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Background/Aims: Estrogen receptor-α (ERα) splice variants are important for understanding estrogen effects on the brain and estrogen therapy pitfalls. We addressed the question whether a novel ERα splice variant TADDI is expressed at the protein level in the human brain and whether it changes in relation to aging and Alzheimer’s disease (AD). Methods: Immunoreactivity (-ir) for TADDI was assessed on postmortem human brain material from a total of 116 cases. Results: The highest levels of this splice form were found in the hypothalamic supraoptic nucleus (SON), pontine nuclei, medulla oblongata, gray matter of the spinal cord, the hippocampus, glomeruli of the cerebellum, the nucleus basalis of Meynert (NBM), and the tuberomamillary nucleus (TMN). TADDI-ir was mainly confined to the cytoplasm but was also determined in the nuclei of hippocampal neurons from young patients. In the hippocampus, the NBM, and the TMN, TADDI-ir was higher in postmenopausal women than in women ≤50 years old. In these brain areas and in the SON, it was diminished in AD women. In the NBM of AD men, TADDI-ir was enhanced. Conclusion: Aging- and AD-related changes in TADDI-ir show that it should be considered for the sensitivity of the neural tissue to estrogen therapy.

Background/Aims: Depression occurs in 20–50% of the Alzheimer disease (AD) patients. It is not known whether depression in AD shares its pathophysiology with depressive disorder. Previously we found a fourfold increase of corticotropin-releasing hormone (CRH)-immunoreactive (IR) neurons in the hypothalamic paraventricular nucleus in depression. The objective of the present study was to find out whether in depression in AD the same phenomenon of an increased number of CRH-IR neurons could be observed. Methods: Post-mortem brain tissue was obtained from a cohort of 23 AD patients prospectively studied using the Cornell Scale for Depression in Dementia to measure depressive symptoms. The number of CRH-IR neurons was determined using immunocytochemistry and the Image Pro Plus analysis program. Results: A significant positive correlation was found between the Cornell scores and the number of CRH-IR neurons (p = 0.039) in AD patients. Conclusion: These results suggest that depressive disorder and depression in AD share, at least partly, their pathophysiology.

Dysfunction in water intake and metabolism has frequently been reported in schizophrenia. The general population of schizophrenics under neuroleptic treatment secretes lower amounts of vasopressin than controls at comparable values of plasma osmolality. The purpose of the present study was to investigate the synthetic activity of vasopressin neurons of the dorsolateral supraoptic nucleus in schizophrenia on postmortem material using a battery of histochemical activity markers. Our material consisted of formalin-fixed and paraffin-embedded hypothalami from 5 schizophrenic patients under neuroleptic treatment and from 5 matched controls, obtained from The Netherlands’ Brain Bank. DSM-III or DSM-IV criteria were used for the clinical diagnosis. The histochemical markers used to study the neuronal activity of the magnocellular vasopressin-synthesizing neurons were: cell size, size of the Golgi apparatus, and expression of vasopressin and tyrosine hydroxylase mRNA by in situ hybridization. Morphometric evaluation and statistical analysis (Mann-Whitney U test) were performed. Our results showed no statistically significant differences in any of the neuronal activity markers between schizophrenic patients and controls. Therefore, the neurosecretory activity of vasopressin neurons of the dorsolateral part of the supraoptic nucleus does not appear to be changed in schizophrenic patients under medication. Since our sample did not include patients with reported polydipsia or hyponatremia, prospective investigation is needed to evaluate the above-mentioned neuronal activity markers in such a particular subgroup of schizophrenic patients.

Previous studies indicated that in the human paraventricular nucleus (PVN) and in the supraoptic nucleus (SON) tyrosine hydroxylase (TH) – the first and rate-limiting enzyme in catecholamine synthesis – is localized mainly in magnocellular neurosecretory neurons. Individual differences were observed among control subjects in number and distribution of TH-immunoreactive (IR) perikarya, indicating that antemortem factors may regulate TH expression. Since a large number of TH-IR perikarya were observed in subjects who suffered from somatic illnesses leading to prolonged osmotic or nonosmotic stimulation of vasopressin (VP) release, we suggested that TH expression is related to the activation of VP neurons. The purpose of our study was to apply (1) in situ hybridization for TH mRNA on human PVN and SON to investigate how the previously reported individual differences in TH protein expression are depicted at the transcriptional level and (2) quantitative TH immunohistochemistry and in situ hybridization for VP mRNA throughout the dorsolateral part of the SON (dl-SON) in order to elucidate whether indeed expression of TH in neurosecretory nuclei depends on activation of VP neurons. Postmortem formalin-fixed, paraffin-embedded hypothalamic sections of 16 control subjects were studied for TH protein and TH and VP mRNAs. For 6 of the above cases, the number of TH-IR neurons and the total VP mRNA levels were estimated throughout the entire dl-SON using an image analysis system. Individual variation was observed in TH mRNA expression which appears to parallel the expression of TH-protein. Using Spearman’s bivariate test, a positive correlation was found between the number of TH-IR- and TH-mRNA-expressing neurons in both PVN and SON (p < 0.01) as well as between the number of TH-IR neurons and the total VP mRNA in the dl-SON (p < 0.05). Our results show (1) that the individual variability in the number of TH-IR neurons within the neurosecretory nuclei might be due to differential expression and/or stability of TH mRNA and (2) that expression of TH-immunoreactivity in human PVN and SON depends on the activation of VP neurons.

Our previous studies indicated that in the human para-ventricular (PVN) and supraoptic (SON) nuclei, tyrosine hydroxylase (TH) - the first and rate-limiting enzyme in catecholamine synthesis - is localized mainly in magnocellular neurons and that antemortem factors regulate its expression. The purpose of the present study was to investigate the distribution of TH-immunoreactive (TH-IR) perikarya of the hypothalami of a large sample of well-documented adult subjects without neurological, psychiatric or endocrinological disease in order to identify factors that could regulate the expression of TH in the human neurosecretory neurons. Our material consisted of the hypothalami of 38 subjects studied immunohistochemically for TH using the peroxidase-antiperoxidase method. Striking individual differences were observed among the subjects studied concerning the number and distribution of TH-IR perikarya within the PVN and SON. These differences were evident throughout the entire rostrocaudal length of the hypothalamus and appeared to be related neither to the age or sex of the subjects nor to the postmortem interval or staining procedures. In the sample studied, a large number of TH-IR perikarya were observed specifically in all subjects that had suffered from right-sided heart failure due to pulmonary hypertension, liver cirrhosis or dehydration. In all the above illnesses, increased production and secretion of vasopressin (VP) are reported to occur due to a decrease in 'effective' blood volume or to osmotic stimulation. We conclude that somatic illnesses leading to prolonged osmotic or nonosmotic stimulation of VP release may induce increased expression of TH immunoreactivity in the human neurosecretory neurons related to neuronal activation. Copyright (C) 2002 S. Karger AG, Basel

The suprachiasmatic nucleus (SCN) is the clock of the brain that orchestrates circadian and circannual biological rhythms, such as the rhythms of hormones, body temperature, sleep and mood. These rhythms are frequently disturbed in menopause and even more so in dementia and can be restored in postmenopausal women by sex hormone replacement therapy (SHRT). Although it seems clear, both from clinical and experimental studies, that sex hormones influence circadian rhythms, it is not known whether this is by a direct or an indirect effect on the SCN. Therefore, using immunocytochemistry in the present study, we investigated whether the human SCN expresses sex hormone receptors in 5 premenopausal women and 5 young men. SCN neurons appeared to contain estrogen receptor-α (ERα), estrogen receptor-β (ERβ) and progesterone receptors. Median ratings of ER immunoreactivity per individual and per gender group revealed a statistically significantly stronger nuclear ERα expression pattern in female SCN neurons (p < 0.05). No significant sexual dimorphic tendency was observed for nuclear ERβ (p > 0.1) and progesterone receptors (p > 0.7). These data seem to support previously reported functional and structural SCN differences in relation to sex and sexual orientation and indicate for the first time that estrogen and progesterone may act directly on neurons of the human biological clock. In addition, the present findings provide a potential neuroendocrine mechanism by which SHRT can act to improve or restore SCN-related rhythm disturbances, such as body temperature, sleep and mood.

Observations in experimental allergic encephalomyelitis (EAE), a model for multiple sclerosis (MS), have indicated that a low activity of the hypothalamo-pituitary-adrenal (HPA) system is accompanied by a high susceptibility for EAE in rat strains and that elevated corticosteroid levels are necessary for spontaneous recovery from EAE. The HPA axis activity is regulated by both corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP). Both types of neurons are localized in the paraventricular nucleus (PVN) of the hypothalamus. We determined the number of immunocytochemically identified CRH-immunoreactive (CRH-IR) and AVP-immunoreactive (AVP-IR) neurons in the PVN of the human hypothalamus of 8 MS patients, aged 34-63 years, and 8 age-matched control subjects without any primary neurological or psychiatric disorders, aged 30-59 years. In addition, the number of oxytocin (OXT) immunoreactive (OXT-IR) neurons was determined, since these neurons innervate brain stem nuclei and might thus be related to autonomic disturbances in MS. In MS the staining intensity for AVP was clearly lower and for OXT slightly lower. For CRH, the staining intensity was similar in both groups, and, moreover, in MS patients the number of CRH-IR cells in the PVN was found to be about 2.4 times higher than that in the control group. The number of OXT-IR or AVP-IR cells in the PVN of MS patients was not significantly different from that of the control group. Our results point to an activation of the neuroendocrine HPA axis which may be compatible with the idea that the HPA axis is involved in recovery from MS.(ABSTRACT TRUNCATED AT 250 WORDS)

We have studied the effects of gonadectomy and testoterone supplementation on the development of the vasopressin- and oxytocin-containing nucleus (VON) of the pig hypothalamus that shows a decrease in neuron number during the first weeks postnatally, followed by an increase during puberty. Neonatal gonadectomy caused a 2.5-fold increase in VON volume and neuron number in males and 3-fold in females at the age of 16 weeks, the onset of puberty. However, the difference between gonadectomized and nongonadectomized animals disappeared after puberty (38 weeks). Testosterone replacement from 16 weeks onwards induced a decrease in neuron number and volume of the VON. The present study indicates that the development of the VON is influenced by gonadal steroids although it seems improbable that these hormones affect the VON directly.

Tyrosine hydroxylase (TH), the first and limiting enzyme for catecholamine synthesis, has been identified immunohistochemically (IHC) in human neurosecretory neurons where it is found to colocalize with vasopressin (AVP) or oxytocin. TH expression shows striking interindividual variability and appears to depend on neuronal activation. Since GTP cyclohydrolase I (GCHI), the first enzyme for tetrahydrobiopterin synthesis, the essential cofactor of TH, and aromatic L-amino acid decarboxylase (AADC) have so far not been detected in neurosecretory neurons, the functional role of TH in catecholamine synthesis is still questionable. Our purpose was to investigate in postmortem hypothalamus whether GCHI and AADC mRNAs are co-expressed with TH in human AVP-synthesizing neurons. Total RNA was extracted from laser microdissected TH-IHC-identified neurons as well as from dissected parts of the dorsolateral supraoptic nucleus (dl-SON) of 12 control subjects, i.e. without known neurological, psychiatric or endocrinological illness. GCHI, AADC and TH mRNA expression was determined by real-time PCR. Our results showed that GCHI mRNA is co-expressed with TH in almost all cases that had a considerable number of TH-immunoreactive (TH-IR) neurosecretory neurons. A positive correlation was found between TH-immunohistochemical intensity and the presence of GCHI mRNA. AADC mRNA expression was detected only in microdissected areas of dl-SON in 2 cases that showed an increased number of TH-IR neurons. The co-expression of GCHI with TH indicates that TH is indeed active in human neurosecretory neurons. The apparent limited expression of AADC indicates that dopamine might be produced in human neurosecretory neurons under activation of the hypothalamoneurohypophyseal system, although the possibility that L-dopa is the final product cannot be excluded.

Previous studies have shown that the total number of corticotropin-releasing hormone (CRH)-stained neurons in the human hypothalamic paraventricular nucleus (PVN) increases with age. To determine whether this age-related change depends on gender and whether circulating sex hormones play a role, we analyzed the total number of CRH-immunoreactive neurons by means of immunocytochemistry and image analysis in the postmortem hypothalamic PVN of 22 control subjects (11 males and 11 females) between the ages of 22 and 89 years, and of 10 subjects with abnormal sex hormone status. Our data show that men have a significantly larger number of CRH neurons than women (p = 0.004) and that the total number of CRH neurons increases significantly with age, but only in male controls (p = 0.032), not in female controls (p = 0.733). Female controls do not show a significant change in the total number of CRH neurons either before or after the age (50 years) of menopause (p = 0.792). Male subjects with low testosterone levels due to castration showed significantly fewer CRH neurons than well-matched intact males (p = 0.008), while castrated male-to-female (M-F) transsexuals with estrogen replacement showed normal numbers of CRH neurons. One male case, who had high estrogen levels due to an estrogen-producing tumor, showed a large number of CRH neurons. Thus, although circulating androgens and estrogens both seem to play a stimulatory role with respect to CRH neurons, the age-dependent increase in the number of CRH neurons in the PVN of men, which has been interpreted to reflect activation of the CRH neurons with age, seems to result from factors other than age-related changes of circulating sex hormone levels.

The hypothalamo-pituitary-adrenal (HPA) axis is known to be activated in depressed patients. Although direct evidence is lacking, this activation is hypothesized to be due to hyperactivity of corticotropin-releasing hormone (CRH) neurons of the hypothalamic paraventricular nucleus (PVN). Recent immunocytochemical studies in experimental animals and in humans showed that the number of CRH-expressing neurons correlated with the activity of these neurons. In addition, colocalization of AVP in CRH neurons has been shown to be an index for the secretory activity. Therefore, we estimated the total number of CRH-immunoreactive neurons and their fraction showing colocalization with AVP in the PVN of 10 control subjects and of 6 depressed patients who were diagnosed to be suffering from a major depression or a bipolar disorder. The mean total number of CRH-expressing neurons of the 6 depressed patients was four times higher, and the number of CRH neurons co-expressing AVP was almost three times higher than those in the control group. We also determined the two activity parameters of CRH neurons in the PVN of 2 subjects with a depressive organic mood syndrome or a depressive disorder not otherwise specified. In these two 'non-major depressed' subjects, the activity parameters of CRH neurons were comparable to those of control subjects. Our observations strongly support the hypothesis that CRH neurons in the PVN are hyperactivated in major depressed patients. This hyperactivity might be causally related to at least part of the symptomatology of depression.

The present work deals with the relationship between gonadotropic hormones and neurosecretory activity. For this purpose, the oestrous cycle was studied during elevated vasopressin blood levels due to thirst. In addition, the neurosecretory activity in the magnocellular supraoptic and paraventricular nuclei (SON and PVN) was determined after administration of oestrogens and gonadotropic hormones. The parameter for neurosecretory activity in this investigation was the distribution of the Golgi-apparatus specific enzyme, thiamine diphosphate-phosphohydrolase (TPP-ase), as measured by a semi-quantitive histochemical method. During water deprivation, no increase in the amount of pro-oestrous and oestrous smears was found. After injection of oestrogens in ovariectomized rats, the neurosecretory activity decreased, while a reactivation was observed after gonadotropic hormone (HMG, HCG, NIH-LH, NIH-FSH) administration. This reactivation was not observed after prolactin (NIH) administration. The changes in neurosecretory activity found under conditions that cause alterations in the gonadotropic-hormone and oestrogen levels are, therefore, due to the influence of FSH and LH on the neurosecretory activity.

The neurosecretory activity in the magnocellular supra-optic and paraventricular nuclei (SON and PVN) of the rat was studied during the course of pregnancy, parturition, and lactation, during the oest