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S Honma

Publications and source records attributed to S Honma.

At least 199 records · Page 11Linked to original sources
PubMed1987

[The regulation system of brain aromatase activity; distribution and changes with age of the aromatase activity of the rat brain].

Sexual differentiation of brain structure and function is dependent on the hormonal environment during perinatal life. Recently, some studies have found the greatest aromatase activity in brain areas associated with sexual differentiation and sexual behavior, namely the hypothalamic and limbic structures. We have characterized the developmental and anatomical patterns of aromatase of aromatase activity in brains of fetal, neonatal, infantile and adult rats of both sexes. Aromatase activities in slices of brain were assayed by measuring the amount of 3H2O formed during the conversion of [1 beta-3H] androstenedione to estrogen. We have demonstrated major changes of the aromatase activity in the brain with age. Aromatase activities of both sexes reached peak values in the hypothalamus-preoptic area (HPOA) at least 3 days before birth. Thereafter, the activities declined to 3 weeks after birth. We have found the greatest amount of aromatase activity in HPOA and amygdala of both sexes. Aromatase activities in HPOA and amygdala of neonatal male rat were higher than adult male rat. The hippocampus, thalamus, pituitary, cerebral cortex and cerebellum all contained negligible aromatase activity. And, we studied HPOA in detail, aromatase activities in preoptic area and anterior part of hypothalamus were twice higher than that in posterior part of hypothalamus. Aromatase activity reached peak values at the critical period of the sexual differentiation of the brain in HPOA and amygdala, associated with sexual behavior and sexual differentiation. We have reported that aromatase activity was regulated by androgen. We suggested that aromatization didn't occur effectively in female rat, owing to scarcity of androgen, which was activator and substrate of aromatase.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1987

Entrainment of human circadian rhythms by artificial bright light cycles.

Artificial bright light cycles (LD 8:16) of about 5000 lux during the light period were applied to two subjects in a temporal isolation unit, who had shown free-running circadian rhythms in sleep-wakefulness and rectal temperature. The circadian rhythms were successfully entrained by the artificial light cycle, but the phase relation of the rhythms to the light cycle was substantially different between the two subjects. The result indicated that the artificial bright lights are able to reset human circadian rhythms.

Adult↗
PubMed1987

The ventromedial hypothalamic nucleus is not essential for the prefeeding corticosterone peak in rats under restricted daily feeding.

The role of the ventromedial hypothalamic nucleus (VMH) in the generation of the prefeeding corticosterone peak was examined in rats under restricted daily feeding, under which daily meal supply was restricted to a fixed time in the early light period. Rats were lesioned in the VMH bilaterally and subjected to restricted daily feeding during two different post-operative phases and with two different durations of food presentation. A restricted feeding with free access to meal for 4 hr was imposed on the VMH-lesioned rats from 2 to 4 weeks after the lesion, when the daily food intake increased significantly (dynamic phase). The restricted feeding induced the prefeeding hormone peak in sham operated rats, but failed to develop it in the VMH-lesioned rats. On the other hand, the hormone peak appeared in the VMH-lesioned rats subjected to the feeding schedule from 8 to 10 weeks after the lesion, when the daily food intake was not different from the control (static phase). Moreover, the VMH-lesioned rats showed the hormone peak even in the dynamic phase when the access to meal was shortened to 1 hr. These results indicate that the VMH is not essential for the generation of the prefeeding corticosterone peak under restricted daily feeding, and suggest that a special metabolic state observed during the dynamic phase of VMH lesion prevents the development of the feeding-associated oscillation or its expression upon plasma corticosterone level.

Animals↗
PubMed1987

Activity rhythms in the circadian domain appear in suprachiasmatic nuclei lesioned rats given methamphetamine.

Female rats were lesioned in the suprachiasmatic nuclei (SCN) electrolytically and treated with methamphetamine. The SCN lesions abolished the circadian locomotor rhythm completely. When methamphetamine was administered in the drinking water, robust rhythmicities in locomotor activity appeared in the SCN lesioned rats, which did not entrain to the 24 hr light cycle. The period of the activity rhythm was dose-dependent; the lower the concentration of methamphetamine was, the shorter the period of the rhythm became. When rats were treated with 0.005% methamphetamine, the mean period was 26.4 hours. In addition, activity time (alpha) became shorter, rest time (rho) longer and alpha/rho ratio lower, when methamphetamine concentration was decreased. After methamphetamine withdrawal, the rhythmicity disappeared and locomotor activity became aperiodic again. When methamphetamine was administered continuously by means of an osmotic minipump, similar rhythmicities appeared in locomotor activity of the SCN lesioned rats. It is concluded that methamphetamine manifests an activity rhythm whose period is in the circadian range. The rhythmicity is independent of the SCN and is not entrained by the light-dark cycle.

Administration, Oral↗
PubMed1987

Phase setting of circadian locomotor rhythm of infant rats.

Postnatal phase setting of pup circadian rhythm by nursing mother was examined in rats by mother-pup exchange experiments. To know the effect of phase reversal of the nursing mother, pups were exchanged after birth so that a mother rat raised pups, half of which were born to her and the other half which came from a reversed mother, and activity onset and offset of pup locomotor rhythm were measured at weaning. Effects of litter size were also examined. Direct entrainment to light-dark cycles was excluded by blinding pups. In the unexchanged group, a strong positive correlation was detected between the phase of the circadian rhythm at weaning and the free-running period measured after weaning. The area covered by the 99% confidence interval of the regression line was used for the phase reference zone, and the circadian rhythm of an exchanged pup whose phase at weaning was located outside the reference zone was regarded as having been influenced by the nursing mother. The complete phase reversal occurred in two out of seven exchanged pups when litter size was relatively large (n = 5-7) and in 9 out of 11 when litter size was small (n = 2). It is concluded that the nursing mother rat is capable of phase setting the circadian locomotor rhythm of blinded pups. This maternal effect seems to be related to litter size.

Animals↗
PubMed1987

Restricted daily feeding during nursing period resets circadian locomotor rhythm of infant rats.

Phase setting of the circadian rhythm by restricted daily feeding (RF) was examined in rat pups. Feeding of virgin, pregnant, and nursing rats together with pups was restricted to 4 h at a fixed time of the day. Phases of the circadian rhythm developed in neonatally blinded pups were measured on the day of weaning to evaluate the effect of RF on phase setting. The activity onset and offset of the locomotor rhythm were used for the phase reference. In blinded pups born and raised under ad libitum feeding, the phase at weaning was a function of the free-running period measured after weaning and located in a narrow range (control zone). When RF was imposed from 2 wk prior to the conception (C) until weaning (3w), the pups phases were located outside the control zone and related to the feeding time. To identify the period in which the phase setting is effective, RF was imposed during 5 different periods (C-0w, C-1w, C-2w, 2-6w, and 3-6w). The circadian rhythm of all pups in the C-2w group and some in the C-1w was phase set, but those in other groups were not affected. It is concluded that RF imposed during the early nursing period is capable of phase setting the circadian system of blinded infant rats.

Activity Cycles↗
PubMed1987

The metabolism of roxatidine acetate hydrochloride in rat and dog liver homogenates.

The metabolites were identified by gas chromatography-mass spectrometry (GC-MS). When an equimolar mixture of roxatidine acetate hydrochloride and its deuterated compound, labeled with ten deuterium atoms in the piperidine ring, was incubated with the 9000 X g supernatant (S-9) fraction of either rat or dog liver homogenate, the oxygenated metabolites of the piperidine ring such as the 3-hydroxypiperidine derivative (M1) and the 2-oxopiperidine derivative (M2) were isolated from rats but M2 was not isolated from dogs. These results suggested that the species differences in the metabolism of the piperidine ring in vitro are similar to that in vivo. The deuterium isotope effect (H/D) was 1.34 for M1 and 1.47 for M2 in rats, while the value for M1 in dogs was 1.69. On the other hand, the formation of these oxidative metabolites was inhibited by carbon monoxide in incubations using hepatic microsomes, suggesting that the reaction was catalyzed by cytochromes P-450.

Animals↗
PubMed1986

[The regulation system of brain aromatase activity; effects of androgens on hypothalamic aromatase in the male rat].

Recently, some studies have found the greatest aromatase activity in brain areas associated with sexual differention and sexual behavior, namely the hypothalamic and limbic structures. We studied the regulation of aromatase activity in the hypothalamic area of male rats, using a sensitive in vitro assay which measures the amount of 3H2O formed by tissue homogenates during the conversion of [1 beta-3H] androstenedione to estrogen. After castration, hypothalamic aromatase activity was significantly decreased (P less than 0.01), and seminal vesicle (SV) and prostate (PR) weights were also significantly decreased (P less than 0.01). Castrated male rats were given testosterone (T), 5 alpha-dihydrotestosterone (DHT), 5 alpha-androstane-3 alpha, 17 beta-diol (A3 alpha), 5 alpha-androstane-3 beta and 17 beta-diol(A3 beta) in various doses (200-1000 micrograms/day) for 10 days, and were given 600 micrograms/day T, DHT, A3 alpha and A3 beta for various durations (1-10 days). We found that T, DHT and A3 alpha but not A3 beta reversed the effects of castration on the hypothalamic aromatase activity. The order of this reversible effect of androgens was as follows: T greater than or equal to DHT greater than A3 alpha. T, DHT, A3 alpha and A3 beta increased SV and PR weights, and the order of this effect was as follows: DHT greater than T greater than A3 alpha much greater than A3 beta. We administered the antiandrogen (flutamide) to intact male rats (8 mg/day for 6 days). Flutamide decreased hypothalamic aromatase activity at the same level as that of castrated rats. Likewise, administration of both flutamide and T to castrated rats blocked the T-induced increase in hypothalamic aromatase activity and accessory sexual organ weight. From these results, we suggest that T, DHT and A3 alpha regulated hypothalamic aromatase activity, that T was the most effective of the androgens, and that was different from peripheral androgen target organs.

Androgens↗
PubMed1986

Food ingestion is more important to plasma corticosterone dynamics than water intake in rats under restricted daily feeding.

The roles of food and/or water ingestion in the regulation of plasma corticosterone level were examined in rats under restricted daily feeding. When the time of food-pellets and water supply was restricted to 2 hours in the early light period (meal feeding) for 2 weeks, the corticosterone level increased prior to meal (prefeeding peak). A similar prefeeding hormone peak was observed when supply of food-pellets was restricted to 2 hours with free-access to water (food restriction). In contrast, when water supply was restricted to 2 hours with free-access to food-pellets (water restriction), the hormone level before water supply did not increase as much as that under meal feeding or food restriction. Shortening of an available time for water under water restriction or prolongation of the restriction schedule failed to elevate the hormone level furthermore. On the other hand, the high prefeeding corticosterone level before meal decreased subsequently to meal feeding (prandial fall), which was not observed when rats were kept fasting during the meal time. This prandial fall of the hormone level was not observed by water intake alone, and closely related to food-pellets ingestion. It is concluded that food ingestion is more important than water intake to the formation of the prefeeding corticosterone peak and to the prandial fall of the hormone level under restricted daily feeding.

Adrenocorticotropic Hormone↗
PubMed1986

Disorganization of the rat activity rhythm by chronic treatment with methamphetamine.

Remarkable changes in the circadian activity rhythm of rats were observed when they were chronically treated with methamphetamine dissolved in drinking water. The circadian rhythm was phase-delayed with respect to the light-dark (LD) cycle, and showed signs of relative coordination. In some rats, the circadian organization was disturbed and two activity components appeared, with one component free-running and the other entrained by the LD cycle. After methamphetamine withdrawal, these changes disappeared rapidly but there were transient periods of 2-3 days before establishment of a stable entrainment to the LD cycle. The changes in the circadian rhythm persisted even in constant darkness (DD). The period around 24 hr in DD was significantly shorter during methamphetamine treatment than after the drug withdrawal. These results indicate that neither alteration of the sensitivity to light nor lengthening of the intrinsic period is involved in the methamphetamine induced disorganization of the circadian rhythm. Possible mechanisms are discussed in terms of a multi-oscillatory system.

Animals↗
PubMed1986

Characterization of the prandial plasma corticosterone peak in the freely moving rat.

To characterize the prandial plasma corticosterone peak, three experiments were done on adult male Wistar rats: (1) the prandial hormone peak was followed at three different times of day, 0800 h, 1900 h, and 0100 h, in starved rats; (2) a 20% glucose solution was infused into the jugular vein or was given as a drinking solution after a 24-h starvation; (3) in order to determine the role of vagal proprioceptive inputs, the hormone peak was examined at two times of day, 0800 h and 0100 h, in starved vagotomized rats. The prandial hormone peak was more conspicuous at midnight than in the daytime. Exposure to food pellets without feeding failed to induce a hormone rise. The peak appeared after oral ingestion, but not after intravenous infusion, of glucose solution. Ingestion of water alone was without effect. The peak was not affected by bilateral vagotomy. Thus, as far as glucose as a metabolite is concerned, the possibility that glucose per se works directly on the brain or indirectly through glucoreceptors in the gut was excluded. Possible modes of action of glucose ingestion are discussed.

Animals↗
PubMed1986

Effects of methamphetamine on development of circadian rhythms in rats.

To determine the effect of continuous methamphetamine treatment on development of the circadian system, the daily courses of spontaneous locomotor activity and plasma corticosterone level were determined in infant rats. Methamphetamine was dissolved in drinking water at a concentration of 0.005%, and administered to rats from postnatal day 14. The circadian locomotor rhythm in methamphetamine treated rats was not significantly different from that in non-treated rats for the first 4 weeks of drug treatment. Then the rhythm began to show signs of relative coordination and finally split into two activity components. One component entrained to the light-dark cycle, whereas the other free-ran in spite of the light cycle. The rhythm of plasma corticosterone in the methamphetamine treated group was not different from that in the control group at 4 weeks after birth, but was significantly phase-delayed at 8 weeks. Splitting was not observed for the corticosterone rhythm. It is concluded that continuous administration of methamphetamine to infant rats affects the circadian rhythms for spontaneous locomotor activity and plasma corticosterone level. Possible mechanisms of methamphetamine effects were discussed in terms of the circadian system underlying these rhythms.

Administration, Oral↗
PubMed1986

Reactivity of two monoclonal antibodies (Troma 1 and CAM 5.2) on human tissue sections: analysis of their usefulness as a histological trophoblast marker in normal pregnancy and trophoblastic disease.

In normal and molar pregnancy, a morphological discrimination between nonvillous trophoblasts which lie scattered in the placental bed and surrounding maternal cells is considered to be difficult. We examined the reactivity of two monoclonal antibodies (Troma 1 and CAM 5.2) against cytokeratin by an immunoperoxidase technique and analyzed their usefulness as a histological trophoblast marker. Materials were taken from 42 uteri with normal pregnancy, 7 uteri with hydatidiform mole, 2 uteri with gestational choriocarcinoma, 1 fallopian tube with nongestational choriocarcinoma, 5 delivered term placentae of normal pregnancy, and 5 nongestational uteri. The reactivities of Troma 1 on frozen sections and those of CAM 5.2 on paraffin sections were identical. They reacted with surface epithelium and gland epithelium in the nongestational uterine corpus. In the implantation site of normal and molar pregnancy, they reacted with villous and nonvillous trophoblasts as well as endometrial gland epithelium. In gestational and nongestational choriocarcinoma, they reacted with carcinoma cells specifically. Since the histological detection of gland epithelium may not be difficult, it was concluded that the two antibodies were very beneficial as a histological marker for trophoblasts in normal pregnancy and trophoblastic disease.

Antibodies, Monoclonal↗
PubMed1986

[Reactivity of two monoclonal antibodies (Troma 1 and CAM 5.2) on tissue sections--as a histological trophoblast marker in normal pregnancy and trophoblastic disease].

In normal and molar pregnancy, non-villous trophoblasts which exist in the placental bed are thought to be difficult to be distinguished morphologically from the surrounding maternal cells. We examined the reactivities of two monoclonal antibodies (Troma 1 and CAM 5.2) by an immunoperoxidase technique and analyzed their usefulness as histological trophoblast markers. Materials were taken from 41 uteri of normal pregnancy, 7 uteri of hydatidiform mole, 2 uterine gestational choriocarcinoma, 1 tubal tissue of non-gestational choriocarcinoma and 5 non-gestational uteri. The reactivity of Troma 1 was observed on frozen sections and paraffin sections were employed in the analysis of CAM 5.2. The reactivities of these antibodies were the same. In nongestational tissue, they reacted with endometrial gland epithelia and endometrial covering epithelia. In placental bed of normal pregnancy, they reacted with villous and non-villous trophoblasts, besides endometrial gland epithelia. In molar sections, they reacted with gland epithelia, villous trophoblasts and also non-villous trophoblasts which proliferated towards maternal tissue. In choriocarcinoma, they reacted with carcinoma cells specifically. Since endometrial gland epithelia are easily identified histologically, it was concluded that these antibodies could work as histological trophoblast markers in normal pregnancy and trophoblastic disease.

Antibodies, Monoclonal↗
PubMed1986

[Studies on the interaction between trophoblastic invasion and maternal immune cell infiltration at the implantation site in early human pregnancy by means of double immunoperoxidase technic using monoclonal antibodies].

Interaction between trophoblastic invasion and maternal immune cell infiltration at the implantation sites in early human pregnancy was analyzed by means of a double immunoperoxidase technique using Troma-1, a rat monoclonal antibody, which recognizes trophoblastic cells and a set of mouse monoclonal antibodies to react with various immune cells. The results were as follows. The most prominent immune cells in the implantation sites were monocytes/macrophages, which were positive for HLA-DR. These cells were adjacent to trophoblastic cells which were infiltrating into the decidua basalis. It therefore appeared that these cells function as "antigen presenting cells" which recognize and present the processed fetal information to maternal T cells. A small number of cells with mature T cell markers were found to be infiltrating around the anchoring villi and the extra-villous trophoblastic cells in the decidua compacta. But a larger number of T cells were adjacent to the villi in the decidua spongiosa and the extra-villous trophoblastic cells invading the decidua spongiosa and the myometrium. These cells may therefore play a role in preventing trophoblastic cells from invading the myometrium in the implantation sites. A relatively large number of cells with E rosette receptors but without mature T cell markers were observed in the decidua basalis, but few were found in the myometrium, into which a larger number of mature T cells were infiltrating. The distribution of particular cells was similar to that of endometrial granulocytes studied in our laboratory. There were thus likely to be immune cells in humans equivalent to non-T granulated suppressor cells in mice, which have been shown to suppress the generation of cytotoxic T cells (Clark et al.).

Antibodies, Monoclonal↗