[Lamellar complex changes in the human basal forebrain and hypothalamic nuclei neurons in different age groups].

In the present study the lamellar complex (LC, Golgi complex) changes in the major cholinergic nuclei of the human basal forebrain - the nucleus basalis of Meynert (NBM), the vertical nucleus of the diagonal band of Broca (VDB) and hypothalamus--the tuberomamillary (TMN), the medial mammillary (MMN) and supraoptic (SON) nuclei were analyzed considering the WHO aging classification. The increase in the size of the LC was present in NBM, MMN and SON in the 3rd age group of elderly people (60-74 years of age), in the VDB--in the 4th group (75-89 years of age), whereas in the TMN LC changes were not apparent. In conclusion, the WHO aging classification reflects the LC values age ranges and can be used to estimate age-related alterations of this parameter. The increase in the size of the neuronal LC in elderly people may represent the compensatory reaction of neuroplasticity triggered by the aging process.

Colocalization of kisspeptin and gonadotropin-releasing hormone in the ovine brain.

Kisspeptin is a peptide that has been implicated in the regulation of GnRH cells in the brain. Immunohistochemical studies were undertaken to examine the distribution of kisspeptin-immunoreactive (IR) cells in the ovine diencephalon and determine the effect of ovariectomy in the ewe. We report that kisspeptin colocalizes to a high proportion of GnRH-IR cells in the preoptic area, which is a novel finding. A high level of colocalization of kisspeptin and GnRH was also seen in varicose neuronal fibers within the external, neurosecretory zone of the median eminence. Apart from the kisspeptin/GnRH cells, a population of single-labeling kisspeptin-IR cells was also observed in the preoptic area. Within the hypothalamus, kisspeptin-IR cells were found predominantly in the arcuate nucleus, and there was an increase in the number of immunohistochemically identified cell within this nucleus after ovariectomy. Kisspeptin-IR cells were also found in the periventricular nucleus of the hypothalamus, but the number observed was similar in gonad-intact and ovariectomized ewes. The colocalization of GnRH and kisspeptin within cells of the preoptic area and GnRH neurosecretory terminals of the median eminence suggests that the two peptides might be cosecreted into the hypophyseal portal blood to act on the pituitary gland. Effects of ovariectomy on the non-GnRH, Kisspeptin-IR cells of the hypothalamus suggest that kisspeptin production is negatively regulated by ovarian steroids.

Estrogen receptor-alpha distribution in the human hypothalamus in relation to sex and endocrine status.

The present study reports the first systematic rostrocaudal distribution of estrogen receptor-alpha immunoreactivity (ERalpha-ir) in the human hypothalamus and its adjacent areas in young adults. Postmortem material taken from 10 subjects (five male and five female), between 20 and 39 years of age, was investigated. In addition, three age-matched subjects with abnormal levels of estrogens were studied: a castrated, estrogen-treated 50-year-old male-to-female transsexual (T1), a 31-year-old man with an estrogen-producing tumor (S2), and an ovariectomized 46-year-old woman (S8). A strong sex difference, with more nuclear ERalpha-ir in women, was observed rostrally in the diagonal band of Broca and caudally in the medial mamillary nucleus. Less robust sex differences were observed in other brain areas, with more intense nuclear ERalpha-ir in men, e.g., in the sexually dimorphic nucleus of the medial preoptic area, paraventricular nucleus, and lateral hypothalamic area, whereas women had more nuclear ERalpha-ir in the suprachiasmatic nucleus and ventromedial nucleus. No nuclear sex differences in ERalpha were found, e.g., in the central part of the bed nucleus of the stria terminalis. In addition to nuclear staining, ERalpha-ir appeared to be sex-dependently present in the cytoplasm of neurons and was observed in astrocytes, plexus choroideus, and other non-neuronal cells. ERalpha-ir in T1, S2, and S8 suggested that most of the observed sex differences in ERalpha-ir are "activational" (e.g., ventromedial nucleus/medial mamillary nucleus) rather than "organizational." Species similarities and differences in ERalpha-ir distribution and possible functional implications are discussed.

Effects of naloxone on the serum luteinizing hormone level and the number of Fos-positive gonadotropin-releasing hormone neurons in immature female rats.

To examine developmental changes in the number of gonadotropin-releasing hormone (GnRH) neurons activated by an opioid receptor antagonist in female rats, blood sampling and double-labeled immunocytochemistry for Fos and GnRH were performed after the injection of naloxone (NAL) in immature (postnatal d16 and d30) and mature female rats. Three age groups of rats were perfused with 4% paraformaldehyde-PB 90 min after the subcutaneous injection of NAL (2.5 mg/kg) or saline. All tissue incubation and staining for double-labeled immunocytochemistry were simultaneously performed. Although no significant developmental change was observed in the total number of GnRH neurons (p0.05), NAL-induced increases in serum luteinizing hormone (LH) concentrations were much greater in the d16 group than those in the d30 and mature groups (p<0.01). Conversely, Fos-positive GnRH neurons were rarely observed in d16, and some Fos-positive GnRH neurons were observed in the d30 group (p<0.05 vs. saline) and the mature group (p<0.01 vs. saline). These results suggest that opiatergic inhibitory system on GnRH neuron in immature female rats is different from that in mature female rats.