Dopamine (DA) is one of the main catecholamines in the brain and is crucial for movement coordination, endocrine function, reward, mood, memory and emotions. The dopaminergic system is the primary therapeutic target in the treatment of Parkinson’s disease (PD), drug addiction and schizophrenia. Notwithstanding, dysfunction of central dopaminergic neurotransmission has also been associated to de...

BACKGROUND The relationship between the striatal dopaminergic system and cardiovascular activity is not well known. The aim of this study is to investigate the relationship between striatal D2/D3 receptor binding and cardiovascular activity. METHODS The striatal D2/D3 receptor binding of 34 healthy volunteers was assessed by the single-photon emission computed tomography (SPECT) imaging metho...

Descending monoaminergic systems modulate spinal cord function, yet spinal dopaminergic actions are poorly understood. Using the in vitro lumbar cord, we studied the effects of dopamine and D2-like receptor ligands on spinal reflexes in wild-type (WT) and D3-receptor knock-out mice (D3KO). Low dopamine levels (1 microM) decreased the monosynaptic "stretch" reflex (MSR) amplitude in WT animals a...

Brain dopamine (DA) systems are involved in the modulation of the sensorimotor gating phenomenon known as prepulse inhibition (PPI). The class of D2-like receptors, including the D2, D3, and D4 receptor subtypes, have all been implicated in the control of PPI via studies of DA agonists and antagonists in rats. Nevertheless, the functional relevance of each receptor subtype remains unclear becau...

Introduction Dopamine receptors are divided into two families: D1 including D1 and D5 receptors and D2 including D2, D3 and D4 receptors. The role of the D3 receptor subtype in the brain and behavioral actions remains controversial. Further, synthesis of novel ligands targeting these receptors requires a means for assessing selectivity of the ligands in cases where radiolabels do not exist. We ...

It has been shown that mammalian cytochrome P450scc can metabolize vitamin D3 to 20-hydroxyvitamin D3 (20(OH)D3) and 20,22(OH)2D3. To define the biological significance of this pathway, we tested the effects of 20(OH)D3 on the differentiation program of keratinocytes and on the expression of enzymes engaged in vitamin D3 metabolism. Immortalized HaCaT and adult human epidermal keratinocytes wer...

BACKGROUND Klotho, a transmembrane protein, protease and hormone mainly expressed in kidney, is required for the suppression of 1,25(OH)2D3-generating 25-hydroxyvitamin D3 1-alpha-hydroxylase (Cyp27b1) by FGF23. Conversely, 1,25(OH)2D3 stimulates, by activating the vitamin D3 receptor (Vdr), the expression of klotho, thus establishing a negative feedback loop. Klotho protects against renal and ...

BACKGROUND Deficiency in Vitamin D3 (cholecalciferol) may predispose to some malignancies, including gonadal tumors and in experimental models vitamin D3 has been proven to inhibit the growth of cancer cells. To learn more about the potential role of vitamin D3 in cancerogenesis, we evaluated the expression and functionality of the vitamin D receptor (VDR) and its role in metastasis of ovarian ...

We previously revealed that the anti-proliferative activity of 25-hydroxyvitamin D3 (25(OH)D3) in human prostate PZ-HPV-7 cells depends on direct action 25(OH)D3 through vitamin D receptor (VDR). then attempted to confirm vivo using Cyp27b1 knockout (KO) mice. Daily administration at 250 μg/kg bw/day rescued rachitic conditions KO The plasma levels calcium, phosphorus, and parathyroid hormonea ...