Androgen-concentrating cells in the periventricular brain of the female rhesus monkey.

Although androgens act on the primate central nervous system to modulate both endocrine functions and a number of limbic-related behaviors, little is known about the anatomical location of the neurons which sequester these steroids in primates. To determine the prime location of these androgen-concentrating neurons in the forebrain of the primate, we injected three castrated female rhesus monkeys in the femoral vein with 1 microgram of 5 alpha-dihydro (1,2,4,5,6,7-3H) testosterone (3H-DHT, 107 Ci/mmole) per kg of body weight. One of these animals also received an IV injection of 100 micrograms/kg body weight of unlabeled dihydrotestosterone (DHT) to serve as a control. One hour after the injection of 3H-DHT we rapidly exsanguinated each animal. The forebrain was sliced and blocks containing the amygdala, diencephalon, frontal pole, and hippocampus were frozen and stored in liquid nitrogen until processing. The tissue was then processed for autoradiography. A specific topographic pattern of nuclear concentration of DHT or one of its metabolites was obtained in neurons of the basal hypothalamus, preoptic region, amygdala, and hippocampus. This pattern was similar to that found in rodent species.

Afferents to the periaqueductal gray in the rat. A horseradish peroxidase study.

Afferent projections to the periaqueductal gray matter in the rat have been studied by use of the retrograde axonal transport of horseradish peroxidase. Iontophoretic injections of horseradish peroxidase were made in dorsal, lateral and medial areas of the periaqueductal gray, primarily at intercollicular levels. The pattern of projections was similar in all of the injections restricted to the periaqueductal gray. Within the brainstem, numerous reticular formation nuclei were labeled, including nucleus reticularis lateralis, nucleus raphe magnus, pallidus and obscurus, the nucleus reticularis pontis oralis and caudalis, the paralemniscal nucleus and the dorsal and ventral parabrachial nuclei. At diencephalic levels, dense projections were seen from the parafascicular nucleus, dorsal premamillary nucleus, zona incerta, dorsomedial and ventromedial nuclei of the hypothalamus and the retrochiasmatic area, in the ventral portion of the anterior hypothalamus. At forebrain levels, occasional cells were seen in the medial preoptic area, lateral septum and the anterior cingulate cortex. Control injections of horseradish peroxidase into structures adjacent to the periaqueductal gray matter included three well localized deposits in the dorsal raphe. Retrogradely-labeled cells were found in lateral reticular nucleus of the medulla, nucleus raphe magnus, nucleus reticularis pontis caudalis, locus ceruleus, dorsal and ventral parabrachial nuclei, substantia nigra and the lateral hypothalamus. No labeled cells were found in the habenular nuclei. It is suggested that many of the descending hypothalamic and forebrain afferents may be relay centers for descending hippocampal formation efferents. Many of the periaqueductal gray afferent systems receive a direct projection from the hippocampal formation and could therefore coordinate influences from this limbic center with information on homeostatic mechanisms controlled by the hypothalamus. The numerous brainstem afferents to the periaqueductal gray could be involved in relay of ascending sensory information important for initiating any of several behavioral responses known to be controlled by the periaqueductal gray. In addition, certain raphe afferents might play a part in a feedback loop of the pain suppression circuit of which the periaqueductal gray is an important component.

An animal model of corpus callosum impingement as seen in patients with normal pressure hydrocephalus.

RATIONALE AND OBJECTIVES: Callosal impingement has been postulated to cause the symptoms associated with normal pressure hydrocephalus. The authors developed an animal model for the investigation of corpus callosum impingement by the falx cerebri. METHODS: The corpus callosum was compressed from above by a plastic blade and surgically placed in the interhemispheric fissure in adult Sprague-Dawley rats. Magnetic resonance imaging (MRI) was performed both preoperatively and postoperatively. The brains of the rats also were examined grossly at the time of autopsy. RESULTS: All rats survived the surgical procedure. MRI proved to be a suitable method to image the corpus callosum, to confirm the location of the blade, and to demonstrate the corpus callosum impingement. MRI correlated well with necroscopy sections. CONCLUSIONS: It was possible to surgically produce callosal impingement in rats, and this impingement could be confirmed by MRI. In the future, this rat model of callosal impingement will be used to search for evidence of changes in metabolism, neuroelectrical activity, behavior, and neuronal anatomy which are known or are thought to be associated with hydrocephalus.

[3H]Nicotine binding sites in developing fetal brains in rats.

[3H]Nicotine binding sites were examined in developing fetal brains in rats. The fetal brain membranes bound [3H]nicotine with a similar affinity to that of adult brain membranes. This binding was displaced by unlabelled nicotine or carbamylcholine, the inhibition concentrations being approximately the same for fetal and adult brain preparations. alpha-Bungarotoxin had no effect on [3H]nicotine binding to fetal brain membranes as well as to adult brain preparations. The specific [3H]nicotine binding was first detectable on day 16 of gestation and it increased several folds until birth.

Ontogenesis of the GnRH neuron system in the rat. A quantitative immunohistochemical study with special reference to the extra cerebral GnRH-positive cells and the occupation of intracerebral termination fields.

The distribution of GnRH immunopositive cells in the rat was studied from day 13 of fetal life to day 10 of postnatal life with the aid of a GnRH antibody (H-16) generated against the decapeptide p-Glu1-LHRH in the rabbit and following a PAP immunohistochemical staining protocol on 70 um serial Vibratome sections. The first appearance of GnRH cells was observed simultaneously in both intra- and extra-cerebral regions on day 16 of fetal life. At all stages of development, at least 10 times more GnRH cells were found in the brain than in extracerebral areas. The population of GnRH cells was maximum in the nasal mucosa on day 20, and in intracranial, extracerebral regions (along the anterior cerebral artery and the terminal nerve) on day 22 of fetal life: it declined thereafter. The population of GnRH cells in the brain continued to increase until the day of birth and remained unchanged thereafter. Our findings are in accordance with the theory of nasal placodal origin of the GnRH neuronal system, but also suggest that in the rat, shifting of the cells from the nasal placode to the brain is somewhat preceding the onset of GnRH synthesis. Our other field of endeavor was to examine the GnRH axon terminal fields in the course of development. On day 18 of fetal life, the vascular organ of the lamina terminalis, the median eminence and the medial habenular nuclei received their GnRH axon terminals. On day 19 the subfornical organ, mammillary nuclei and the central nucleus of the amygdala, and on day 21 the periaqueductal gray and the interpeduncular nucleus became invaded by GnRH axons. These data serve the better understanding of the onset of the different functional activities of the GnRH system in the rat.

Hypothalamic dopamine may play a role in inducing prolactin in pituitary cells.

The effects of hypothalamic dopamine on the functional differentiation of prolactin cells was investigated in the developing rat brain. The treatment of pregnant rats with alpha-methyl-p-tyrosine (tyrosine hydroxylase inhibitor) resulted in a noticeable decrease of dopamine concentration in the hypothalamus at birth and at 5 days of age of offspring. Moreover, treatment with this regimen caused a marked decrease in the population of prolactin cells and in the production of prolactin at birth and at 5 days of age of offspring. It seems, then, that hypothalamic dopaminergic neurons precede the functional differentiation of prolactin cells in the developing brains and that hypothalamic dopamine may play an important role in producing prolactin in the anterior pituitary during development.

Effect of maternal nicotine on the development of sites for [(3)H]nicotine binding in the fetal brain.

The sites for [(3)H]nicotine binding in fetal brains were examined after administration of nicotine into pregnant rats. Administration of unlabelled nicotine into the pregnant rats increased Bmax values for the sites for [(3)H]nicotine binding without affecting Kd values in the fetal brains. Treatment with this regimen, however, did not show any significant change in the sites for [(3)H]quinuclidinyl benzylate (QNB) binding. In addition, treatment with this regimen increased Bmax values of the sites for [(3)H]nicotine binding in the brains of pregnant rats. α-Bungarotoxin had no effect on the sites for [(3)H]nicotine binding. It is inferred, therefore, that a similar response is elicited by nicotine binding sites to administered nicotine in both the fetal and maternal brains. Furthermore, a possible effect of nicotine in pregnant rats may be the facilitation of the development of nicotine acetylcholine receptors in the fetal brain.

Effect of exogenous dopamine on hypothalamic dopamine and norepinephrine concentrations in the neonatal brain in rats.

Hypothalamic dopamine (DA) and norepinephrine (NE) concentrations were studied in the neonatal rats after acute (postnatal day 4) or chronic (postnatal days 1-10) DA injections (0.5 mg in 5% dextrose in 0.45% saline). Acute injection of DA twice on postnatal day 4 resulted in an increase of hypothalamic DA and NE concentrations 16 hr later. Chronic treatment with the DA (twice in a day) for 10 days resulted in a reduction of NE concentration in the hypothalamus. The results of these studies suggest that the amount and duration of exposure to exogenous DA during postnatal development may result in divergent effects on hypothalamic catecholamine concentration.

Radioimmunoassay of 3 alpha-hydroxy-5 alpha-pregnan-20-one in rat and human plasma.

A radioimmunoassay for measuring 3 alpha-hydroxy-5 alpha-pregnan-20-one in plasma has been developed. Polyclonal antibodies were raised in rabbits against 3 alpha-hydroxy-20-oxo-5 alpha-pregnan-11 alpha-yl carboxymethyl ether coupled to bovine serum albumin. 3 alpha-Hydroxy-5 alpha-pregnan-20-one was purified from either extracts of plasma by high-performance liquid chromatography. These antibodies were then used for the radioimmunoassay of this centrally active progesterone metabolite in rat and human plasma. 3 alpha-Hydroxy-5 alpha-pregnan-20-one was detected in plasma from female rats on the day of estrus (2.0 to 9.3 ng/ml) and in the plasma of women during the luteal phase of the menstrual cycle at levels ranging from 0.25 to 2.5 ng/ml. The latter was highly correlated with plasma progesterone levels.

Evaluation of histopathologic changes in an animal model of mechanical corpus callosum impingement as seen in hydrocephalus.

RATIONALE AND OBJECTIVES: We evaluated histologic changes associated with chronic impingement of the corpus callosum. Similar callosal impingement has been postulated to be responsible for some of the symptoms in people who have hydrocephalus. METHODS: Eight rats with callosal impingement produced by surgical implantation of a blunt blade in the interhemispheric fissure and four control animals with no callosal impingement were evaluated by magnetic resonance (MR) imaging and by direct histologic evaluation after autopsy. The histologic evaluations occurred 1 month after surgery in half the animals and 6 months after surgery in the other half. RESULTS: MR imaging results showed that the implanted blade was in a good position in all animals. Histologically, the corpus callosum appeared normal 1 month after implantation of the impingement blade. Six months after surgery, the experimental group demonstrated decreased callosal thickness and a loss of axonal fibers in the corpus callosum both near and remote to the blade. CONCLUSION: Chronic impingement of the corpus callosum was associated with callosal thinning and by loss of callosal axons. Further research will be required to investigate the possible relation of these histologic findings to the clinical findings in normal-pressure hydrocephalus.

Effect of toki-shakuyaku-san on ovulation induced by human menopausal gonadotropin in rats.

One hundred and thirty-five immature female rats were treated with Toki-Shakuyaku-San (TSS:500 mg/kg, Bwt in drinking water) beginning at 25 days of age and continuing during experimental sessions. Fifteen IU of the human menopausal gonadotropin (hMG:Gonadoryl:GNR:GNR 4 contains 4 to 1 ratio of FSH and LH) was injected intraperitoneally on the morning of 28 days of age, and ovulation (presence of tubal ova) was examined on the morning of 29, 30 and 31 days of age. GNR 4 alone induced ovulation at 29 days of age (70%) and at 30 days of age (35%); however, no ovulation was observed at 31 days of age. TSS treatment alone causes 30% to ovulate at 31 days of age. When GNR 4 was combined with TSS treatment, animals demonstrated ovulation at 31 days of age, that is, they ovulated at 29 days of age (93%), at 30 days of age (30%) and at 31 days of age (90%). These results infer that TSS treatment may accelerate the chain of events in the neuroendocrine control on ovulation, thus causing more frequent ovulation in rats.

Direct ovulatory response with human menopausal gonadotropin of FSH/LH ratio 4 to 1.

The experiment was designed to examine if human menopausal gonadotropin (Gonadoryl, GNR, Mochida, Tokyo) influences the ovary and induces ovulation. When fifteen I.U. of GNR 4 (the ratio of FSH to LH is 4 to 1) was given on 28 days of age to immature female rats, ovulation was observed within 24 hours. Neither administration of GNR 1.6 (FSH to LH ratio is 1.6 to 1) nor GNR 3.1 (FSH to LH ratio is 3.1 to 1) induced ovulation. Administration of sodium pentobarbital (Nembutal) on the afternoon in GNR 4 treated rats did not block ovulation. It infers that GNR 4 acts on the ovary directly and induces ovulation within 24 hours.

Neuroendocrine effect of toki-shakuyaku-san on ovulation in rats.

In this study, the experiments were designed to examine if Toki-Shakuyaku-San (TSS) has a neuroendocrine effect on ovulation. TSS (500 mg/kg Bwt in drinking water) was given to Sprague Dawley immature female rats on 25 days of age and during experimental sessions. Fifteen IU of the hMG (Gonadoryl 4; GNR 4) was injected intraperitoneally on the morning of 28 days of age, and ovulation occurred in 70% of rats on the following day. In TSS drinking immature female rats, administration of GNR 4 on 28 days of age results in ovulation twice: once on 29 days of age and again on 31 days of age. Administration of sodium pentobarbital (Nembutal) at 12:30 p.m. on 28 days of age did not block the first ovulation on 29 days of age, but administration at 12:30 p.m. on 30 days of age blocked the second ovulation on 31 days of age. However, delayed ovulation was observed on 32 days of age. This evidence indicates that GNR 4 acts on the ovary directly and induces first ovulation in TSS treated rats. However, TSS treatment modulates the chain of events in the neuroendocrine control of ovulation and results in the second ovulation.

Estrogen in cognetive behaviors--clinical application of estrogen for dementia of Alzheimer type.

We may assume the presence of specific neuron elements in the region between the optic chiasma and the paraventricular nuclei, which are sensitive to estrogen and may be inhibited (or excited) by the estrogen level of the blood and in turn regulate (increase or decrease) the secretion of gonadotropin.

[Experience of multimodal therapy for advanced neuroblastoma].

The prognosis of advanced neuroblastoma is extremely poor. We treated 5 patients with advanced neuroblastoma, older than 3 years, with multimodal therapy including intraoperative irradiation and autologous bone marrow transplantation. Elevated serum NSE and ferritin level and unfavorable histology according to the Shimadas histological classification, all of which are indicators of poor prognosis, were found in all of them. N-myc oncogene was amplified in 3 cases. After preoperative intensive induction chemotherapy, delayed primary operation and intraoperative irradiation (10-15 Gy) were performed. The postoperative lethal dose chemotherapy and total body irradiation (33 Gy x 3 days) were followed by autologous bone marrow transplantation. Tumor cells were purged using immunomagnetic beads method. Two cases showed recurrence (brain; 1, bone and bone marrow; 1) and a metastatic brain tumor was extirpated completely. All of them are alive during the follow up period from 6mo. to 4y8mo. (mean; 2y5mo.) with no evidence of disease except one. It may be concluded that our multimodal therapy is effective in achieving better results for advanced neuroblastoma.