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M Najimi

Publications and source records attributed to M Najimi.

28 records · Page 2Linked to original sources
PubMed1991

Regional distribution of somatostatin binding sites in the human hypothalamus: a quantitative autoradiographic study.

Using in vitro quantitative autoradiography and [125I]Tyr0-D-Trp8SRIF 14 as radioligand, we characterized the detailed distribution of somatostatin binding sites in human hypothalamus of both infants and adults. Guanosine triphosphate pretreatment, before incubation, allowed us to detect higher [125I]Tyr0-D-Trp8SRIF 14 binding site densities in hypothalamic structures such as preoptic and anterior hypothalamic areas and ventromedial and dorsomedial nuclei. In contrast, guanosine triphosphate was without effect in the other hypothalamic regions. The regional effects of guanosine triphosphate pretreatment were not different in infant and adult hypothalamus. Scatchard analysis showed that in a guanosine triphosphate-sensitive region (preoptic area) and a guanosine triphosphate-insensitive area (infundibular nucleus), [125I]Tyr0-D-Trp8SRIF 14 bound to a single class of binding sites. Affinities were similar in both regions, not modified by guanosine triphosphate pretreatment and not different in the adult (1.5 +/- 1.2 nM vs 3.2 +/- 2.1 nM for preoptic area and infundibular nucleus, respectively) and infant (0.9 +/- 0.5 nM vs 2.4 +/- 1.7 nM for preoptic area and infundibular nucleus). [125I]Tyr0-D-Trp8SRIF 14 binding sites were widely distributed in the anterior, mediobasal and posterior hypothalamus. Somatostatin 28 was twice as potent as somatostatin 14 to displace [125I]Tyr0-D-Trp8SRIF 14 binding in the preoptic area and infundibular nucleus. However, IC50s were 30 times lower in the preoptic area as compared with the infundibular nucleus. In adult as well as in infant, high densities were found mainly in the diagonal band of Broca, preoptic area and infundibular nucleus. Intermediate densities were localized in the anterior hypothalamic area, ventromedial, dorsomedial and lateral mammillary nuclei. The dorsal hypothalamic area, the paraventricular and medial mammillary nuclei displayed low but measurable densities. The only marked difference in the distribution of [125I]Tyr0-D-Trp8SRIF 14 binding sites in adult vs infant was observed in the medial and tuberal nuclei where the concentrations were seven-fold higher in adult hypothalamus.

Adult↗
PubMed1991

Anatomical distribution of substance P-immunoreactive neurons in human brainstem during the first postnatal year.

The localization of substance P (SP)-immunoreactive structures in the infant brainstem was investigated by immunohistochemistry using the peroxidase antiperoxidase technique. SP-immunoreactive structures are widely distributed throughout the brainstem region. SP-immunoreactive cell bodies are prominent in the superior colliculis, the central grey, the nucleus tractus solitarius and the reticular formation. A high density of SP-immunoreactive fibers is found in the nucleus tractus solitarius, the trigeminal nucleus and the dorsal horn of the spinal cord. Large SP-immunoreactive fibers are seen in the substantia nigra. In the present study, we also investigated the development of substance P-immunoreactive fibers in the infant brainstem during the first postnatal year. We note a qualitative increase in the density of SP-immunoreactivity in some brainstem regions such as colliculus superior and substantia nigra with respect to age.

Aging↗
PubMed1990

Anatomical distribution of LHRH-immunoreactive neurons in the human infant hypothalamus and extrahypothalamic regions.

The morphological features and distribution of luteinizing hormone-releasing hormone (LHRH)-immunoreactive cell bodies and fibers of the hypothalamic and the neighboring mesencephalic regions were studied in the normal newborn infant by immunohistochemistry. Within the hypothalamus, numerous LHRH-immunoreactive like (IL) cell bodies were found mainly in the ventral portion of the infundibular nucleus close to the median eminence and at a lower extent in the medial preoptic area. In addition, sparse immunoreactive cell bodies were displayed in the paraventricular and medial mammillary nuclei. The mesencephalon also exhibited rare immunoreactive cell bodies in the periaqueductal gray. LHRH-IL fibers, predominantly varicose, formed a continuum from the septo-preoptico level to the mesencephalon. In the hypothalamus, the median eminence exhibited the highest LHRH innervation. LHRH-IL fibers are also observed in the lamina terminalis, the medial preoptic area, the suprachiasmatic, the supraoptic, the peri- and the paraventricular nuclei. In the last two nuclei, some fibers projected to the dorsomedial and ventromedial nuclei whereas others were in close relation with the ependyma. The mesencephalon displayed low LHRH-IL fibers, present essentially in the raphe and interpeduncular nuclei and around the ependyma. When compared with data obtained in other mammals, the present findings agree well with the general distribution and morphological features of LHRH-IL neuronal structures reported elsewhere.

Brain↗
PubMed1989

Immunohistochemical distribution of somatostatin in the infant hypothalamus.

Somatostatin (SS)-containing neurons were mapped in the normal infant hypothalamus with immunohistochemistry, using the peroxidase anti-peroxidase technique. Neurons displaying SS immunoreactivity show a widespread distribution throughout the hypothalamic region. Principal SS-immunoreactive like (SS-IL) perikarya are located in the paraventricular, infundibular and posterior nuclei and in the preoptic region. High SS innervation is also found in the ventromedial and in the lateral mammillary nuclei, and in the median eminence. In general this distribution of SS-IL agrees well with that reported for rat. Compared to the immunohistochemical distribution of SS in human adult hypothalamus, this mapping in the infant hypothalamus is grossly similar. However some differences may be underlined: the presence of a moderately dense group of SS-IL perikarya in the tuberal and posterior nuclei, and a dense innervation of the ventromedial nucleus and in the median eminence. This first detailed distribution of SS immunoreactivity in infant hypothalamus can provide basic knowledge for further studies of infant neuropathology.

Humans↗
PubMed1989

Anatomical distribution of somatostatin immunoreactivity in the infant brainstem.

The distribution of somatostatin-immunoreactive structures in the infant brainstem was investigated using the peroxidase-antiperoxidase technique. A wide distribution of somatostatin-immunoreactive cell bodies and fibers was observed throughout the brainstem. Numerous somatostatin-immunoreactive cell bodies and fibers were present in several areas of the brainstem including the substantia grisea centralis and the reticular formation. Some immunoreactive cell bodies were seen in cranial nerve nuclei such as the nucleus praepositus, the nucleus nervi hypoglossi and the vestibular nuclei. Immunoreactive fibers were seen in the nucleus cuneatus, the locus coeruleus, the nucleus tractus solitarius, the nucleus ambiguus, the nucleus tractus spinalis nervi trigemini and the dorsal horn of the spinal cord. These data were in agreement with previous works on the human adult. However, a high density of somatostatin-immunoreactive cell bodies and fibers in the interpeduncular nucleus and in the nucleus centralis superior, and a dense network of somatostatin-immunoreactive fibers in the dorsal part of the nucleus inferior olivarius, were also observed. The role of somatostatin in some brainstem nuclei and its probable implication in some specific neuropathological diseases of the infant brainstem is discussed.

Brain Stem↗
PubMed1989

[LHRH in the human hypothalamus. Immunohistochemical mapping in normal newborn infants or in sudden death infants].

The topographical distribution of neurons containing LHRH has been investigated in newborn hypothalamus using the peroxidase anti-peroxidase technique. In control subjects, LHRH immunoreactive (LHRH-IR) perikarya have been mainly observed essentially in the infundibular nucleus. The preoptic region displayed a moderate density of LHRH-IR cell bodies. High LHRH innervation was observed in the anterior hypothalamus in the lamina terminalis and in the mediobasal hypothalamus in the median eminence, and in the peri- and paraventricular regions. In sudden death infant syndrome, a comparable mapping was observed, except a low density in the mediobasal peri- and paraventricular areas.

Brain Mapping↗
PubMed1989

[Immunohistochemical absence of adrenergic neurons in the dorsal part of the solitary tract nucleus in sudden infant death].

The immunohistochemical distribution of TH and PNMT containing neuronal elements was investigated utilizing peroxidase anti-peroxidase methods in newborn control and sudden infant death syndrome (SIDS) brainstems. The TH immunoreactive neurons, within the medulla oblongata, displayed a similar distribution in both control and SIDS tissue. However, PNMT immunoreactive neurons seen in the dorsal part of the nucleus of tractus solitarius in control tissue were not observed in SIDS tissue. This alteration of adrenergic neurons in the dorsal part of NTS (region reported to be implicated in the control of blood pressure and respiration) could explain the cardiorespiratory disorders in SIDS.

Epinephrine↗
PubMedDate not supplied

Potentiation by propranolol of stress-induced changes in passive avoidance and open-field emergence tests in mice.

Noradrenergic and serotonergic systems are known to be stimulated during various forms of stress. The present study examined the effect of the beta-adrenergic serotonin1A receptor blocker propranolol on the ability of stress to elicit behavioral inhibition in mice. Mice were given the drug before immobilization or tube-restraint stress, and then were tested for either passive avoidance performance or time to emerge into an open field. Propranolol markedly potentiated stress-induced increases in latency in both of these tests, suggesting that it exacerbated reactions to stress. These results agree with previous data indicating that under certain conditions, propranolol can potentiate the effects of stress in rodents. The results support the hypothesis that the response of the noradrenergic and/or serotonergic systems to stress may have anxiolytic or antistress effects.

Animals↗
PubMedDate not supplied

Modulation of central GABAA receptor complex by somatostatin: a pharmacological study.

The goal of the present study was to determine the possible interactions between somatostatin (SST) and gamma-aminobutyric acid (GABA). We thus investigated the SST interaction with [35S]-tertiary butylbicyclophosphorothionate (TBPS) binding sites of the cortical and hippocampal regions of the rat brain. The method used to identify such effects is in vitro quantitative autoradiography. Thus, the binding of the cage convulsant [35S]-TBPS to a picrotoxin-sensitive site in the rat brain was used to investigate the modulatory action of SST on the GABAA receptor complex. The addition of the peptide to the incubation medium results in a dose-dependent inhibition of [35S]-TBPS in cortical and hippocampal structures. Detailed analysis showed a dose-related effect of SST with relative potencies comparable to those observed for 5 alpha 3 alpha P and 5 beta 3 alpha P. In addition, these neurosteroids were able to enhance the efficacy of SST in inhibiting [35S]-TBPS binding. The efficacy of SST in enhancing the inhibitory action of neurosteroids was also evidenced. Furthermore, SST seems to mimic the effects of these neurosteroids as well as GABA and picrotoxin on [35S]-TBPS binding to the rat brain in every context examined. This suggests that somatostatin allosterically modifies [35S]-TBPS binding through a mechanism similar to that of GABA. On the other hand, a possible action of SST via transduction systems on the GABAA receptor complex could also be suggested. These results illustrate the importance of interactions in SST-mediated GABA transmission in these brain regions.

Animals↗