The development of the corticoliberin- and vasopressinergic elements of the rat hypothalamus during postnatal ontogeny

In 10--81-day and adult Wistar rats, neurosecretory cells were revealed which react with antisera to corticoliberin and vasopressin. Morphometric analysis of these cells in the supraoptic, paraventricular and anterior commissural nuclei shows that in the latter vasopressinergic cells develop somewhat later than in the supraoptic and paraventricular nuclei. Complete differentiation of neurosecretory cells in all the centres investigated is observed in 2-month animals. Studies were also made on the amount of corticoliberin- and vasopressinergic terminals in the external zone of the median eminence. Vasopressin-immunoreactive fibers are more numerous in young rats than in adult ones. Corticoliberin-positive neurosecretory fibers are more abundant in adult animals. Earlier development of vasopressinergic elements corresponds to a hypothesis of a more ancient origin of nonapeptidergic structures as compared to those producing liberins and statins.     

Ethanol intake and 3H-serotonin uptake I: A study in Fawn-Hooded rats

Ethanol intake and synaptosomal 3H-serotonin uptake were studied in male Fawn-Hooded and Sprague-Dawley rats. Fawn-Hooded rats consumed more alcohol and more water than Sprague-Dawley rats. Plasma alcohol levels of Sprague-Dawley rats were not detectable but were about 5 mg/dl in Fawn-Hooded rats. Ethanol intake increased the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex, but not in thalamus. In Fawn-Hooded rats, serotonin uptake (Vmax) was higher than in Sprague-Dawley rats cortex. Ethanol intake reduced the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex. In cortex, the carrier affinity for serotonin was increased in alcoholized Fawn-Hooded rats. These results indicate that synaptosomal 3H-serotonin uptake is affected by ethanol intake. In Fawn-Hooded rats, high ethanol consumption is associated with high serotonin uptake. In rats presenting high serotonin uptake, alcoholisation reduces 3H-serotonin internalisation in synaptosomes, indicating a specific sensitivity to alcohol intake of serotonin uptake system.     

Determination of the reversible uptake of 3H-serotonin in synaptosomes: an adequate evaluation of the contribution of nonspecific uptake

Serotonin (5-HT) uptake in synaptosomes was studied at 0 degree C (1), at 37 degrees C in the presence of 100 microM imipramine (IIa) or 100 microM zimelidine (IIb), in the absence of Na+ ions (III) in the incubation medium. A significant decrease (P less than 0.01) of the uptake rate has been found (III greater than IIa, b greater than I). Nonspecific uptake inhibition was thought to be the cause of these differences. Determination of specific uptake, using control III, has shown Na+-dependent transport of 5-HT only on the one type of carrier (Km = 174 + 24 nM). It is concluded that determination of 5-HT nonspecific uptake, using control III, has permitted a more exact evaluation of specific uptake parameters, than determination, using controls I and IIa, b.     

Reduced Vmax of 3H-serotonin uptake but unchanged 3H-imipramine binding in the platelets of untreated hypertensive subjects

The uptake of 3H-serotonin, endogenous serotonin content and 3H-imipramine binding were measured in platelets of subjects with essential hypertension and matched control volunteers. The uptake of 3H-serotonin and endogenous serotonin levels in platelets were significantly reduced while 3H-imipramine binding did not differ in the two experimental groups. These results provide further evidence that the uptake site for serotonin and the binding site for 3H-imipramine although associated, may be modified independently.     

Ontogenesis of the LH-RH-containing neuronal elements in the hypothalamus of the rat.

LH-RH-containing neuronal elements were detected earliest in the median eminence and in the vascular organ of the lamina terminalis of newborn rats. The peroxidase-labeled antibody method was used. Since the synthesis of the gonadotrophic hormones starts already on the 18th day of intrauterine life in the rat, this finding does not support the view that LH-RH could have inductive effect on the differentiation of the gonadotropic cells of the anterior pituitary gland.     

Morphogenesis of structural elements of the cervical spine in the white rat in prenatal ontogeny

Embryonal development of the spinal column cervical part has been studied in 100 series of sagittal, transversal, frontal sections; time of the main structural elements anlagen (vertebral bodies, arches, joints, ligaments) is noted. The prenatal development of the spinal column cervical part is divided into 3 stages--mesenchymal, cartilagenous, osseous. The first stage lasts up to 16 days of development; during this period anlagen of vertebral bodies, arches, joints, ligaments are formed. The second stage--cartilagenous; mesenchyma is substituted for cartilagenous tissue, cartilagenous cells are differentiated. This stage lasts from the 16th up to the 18th day of embryogenesis. The third stage--osseous--lasts from the 18th up to the 21st day of embryogenesis. During this period structures of the spinal column cervical part acquire a definitive form, the cartilagenous tissue is substituted for the osseous one.     

Postnatal ontogeny of uridine kinase in the cerebellum,hypothalamus, and cerebral cortex of the rat

Postnatal developmental patterns of uridine kinase were determined in crude subcellular fractions of the rat cerebellum, hypothalamus and cerebral cortex at ages 3 through 60 days. The highest specific activity and predominant distribution of enzyme was in the 105,000g supernatant of the 3 brain regions. Enzyme activity in hypothalamus and cerebral cortex was maximum at 3 days and decreased with age; in cerebellum it increased through 13 days and decreased thereafter. Thus, the pattern of activity in hypothalamus and cerebral cortex paralleled changes in DNA and RNA synthesis through age 60 days; in cerebellum, it more closely approximated changes in DNA synthesis during early development. Changes inK _m with aging suggest that the brain regions contain more than one form of enzyme. The highest particulate activity was in the microsomal fraction of the cerebellum and hypothalamus at all ages and in the cortex at 35 and 60 days. Relative specific activity for microsomal fractions of the brain regions at 60 days indicate a concentration of the enzyme which may be relevant in the maintenance of RNA activity in adult brain.     

The developmental patterns of the cartilaginous elements in vertebrate ontogeny]

Comparative embryological data presented in the paper support an idea that chondrification of the mesenchyme does not begin until the latter becomes condensated. Size and density of the skeletogenous rudiments are not the same in different vertebrates. As a rule, in animals with much of the mesenchyme (chondrichthyans, amniotes), the prochondral condensations contain more cells and have both greater mass and density. The distribution pattern of the mesenchyme is also significant for the future development of the cartilaginous elements which at the earlier stages grow largely by the recruitment of surrounding mesenchymal cells. Such kind of the growth mode is probably most similar to the cartilage fusion mode: both processed take place in the absence of the perichondrium. The non-skeletal dense structures influence on the development of the cartilaginous skeleton primarily by determining distribution pattern of the mesenchyme, particularly the condensation of skeletogenous cells. THe growing cartilages themselves can influence mechanically on the surrounding organs.     

The kallikrein-kinin system in the rat hypothalamus

Summary High molecular weight kininogen (HKg) and T kininogen (TKg) were detected and localized by immunocytochemistry in adult rat hypothalamus. In addition, kininogens were measured by their direct radioimmunoassay (RIA) or by indirect estimation of kinins released after trypsin hydrolysis and high pressure liquid chromatography (HPLC) separation of bradykinin (BK) and T kinin. A specific HKg immunoreactivity demonstrated with antibodies directed against the light chain (LC) of HKg was colocated with SRIF in neurons of hypothalamic periventricular area (PVA) projecting to external zone (ZE) of median eminence (ME). Heavy chain (HC) immunoreactivity which could be related to HKg or to low molecular weight kininogen (LKg) was detected in some other systems: i) parvocellular neurons of suprachiasmatic (SCN) and arcuate nuclei containing SRIF, ii) magnocellular neurons (mostly oxytocinergic) of paraventricular (PVN) and supraoptic (SON) nuclei, iii) neurons of dorsomedian and lateral hypothalamic areas. TKg immunostaining was restricted to magnocellular neurons of PVN, SON, accessory nuclei (mostly vasopressinergic) and to parvocellular neurons of SCN (vasopressinergic). TKg projections are directed towards the internal zone (ZI) of ME, but very few immunoreactive terminals are detectable in neurohypophysis. TKg staining parallels with vasopressin during water deprivation, and is undetectable in homozygous Brattleboro rats. In some magnocellular neurons, TKg and HC (related to HKg or LKg) are coexpressed. TKg, was also detected in hypothalamus and cerebellum extracts by direct RIA, and BK and T kinin were identified after trypsin hydrolysis. HKg and LKg can act as precursor of BK which can play a physiological role as releasing factor, neuromodulator — neurotransmitter, — or modulator of local microcirculation in hypothalamus. The three kininogens are also potent thiolprotease inhibitors which could modulate both the maturation processes of peptidic hormones and their inactivation and catabolism.     

In vitro and in vivo effect of fluoxetine on the permeability of 3H-serotonin across rat intestine

The aim of this work was to characterize the mucosal-to-serosal (apical to basolateral; AP-BL) and serosal-to-mucosal (basolateral to apical; BL-AP) transport of serotonin (5-HT) across rat jejunum, ileum, and colon, and to determine the influence of serotonin neuronal transporter inhibitors on this transport. The AP-BL apparent permeability (Papp) of 3H-5-HT increased in the order colon = jejunum < ileum, and the BL-AP Papp of 3H-5-HT increased in the order colon < jejunum = ileum. In vitro, neither fluoxetine (0.02 or 0.2 micromol/L) nor desipramine (0.4 or 4 micromol/L) had a significant effect upon the AP-BL or BL-AP Papp of 3H-5-HT in any of the intestinal regions. However, fluoxetine (0.2 micromol/L) decreased the accumulation of 3H-5-HT in the ileum (to 65% of control) in the BL-AP experiments. In vivo, chronic fluoxetine (10 mg/kg daily administered orally for 15 days), as assessed in the ileum, significantly increased (to +/-180% of control levels) the BL-AP Papp of 3H-5-HT and tended to increase the AP-BL Papp of 3H-5-HT. In conclusion, the increase in the Papp of 3H-5-HT after chronic administration of fluoxetine suggests that this treatment is able to increase the extracellular concentration of 3H-5-HT at the intestinal level.     

Ethanol intake and 3H-serotonin uptake. II: A study in alcoholic patients using platelets 3H-paroxetine binding.

The kinetic parameters of 3H-paroxetine binding and 3H-serotonin uptake were studied in platelets of alcoholic patients. There was no difference between alcoholic and non alcoholic subjects in 3H-paroxetine binding. When binding and 3H-serotonin uptake were studied, in the same plasma of the same subjects, the Vmax of serotonin uptake was increased in alcoholics. The data confirm the involvement of serotonin uptake system in alcohol dependence and suggest that serotonin uptake and paroxetine binding sites may be regulated independently in this pathology.     

Morphofunctional characteristics of serotonin-like neurons in the hypothalamus of rats in ontogeny

An attempt has been made to reveal 5-HT immunopositive (IP) neurones in the hypothalamus of intact foetuses (18th day of gestation) and neonatal (9-day) rats under normal conditions and after their treatment with drugs involved into 5-HT metabolism or into regulation of its uptake by serotoninergic neurones. 5-HTIP cells were not observed in intact animals as well as after L-tryptophan treatment, whereas two large colonies of these neurones were found in the anterio-lateral hypothalamus and dorsomedial nucleus after subsequent injections of monoamine oxidase inhibitor, pargyline, and amino acid precursor of 5-HT synthesis, L-tryptophan. Significantly less intensive reaction was observed after injections of another precursor of 5-HT synthesis, 5-hydroxytryptophan, or pargyline only. Immunostaining evoked by pargyline or L-tryptophan can be prevented by preliminary injections of fluoxetine, a specific inhibitor of 5-HT uptake by serotoninergic neurones. These data suggest that the immunostaining of hypothalamic neurones is due to their capacity to take up specifically 5-HT from the environment rather than to its intraneuronal synthesis from L-tryptophan. However, 5-HT synthesis from 5-hydroxytryptophan in the same cells may also take place. The uptake of extracellular 5-HT by catecholaminergic neurones is absent, since nomifensine, a specific inhibitor of this uptake, does not affect immunostaining.     

Evolvement of systems of serotonin uptake in rat hypothalamus during its development]

Kinetics of 3H serotonin accumulation into slices from hypothalamus have been compared in adult, puppy and foetus rat. In 15 days-old, as in adult rat, there are two components of 5 HT accumulation corresponding to the low and high affinity transport systems. For this latter, Km and Vmax values are much higher in adult than in 15 days old rat (in adult, Km=1,3 X 10(-7) and Vmax=0,33 X 10(-10); in 15 days old rat, Km=0,5 X 10(-7) and Vmax=0,125 X 10(-10)). On the opposite, in the 7 days old rat and in the 21 days old foetus, it is only possible to arbitrarely define one uptake system corresponding to the following apparent values: in the 7 days old rat, Km= 5 X 10(-7) and Vmax=2 X 10(-10), in the foetus, Km=0,2 X 10(-7) and Vmax=0,15 X 10(-10). These results showed important developmental differences in affinity of 3H serotonin to hypothalamus. The low and high affinity uptake systems existing in adult are only individualized in the 15 days old little rat.     

The uptake of L-(methyl- 3 H) carnitine by the rat epididymis

The uptake of radioactivity by the epididymis and other tissues was measured following administration of L-[methyl-³H]carnitine to male rats. Rapid uptake occurred in both the caput and cauda epididymides. This radioactivity was shown to be present in carnitine and was located almost exclusively within the epididymal lumen.