Reduced Luteinizing Hormone Induction Following Estrogen and Progesterone Priming in Female-to-Male Transsexuals.

Anatomical studies have suggested that one of the brain structures involved in gender identity is the bed nucleus of the stria terminalis, though this brain structure is probably not the only one to control gender identity. We hypothesized that, if this brain area also affected gonadotropin secretion in humans, transsexual individuals might produce different gonadotropin levels in response to exogenous stimulation. In the present study, we examined whether estrogen combined with progesterone might lead to a change in luteinizing hormone (LH) secretion in female-to-male (FTM) transsexual individuals. We studied female control subjects (n = 9), FTM transsexual subjects (n = 12), and male-to-female (MTF) transsexual subjects (n = 8). Ethinyl estradiol (50 µg/tablet) was administered orally, twice a day, for five consecutive days. After the first blood sampling, progesterone (12.5 mg) was injected intramuscularly. Plasma LH was measured with an immunoradiometric assay. The combination of estrogen and progesterone resulted in increased LH secretion in female control subjects and in MTF subjects, but this increase appeared to be attenuated in FTM transsexual subjects. In fact, the %LH response was significantly reduced in FTM subjects (P < 0.05), but not in MTF subjects (P > 0.5), compared to female control subjects. In addition, the peak time after progesterone injection was significantly delayed in FTM subjects (P < 0.05), but not in MTF subjects (P > 0.5), compared to female control subjects. We then compared subjects according to whether the combination of estrogen and progesterone had a positive (more than 200% increase) or negative (less than 200% increase) effect on LH secretion. A χ2 analysis revealed significantly different (P < 0.05) effects on LH secretion between female controls (positive n = 7, negative n = 2) and FTM transsexual subjects (positive n = 4, negative n = 8), but not between female controls and MTF transsexual subjects (positive n = 7, negative n = 1). Thus, LH secretion in response to estrogen- and progesterone priming was attenuated in FTM subjects, but not in MTF subjects, compared to control females. This finding suggested that the brain area related to gender identity in morphological studies might also be involved in the LH secretory response in humans. Thus, altered brain morphology might be correlated to altered function in FTM transsexuals.

Sex differences in feeding behavior in rats: the relationship with neuronal activation in the hypothalamus.

There is general agreement that the central nervous system in rodents differs between sexes due to the presence of gonadal steroid hormone during differentiation. Sex differences in feeding seem to occur among species, and responses to fasting (i.e., starvation), gonadal steroids (i.e., testosterone and estradiol), and diet (i.e., western-style diet) vary significantly between sexes. The hypothalamus is the center for controlling feeding behavior. We examined the activation of feeding-related peptides in neurons in the hypothalamus. Phosphorylation of cyclic AMP response element-binding protein (CREB) is a good marker for neural activation, as is the Fos antigen. Therefore, we predicted that sex differences in the activity of melanin-concentrating hormone (MCH) neurons would be associated with feeding behavior. We determined the response of MCH neurons to glucose in the lateral hypothalamic area (LHA) and our results suggested MCH neurons play an important role in sex differences in feeding behavior. In addition, fasting increased the number of orexin neurons harboring phosphorylated CREB in female rats (regardless of the estrous day), but not male rats. Glucose injection decreased the number of these neurons with phosphorylated CREB in fasted female rats. Finally, under normal spontaneous food intake, MCH neurons, but not orexin neurons, expressed phosphorylated CREB. These sex differences in response to fasting and glucose, as well as under normal conditions, suggest a vulnerability to metabolic challenges in females.

Expression of phosphorylated cyclic AMP response element-binding protein in melanin-concentrating hormone neurons and orexin neurons in male and female rats during ad-libitum feeding.

Using phosphorylated cyclic AMP response element-binding protein (pCREB) as a marker of neural activity, we previously suggested that orexin neurons and melanin-concentrating hormone (MCH) neurons play distinct roles in feeding behavior. In the present study, we examined the expression of pCREB during ad-libitum feeding; previously, only fasted animals were examined. MCH neurons, but not orexin neurons, expressed pCREB during spontaneous food intake. The induction of pCREB expression did not differ by sex, but attenuation seemed to occur faster in females than in males. On the basis of the results of the present study, we speculate that MCH neurons respond to nutrition-related feeding, but the feeding-related activity of orexin was not evident unless hunger was accompanied by stress, such as the stress caused by the absence of food in the case of fasting. Therefore, the desire to eat under normal conditions does not drive orexin neurons, but it does drive MCH neurons. We tested this hypothesis by examining the effects of consuming glucose or saccharin, a nonmetabolized sweetener, in fasted male and female rats. Glucose and saccharin were equally effective in reducing pCREB expression in the orexin neurons of female rats. In MCH neurons, glucose attenuated the expression of pCREB, but saccharin had no effect, irrespective of sex. Taken together, the results indicate that MCH and orexin peptides play physiologically distinct roles in feeding behavior.

Developmental trajectory of contextual learning and 24-h acetylcholine release in the hippocampus.

To determine the developmental trajectory of hippocampal function in rats, we examined 24-h changes in extracellular acetylcholine (ACh) levels and contextual learning performance. Extracellular ACh significantly correlated with spontaneous behavior, exhibiting a 24-h rhythm in juvenile (4-week-old), pubertal (6-week-old), and adult (9- to 12-week-old) rats. Although juveniles of both sexes exhibited low ACh levels, adult males had higher ACh levels than adult females. Moreover, juveniles exhibited much more spontaneous activity than adults when they showed equivalent ACh levels. Similarly, juveniles of both sexes exhibited relatively low contextual learning performance. Because contextual learning performance was significantly increased only in males, adult males exhibited better performance than adult females. We also observed a developmental relationship between contextual learning and ACh levels. Scopolamine pretreatment blocked contextual learning and interrupted the correlation. Since long-term scopolamine treatment after weaning impaired contextual learning in juveniles, the cholinergic input may participate in the development of hippocampus.

Phosphorylation of cAMP response element-binding protein in the extended amygdala of male rats is induced by novel environment and attenuated by estrous female-bedding.

OBJECTIVE: We examined whether female pheromone, which would be contained in female-soiled bedding, affected the expression of phosphorylated cAMP response element-binding protein-like (pCREB) immunoreactive cells in the extended amygdala. METHODS: Male rats were exposed to following conditions: maintained in their home cage (home cage group), or relocated to a cage containing clean bedding (clean-bedding exposed group), ovariectomized (OVX) rat-soiled bedding (OVX-bedding exposed group) or estrogen-treated OVX rat-soiled bedding (OVX+E2-bedding exposed group). Rats were sacrificed 10-20 min after exposure and brain sections were subject to immunocytochemical processing. RESULTS: In the medial subdivision of the bed nucleus of the stria terminalis (BST) and the central amygdala (CeA), the number of pCREB immunoreactive (pCREB-ir) cells in the clean-bedding exposed group was significantly larger than in the home cage group, while the number of pCREB-ir cells in the OVX+E2-bedding exposed group did not differ from that in the home cage group. The bedding soiled by OVX rats was less effective. No significant difference in the number of pCREB-ir cells was detected in the other regions of the extended amygdala among all groups. CONCLUSIONS: The present study suggests that the exposure of clean bedding to male rats induces the expression of pCREB-ir in the medial BST and the CeA; exposure to female pheromone attenuates this expression.

Sex-specific differences in pain response by dopamine in the bed nucleus of the stria terminalis in rats.

The formalin test for nociception shows characteristic sex differences in the pain response during the interphase period of the test. However, the mechanism underlying these differences remains unclear. We have recently reported the sex-specific involvement of the lateral subdivision of the bed nucleus of the stria terminalis (BSTL) in the formalin test in rats. Here, we evaluated whether sex-specific differences in the pain response were modulated by the dopamine system in the BSTL. We first examined the effects of injecting a dopamine D1 receptor agonist, dihydrexidine, or antagonist, SCH23390, into the BSTL on the formalin test. During the interphase of the formalin test, injection of the D1 receptor agonist exerted no effect in male or female rats. The antagonist significantly enhanced the nociceptive response in female rats but not in males, indicating a sex difference in the involvement of the dopamine system in the formalin test. Next, we examined the expression of dopamine D1 receptors in the BSTL. Immunohistochemical analysis showed that the dopamine D1 receptor was expressed in the BSTL in both sexes but showed stronger immunoreactivity in male rats than in females. These results suggest sex-specific differences in the formalin test in which the response of dopamine neurons projecting to the BSTL plays a role in attenuating pain in female rats.

Testosterone exposure during the critical period decreases corticotropin-releasing hormone-immunoreactive neurons in the bed nucleus of the stria terminalis of female rats.

We previously described sex differences in the number of corticotropin-releasing hormone-immunoreactive (CRH-ir) neurons in the dorsolateral division of the bed nucleus of the stria terminalis (BSTLD). Female rats were found to have more CRH neurons than male rats. We hypothesized that testosterone exposure during the critical period of sexual differentiation of the brain decreased the number of CRH-ir neurons in the hypothalamus, including the BSTLD and preoptic area. In the present study we confirm that testosterone exposure during the neonatal period results in changes to a variety of typical aspects of the female reproductive system, including estrous cyclicity as shown by virginal smear, the positive feedback effects of estrogen alone or combined with progesterone, luteinizing hormone secretions, and estrogen and progesterone-induced Fos expression in gonadotropin-releasing hormone neurons. The number of CRH-ir neurons in the preoptic area did not change, whereas CRH-ir neurons in the BSTLD significantly decreased in estrogen-primed ovariectomized rats exposed to testosterone during the neonatal period. These results suggest that the sexual differentiation of CRH neurons in the BSTLD is a result of testosterone exposure during the critical period and the BSTLD is more fragile than the preoptic area during sexual differentiation. Furthermore, sex differences in CRH in the preoptic area may not be caused by testosterone during this period.

Progesterone receptor immunoreactivity in the brains of ovariectomized aged rats.

We examined the induction of progesterone receptor-immunoreactive (PR-ir) cells by estrogen in the rat preoptic area and ventromedial hypothalamic nucleus. Ovariectomized young (3-month-old) and old (24-month-old) female rats were treated with estrogen or cholesterol for 4 days. Estrogen significantly increased PR-ir cells in the preoptic area and ventromedial hypothalamic nucleus in young rats. Cholesterol-treated old rats had very few PR-ir cells; estrogen treatment significantly increased the number of PR-ir cells in both the preoptic area and the ventromedial hypothalamic nucleus in old rats, although less than in young rats. Therefore, the ability of estrogen to induce PR immunoreactivity in the hypothalamus in ovariectomized rats is attenuated in old rats compared with young rats.

Formalin-induced nociceptive behavior and c-Fos expression in middle-aged female rats.

The impact of the estrous cycle on the nociceptive response in middle-aged female rats was assessed using the formalin test and c-Fos immunoreactivity as a marker of neural activation. Young (2-month-old) and middle-aged (11-month-old) rats were examined, dividing the middle-aged rats into two groups based on their estrous cycle: regular 4-day estrous cycle and irregular estrous cycle. The right hind paw was subcutaneously injected with 50microl of 2% formalin or saline as a control. Behavioral changes were observed for 1h. Cycling rats were used during proestrus. Middle-aged female rats had a significantly higher score for nociceptive behavior compared to young rats, irrespective of estrous cyclicity, which suggests that aging, not the ability to maintain estrous cyclicity, causes hypersensitivity to the formalin injection. Immunohistochemical analysis found that the brain response to formalin injection was also more sensitive in middle-aged rats than young rats; a significant increase in the number of c-Fos immunoreactive cells was found in the ventral portion of the lateral septum of middle-aged rats injected with formalin compared to young and middle-aged rats injected with saline, irrespective of estrous cyclicity. Based on these results, we conclude that the sensitivity to painful stimuli in middle-aged female rats, which are in a neuroendocrine state similar to pre- and peri-menopausal women, is associated with age and not affected by reproductive ability.

Age- and sex-specific changes in naloxone-induced luteinizing hormone secretion and Fos expression in gonadotropin-releasing hormone neurons of gonadectomized rats.

In the present study, we examined sex-specific changes in luteinizing hormone (LH) secretion and Fos expression in gonadotropin-releasing hormone (GnRH) neurons in response to naloxone in young (3 months old) and old (24 months old), gonadectomized male and female rats. We revealed by immunocytochemistry that, regardless of age and sex, naloxone significantly increased the number of GnRH neurons expressing Fos, which was associated with increased LH secretion. Additionally, although the magnitude of the increase in Fos-expressing GnRH neurons did not change in old males compared to young males, it was attenuated by almost half in old females compared to young females. LH levels decreased 60% in old males compared to young males and 15% in old females compared to young females. These results suggest LH secretion is impaired with age, but the ability of GnRH neurons to be stimulated by naloxone is preserved. However, the opioid-controlling mechanism is more fragile in females than males during aging.

Food availability affects orexin a/ hypocretin-1-induced inhibition of pulsatile luteinizing hormone secretion in female rats.

Orexin A/hypocretin-1 inhibits pulsatile luteinizing hormone (LH) secretion in female rats. In this study, we investigated whether this inhibition was tied to the fasting state, as suggested by our previous study. We first examined whether orexin A inhibited pulsatile LH secretion when food was available ad libitumduring blood sampling. Next, we investigated the effect of intravenous administration of glucose (400 mg/kg) or lactic acid (negative control; 400 mg/kg) on orexin A-induced inhibition of pulsatile LH secretion. We found that orexin A did not affect pulsatile LH secretion in the presence of food, although it increased feeding behavior. Injection of orexin A significantly inhibited pulsatile LH secretion when food was withheld during blood sampling (p < 0.05); this inhibitory effect was rapidly reversed by intravenous injection of glucose but not lactic acid. Because orexin A did not seem to affect pulsatile LH secretion when food was available ad libitum, we speculate that orexin A has an effect on LH secretion when orexin A-induced hunger is accompanied by stress, such as the absence of food. Furthermore, glucose as well as food may act as a satiety factor in gonadotropin-releasing hormone pulse generation.

The cAMP response element-binding protein in the bed nucleus of the stria terminalis modulates the formalin-induced pain behavior in the female rat.

Abstract Differences in male and female responses to pain are widely recognized in many species, including humans, but the cerebral mechanisms that generate these responses are unknown. Using the formalin test, we confirmed that proestrus female rats showed nociceptive behavior, modulated by estrogen that was distinct from male rats, particularly during the interphase period. We then explored the brain areas, which were involved in the female pattern of nociceptive behavior. We found that, after a formalin injection and at the time corresponding to the behavioral interphase, the number of phosphorylated cAMP response element-binding protein (pCREB)-immunoreactive neurons observed by immunocytochemistry increased in the dorsolateral division of the bed nucleus of the stria terminalis (BSTLD) in female but not male rats. There were no significant sex differences in pCREB expression following formalin in any region other than the BSTLD. The increased pCREB in female rats was eliminated after an ovariectomy and restored with 17beta-estradiol treatment. Neither an orchidectomy nor 17beta-estradiol treatment affected the pCREB response in male rats. The increase in pCREB expression in the BSTLD in female rats after formalin injection was confirmed with immunoblotting. To determine the role of CREB in the BSTLD, adenovirus-mediated expression of a dominant-negative form of CREB (mCREB) was carried out. The nociceptive behavior during interphase was significantly attenuated by injection of virus carrying mCREB into the BSTLD in female rats but not in male rats. These results suggest a novel role for CREB in the BSTLD as a modulator of the pain response in a female-specific, estrogen-dependent manner.

Sex differences in the responses of orexin neurons in the lateral hypothalamic area and feeding behavior to fasting.

Because there are sex differences in feeding-related behavior and orexin neurons are involved in feeding, we looked for a possible sex difference in the response of orexin neurons in the lateral hypothalamic area to fasting, using the phosphorylated cyclic AMP response element-binding protein (pCREB) as a marker of neural activity. Intact male and female rats at proestrus, estrus, or diestrus, were fed normally or fasted for 48h. After fasting, they were intravenously injected with saline or glucose and subjected to immunohistochemical processing for the detection of orexin and pCREB. In the rats fed normally and injected with saline, only a small population of orexin neurons expressed pCREB in both male and female rats. However, fasting increased the number of orexin neurons with pCREB (double-stained cells) in female rats regardless of the estrous day but not in male rats, revealing a significant sex difference in the response of orexin neurons to fasting. Glucose injection in fasted rats decreased the number of double-stained cells in female rats, and the magnitude of glucose-dependent decrease was greater at proestrus and estrus than at diestrus 2. We also found that female rats, but not male rats, showed an increase in total food intake after fasting (rebound feeding). We speculate that the demonstrated sex differences in the response of orexin neurons to fasting reflect the vulnerability of feeding mechanisms in females.

Sex-specific 24-h profile of extracellular serotonin levels in the medial prefrontal cortex.

The medial prefrontal cortex (mPFC) controls emotional responses in many species,receiving serotonergic innervation from the dorsal and median raphe nucleus (DRN and MRN). To examine the sex difference in 24-h profiles of extracellular serotonin (5HT) levels in the mPFC, an in vivo microdialysis study was performed using intact male, diestrous female, and proestrous female rats. Dialysates were automatically collected by a microdialysis probe from the mPFC every 30 min for more than 24 h under freely moving conditions. The levels of 5HT in dialysates were quantified by high performance liquid chromatography. Extracellular 5HT levels exhibited episodic changes in the mPFC of both sexes of rats, with both diestrous and proestrous females exhibiting a clear diurnal change;the 5HT levels were high during the dark phase, but low during the light phase. In contrast,male rats exhibited relatively high 5HT levels throughout the day without significant diurnal changes. At mathematically analyzed trough, males showed higher 5HT levels than diestrous or proestrous females. The overall 24-h 5HT levels in males were significantly greater than proestrous females, but were not different from diestrous females. Further,stereological methods were used to examine the number of tryptophan hydroxylase (TrpH),but no sex differences in the number of TrpH immunoreactive cells in the DRN and MRN were observed. These results suggest that sex and/or the gonadal steroid environment may affect the 24-h profile of extracellular 5HT in the mPFC of rats without changes in the number of 5HT neurons in the DRN and MRN.

Gonadal steroids maintain 24 h acetylcholine release in the hippocampus: organizational and activational effects in behaving rats.

Extracellular acetylcholine (ACh) levels in the dorsal hippocampus increases during learning or exploration, exhibiting a sex-specific 24 h release profile. To examine the activational effect of gonadal steroid hormones on the sex-specific ACh levels and its correlation with spontaneous locomotor activity, we observed these parameters simultaneously for 24 h. Gonadectomy severely attenuated the ACh levels, whereas the testosterone replacement in gonadectomized males or 17beta-estradiol replacement in gonadectomized females successfully restored the levels. 17beta-Estradiol-priming in gonadectomized males could not restore the ACh levels, and testosterone replacement in gonadectomized females failed to raise ACh levels to those seen in testosterone-primed gonadectomized males, revealing a sex-specific activational effect. Spontaneous locomotor activity was not changed in males by gonadectomy or the replacement of gonadal steroids, but 17beta-estradiol enhanced the activity in gonadectomized females. Gonadectomy severely reduced the correlation between ACh release and activity levels, but the testosterone replacement in gonadectomized males or 17beta-estradiol replacement in gonadectomized females successfully restored it. To further analyze the sex-specific effect of gonadal steroids, we examined the organizational effect of gonadal steroids on the ACh release in female rats. Neonatal testosterone or 17beta-estradiol treatment not only increased the ACh levels but also altered them to resemble male-specific ACh release properties without affecting levels of spontaneous locomotor activity. We conclude that the activational effects of gonadal steroids maintaining the ACh levels and the high correlation with spontaneous locomotor activity are sex-specific, and that the organizational effects of gonadal steroids suggest estrogen receptor-mediated masculinization of the septo-hippocampal cholinergic system.

Symptom prevalence and longitudinal follow-up in cancer outpatients receiving chemotherapy.

Palliative care for cancer patients receiving chemotherapy in the outpatient setting is important. The aims of this study were 1) to identify symptom prevalence and intensity in cancer patients receiving chemotherapy and 2) to describe longitudinal follow-up data obtained from repeated assessment using the distress thermometer (DT). Questionnaires were distributed to consecutive cancer outpatients newly starting chemotherapy at the first appointment and at every hospital visit. The questionnaire included the severity of 11 symptoms (M. D. Anderson Symptom Inventory [MDASI], Japanese version), the DT, and the need for help in four psychosocial areas (decision-making, economic problems, nutrition, and daily activities). In total, 4000 questionnaires were returned by 462 patients. The frequently identified problems were oral problems (21%), insomnia (19%), psychological distress (defined as a DT score of 6 or more; 15%), help with information and decision-making (14%), severe fatigue (8.2%), and severe appetite loss (6.3%). Cluster analysis identified four symptom clusters: 1) fatigue and somnolence; 2) pain, dyspnea, and numbness; 3) nausea, appetite loss, and constipation; and 4) psychological distress. Of 165 patients with a DT of score 6 or more, 115 patients (70%) demonstrated a DT score below 6 at a median of 17 days follow-up. In the remaining 50 patients who had a DT score of 6 or more at follow-up, 34 patients (68%) had one or more physical symptoms rated at 7 or more on an 11-point numeric rating scale. Compared with patients with a DT score below 6 at follow-up, patients with a DT score of 6 or more at follow-up had higher levels of all physical symptoms. Frequent symptoms experienced by cancer outpatients receiving chemotherapy may be categorized as: 1) psychosocial issues (insomnia, psychological distress, decision-making support); 2) nutrition-gastrointestinal issues (oral problems, appetite loss, nausea); 3) fatigue; and 4) pain, dyspnea, and numbness. Developing a systematic intervention program targeting these four areas is urgently required. The DT score may be highly influenced by coexisting physical symptoms, and future studies to develop an appropriate system to identify patients with psychiatric comorbidity are necessary.

Gonadal steroid hormones maintain the stress-induced acetylcholine release in the hippocampus: simultaneous measurements of the extracellular acetylcholine and serum corticosterone levels in the same subjects.

To examine the role of gonadal steroid hormones in the stress responses of acetylcholine (ACh) levels in the hippocampus and serum corticosterone levels, we observed these parameters simultaneously in intact, gonadectomized, or gonadectomized steroid-primed rats. In both sexes of rats, neither gonadectomy nor the replacement of gonadal steroid hormone affected the baseline levels of ACh. However, gonadectomy severely attenuated the stress response of ACh, whereas the replacement of corresponding gonadal hormone successfully restored the response to intact levels. The gonadal hormones affected the serum corticosterone levels in a different manner; the testosterone replacement in orchidectomized rats suppressed the baseline and the stress response of corticosterone levels, whereas the 17beta-estradiol replacement in ovariectomized rats increased the levels. We further found that letrozole or flutamide administration in intact male rats attenuated the stress response of ACh. In addition, flutamide treatment increased the baseline levels of corticosterone, whereas letrozole treatment attenuated the stress response of corticosterone. Moreover, we found a low positive correlation between the ACh levels and corticosterone levels, depending on the presence of gonadal steroid hormone. We conclude that: 1) gonadal steroid hormones maintain the stress response of ACh levels in the hippocampus, 2) the gonadal steroid hormone independently regulates the stress response of ACh in the hippocampus and serum corticosterone, and 3) the sex-specific action of gonadal hormone on the cholinergic stress response may suggest a neonatal sexual differentiation of the septohippocampal cholinergic system in rats.

Postpubertal feeding experience affects sex-specific spatial ability in rats.

We previously reported that feeding with powdered diet after weaning (3 weeks of age) enhanced spatial ability, and increased the amount of acetylcholine (ACh) released in the dorsal hippocampus in female rats. In the present study, to specify the time when feeding conditions caused these effects, a radial 8-arm maze task and an in vivo microdialysis study were performed in both sexes of rats. In rats fed standard laboratory diet (i.e., pelleted diet), males learned the radial 8-arm maze faster than females. Moreover, the ACh release showed a distinct diurnal rhythm which was high during the dark phase and low during the light phase, but males showed a greater amount of ACh released in the dorsal hippocampus than females. However, in rats fed powdered diet after 6 weeks of age, no significant sex differences were observed in the radial 8-arm maze task or in the amount of ACh released, since feeding with powdered diet enhanced spatial ability, and increased the amount of ACh released only in females. These results suggest that feeding conditions after 6 weeks of age may contribute to the sex difference in the spatial ability associated with the changes in the amount of ACh released in the dorsal hippocampus in rats.

Sex difference in the 24-h acetylcholine release profile in the premotor/supplementary motor area of behaving rats.

The sex differences in various motor functions suggest a sex-specific neural basis in the nonprimary or primary motor area. To examine the sex difference in the 24-h profile of acetylcholine (ACh) release in the rostral frontal cortex area 2 (rFr2), which is equivalent to the premotor/supplementary motor area in primates, we performed an in vivo microdialysis study in both sexes of rats fed pelleted or powdered diet. The dialysate was automatically collected from the rFr2 for 24 h under freely moving conditions. Moreover, the number of cholinergic neurons in the nucleus basalis magnocellularis (NBM) was examined. Further, to confirm the relation between ACh release in the rFr2 and motor function, the spontaneous locomotor activity was monitored for 24 h. Both sexes showed a distinct 24-h rhythm of ACh release, which was high during the dark phase and low during the light phase. Female rats, however, showed a greater ACh release and more cholinergic neurons in the NBM than male rats. Similarly, spontaneous locomotor activity also showed a 24-h rhythm, which paralleled the changes in ACh release in both sexes, and these changes were again greater in female rats than in male rats. In addition, feeding with powdered diet significantly increased the ACh release and spontaneous locomotor activity. The present study is the first to report the sex difference in the 24-h profile of ACh release in the rFr2 in rats. The sex specific ACh release in the rFr2 may partly contribute to the sex difference in motor function in rats.

Bisphenol A induces transforming growth factor-beta3 mRNA in the preoptic area: a cDNA expression array and Northern blot study.

To gain better understanding of the effects of bisphenol A (BPA) in the adult brain, a cDNA expression array was used to screen possible candidates for BPA-inducible genes in the medial preoptic area (MPOA). Adult ovariectomized rats were given a subcutaneous injection of 10 mg BPA or sesame oil alone as a control. Twenty-four hours after the injection, the MPOAs were dissected and total RNAs were extracted. When expression levels of cDNAs derived from pooled samples were compared to controls, the expression levels of some genes in BPA-injected rats appeared to be different from those in sesame oil-injected rats. Among the candidate genes, we focused on an increase in the expression of transforming growth factor (TGF)-beta3 mRNA. To quantify the change in TGF-beta3 mRNA by BPA, we examined the effects of 10 mg BPA (n=6), 1 microg 17beta-estradiol (n=6), or oil injection (n=6) on the expression of TGF-beta3 mRNA in the MPOA of ovariectomized rats by Northern blot. The TGF-beta3 mRNA level in the MPOA of BPA-injected rats was significantly increased compared to the level in oil-injected rats (p<0.05). Injection of 1 microg 17beta-estradiol did not have any significant effect. The results suggest that, in the adult female rat, BPA acts on the MPOA by altering the expression of the TGF-beta3 gene in a manner distinct from that of estrogen.