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  • 1
    Electronic Resource
    Electronic Resource
    Nigrostriatal and mesolimbic dopaminergic activities were modified throughout the ovarian cycle of female rats (1991)
    Springer
    Journal of neural transmission 85 (1991), S. 223-229 
    Details
    ISSN: 1435-1463
    Keywords: Sexual steroids ; estrous cycle ; limbic forebrain ; striatum ; dopamine ; DOPAC ; tyrosine hydroxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this work, we have studied the changes in the functional state of nigrostriatal (NSDA) and mesolimbic (MLDA) dopaminergic neurons during the estrous cycle of the female rat. The activity of tyrosine hydroxylase (TH), the turnover rate (Kt) after inhibition of dopamine (DA) synthesis and the ratio between the contents of this amine and its metabolite, L-3,4 dihydroxyphenylacetic acid (DOPAC), were used as indices of neuronal activity. The neuronal activity of NSDA neurons rose during estrous and declined during proestrous, as reflected by the values of Kt and DOPAC/DA ratio measured during both phases. Interestingly, the course of variations in striatal TH activity was similar, although retarded in relation to the changes in neuronal activity. Thus, TH activity was high during diestrous, whereas it was low during estrous. The activity of MLDA neurons was reduced during proestrous. This can be concluded from the decreased Kt and DOPAC/DA ratio measured in this phase and it was accompanied by a low TH activity. Thereupon, both Kt and TH activity increased during estrous. These results indicate the existence of physiological changes in the functional state of both dopaminergic systems during the ovarian cycle, which are partially different for each neuronal pathway. This supports the existence of a specific regulation, and not indiscriminate effects, by the hormones involved in this cycle, mainly estradiol and progesterone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244947
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  • 2
    Electronic Resource
    Electronic Resource
    Ontogeny of immunoreactive somatolactin cells in the pituitary of gilthead sea bream (Sparus aurata L., Teleostei) (1997)
    Springer
    Anatomy and embryology 196 (1997), S. 227-234 
    Details
    ISSN: 1432-0568
    Keywords: Key words Pituitary gland ; Somatolactin ; Development ; Immunocytochemistry ; Sparus aurata (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This is the first report on the identification of somatolactin (SL) cells during the early developmental stages of the teleost fish Sparus aurata. The SL cells were followed from newly hatched until 46 months. SL cells were immunocytochemically identified at light microscopical level with anti-cod SL in the developing pituitary using the peroxidase-antiperoxidase method. SL cells first appeared in newly hatched specimens, in which the pituitary gland lacked the neurohypophysis. They were scarce and located from the middle to the posterior region of the adenohypophysis. As the fish developed, the cells progressively increased in number and surrounded the developing neurohypophysis, which could be distinguised from 12-day-old larvae onwards in the caudal region of the gland. From 51 days onwards, SL cells were found in a discontinuous layer surrounding the neurohypophysis branches that entered the pars intermedia as clustered or isolated cells among non-SL-immunoreactive cells of the pars intermedia, and in the proximal pars distalis. The somatolactin-immunoreactive cells are periodic acid-Schiff-positive only in the adult stages. These data confirm, previous findings concerning the presence of two molecular forms of SL, glycosylated and nonglycosylated, in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050093
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  • 3
    Electronic Resource
    Electronic Resource
    Early organization of the pituitary gland in Sparus aurata L. (Teleostei) An ultrastructural study (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 441-452 
    Details
    ISSN: 1432-0568
    Keywords: Pituitary gland ; Development ; Ultrastructure ; Sparus aurata (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The cell organization of the pituitary gland and the relationship between neurohypophysis and adenohypophysis in the early developmental stages of the gilthead sea bream, Sparus aurata, were studied by electron microscopy. In newly hatched larvae, the pituitary gland was embedded in the ventral floor of the diencephalon and separated from the hypothalamus by a continuous basal lamina. Elongated mesenchymal cells next to the ventral surface were observed. At this stage, there was no neurohypophysis and the adenohypophysis consisted of undifferentiated endocrine cells with small scarce secretory granules and a few stellate cells, with no distinctive zonation. An incipient neurohypophysis was present in 1-day-old larvae. The first evagination of the neurohypophysis into the adenohypophysis were observed in 2-day-old larvae and developed progressively with age, being deeper in the caudal zone. Two regions in the adenohypophysis, one anterior — the presumptive pars distalis — and one posterior — the presumptive pars intermedia — were found in 2-day-old larvae. Three regions (rostral and proximal pars distalis and pars intermedia) were clearly distinguishable in 4-day-old larvae. The ultrastructural features of the pituitary endocrine cells varied during gland differentiation, with the secretory granules gradually increasing in number and size, accompanying organelle development. Nevertheless, even in the oldest larvae studied (65 days), undifferentiated cells similar to those in the earliest stages were observed. The first blood vessels appeared in the neurohypophysis around 16 days after hatching. During early development, the pituitary gland progressively emerged from the ventral floor of the brain. By 16 days, the principal pattern of the pituitary gland architecture appeared to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185875
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  • 4
    Electronic Resource
    Electronic Resource
    Modifications of mesolimbic and nigrostriatal dopaminergic activities after intracerebroventricular administration of prolactin (1994)
    Springer
    Journal of neural transmission 96 (1994), S. 63-79 
    Details
    ISSN: 1435-1463
    Keywords: Prolactin ; striatum ; limbic forebrain ; dopamine ; DOPAC ; tyrosine hydroxylase ; D1 and D2 receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the present study we examined the effects of intracerebroventricular (i.c.v.) injections of prolactin (PRL) on the presynaptic activity and postsynaptic sensitivity of mesolimbic and nigrostriatal dopaminergic neurons. In addition, the effects of PRL onin vitro release of dopamine (DA) from perifused striatal fragments were examined. Tyrosine hydroxylase (TH) activity and D2 receptor density in the striatum decreased after i.c.v. PRL administration; this was accompanied by an increase in D2 receptor affinity. These effects occurred after i.c.v. administration of PRL to normoprolactinemic rats, although normally they did not appear after administration to animals with pituitary grafting-induced hyperprolactinemia. Thus, in these animals, i.c.v. PRL failed to decrease TH activity and D1 and D2 receptor densities to a significant extent. In the case of D2 receptors, this was probably due to the fact that pituitary grafting-induced hyperprolactinemia itself was able to reduce the density of this receptor. No changes were observed in DA or L-3, 4-dihydroxyphenylacetic acid (DO-PAC) contents after i.c.v. administration of PRL to both normo- and hyperprolactinemic animals. Basal and K+-evoked DA releasein vitro from perifused striatal fragments of normoprolactinemic rats were not affected by the addition of PRL, whereas this hormone enhanced K+-evoked DA release when added to perifused striatal fragments from hyperprolactinemic animals. In the limbic forebrain, i.c.v. administration of PRL to normoprolactinemic animals produced a decrease in DA and DOPAC contents and D1 receptor density. Interestingly, none of these effects appeared when PRL was injected to hyperprolactinemic animals. In summary, our results suggest a possible inhibitory role of PRL on the activity of both the nigrostriatal and mesolimbic dopaminergic neuronal systems. These inhibitory effects were reflected in the decreases elicited in a set of neurochemical parameters, indicating either presynaptic activity or postsynaptic sensitivity, after i.c.v.-administered PRL. This observation supports the hypothesis of a possible neuromodulatory role for an extrapituitary PRL on the activity of these neurons, although the fact that most of these effects did not appear when i.c.v. administration was performed in hyperprolactinemic rats also suggests that they are influenced by peripheral PRL levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01277929
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