5%) not significantly different in the two groups. Clinical features of heterozygotes were indistinguishable to those of wild‐type patients, with mean disease onset 10 years later than in carriers of two mutations but worse disease progression. A meta‐analysis indicated that, in PINK1 heterozygotes, the PD risk is only slightly increased with a non significant odds ratio of 1.62. These findings suggest that PINK1 heterozygous rare variants play only a minor susceptibility role in the context of a multifactorial model of PD. Hence, their significance should be kept distinct from that of homozygous/compound heterozygous mutations, that cause parkinsonism inherited in a mendelian fashion.

Strain-dependent variations in the number of forebrain cholinergic neurons

The morphological organization of putatively cholinergic neurons was studied in the forebrain of two inbred mouse strains (C57BL/6 and DBA/2) by means of acetylcholinesterase pharmacohistochemistry. In both strains, putatively cholinergic perikarya were seen in the caudato-putamen, medial septum, diagonal band, and basal nucleus of Meynert: in all these regions, their distribution was similar in both strains, but their density was significantly higher (from 20 to 32%) in DBA/2 mice. The present data demonstrate the existence of genetically determined differences in the organization of forebrain cholinergic systems.

Cholinergic and non-cholinergic forebrain projections to the interpenduncular nucleus

A combined fluorescent retrograde tracing and acetylcholinesterase (AChE) histochemical technique was used for the study of some forebrain projections to the interpeduncular nucleus (IPN). After injections of a fluorescent tracer into the IPN, the distribution of AChE-containing and of fluorescent retrogradely labeled neurons was simultaneously studied in the habenular nuclei, medial septum and diagonal band of Broca. In all these regions, the majority of retrogradely labeled neurons also contained AChE: neurons located in the habenular nuclei stained lightly or moderately for the enzyme, while neurons located in the diagonal band and medial septum displayed intense AChE staining and were classified as putatively cholinergic perikarya. In all regions, a minority of labeled neurons did not stain for AChE, and were identified as non-cholinergic neurons projecting to the IPN. The present study shows the existence of a biochemical heterogeneity in the habenulo-interpeduncular and telencephalo-interpeduncular pathways, and indicates that the latter contains putatively cholinergic as well as non-cholinergic fibers.

Age-dependent loss of cholinergic neurones in basal ganglia of rats

A morphometric study of the striatal complex has been performed in adult and aged rats, by means of Butchers acetylcholinesterase (AChE) staining. The size of neostriatum, and the number of putatively cholinergic AChE-positive perikarya, are significantly reduced in two-year-old rats. Consequently, mean cell density is decreased in the striatal complex by 15.58%; age-dependent loss is more pronounced: (1) in the dorsal and lateral parts of neostriatum, which in adults have a higher neural density; and (2) in the ventromedial part, which in the aged becomes almost void of neurones. It is concluded that depletion of cholinergic perikarya is a specific feature of natural ageing, which affects diffusely the neostriatum, and particularly its ventromedial territories.

Neuroleptic malignant syndrome and catatonia. A report of three cases.

SummaryIn a series of 1007 consecutively admitted patients, 3 cases of neuroleptic malignant syndrome (NMS) were identified (0.3%). All three patients were affected by mood disorders with congruent psychotic features, had shown catatonia just before the onset of NMS, and had been treated with low neuroleptic doses. All of them presented low serum iron levels. The relationship between NMS and catatonia and possible therapeutic decisions are discussed.

Frequency and phenotypes of LRRK2 G2019S mutation in Italian patients with Parkinson's disease

To evaluate the frequency of the LRRK2 G2019S mutation in Italy, we tested 1,072 probands with Parkinsons disease (PD; 822 sporadic and 250 familial): 20 patients (1.9%) carried the G2019S mutation, 11 patients (1.3%) were sporadic, and 9 (4.3%) had a positive family history. Considering only probands with autosomal dominant inheritance, the G2019S frequency raises to 5.2%. All presented a typical phenotype with variable onset and shared the common ancestral haplotype. Mutation frequency raised from 1.2% in early onset PD to 4.0% in late onset PD.

Genetically determined cholinergic deficiency in the forebrain of C57BL/6 mice

This study demonstrates that a deficiency of forebrain cholinergic neurons occurs in C57BL/6 (C57) mice, a strain characterized by poor learning capabilities. The brains of 21-day-old and 18-week-old C57 and DBA/2 (DBA) mice were studied by means of acetylcholinesterase (AChE) histochemistry and of choline acetyltransferase (ChAT) immunocytochemistry. Computer-assisted image analysis was performed on sections through the medial septum, the diagonal band of Broca, the basal nucleus of Meynert and the neostriatum. As compared to the DBA strain, C57 mice had a reduced number of forebrain cholinergic neurons. This feature was present at the age of 21 days and persisted to 18 weeks. Between-strain variations in the density of neurons were more obvious in ChAT-stained material than in AChE-stained sections. These data show that C57 mice can be regarded as a genetic mutant, whose phenotype is characterized by a reduced number of forebrain cholinergic neurons and by cognitive abnormalities. C57 mice represent a valuable model for studying the influence of genetic factors on central nervous system cholinergic mechanisms and the effects of genetically determined cholinergic deficiency on behavior and learning.

Severe Barbiturate Withdrawal Syndrome in Migrainous Patients

Three patients who presented with grand real seizures and an associated behavioral disorder were recognized as suffering from a severe butalbital withdrawal syndrome. All were migraineurs who had become dependent on barbiturates. We propose that the occurrence of seizures, psychotic behavior, or a recent personality change should be considered clues to possible barbiturate abuse in patients with migraine.

Quantitative pharmacohistochemistry of acetylcholinesterase in neostriatum of inbred strains of mice

A quantitative pharmacohistochemical technique has been used in the present study to assay acetylcholinesterase (AChE) activity in the neostriatum of C57BL/6 and DBA/2 mice. This technique permits the measurement of enzyme activity into microscopically defined compartments and is suitable for the study of striatal AChE-containing, putatively cholinergic, neurons. Microphotometric measurements have been performed in the cytoplasm of AChE-containing perikarya and in the striatal matrix: in both compartments, AChE activity was significantly higher in DBA/2 than in C57BL/6 mice. The present data show that AChE quantitative pharmacohistochemistry is suitable for studying the enzyme activity in nervous tissue and, particularly, in the cytoplasm of individual AChE-containing neurons. In addition, interstrain comparison indicates the presence of a genetically determined higher AChE content in striatal neurons of the DBA/2 strain.