Immunohistochemical distribution of somatostatin in the infant hypothalamus
M. Najimi 1, F. Chigr 1, P. Leduque 2, D. Jordan 1, Y. Charnay 2, J.A. Chayvialle 3, M. Tohyama 4 and N. Kopp 1
l Laboratoire d'Anatomie Pathologique, FacultO de MOdecine Alexis Carrel, Lyon (France), 2C.N.R.S. UA 559, Laboramire d'Histologie-Embryologie, FaculM de M~decine Lyon-Sud, Oullins (France), 31. N. S. E. R.M. U45, Pavillon Hbis, H6pital Edouard Herriot, Lyon (France)and 4Department of Neuroanatomy, Institute of Higher Nervous Activity, Osaka University Medical School,
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 tfiroughout 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 hypotha[amus, this mapping in the infant hypothalamus is grossly similar. However some differences may be underlined: the presence of a moderately dense group of SS-tL 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.
INTRODUCTION
It is well establ ished that of the whole mammal ian
brain, the hypothalamus comprises the highest con-
centra t ion of the te t radecapept ide somatostat in (SS- 14) 11"17"28"36"39"43. Several immunohis tochemical
studies in the rat show that this pept ide is widespread in all hypothalamic regions 1"7"2°'2z-25"33-35"37"44-46.
Since then, the existence of o ther forms of somato-
statin, such as the N-terminal ex tended somatostat in
28(1-12) and somatostat in 28 have been repor ted 2
3.47 Previous immunohis tochemical studies have
shown that these two forms are present in the same cell bodies and fibers 14"41.
As far as the human is concerned, the setting of
somatosta t in immunoreact ive like (SS-IL) neurons
appears at the 16th week of the fetal life as repor ted by Bugnon et al. ~2'13. In adults, Bouras et al. 1°
r epor ted prosomatos ta t in der ived- immunoreact ive
like cell bodies and fibers in the preopt ic region, the
paraventr icular , supraopt ic , ven t romedia l and mam-
millary nuclei and in the median eminence. How-
ever, to our knowledge no reports describe the SS-IL
per ikarya and fibers in the human infant.
According to previous studies in rat , it has been
suggested that the medial preopt ic area (e.g. the
periventr icular preopt ic area and preopt ic part of
suprachiasmatic nucleus) may be involved in the
regulat ion of growth hormone (GH) secret ion 49. On
the other hand, o ther studies have repor ted that the
inhibiting control of G H release may be assumed by
SS-IL neurons in the medial preopt ic area as shown
by immunohis tochemical studies 61. Therefore , since
the role played by G H in infant growth is impor tant ,
the aim of the present study was to give detai led
mapping of the normal infant hypothalamic SS-IL
structures by the peroxidase-ant iperoxidase method.
Correspondence: M. Najimi, Laboratoire d'Anatomie Pathologique, Facult6 de Mddecine Alexis Carrel, 69008 Lyon, France.
The 4 hypothalami used for this immunohistoche- mical study were obtained from Edouard Herriot hospital (Lyon, France). The donors were male infants aged 26, 30, 40 and 60 days. None of them presented any sign of neurological or endocrinolog- ical disease. The post mortem autopsy delays prior to fixation were respectively 6, 8, 10 and 12 h.
Fixation was achieved after autopsy by perfusion through the carotid, at a pressure of 0.5 m of water, with first 200 ml of saline buffer and then 1.5-2 liters of 4% paraformaldehyde in 0.1 M phosphate buffer at pH 7.4. The saline and paraformaldehyde solu- tions were perfused at room temperature during approximately 30 min. Then, the hypothalamic region was dissected and immersed in the same fixative for 6-10 days at 4 °C. Following one week immersion in 20% sucrose at 4 °C, the samples were frozen in liquid nitrogen, and cut with a cryostat into
20/~m-thick coronal sections. Finally, the sections were mounted on chrome alum gelatin-coated slides and stored frozen at -20 °C.
Somatostatin antisera In this study 3 different antisera were used,
ries) and anti-SS 14 (M. Tohyama). The first antiserum recognized the N-terminal part of SS-28 and SS-28 (1-12) but not SS-14 and has been thoroughly tested and described in detail elsewhere. The second antiserum cross-reacted with SS-14 and 8S-28 (15-28) 14. The immunohistochemical controls consisted of: first, the omission of the specific antiserum or its substitution by non-immune serum gave no positive reaction; second, each antiserum used reacted only with its homologous peptide (1 ktM) and produced the same results preabsorbed or not with other peptides tested such as neurotensin, vasoactive intestinal peptide, fl-endorphin, cholecys- tokinin-8 and substance P (peptides concentrations
20/zM). Of the SS antisera tested, the SS-28 (1-12) was chosen for the mapping of SS in the infant hypothalamus.
Immunohistochemical procedures In this study, the sections were processed by the
peroxidase-antiperoxidase (PAP) technique 5s with
minor modifications: (1) pretreatment of the sec- tions with 0.1% hydrogen peroxide for 20 min at room temperature to inhibit the endogenous perox- idase, and (2) addition of 0.5% of nickel ammonium sulfate to the final color developing solution. This increases the sensitivity. Primary antisera: anti- SS-28(1-12) and anti-SS-28 were used at a titer of 1:4000. Neighbouring sections were stained with the Cresyl violet technique to delineate the hypotha- lamic structures. Black and white microphotographs were taken with an Ilford FP4 and a Kodak TRI X films on a Leitz microscope.
Presentation of results The distribution of SS-IL structures is shown in
schematic drawings of rostro-caudal coronal sections (Fig. 1A-M). These drawings are based on an unpublished atlas of human hypothalamus made in our laboratory. Each SS-IL cell group containing 5-8 cells per section is indicated by a star; medium-sized dots indicate the second population fiber type (large fibers) and small dots indicate the abundant first population type (thin fibers). We have attempted to grade the density of SS-IL cell bodies and that of SS-IL fibers belonging to the first population. Cell bodies: 4-6 cells (low density); 7-11 cells (moderate density); 12-20 cells (higher density) and more than 20 cells (very high density). Fibers: 4+: very dense group; 3+: dense group; 2+: moderately dense group and 1 + : low dense group. The cell bodies with diameter below 15 ktm are termed small, with 15-25 ltm are termed medium and over 25 ktm are termed large.
Fig. 1. Atlas of topographical distribution of SS-immunoreactive perikarya and fibers in the human infant hypothalamus. The atlas consists of rostral to caudal coronal 20-ym sections. A-F: sections throughout the anterior hypothalamus. G-L: sections throughout the mediobasal hypothalamus. M: section throughout the posterior hypothalamus. , , Cell bodies; e o e , large fibers; J-, thin fibers.
207
41 ~ 2~
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3V
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208
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Fig. 2. These microphotographs show a variety of neuronal cell bodies which demonstrate SS-LL and were observed in various hypothalamic regions, a: a low dense group of SS-IL neurons in the suprachiasmatic nucleus, b: a bipolar SS-IL neuron in the paraventricular nucleus, c: two SS-immunoreactive neurons in the posterior hypothalamic area. Bars for a - c = 40 ~m.
RESULTS
In infant hypothalamus the relative staining of cell bodies and fibers is similar with the 3 antisera. In addition, no noticeable differences are found in the mapping of SS-28(1-12), SS-28 and SS-14.
occurring in moderately dense groups are observed in the rostro-posterior part of this area (Fig. 1A-C). The immunoreactive cells appear oval, medium- sized with 2 or 3 immunoreactive processes (Fig. 6b).
Lateral preoptic area. This region exhibits a relatively large number of immunoreactive medium- sized and oval perikarya (Fig. 1A-C). More cau- dally, the cell bodies extend laterally in the medial preoptic area (Fig. 1B,C).
Supraoptic nucleus. No immunostaining is present in the principal part: the dorso-medial part. In contrast, we observe a low density number of medium-sized cell bodies in the dorso-lateral part, some of them exhibiting two or more immunoreac- tive processes (Figs. 1D,E and 4a).
Suprachiasmatic nucleus. A low density of immu- noreactive medium-sized and fusiform cell bodies is observed without immunoreactive processes (Figs. 1D,E; 2a and 4b).
Paraventricular nucleus. An important very dense group of small- and medium-sized unipolar and multipolar immunoreactive neuronal cell bodies (Figs. 2b and 3) is seen principally in the parvocel- lular part of the paraventricular nucleus (Fig. 1D-J), whereas scattered positive large cells are present in the magnocellular part. In addition, at the end of the mediobasal level, few oval or fusiform small-sized SS-IL perikarya are scattered in the rostro-caudal extent (Fig. 1D-J).
Anterior area of hypothalarnus. Scattered me-
Fig. 3. Light microscopic montage of the paraventricular nucleus, PAP method. Numerous SS-positive cell bodies (arrows) and moderate ly dense group of SS-positive fibers (arrowheads) are seen. Bar = 100 ~m.
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209
210
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Fig, 4. Different morphology of SS-IL perikarya, PAP method, a: multipolar neuron in the supraoptic nucleus, b: perikarya with apparently no immunoreactive processes in the suprachiasmatic nucleus, c: small bipolar perikarya in the tuberal nuclei, d: medium-sized bipolar neuron in the dorsomedial nucleus. Bars for a -d = 20 pm.
211
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a Fig. 5. a: lmmunoreact ive cell bodies in the infundibular nucleus, b: a dense group of SS-positive cell bodies in the lateral mammil lary nucleus, c: SS-positive large fibers in the medial preoptic area. d: some SS-IL cell bodies in the tuberomammil lary nucleus. Bars for a - d = 20 ~tm.
212
dium-sized immunoreactive perikarya with oval and
rounded shape are mainly observed in the rostral
and periventricular portions.
Mediobasal hypothalamus Dorsomedial nucleus. A low density group of
immunoreactive cell bodies is found in this region
(Figs. 1J and 4d). These structures are medium-sized and generally display 2 or 3 positive processes. Since
the morphological studies cannot delineate precisely
the anatomical limits between the ventromedial nucleus and the dorsomedial nucleus 42, some immu-
noreactive neurons present in the ventral part of the dorsomedial nucleus may be taken as the dorsal part
of the ventromedial nucleus.
Ventromedial nucleus. Very few immunoreactive
cell bodies are detected in the nucleus (Fig. 7).
Infundibular nucleus. A dense group of medium- sized oval, fusiform and immunoreactive cell bodies is shown in the rostral part of the nucleus (Figs. 1F, G
and 5a). The cell bodies are unipolar or multipolar.
Some immunoreactive elements of this neuronal
population seem to extend dorsally around the
ventro-caudal part of the ventromedial nucleus. At the caudal level, the density of immunoreactive
perikarya decreases (Fig. 1F-K).
Tuberal nuclei. The medial tuberal and the lateral tuberal nuclei display a dense to moderately dense
group of small-sized immunoreactive cell bodies particularly in its ventral and medial parts with one
or two immunoreactive processes (Figs. 1J,K and
4c). Caudally, only the medial tuberal nucleus
contains a low density of SS-IL perikarya (Fig. 1L) which may extend laterally in the ventral part of the tuberomammillary nucleus.
Tuberomammillary nucleus. A low density of
small- to medium-sized SS-containing perikarya is
observed in the tuberomammillary nucleus, princi- pally in the dorsal part. The positive cells are generally unipolar (Figs. 1J -L and 5d).
Posterior hypothalamus Posterior hypothalamic area; a moderately dense
group of positive medium-sized perikarya is distrib-
uted in the area (Fig. 1M). These cell bodies display
one or two immunoreactive processes (Fig. 2c). The
positive cells are numerous in the ventral part of the area surrounding the dorsal part of the mammillary
nucleus. More dorsally, only some immunoreactive perikarya are scattered and extend into the mesen-
cephalon.
Lateral hypothalamus Small- and medium-sized immunoreactive neuro-
nal cell bodies occurring in dense groups are present
at the anterior hypothalamic level and at the rostral
part of the mediobasal level of the lateral hypotha- lamic area (Fig. 1E-G) . In the ventral and medial
parts, the positive neurons are unipolar. Caudally,
the positive neurons are small-sized and form a low dense group. More caudally at the posterior hypo-
thalamic level, there are no stained cells (Fig.
1K-M).
Immunostained fibers
Immunostained varicose fiber processes show a
widespread distribution throughout the hypothala- mus. In general, they present two varieties: one with
a small diameter (thin) abundant in the entire
hypothalamus, and a second population type with a large diameter (Fig. 8), only abundant in the
anterior hypothalamus.
Anterior hypothalamus The medial preoptic area displays dense patches
of SS-IL fibers; rostrally they are thin (Figs. 1A,B
and 6b) whereas in the caudal portion they are
mostly large (Figs. 1C,D, 5c and 8) and seem to be continuous with small patches of the same fibers present in the lateral preoptic area (Figs. 1D and
6d). This last area also contains a few immunoreac-
Fig. 6. Distribution of SS-IR fibers, PAP method, a: a densely structured group of immunoreactive fibers surrounding blood vessels, in the median eminence. Bar = 50 ¢tm. b: moderate density of SS-positive fibers in the anterior part of the preoptic medial area. Bar = 100 ktm. c: some scattered fibers in the suprachiasmatic nucleus. Bar = 30 jzm. d: a dense network of SS-positive fibers in the lateral preoptic area. Bar = 40 ¢tm. e: an important group of SS-positive in the ventromedial nucleus. Bar = 50/~m. f: a fine varicose fiber in the caudal part of the lateral hypothalamus. Bar = 30 ktm.
Fig. 7. Light microscopic montage of the ventromedial nucleus, PAP method. The dense network of SS-IL fibers covers all the nucleus, note the presence of few cell bodies (arrow). Bar = 45/~m.
• %
j ~
iP
e ~
Fig. 8. High magnification of a large fiber in the medial preoptic area. Bar = 20/~m.
215
tive thin fibers (Fig. 1A-D).
The suprachiasmatic and supraoptic nuclei display rare immunoreactive fibers (Figs. 1D,E and 6c). In the paraventricular nucleus, the SS-IL fibers form a moderately dense cluster distributed homogeneously in the magnocellular and the parvocellular parts
(Figs. 1D-J and 3). In contrast the anterior hypo- thalamic area displays a dense network of large immunoreactive fibers (Figs. 1E and 6d). These fibers are concentrated in the dorsal portion of the area. This group extends dorsally and laterally and surrounds the fornix (Fig. 1E). The density of the immunostained fibers tends to decrease in the rostrocaudal direction. Laterally the staining seems to be continuous with a patch of stained fibers in the
lateral hypothalamic area (Fig. 1E). The small-sized fibers form a moderate density and are present essentially in the ventral part (Fig. 1E,F).
Mediobasal hypothalamus A few immunoreactive fibers are distributed in
the dorsomedial nucleus (Fig. 1G-J) , contrasting with the immunostained pattern of the ventromedial nucleus which exhibits a high density of immuno- stained fibers (Figs. 1G-J , 6e and 7). These fibers are distributed homogeneously throughout the nu- cleus (Fig. 7). This dense group seems to extend into the infundibular and tuberal nuclei ventrally and in the dorsomedial nucleus dorsally (Fig. 1G-J). A moderately dense group of SS-IL fibers is distributed throughout the infundibular nucleus (Fig. 1G-K). The fibers become more dense near the median eminence. A low dense group of immunoreactive fibers is distributed in the tuberolateral and medial lateral nuclei (Fig. 1J,K). Dorsally, there are few fibers which extend laterally in the tubero mammil- lary nucleus which, as the last nuclei, displays low
dense SS-IL fibers (Fig. 1J,K). The median emi- nence displays a very dense group of SS-IL fibers (Fig. 1G,H). The very dense network is present in the external layer where the fibers are concentrated mostly near the blood vessels (Fig. 6a).
Posterior hypothalamus The principal mammillary part, i.e. the medial
mammillary nucleus, does not exhibit any immuno- reactive fibers. In contrast, the lateral mammillary nucleus exhibits a dense to moderately dense group
216
of SS-IL fibers mainly in the ventral part (Figs. 1M and 5b). Dorsally, the fibers are less numerous and extend laterally in the posterior hypothalamic area. This last area displays a dense group of immuno- reactive fibers localized principally in the ventral part, while dorsally, there are only a few positive fibers. Ventrally the positive fibers seem to extend into the lateral mammillary nucleus, and dorsally in the mesencephalon (Fig. 1M).
Lateral hypothalamus The lateral hypothalamic area displays at the
anterior hypothalamic level, the two varieties of immunoreactive fibers which occur in dense patches (Fig. 1E,F). At the mediobasal level, the small-sized immunoreactive fibers form a moderate dense patch- like pattern (Fig. 1J,K). More caudally, only a few scattered positive fibers are seen (Fig. 6 0 .
DISCUSSION
The present study provides the first detailed atlas of the location of SS-immunoreactive cell bodies and fibers in the infant hypothalamus. The majority of immunohistochemical studies in human brain meets the difficulty of delineating precisely the anatomical regions where the immunostaining is present. Hu- man brain atlases are mostly based on myelin stains so that nuclear structures and other areas are not well delineated. Often, interspecies comparisons are made reducing credibility. In our case, parallel to the immunohistochemical study, a histological atlas us- ing Cresyl violet technique to delineate different structures such as nuclei (groups of perikarya) and
areas between nuclei of the human hypothalamus was made (unpublished). This gives our immuno- histochemical results more precision than other immunohistochemical studies on human hypothala- m u s .
It is important to note that immunohistochemical investigations in the human brain are limited by the post mortem delay prior to fixation and by the impossibility of using treatments which can enhance the intensity of the staining such as colchicine
treatment. Concerning the post mortem delay, in this report, 4 cases with different post mortem delay were used (6-12 h). The staining is not only preserved in the case of the higher post mortem
delay but it is generally similar in intensity in all 4 cases, suggesting that moderate differences in post mortem delay do not noticeably modify immuno- histochemical data on the distribution of SS in the infant hypothalamus. Moreover radioimmuno- assays w'56 show that SS can be remarkably stable in
human brains (and especially in the human hypo- thalamus) with no change and loss of immunoreac- tivity 36 or 48 h after death.
In the present study, the distribution of SS- containing neuronal elements, respects the anatom-
ical limits of nuclei and areas. In addition, our immunohistochemical findings show that both SS-IL cell bodies and fibers have a widespread distribution throughout the infant hypothalamus. The anterior hypothalamic part contains the highest density of immunoreactive cell bodies. Most of them are concentrated in the paraventricular nucleus. The magnocells of the supraoptic and the paraventricular nuclei display few or rare immunostained perikarya.
Concerning the distribution of SS-IL fibers, the mediobasal hypothalamus including the ventrome- dial nucleus and the median eminence, exhibits the highest SS-IL fiber density.
As shown by our work, a variety of large-sized fibers are present essentially in the anterior hypo- thalamus. This morphological type of fiber has been shown to display immunoreactivity for substance P in rat and human pallidal areas 4"29 and for SS in the
human septal area z6. The authors have used the term
'woolly-fiber networks' as termed originally by Haber and Nauta 3°.
Several radioimmunological studies have reported the distribution and concentration of SS in the main human hypothalamic nuclei and areas 2g'39. The
highest concentrations are observed in the entire mediobasal hypothalamus: infundibular nucleus and ventromedial nucleus. A relatively high concentra- tion of SS is observed in the lateral hypothalamus, paraventricular nucleus, posterior hypothalamus and dorsomedial nuclei. Mammillary nuclei display the lowest concentration of SS. Our immunohistoche- mical data are in good agreement with the radioim- munoassay reports.
The present description of the immunohistoche- mical distribution is in general in agreement with previous immunohistochemical studies relating the distribution of SS in human hypothalamus. For
example, Bouras et al. in adult 1° and Bugnon et al. in human fetus 12"13 describe immunoreactive cell bodies in the paraventricular nucleus, in the su-
praoptic nucleus and periventricular area and immu- noreactive fibers in the median eminence. The majority of the results of Bouras et al. "~ are confirmed in the present study emphasizing the presence of immunoreactive somatostatin-containing cell bodies in the suprachiasmatic, supraoptic and infundibular nuclei and in the lateral hypothalamic area and immunostained fibers, in the mammillary bodies, in the anterior part of the hypothalamus and in the median eminence. However these authors report a medium density in the paraventricular nucleus contrasting with our findings showing a high density localized principally in the parvocellular part. The present study also demonstrates the presence of a moderate density of SS-IL perikarya in the infundibular and the posterior nuclei, whereas Bouras et al. reported only scattered immunoreac- tive cell bodies. With regard to the SS-IL fibers, their report in the adult does not describe a very dense immunoreactive fiber network in the ventro- medial nucleus nor the very dense somatostatinergic innervation in the median eminence. They also
report a low density of immunoreactive fibers in the mammillary bodies without specifying which mam- millary nuclei are stained. The differences between
our data and these other studies could be explained by the technical methods or the antibodies used. It should be noted that differences could be explained by age differences since it has been reported that SS may function specifically in the development of various systems 3~38. This could explain why certain
SS structures are immunoreactive in neonatal but not in adult human hypothalamus as shown in neonatal and adult rats 31"52"53-55. This has also been
reported for the distribution of neurotensin in human newborn infant and adult 5°.
Recently, several groups have mapped the distri- bution of SS receptors in the adult human and primate brains 6"48. In general terms, there is a good
correlation between the distribution of SS receptors and the distribution of the endogenous SS detected by immunohistochemistry in the human hypothala- mus. This relative correlation supports the possible presence of intrinsic circuits of SS in the hypothal-
amus.
217
In recent years, several groups have mapped the distribution of SS-containing neurons in the rat hypothalamus using immunohistochemical tech-
niques similar to those employed in the present study 24"25"33"6°. The distribution of SS-IL neurons in
the infant hypothalamus presents some similarity to that reported in rat but considerable species differ-
ences are observed. With regard to cell bodies, in contrast to our findings, some authors 33 have re-
ported that the ventromedial nucleus contains a high density of SS-IL perikarya. The present study dem- onstrates a moderate density of SS-containing cell
profiles and fibers in the posterior hypothalamic nucleus and moderately dense fibers in the lateral mammillary nucleus; these were not reported in rat by Johansson et al. 33. Finally, the presence of a dense network of SS-positive fibers in the rat suprachiasmatic nucleus 33 was not seen in the infant
hypothalamus. Fiber connections between the hypothalamic nu-
clei groups and areas and other brain regions have not been well described especially in the human brain. Inagaki et al. 32 in experimental immunohisto- chemical studies have shown that knife-cut lesion operations made just rostral and caudal to the
ventromedial nucleus and sagittal cuts just lateral to this nucleus did not cause any reduction of SS in it. So, they have postulated that the somatostatinergic
fibers present in this hypothalamic nucleus can originate from SS-IL perikarya intrinsic to or in areas adjacent to the nucleus. Thus, the few SS-IR perikarya present within the confines of the ventro- medial nucleus of the infant hypothalamus and the more numerous perikarya located outside its limits (dorsal pole, in contact of the dorsomedial nucleus) could possibly, as mentioned for the rat 32, be the
source of at least a part of the SS-IL fibers of this
nucleus. On the other hand, other experimental studies in rat have reported that amygdaloid lesions produce a 50% reduction of SS in the ventromedial nucleus 5"51. This somatostatinergic pathway was con-
firmed recently by a study using a technique com- bining immunohistochemistry with retrograde axo- nal transport 4°. This study supports that this nucleus is probably a major target of the amygdaloid SS-IL projections. Also previous immunohistochemical studies and lesion experiments in rats have shown that rostral deafferentation of the paraventricular
218
nucleus causes disappearance of SS in fibers in the median eminence TM accompanied by a decrease of SS
in the median eminence. This supports the existence
of a descending SS-containing pathway from the anterior periventricular hypothalamic area to the
median eminence. Our immunohistochemical stud-
ies are in good agreement with the previous reports
and can p!ead for the existence of these somatosta- tinergic pathways in human.
The localization of SS perikarya in several nuclei
and areas, where a multitude of neurotransmitters,
neuromodulators and neuropeptides are present, can lead to the possible relationship between SS and the
other compounds. Such interactions would be all the more interesting as the SS neurons of the paraven- tricular nucleus, known to contain oxytocin 19'21, vasopressin 19'21, catecholamines 27"57 and substance P
(SP) 9, could be under oxytocinergic, vasopressiner-
gic, catecholaminergic or sPergic control. The pres- ence of all these neurosubstances in the paraventric-
ular nucleus calls up the possibility of the coexistence
of SS with other substances in the same neurons.
Our immunohistochemical data show that SS
perikarya and fibers are located in some interesting
areas of the hypothalamus that have been implicated by physiological studies in the neuronal control of
thermoregulation. These areas include the anterior
area of hypothalamus known to be implicated in the
ABBREVIATIONS
AA AC CP DBH DBV DM F FF I LT LH LM LP ME
Anterior hypothalamic area Anterior commissure Cerebral peduncle Diagonal band horizontalis Diagonal band verticalis Dorsomedial nucleus Fornix Field of Forel Infundibular nucleus Lateral tuberal nucleus Lateral hypothalamic area Lateral mammillary nucleus Lateral preoptic area Median eminence
control of thermoregulation in rat 8"16. On the other
hand, the possibility that SS plays a major role in
control of feeding and satiety is strengthened by the
localization of immunoreactive fibers in the lateral hypothalamic area and ventromedial nucleus, the feeding and satiety control centers 59.
In conclusion, we bring evidence for the presence of SS-IL elements in the newborn infant hypothal-
amus not reported in adult, and provide useful basic
knowledge for further studies of the newborn infant
neuropathology (i.e. Sudden Infant Death Syn- drome). On the other hand, the present report
confirms that immunohistochemistry provides a sen-
sitive and precise method for the localization of SS
neurons in the human hypothalamus and in general
terms, in the human brain.
ACKNOWLEDGEMENTS
This work was supported by grants from
I.N,S.E.R.M. no. 876013 and from Biologic Hu-
maine no. 925-358. The authors would like to thank
P. Gilly and Drs. R. Bouvier, P. Rebau and S. Gallet for efficient help in obtaining human tissue samples.
We would also like to thank Ms. C. Eymin for her assistance and Drs. J. Champier, L. Leger and L.
Paut for comments and stimulating discussions.
MES Mesencephalon MM Medial mammillary nucleus MP Medial preoptic area MT Medial tuberal nucleus OC Optic chiasma ON Optic nerve OT Optic tract PH Posterior hypothalamic area PV Paraventricular nucleus Sc Suprachiasmatic nucleus SO Supraoptic nucleus TM Tuberomammillary nucleus VM Ventromedial nucleus ZI Zona incerta 3V Third ventricle
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