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Recently we have shown that in vitro binding of the proximal part of the human tyro­sine hydroxylase gene to the nuclear matrix is correlated with its transcriptional activ­ity. The strongest binding potential was predicted by computing for the first intron se­quence (Lenartowski & Goc, 2002, Neurosci Lett.; 330: 151-154). In this study a 16 kb fragment of the bovine genomic DNA containing the tyrosine hydroxylase gene was investigated for its affinity to the nuclear matrix. Only a 950 bp fragment encod­ing the distal part of the first intron, second exon and a few nucleotides of the second intron bound to the nuclear matrix. The binding was independent of the tissue-specific tyrosine hydroxylase gene activation. The fragment was subcloned and sequenced. Computer search pointed to one potential intronic matrix attachment region with two AP1-like sites embedded in the sequence. We conclude that even if the position of the matrix binding region is conserved among the tyrosine hydroxylase genes in mam­mals, its tissue specificity and/or function is not preserved or is achieved by different mechanisms.
Vulnerability of midbrain dopaminergic (DA) neurons in the weaver mouse was studied at postnatal (P) days 8 and 90, in chosen coronal levels throughout the anteroposterior (AP) extent of the substantia nigra pars compacta (SNc). Wild-type (+/+) and homozygous weaver (wv/wv) mice used were the offspring of pregnant dams injected in several cases with tritiated thymidine on embryonic days 11-15. DA neurons were identified for their tyrosine hydroxylase immunoreactivity. Data reveal that at P8, the frequency of both +/+ and wv/wv late-generated DA cells increases from rostral to caudal SNc. No apparent DA-cell loss was observed at P8 in the mutant genotype, irrespective of the AP level considered. However, throughout the AP, there was a significant reduction in the number of these neurons at any level in 90-day-old weavers. Comparison of P8 and P90 +/+ SNc suggests that cell death is not a major aspect in the developmental regulation of normal DA neurons, although numerical cell depletion in the postnatal development of weaver SNc probably results from the amplification of a basal cell-death process, which affected all the coronal levels studied.
The hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei are activated by body salt-fluid variations. Stimulation of 2-adrenoceptors by an agonist-xylazine (XYL) activates oxytocinergic but not vasopressinergic magnocellular neurons. In this study, tyrosine hydroxylase (TH), corticoliberine (CRH), and neuropeptide Y (NPY) magnocellular phenotypes, were analysed in response to 2-adrenoceptor manipulations and sustained hyperosmolality in vasopressin deficient homozygous Brattleboro (di/di) rats. Saline (0.9% NaCl, 0.1 ml/100g/bw), XYL (10 mg/kg/bw), atipamezole (ATIP, 2-adrenoceptors antagonist, 1 mg/kg/bw), and ATIP 5 min later followed by XYL, were applied intraperitoneally. Presence of immunolabeled Fos peptide signalized the neuronal activity. Ninety minutes after injections, the rats were anesthesized and sacrificed by transcardial perfusion with fixative. Coronal sections of 30 µm thickness double immunolabeled with Fos/neuropeptide were evaluated under light microscope. Under basal conditions, di/di in comparison with control Long Evans rats, displayed significantly higher number of TH, CRH, and NPY immunoreactive neurons in the SON and PVN (except NPY cells in PVN) and more than 90%, 75%, and 86% of TH, NPY, and CRH neurons, respectively, displayed also Fos signal in the SON. XYL did not further increase the number of Fos in the PVN and SON and ATIP failed to reduce the stimulatory effect of hypertonic saline in all neuronal phenotypes studied. Our data indicate that hyperosmotic conditions significantly influence the activity of TH, CRH, and NPY magnocellular neuronal phenotypes, but 2-adrenoceptors do not play substantial role in their regulation during osmotic challenge induced by AVP deficiency.
Immunohistochemical characteristics of neurones innervating the porcine uterus located in paracervical ganglia were studied with a combination of retrograde fluorescent tracing and immunofluorescence. Retrograde fluorescent tracer Fast Blue (FB) was injected into the uterine horn and uterine cervix. The presence of biologically active substances, tyrosine hydroxylase (TH), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), galanin (GAL), Met-enkephalin-Arg-GlyLeu (MEAGL) and calcitonin gene-related peptide (CGRP) was studied in FBpositive neurones localised in paracervical ganglia. FB-positive neurones containing TH, NPY, VIP and MEAGL were numerous, while those containing CGRP were scarce. The results pointed to some species-related differences in immunohistochemical coding of neurones of paracervical ganglion responsible for uterus innervation.
Malfunction of glutamatergic neurotransmission in postnatal period is considered to be a risk factor for development of schizophrenia. Thus, the present study investigates the impact of NMDA receptor blockade in the postnatal period on the density of tyrosine hydroxylase immunoreactive axonal arbors in the rat medial prefrontal cortex. Behavioral experiments revealed that adult rats (60 days old) treated in the postnatal period with a competitive antagonist of NMDA receptors, CGP 40116 (1.25 mg/kg on days 1, 3, 6, 9; 2.5 mg/kg on days 12, 15, 18; and finally 5 mg/kg on day 21, all injections s.c.), showed enhancement of the locomotor activity stimulated by quinpirole (0.3 mg/kg s.c.) and amphetamine (0.5 mg/kg s.c.), which suggests development of functional supersensitivity of dopaminergic systems. It has been found that CGP 40116, given in postnatal period decreased the density of tyrosine hydroxylase immunoreactive axonal arbors in the medial prefrontal cortex of adult animals. The decrease was observed in superficial (II/III) and deep (V/VI) layers of the medial prefrontal cortex, while the average length of tyrosine hydroxylase immunoreactive axonal arbors was increased in both superficial and deep cortical layers. Changes in the density of tyrosine hydroxylase immunoreactive axonal arbors have not been followed by a significant decrease in the content of tyrosine hydroxylase protein measured by Western blot. Thus, NMDA receptor blockade in the early period of life evokes changes in architecture of tyrosine hydroxylase immunoreactive axonal arbors and that malfunction of glutamatergic neurotransmission, in early period of life may produce anatomical changes which resemble those observed in the brains of schizophrenics.
The uterine cervix-projecting neurons located in the lumbar paravertebral ganglia were identified by retrograde tracing. These contained immunoreactivity to TH and DBH. No immunoreactivity to GAL, VIP and SP was found in the neurons. Extirpation of the uterus reduced the expression of TH and induced the expression of GAL in the neurons. Expression of other substances studied was unchanged.
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