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Biomedical subjects

L Felici

Publications and source records attributed to L Felici.

At least 19 recordsLinked to original sources
PubMed2001

Identification of dopamine plasma membrane and vesicular transporters in human peripheral blood lymphocytes.

Plasma membrane dopamine transporter (DAT), vesicular monoamine transporters (VMAT) type-1 and -2 and the expression of the dopaminergic markers dopamine and tyrosine hydroxylase were assessed in membranes and/or in cytospin centrifuged human peripheral blood lymphocytes. The radiolabeled DAT ligand [3H]GBR12935 was bound to peripheral lymphocytes in a manner consistent with the specific binding to a dopamine uptake system, with a dissociation constant similar to that found in striatum, but with a lower density of binding sites. On the other hand, no specific binding occurred in cerebellum used as a test tissue not expressing DAT. Western blot analysis using antibodies raised against amino or carboxy terminus of DAT or against VMAT-1 or VMAT-2 revealed labeling of single bands of approximately 76, 55 or 68 KDa, respectively, displaying similar migration characteristics in lymphocytes and test tissues used for comparison. Immunofluorescence revealed that anti-dopamine, anti-tyrosine hydroxylase, anti-DAT, anti-VMAT-1 and anti-VMAT-2 antibodies labeled the total population of cytospin-centrifuged lymphocytes mounted on microscope slides. Confocal laser microscopy demonstrated that dopamine and VMAT-2 immunoreactivity was developed mainly in cytoplasmic punctiform areas likely corresponding to vesicles and to a lower extent was associated to plasma membrane. Tyrosine hydroxylase immunoreactivity was diffused to cytoplasm and to plasma membrane of lymphocytes, whereas DAT and VMAT-1 immunoreactivity were located almost exclusively in lymphocyte plasma membrane and cytoplasm, respectively. Lymphocyte DAT characterized in this study has probably functional relevance as [3H]dopamine was taken up by intact lymphocytes and uptake was inhibited specifically by compounds known to affect dopamine transport. These findings indicate that human peripheral blood lymphocytes possess DAT plasma membrane and VMAT-1 and VMAT-2 transporters. Increasing evidence indicates that dopamine transporter changes may be related to neuronal injury. In view of this assessment of lymphocyte DAT and VMAT transporters can be considered for identifying pathologies characterized by impaired dopaminergic neurotransmission.

Adult↗
PubMed2001

Neurotrophins and neurotrophin receptors in human lung cancer.

The expression of neurotrophins (NTs) and related high- and low-affinity receptors was studied in surgical samples of histologically diagnosed human tumors of the lower respiratory tract. The experiment was conducted with 30 non-small cell lung cancer specimens and in eight small cell lung cancer specimens by Western blot analysis and immunohistochemistry to assess expression and distribution of NT and NT receptor proteins in tissues examined. Immunoblots of homogenates from human tumors displayed binding of anti-nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and NT-3 antibodies as well as of anti-tyrosine-specific protein kinase (Trk) A, TrkB, and TrkC receptor antibodies, with similar migration characteristics than those displayed by human beta-NGF and proteins from rat brain. A specific immunoreactivity for NTs and NT receptors was demonstrated in vessel walls, stromal fibroblasts, immune cells, and sometimes within neoplastic cell bodies. Approximately 33% of bronchioloalveolar carcinomas exhibited a strong membrane NGF and TrkA immunoreactivity, whereas 46% adenocarcinomas expressed an intense TrkA immunoreactivity but a weak immunostaining for NGF within tumor cells. Moreover, squamous cell carcinomas developed an intense TrkA immunoreactivity only within stroma surrounding neoplastic cells. A faint BDNF and TrkB immunoreactivity was documented in adenocarcinomas, squamous cell carcinomas, and small cell lung cancers. NT-3 and its corresponding TrkC receptor were found in a small number of squamous cell carcinomas within large-size tumor cells. No expression of low-affinity p75 receptor protein was found in tumor cells. The detection of NTs and NT receptor proteins in tumors of the lower respiratory tract suggests that NTs may be involved in controlling growth and differentiation of human lung cancer and/or influencing tumor behavior.

Aged↗
PubMed2001

Survival trends of childhood cancer during the period 1978-1994 in Italy: a first report from the Italian cancer registries.

This article shows the survival trends of childhood cancers diagnosed from 1978 to 1994 in Italy. A first analysis presents a survival increase for all the diagnostic categories and in both sexes, with the exception of Hodgkin's disease, for which five-year survival is stable at 97%. The results of this analysis show that five-year survival changes from 54% to 72% for all cancers, from 56% to 70% for non Hodgkin's lymphomas, from 53% to 64% for central nervous system tumours, from 59% to 78% for acute lymphatic leukaemia, from 18% to 42% for acute non lymphatic leukaemia, from 30% to 62% for neuroblastoma and from 33% to 71% for malignant bone tumours. Concerning international comparisons, the overall Italian rates and their increases are very similar to the USA ones. Instead, if we consider a comparison between survival trends in Italy and survival trends observed in some European countries, like Great Britain, Slovakia and Denmark, it is evident that in Italy there is a faster improvement of prognosis for almost all diagnostic categories.

Adolescent↗
PubMed2000

Influence of age on L-type Ca2+ channels in the pulmonary artery and vein of spontaneously hypertensive rats.

The influence of age on the density and localization of L-type Ca2+ channels was studied during development of hypertension in the pulmonary artery and vein of spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) rats by radioligand binding assay and light microscope autoradiography. SHR were examined at 6 weeks (juvenile, pre-hypertensive stage), 12 weeks (young, developing hypertension) and 24 weeks (mature, established hypertension). The dihydropyridine-type Ca2+ antagonist [3H]nicardipine was used as a radioligand. It was bound specifically to sections of rat pulmonary artery and vein. Dissociation constant (Kd) values were similar in WKY rats and SHR, whereas maximum density of binding sites (Bmax) values increased in SHR in comparison with WKY rats. This increase was noticeable from the pre-hypertensive phase. The pharmacological profile of [3H]nicardipine binding was similar in different age groups of either normotensive and hypertensive rats. Quantitative analysis of autoradiographs from SHR revealed a progressive increase of silver grains in smooth muscle of tunica media and to a lesser extent in the adventitia of pulmonary artery but not of pulmonary vein from pre-hypertensive stage to developing hypertension. No further changes were observed in established hypertension. The above data indicate that the density of L-type Ca2+ channels of pulmonary arteries is increased in SHR. This augmentation after the pre-hypertensive phase suggests the occurrence of dysregulation of Ca2+ handling in the pulmonary vasculature of developing SHR.

Aging↗
PubMed2000

Localization of dopamine receptor subtypes in systemic arteries.

Dopamine D1-D5 receptor protein immunoreactivity was investigated in different sized pial, renal and mesenteric artery branches using immunohistochemical techniques and anti-dopamine D1-D5 receptor protein antibodies. Faint dopamine D1 receptor protein immunoreactivity was observed in smooth muscle of tunica media of pial, renal and mesenteric artery branches. Dopamine D2 receptor protein immunoreactivity was located in the adventitia and adventitia-media border of pial and renal artery branches and to a lesser extent of mesenteric artery branches. No dopamine D3 receptor protein immunoreactivity was observed in pial and mesenteric arteries. In renal arteries a moderate dopamine D3 receptor immunoreactivity was detectable in the adventitia and adventitia-media border. A strong dopamine D4 receptor protein immunoreactivity displaying the same localization of dopamine D2 receptor protein was observed in pial and mesenteric arteries, but not in renal artery branches. Moderate dopamine D5 receptor protein immunoreactivity was observed in smooth muscle of the tunica media of pial, renal and mesenteric artery branches. Bilateral removal of superior cervical ganglia, from which sympathetic supply to cerebral circulation originate abolished dopamine D2 and D4 receptor protein immunoreactivity in pial arteries but was without effect on dopamine D1 and D5 receptor protein immunoreactivity. These findings indicate that systemic arteries express dopamine D1-like (D1 and D5) and D2-like (D2, D3 and D4) receptor subtypes displaying respectively a muscular (postjunctional) and prejunctional localization. The specific distribution of dopamine D2-like receptor subtypes in systemic arteries suggests that they may have a different role in regulating blood flow through the vascular beds investigated.

Animals↗
PubMed2000

Neurotrophin and neurotrophin receptor expression in alveolar macrophages: an immunocytochemical study.

Alveolar macrophages play a crucial role in regulating lung immune responses and in maintaining the integrity of the respiratory tract. Neurotrophins (NTs), besides to their neurotrophic activities, exhibit physiological effects in the immune system. In this study, nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), NT-3 and low- (p75) and high affinity (Trks) NT receptors were investigated by immunocytochemistry in cytospin centrifuged preparations of human alveolar macrophages. Approximately 2.5% alveolar macrophages were immunoreactive for NGF, whereas no macrophages displaying immunoreactivity for BDNF or NT-3 were observed. A 3.5% macrophages displayed immunoreactivity for TrkA-receptor protein, 10% for TrkB-receptor protein (full length isoform), and 2% for TrkC-receptor protein. No low-affinity p75 NT and TrkB[-] truncated isoform receptor immunoreactive macrophages were found. These findings support the hypothesis that NTs and the corresponding receptors may play a role in regulating immunological and functional activity of alveolar macrophages via paracrine/autocrine mechanisms.

Adult↗
PubMed1999

NADPH-diaphorase histochemistry in the rat cerebral cortex and hippocampus: effect of electrolytic lesions of the nucleus basalis magnocellularis.

Unilateral or bilateral electrolytic lesions of the nucleus basalis magnocellularis (NBM) increased NADPH-diaphorase in the fronto-parietal cortex and in the CA1-CA3 fields of the hippocampus. NBM is the cholinergic basal forebrain nucleus supplying the fronto-parietal cortex but not the hippocampus. This increase was more remarkable at 4 weeks than at 2 weeks after lesioning. Monolateral or bilateral lesioning of the NBM increased to a similar extent NADPH-diaphorase. The number of neurons expressing NADPH-diaphorase was not statistically different between sham-operated and NBM-lesioned rats. These results indicate that similarly as reported in experimental damage of several brain areas, lesions of the NBM induce NADPH-diaphorase. The induction of this marker for nitric oxide synthase occurs both in the target of projections arising from the NBM such as the frontal cortex and in an area not directly supplied by NBM such as the hippocampus. Lesion-induced NADPH-diaphorase increase may contribute to neurodegenerative changes caused by damage of the NBM area.

Animals↗
PubMed1999

Increased expression of dopamine receptors on lymphocytes in Parkinson's disease.

Dopamine D1-like and D2-like receptors on peripheral blood lymphocytes (PBL) were assayed in 50 de novo patients with idiopathic Parkinson's disease (PD), in 36 neurologic control subjects (multiple-system atrophy, n = 16; essential tremor, n = 10; other neurodegenerative diseases, n = 10), and in 26 healthy control subjects by radioligand binding assay techniques using [3H]SCH 23390 and [3H]7OH-DPAT as ligands. Patients with PD revealed a higher density (Bmax) of dopamine D1-like (p <0.001) and D2-like (p <0.00001) receptors on PBL than either neurologic or healthy control subjects, whereas no differences in Bmax were observed among patients affected by other neurologic diseases and healthy control subjects. The affinity (Kd) of both radioligands was similar in the groups investigated. The pharmacologic profile of [3H]SCH 23390 and [3H]7OH-DPAT binding was consistent with the labeling of dopamine D5 and D3 receptor subtypes, respectively. Twenty-five of the 50 patients with PD were retested after 3 months of therapy with levodopa or bromocriptine. Both treatments reduced the density of D1-like (p <0.001) and D2-like (p <0.001) receptors on PBL to values comparable to those of control subjects. The increased density of D1-like and D2-like receptors on PBL in de novo PD patients may represent an upregulation mechanism resulting from the diffuse impairment of the dopaminergic system in PD.

Aged↗
PubMed1999

Dopamine D2-like receptors on human peripheral blood lymphocytes: a radioligand binding assay and immunocytochemical study.

1. Peripheral blood lymphocytes express dopamine D1-like and D2-like receptors which were investigated using radioligand binding assay and molecular biology techniques. Analysis of dopamine D2-like receptors expressed by human peripheral blood lymphocytes with radioligand binding assay may offer a rapid technique for assessing receptor changes in disorders characterized by involvement of the dopaminergic system. However, the suitability of radioligand binding assay techniques to measure dopamine D2-like receptors is questioned. 2. In view of the discrepancy between data of dopamine D2-like receptor determination with molecular biology and radioligand binding assay techniques, we have assayed dopamine D2-like receptors expressed by human peripheral blood lymphocytes using as radioligands the dopamine receptor agonist 7-[3H]-hydroxy-N,N-di-n-propyl-2-aminotetraline ([3H]-7-OH-DPAT) and two antagonists ([3H]-spiperone and [3H]-nemonapride). 3. Analysis of saturation curves revealed a concentration-dependent binding of all compounds to human peripheral blood lymphocytes. Dissociation constant (Kd) values averaged between 0.15 and 0.40 nM for different radioligands. The maximum density of binding sites (Bmax) was low, ranging from 4.15 +/- 0.05 fmol/10(6) cells with [3H]-spiperone and 8.66 +/- 0.04 fmol/10(6) cells with [3H]-7-OH-DPAT. 4. Displacement curves of [3H]-7-OH-DPAT, [3H]-spiperone and [3H]-nemonapride binding to human peripheral blood lymphocytes revealed, using radioligand concentrations giving the highest specific:non-specific binding ratio, a pharmacological profile consistent with the labelling of dopamine D2-like receptors. The use of higher radioligand concentrations resulted in a poorly displaceable and characterizable binding. 5. Detection of dopamine D2, D3 and D4 receptor immunoreactivity in cytospin centrifuged peripheral blood lymphocytes revealed dopamine D3 and D4 but not D2 receptor immunostaining. 6. The above findings indicate in agreement with molecular biology studies, that dopamine D2-like receptors expressed by human peripheral blood lymphocytes belong to the D3 and D4 receptor subtypes. These receptors are detectable using either dopamine D2-like receptor agonists and antagonists as radioligands if controlled experimental conditions are followed. The standardisation of immunocytochemical techniques for detecting human peripheral blood lymphocyte dopamine receptors may contribute to clarify their role in lymphocyte function or as a peripheral marker of the status of the dopaminergic system.

Benzamides↗
PubMed1998

Labeling of dopamine D3 and D4 receptor subtypes in human peripheral blood lymphocytes with [3H]7-OH-DPAT: a combined radioligand binding assay and immunochemical study.

Molecular biology studies have demonstrated that human peripheral blood lymphocytes express dopamine D2-like receptors belonging to the D3 and D4 receptor subtypes, whereas the characterization of these receptors using radioligand binding assay techniques provided conflicting results. The preferential dopamine D3 receptor agonist [3H]7-hydroxy-N, N-di-n-propyl-2-aminotetralin ([3H]7-OH-DPAT) was used recently for labeling lymphocyte dopamine D3 receptor. However, the selectivity of this compound for the D3 receptor was questioned. In this study we have investigated human peripheral blood lymphocyte dopamine receptor subtypes labeled by [3H]7-OH-DPAT using a conventional radioligand binding assay technique and antibodies against dopamine D2-like receptor subtypes. [3H]7-OH-DPAT was specifically bound to intact human peripheral blood lymphocytes with a dissociation constant (Kd) value of 0.32 + 0.03 nM and a maximum density of binding sites (Bmax) of 18.2 + 0.8 fmol/2 x 10(6) cells. [3H]7-OH-DPAT binding was unaffected by antibodies against dopamine D2 and D2S receptors. Anti-dopamine D3 and D4 receptor antibodies reduced [3H]7-OH-DPAT binding by about 53% and 32% respectively. Combination of anti D3 and D4 receptor antibodies reduced remarkably [3H]7-OH-DPAT binding. The above results suggest that the dopamine receptor agonist [3H]7-OH-DPAT labels dopamine D3 and D4 receptor subtypes in human peripheral blood lymphocytes. The use of antibodies raised against dopamine receptor subtypes in combination with radioligand binding assay may contribute to define receptor subtypes expressed by human peripheral blood lymphocytes in health and disease.

Adult↗
PubMed1998

Peripheral blood lymphocyte muscarinic cholinergic receptors in airway hyperresponsiveness: a marker of cholinergic dysfunction?

1. Muscarinic cholinergic receptors were assayed in human peripheral blood lymphocytes of healthy control and airway hyperresponsive subjects using a radioligand binding assay technique and the muscarinic cholinergic receptor antagonist [3H]-quinuclidinyl benzilate (QNB) as a radioligand. Subjects investigated were divided in four different groups based on threshold responses to methacholine inhaled as challenge test. 2. [3H]-QNB was bound to human peripheral blood lymphocytes in a manner consistent with the labelling of muscarinic cholinergic receptors. Dissociation constant (Kd) values of [3H]-QNB binding were similar in the different groups examined, whereas maximum density of binding sites (Bmax) was increased in airway hyperresponsive subjects in comparison with healthy controls. 3. The above findings indicate that the density of muscarinic cholinergic receptors is increased in peripheral blood lymphocytes of airway hyperresponsive subjects. 4. This suggests that airway hyperresponsiveness is associated with cholinergic hyperreactivity and is probably a systemic cholinergic dysfunction since it is accompanied by changes in the density of muscarinic cholinergic receptors expressed by peripheral blood lymphocytes.

Adult↗
PubMed1998

Density and localization of calcium channels of the L-type in human pulmonary artery.

The pharmacological profile and the anatomical localization of Ca2+ channels of the L-type were investigated in the human pulmonary artery to identify possible mechanisms involved in the regulation of the pulmonary vascular tone. Analysis was performed on slide-mounted frozen sections of human pulmonary artery using radioligand binding assay techniques associated with light microscope autoradiography. [3H]-Nicardipine was used as ligand. Human renal and right coronary arteries also were used as systemic reference arteries. Binding of [3H]-nicardipine to sections of human pulmonary artery was time-, temperature- and concentration-dependent, saturable and reversible. In the human pulmonary artery, the apparent equilibrium dissociation constant (Kd) was 0.12+/-0.02 nM and the maximum density of binding sites (Bmax) was 38.15+/-2.25 fmol/mg tissue. Kd values were 0.3+/-0.01 nM and 0.5+/-0.02 in the human renal artery and right coronary artery respectively. Bmax values were 248+/-16 fmol/mg tissue and 173+/-9.5 fmol/mg tissue in the human renal artery and right coronary artery respectively. The pharmacological profile of [3H]-nicardipine binding to sections of human pulmonary artery was consistent with the labeling of Ca2+ channels of the L-type. It was similar in the pulmonary artery and in the human renal and right coronary arteries. Light microscope autoradiography revealed a high density of [3H]-nicardipine binding sites within smooth muscle of the tunica media of human pulmonary artery as well as of human renal and right coronary arteries. A lower accumulation of the radioligand occurred in the tunica adventitia. No specific binding was noticeable in the tunica intima. Our data suggest that human pulmonary artery expresses Ca2+ channels of the L-type sensitive to dihydropyridines. These sites have similar affinity and lower density than those expressed by systemic arteries. The presence of Ca2+ channels of the L-type in human pulmonary artery suggests that their pharmacological manipulation may be considered in the treatment of pulmonary hypertension.

Aged↗
PubMed1997

Dopamine D4 receptor in human peripheral blood lymphocytes: a radioligand binding assay study.

The expression of dopamine D4 receptor was investigated in human peripheral blood lymphocytes with a radioligand binding assay technique, using [3H]clozapine as radioligand. [3H]Clozapine was specifically bound to human peripheral blood lymphocytes. The binding was time-, temperature-, and concentration-dependent and of high affinity, with a dissociation constant (K(d)) value of 0.34 +/- 0.02 nM and a maximum density of binding sites (B(max)) value of 27 +/- 1.4 fmol/10(6) cells. The pharmacological profile of [3H]clozapine binding to human peripheral blood lymphocytes was similar to that found in Chinese hamster ovary (CHO) cells transfected with the D4 clone (D4.2 variant). The above results are consistent with molecular biology studies demonstrating the expression of a dopamine D4 receptor in immune cells and in human peripheral blood lymphocytes. The availability of a rapid and sensitive radioligand binding assay technique for the dopamine D4 receptor in human peripheral blood lymphocytes may contribute to better define the role of this dopamine receptor subtype in neurological and psychiatric disorders.

Adult↗
PubMed1996

Muscarinic cholinergic receptor subtypes in human peripheral blood lymphocytes.

The subtypes of muscarinic cholinergic receptors were studied in human peripheral blood lymphocytes with radioligand binding techniques and the non-selective muscarinic cholinergic receptor antagonist [3H]quinuclidinyl benzylate (QNB) as a ligand. [3H]QNB was bound to human peripheral lymphocytes in a manner consistent with the labelling of muscarinic cholinergic receptors. The dissociation constant (Kd) value was 0.60 +/- 0.08 nM and the maximum density of binding sites (Bmax) was 2.33 +/- 0.03 fmol/2.2 x 10(6) cells. The binding was time-, temperature- and concentration-dependent, belonging to a single class of high affinity sites. Analysis of the pharmacological profile of [3H]QNB binding in the presence of compounds specific for the different muscarinic receptor subtypes suggests that human peripheral blood lymphocytes express mainly muscarinic cholinergic M2 and M3 receptor subtypes and to a lesser extent muscarinic M4 receptors. The characterization of the subtypes of muscarinic cholinergic recognition sites expressed by human peripheral blood lymphocytes may represent a tool for investigating the possible relationships between immune and cholinergic systems in normal and pathologic conditions.

Adult↗
PubMed1996

Pharmacological characterisation of Ca2+ channels of the L-type in human peripheral blood lymphocytes.

Ca2+ channels of the L-type were characterised in intact human peripheral blood lymphocytes using a radioligand binding technique and the dihydropyridine-type Ca2+ channel antagonist [3H](+)-PN 200-110 (isopropyl-4-(2,1,3-benzoxadiazol-4-yl)1,4-dihydro-5-methoxycarbon yl-2, 6-dimethyl-3-pyridine carboxylate) as a ligand. [3H](+)-PN 200-110 binding to human peripheral blood lymphocytes was time-, temperature-, concentration-dependent and of high affinity. The dissociation constant (Kd) value was 0.4 +/- 0.02 nM and the maximum binding capacity (Bmax) was 33.5 +/- 1.6 fmol/10(6) cells. Pharmacological analysis of [3H](+)-PN 200-110 binding to human peripheral blood lymphocytes was consistent with the labelling of a Ca2+ channel of the L-type. In fact, dihydropyridine derivatives were the most potent competitors of [3H](+)-PN 200-110 binding, whereas phenylalkylamine and benzothiazepine compounds or non-selective Ca2+ channel modulators were weak or ineffective displacers. These findings are the first observation that human peripheral blood lymphocytes express Ca2+ channels of the L-type. The possibility that Ca2+ channel antagonists may interfere with immune system function is discussed.

Adult↗
PubMed1996

Muscarinic cholinergic receptor subtypes in the pigeon bursa of Fabricius: a radioligand binding and autoradiographic study.

The pharmacological profile and the anatomical localisation of muscarinic cholinergic receptor subtypes were studied in the pigeon bursa of Fabricius, using radioligand binding and autoradiographic techniques with [3H]quinuclidinyl benzilate (QNB) as a ligand. [3H]QNB was specifically bound to sections of bursa of Fabricius. The binding was time-, temperature- and concentration-dependent. The dissociation constant was 0.31 +/- 0.02 nM, and the maximum density of binding sites averaged 38 +/- 2.5 fmol/mg protein. The pharmacological profile of [3H]QNB binding to sections of pigeon bursa of Fabricius was consistent with the labelling of M2, M3 and M4 muscarinic receptor subtypes. Light microscope autoradiography showed the localisation of [3H]QNB binding sites in the medulla, in follicular septa, in the cortico-medullary border and in lesser amounts in the cortical layer. The functional significance of these receptors should be clarified in future studies.

Animals↗
PubMed1996

Age-dependent changes in the expression of dopamine receptor subtypes in human peripheral blood lymphocytes.

The pharmacological profile and the density of dopamine D3 and D5 receptor subtypes expressed by human peripheral blood lymphocytes of subjects of different ages (ranging from 20 to 75 years) were assessed using radioligand binding techniques. Dopamine D3 receptor was assayed with [3H]7-hydroxy-N,N-di-n-propyl-2-aminotetraline ([3H]7-OH-DPAT) as a ligand. Dopamine D5 receptor was assayed using [3HIR]-(+)-(-chloro-2,3,4,5, tetrahydro-5-phenyl-1H-3-benzazepin-al-hemimaleate) ([3H]SCH 23390) as a ligand. The affinity and the pharmacological profile of [3H]7-OH-DPAT and [3H]SCH 23390 at dopamine D3 and D5 receptor, respectively, were similar in subjects of different ages. The density of dopamine D3 receptor binding sites was slightly decreased in subjects of 30-39 years in comparison with younger individuals. A remarkable loss of dopamine D3 receptor was then found between 40 and 49 years of age in comparison with younger subjects. A further slight decrease was noticeable between 50 and 59 years of age. The number of [3H]7-OH-DPAT binding sites was then stabilized after 60 years of age. The density of dopamine D5 receptor binding sites did not show age-dependent changes. The above findings indicate the occurrence of a decline in the density of lymphocyte dopamine D3 but not D5 receptor between adult and mature subjects. The possibility that dopamine D3 receptor assay in peripheral blood lymphocytes may represent a tool for investigating dopamine receptor function in aging and age-related neurological disorders is discussed.

Adult↗