Female sexual behavior in hypogonadal mice with GnRH-containing brain grafts

Hypogonadal female mice respond to GnRH-containing fetal preoptic area (POA) implants in the third ventricle with vaginal opening and persistent vaginal estrus, ovarian, and uterine development and increased gonadotropin secretion. When these females are mated with normal males, reflex ovulation results in pregnancy. In the present study, POA implants derived from neonatal pups, whether male or female, were also capable of supporting reproductive development in the hypogonadal female mice. Evaluation of female sexual behavior in the mice with grafts showed that these mice responded to normal males with comparable levels of lordosis as are seen in normal female mice on the proestrous days of their cycles.     

Localization of hypophysiotropic neurohormones by assay of sections from various brain areas.

The results of studies of the localization of the hypothalamic hypophysiotropic factors based on their direct determination in sections or nuclear punches are described. Luteinizing hormone-releasing hormone was found in high concentrations in the median eminence-arcuate nucleus complex, in lower concentrations in the mediobasal zone of the preoptic area. In addition to these hypothalamic sites, it is present in all four periventricular organs, especially in the organum vasculosum laminae terminalis. Thyrotropin releasing hormone has a widespread distribution. High concentrations are in the median eminence, arcuate nucleus, dorsomedial nucleus, and anterior part of the ventromedial nucleus. Lower concentrations are in several other structures of the hypothalamus, preoptic area and septum, and low but measurable quantities are found in most of the structures of the brain. Somatostatin is also present in most structures of the central nervous system, with highest concentrations in the median eminence, arcuate nucleus, ventromedial nucleus and periventricular nucleus. There are indications that the ventromedial nucleus or its immediate vicinity contains growth hormone releasing factor. Prolactin releasing activity was present in the median eminence and mediobasal parts of the anterior hypothalamus, whereas prolactin inhibitory activity was in the dorsolateral parts of the anterior hypothalamus and/or preoptic area.     

Changes in the pituitary and hypothalamic content of methionine-enkephalin during the estrous cycle of rats

Met-Enkephalin content of the anterior hypothalamic-preoptic area, medial basal hypothalamus, anterior pituitary, intermediate and posterior pituitary was measured using a specific radioimmunoassay. Met-Enkephalin content of the anterior hypothalamic-preoptic area, medial basal hypothalamus and anterior pituitary was very high on the morning of proestrus but decreased on the afternoon of proestrus and on estrus. The content of met-Enkephalin was more variable in the anterior pituitary than in the anterior hypothalamic-preoptic area and medial basal hypothalamus during the estrous cycle. The results suggest that the met-Enkephalin may be involved in regulating the hypothalamo-hypophyseal function during estrous cycle in the rat.     

Distribution of delta sleep-inducing peptide in the newborn and infant human hypothalamus: an immunohistochemical study

The distribution of delta sleep-inducing peptide immunoreactive cell bodies, fibers, and terminal-like structures was investigated in the normal human hypothalamus during the first postnatal year, using immunohistofluorescence and peroxidase anti-peroxidase techniques. Immunolabeled perikarya were relatively few and were mostly scattered through the anterior (preoptic) and mediobasal regions (infundibular nucleus) of the hypothalamus. DSIP-immunoreactive fibers and terminal-like fibers were observed throughout the entire rostrocaudal extent of the hypothalamus. They exhibit high densities in the preoptic region, the organum vasculosum of lamina terminalis, infundibular nucleus and median eminence. Moderate to low densities of DSIP-immunoreactive fibers were observed in the other hypothalamic structures, located in the anterior and mediobasal regions of hypothalamus, such as periventricular, paraventricular, suprachiasmatic, ventromedial, dorsomedial and parafornical nuclei. In the present study, the analysis of the immunohistochemical pattern of DSIP-immunoreactive neuronal elements in the human infant hypothalamus during the first postnatal year provided evidence of the presence of several differences. We have found qualitative age-related changes in the density of DSIP immunoreactivity in several hypothalamic structures such as the anterior region and the median eminence.     

LHRH-immunoreactive structures in the sheep brain

Neural structures containing luteinizing hormone-releasing hormone (LHRH) are characterized in adult ewe and female lamb brains. Three anti-LHRH antisera are used in an immunofluorescent or immunoperoxidase method. On our preparations, all three gave the same results, expressed as number of labelled cells (about 2500 in a whole brain). It was found that 95% of the LHRH-immunoreactive cells are located in the preoptico-hypothalamic area, where cell bodies are localized mainly (50%) in the area surrounding the organum vasculosum of the lamina terminalis (OVLT); they are also found in a more anterior section of the medial part of the olfactory tubercle and the medial septum (14%), in a more posterior situation in the anterior and lateral hypothalamus (16%), and in the mediobasal hypothalamus (15%). Fibres originating in various part of the whole preoptico-hypothalamic group reach the OVLT and the median eminence. The remaining cells (5%) and fibres are found in various tel-, di-, and mesencephalic areas.     

Possible role of vasoactive intestinal peptide in the hyperprolactinemia induced by ethanol

The effect of the blockade of endogenous VIP by injecting a specific rabbit anti-VIP serum (A-VIP) was studied in rats receiving an acute injection of ethanol. A-VIP administration decreased serum prolactin levels and reduced the hyperprolactinemia induced by ethanol. We also investigated the effect of the acute administration of ethanol on the concentration and release of VIP from the mediobasal hypothalamus. Ethanol decreased VIP concentration in the mediobasal hypothalamus, whereas it stimulated the in vitro K(+)-evoked release of VIP from this tissue. Conversely, ethanol increased VIP concentration in the anterior pituitary gland. The data indicate that VIP may be involved in the pituitary response to ethanol. The increased anterior pituitary VIP after ethanol may be due to an augmented release from the mediobasal hypothalamus.     

Gonadotropin-releasing hormone neurons and pathways in the brain of the female mink (Mustela vison)

Summary The distribution of gonadotropin-releasing hormone-immunoreactive neurons and processes was mapped in the female mink brain using coronal, horizontal and sagittal sections. Perikarya were found along a ventral continuum including the olfactory tubercle, the diagonal band of Broca, the lateral septum, the preoptic and anterior hypothalamic area and the mediobasal hypothalamus; 80% of the perikarya were counted in the mediobasal hypothalamus. Fibres were mainly observed in the organum vasculosum of the lamina terminalis and the median eminence. A few processes terminated in the ependymal cells lining the third and lateral ventricles. The total number of immunoreactive perikarya was the highest in the brains of females sacrificed in July; it then significantly decreased until December. This variation is discussed in relation to the annual breeding cycle.     

LHRH-immunoreactive structures in the sheep brain

Summary Neural structures containing luteinizing hormone-releasing hormone (LHRH) are characterized in adult ewe and female lamb brains. Three anti-LHRH antisera are used in an immunofluorescent or immunoperoxidase method. On our preparations, all three gave the same results, expressed as number of labelled cells (about 2500 in a whole brain). It was found that 95% of the LHRH-immunoreactive cells are located in the preoptico-hypothalamic area, where cell bodies are localized mainly (50%) in the area surrounding the organum vasculosum of the lamina terminalis (OVLT); they are also found in a more anterior section of the medial part of the olfactory tubercle and the medial septum (14%), in a more posterior situation in the anterior and lateral hypothalamus (16%), and in the mediobasal hypothalamus (15%). Fibres originating in various part of the whole preoptico-hypothalamic group reach the OVLT and the median eminence. The remaining cells (5%) and fibres are found in various tel-, di-, and mesencephalic areas.We would like to dedicate this work to the memory of Dr. M.P. Dubois     

Anovulation in adult female rats after neonatal intracerebral implantation of oestrogen.

Four-day-old female rats were bilaterally implanted with paraffin micropellets containing 0.5% oestradiol benzoate (OB) into the mediobasal hypothalamus or the corticomedial amygdala. Controls received intracerebral paraffin pellets or two s.c. OB-paraffin implants. None of the treatments influenced the date of vaginal opening and vaginal cyclicity at 50 days of age. Permanent vaginal oestrus between 100 and 116 days of age and anovulatory ovaries at autopsy on day 116 were found in rats that had been implanted with OB into the mediobasal hypothalamus, but not in the remaining animals. The findings demonstrate that the delayed anovulatory syndrome can be induced in female rats by the neonatal intrahypothalamic implantation of a very low dose of OB, and that the corticomedial amygdala seems not to be a site of oestrogen action in this sterilizing effect.     

Noradrenaline turnover rate in the mediobasal and anterior hypothalamus of the rabbit

Noradrenaline turnover rate in the mediobasal and anterior hypothalamus of the rabbit. Acta Physiol. Pol., 1977, 28 (1): 39-43. The rate of noradrenaline (NA) turnover in mediobasal hypothalamus (MBH) and anterior hypothalamus (AH) of the rabbit was estimated by steady-state isotopic method with a tritiated noradrenaline (3H-NA) as a tracer. The disappearance rate of 3H-NA both in MBH and in AH was found to be biphasic; the first rapid phase of the NA half-life of about 30 min, followed by the second phase of slower decay of the half-life of 2.4 h and 10 h for MBH and AH respectively. The results suggest an existence of more than one metabolic pool of endogenous noradrenaline in MBH and AH and indicate regional difference in the metabolism of NA stores in the hypothalamus.     

Immunocytochemistry of luteinizing hormone releasing hormone (LHRH) and gonadotropic hormones in the sheep after anterior deafferentations of the hypothalamus

Summary Using the immunoperoxidase method, the effect of the anterior deafferentations on the (1) LHRH-neuronal system in the hypothalamus and (2) gonadotropic cells in the adenohypophysis of the ewe were investigated. Two kinds of the anterior deafferentations were placed in the hypothalamus of cycling ewes. The first was performed at the level of caudal border of the chiasma opticum (CB deafferentation) and separated the medio-basal hypothalamus (MBH) from the anterior hypothalamic area (AHA). The second, was placed above the midline of the optic chiasma (MB deafferentation) and detached the AHA from the area praeoptica (AP). Estrous cycles and ovulation ceased in all CB-deafferentation. Immunocytochemical observations revealed a complete lack of LHRH-material both in the hypothalamic nuclei and in all parts of the median eminence (ME) and disappearance of LH-cells in the pituitary gland. In MB deafferented animals, only a diminished density of LHRH-material occurred in the rostral and central parts of the ME, but the ewes continued estrous cycles. Furthermore, numerous LHRH-axons and some LHRH-perikarya were visible in the regions of the AP and AHA. From these results the author is of the opinion, that in the ewe, principally AHA, but not MBH, retains the ability to produce LHRH. Difficulties in staining LHRH-perikarya suggest that in this species LHRH may be synthesized in an immunologically inactive (prohormonal) form.     

Adrenovascular lesions from neurogenic stress modified by suppression of nervous centres in rat

Adrenovascular lesions (hemorrhages and/or edema) caused by neurogenic stress, are modified by suppression of different nervous centres. Spinal transection at Th5 abolishes the adrenovascular response to neurogenic stress. Destruction of the anterior or posterior hypothalamus decreases this vascular response; the greatest effect was obtained by destruction of the hypothalamus medius or by hemidecortication. This effect was bilateral but more manifest contralaterally in cases with unilateral destruction. These results show that the adrenovascular reaction to neurogenic stress is regulated by the central nervous system, mainly by the hypothalamus and cerebral cortex.     

Ethanol-related changes in substance P in the hypothalamus and anterior pituitary.

The effect of the administration of a rabbit anti-substance P serum (ASPS) was studied in rats receiving an acute injection of ethanol. ASPS lowered serum prolactin levels and reduced the hyperprolactinemia induced by ethanol. ASPS also decreased LH serum levels in both saline- and ethanol-treated rats. The effect of ethanol on the concentration of substance P-like immunoreactivity (SP-LI) in the mediobasal hypothalamus and the anterior pituitary gland was also investigated. Ethanol reduced SP-LI in the mediobasal hypothalamus but increased it in the anterior pituitary gland. The presence of ethanol (50 mM) did not affect the K(+)-evoked release of SP-LI from either mediobasal hypothalamus or anterior pituitary gland, though it increased the SP-LI concentration remaining in this gland. These results indicate that ethanol increases the content of SP-LI in the anterior pituitary gland and suggest that substance P may be involved in the prolactin release induced by the acute administration of ethanol.     

LHRH in the human hypothalamus. Immunohistochemical mapping in normal newborn infants or in sudden death infants

The topographical distribution of neurons containing LHRH has been investigated in newborn hypothalamus using the peroxidase anti-peroxidase technique. In control subjects, LHRH immunoreactive (LHRH-IR) perikarya have been mainly observed essentially in the infundibular nucleus. The preoptic region displayed a moderate density of LHRH-IR cell bodies. High LHRH innervation was observed in the anterior hypothalamus in the lamina terminalis and in the mediobasal hypothalamus in the median eminence, and in the peri- and paraventricular regions. In sudden death infant syndrome, a comparable mapping was observed, except a low density in the mediobasal peri- and paraventricular areas.     

Correlation between sexual maturation and induction of persistent estrus by continuous illumination.

The rats brought up under continuous illumination from the neonatal day persist in the rhythmic estrous cycle for long time and do not easily reveal so-called continuous vaginal estrus. On the contrary, immature rats at about 30 days of age show the persistent estrus soon after exposure to continuous illumination as well as adult rats. The purpose of this paper was to examine the relation of the age placed under continuous illumination and the time required to reach the persistent estrus. As the results, it was found that the younger rats need proportionally the longer time to reach the persistent estrus; the rats which were transferred into continuously illuminated environment at 0 (group A), 5 (group B), 10 (group C), 15-16 (group D) and 30 (group E) days of age required a mean time of 132.1 +/- 8.4, 126.8 +/- 8.9, 89.7 +/- 6.2, 91.5 +/- 3.8 and 70.3 +/- 3.0 days after birth to reach the persistent estrus, respectively. In the present data, a significant difference was seen between group B and C. Though all rats were killed after the same length of persistently estrous periods, actual endocrine level appeared to differ among the groups; the rats required longer time to reach the persistent estrus had smaller ovaries and adrenals.     

Estrogen receptor and progesterone receptor-immunoreactive cells are not co-localized with gonadotropin-releasing hormone in the brain of the female mink (Mustela vison)

The distribution of gonadal steroid (estrogen, progesterone) receptors in the brain of the adult female mink was mapped by immunocytochemistry. Using a monoclonal rat antibody raised against human estrogen receptor (ER), the most dense collections of ER-immunoreactive (IR) cells were found in the preoptic/anterior hypothalamic area, the mediobasal hypothalamus (arcuate and ventromedial nuclei), and the limbic nuclei (amygdala, bed nucleus of the stria terminalis, lateral septum). Immunoreactivity was mainly observed in the cell nucleus and a marked heterogeneity of staining appeared from one region to another. A monoclonal mouse antibody raised against rabbit uterine progesterone receptor (PR) was used to identify the PR-IR cells in the preoptic/anterior hypothalamic area and the mediobasal hypothalamus (arcuate and ventromedial nuclei). This study also focused on the relationship between cells containing sex-steroid receptors and gonadotropin-releasing hormone (GnRH) neurons on the same sections of the mink brain using a sequential double-staining immunocytochemistry procedure. Although preoptic and hypothalamic GnRH neurons were frequently in close proximity to perikarya containing ER or PR, they did not themselves possess receptor immunoreactivity. The present study provides neuroanatomical evidence that GnRH cells are not the major direct targets for gonadal steroids and confirms for the first time in mustelids the results previously obtained in other mammalian species.     

Daily Changes of GABA and Taurine Concentrations in Various Hypothalamic Areas Are Affected by Chronic Hyperprolactinemia

This study was designed to characterize, in anterior, mediobasal, and posterior hypothalamic and median eminence, the 24h changes of gamma aminobutyric acid (GABA) and taurine (TAU) contents in adult male rats and to analyze whether chronic hyperprolactinemia may affect these patterns. Rats were turned hyperprolactinemic by a pituitary graft. Plasma prolactin (PRL) levels increased after pituitary grafting at all time points examined. A disruption of the circadian rhythm was observed in pituitary-grafted rats, whereas GABA and TAU content followed daily rhythms in all areas studied in controls. In the mediobasal hypothalamus, two peaks for each amino acid were found at midnight and midday. In the anterior hypothalamus, GABA and TAU showed only one peak of concentration at midnight. In the posterior hypothalamus, the values of both GABA and TAU were higher during the light as compared to the dark phase of the photoperiod. In the median eminence GABA content peaked at 20:00h, the time when TAU exhibited the lowest values. Hyperprolactinemia abolished the 24h changes of GABA in the mediobasal hypothalamus and reduced its content as compared to controls. Hyperprolactinemia advanced the diurnal peak of TAU to 12:00h in the mediobasal hypothalamus and did not modify the 24:00h peak. In the anterior hypothalamus, hyperprolactinemia increased GABA and TAU contents during the light phase while it decreased them during the dark phase of the photoperiod. In the posterior hypothalamus hyperprolactinemia did not modify GABA or TAU patterns as compared to controls. In the median eminence hyperprolactinemia increased the 20:00h peak of GABA and shift advanced the decrease in TAU content at 20:00h and its maximum at 24:00h as compared to controls. These data show that GABA and TAU content exhibit specific daily patterns in each hypothalamic region studied. PRL differentially affects the daily pattern of these amino acids in each hypothalamic region analyzed.     

Daily changes of GABA and taurine concentrations in various hypothalamic areas are affected by chronic hyperprolactinemia

This study was designed to characterize, in anterior, mediobasal, and posterior hypothalamic and median eminence, the 24h changes of gamma aminobutyric acid (GABA) and taurine (TAU) contents in adult male rats and to analyze whether chronic hyperprolactinemia may affect these patterns. Rats were turned hyperprolactinemic by a pituitary graft. Plasma prolactin (PRL) levels increased after pituitary grafting at all time points examined. A disruption of the circadian rhythm was observed in pituitary-grafted rats, whereas GABA and TAU content followed daily rhythms in all areas studied in controls. In the mediobasal hypothalamus, two peaks for each amino acid were found at midnight and midday. In the anterior hypothalamus, GABA and TAU showed only one peak of concentration at midnight. In the posterior hypothalamus, the values of both GABA and TAU were higher during the light as compared to the dark phase of the photoperiod. In the median eminence GABA content peaked at 20:00h, the time when TAU exhibited the lowest values. Hyperprolactinemia abolished the 24h changes of GABA in the mediobasal hypothalamus and reduced its content as compared to controls. Hyperprolactinemia advanced the diurnal peak of TAU to 12:00h in the mediobasal hypothalamus and did not modify the 24:00h peak. In the anterior hypothalamus, hyperprolactinemia increased GABA and TAU contents during the light phase while it decreased them during the dark phase of the photoperiod. In the posterior hypothalamus hyperprolactinemia did not modify GABA or TAU patterns as compared to controls. In the median eminence hyperprolactinemia increased the 20:00h peak of GABA and shift advanced the decrease in TAU content at 20:00h and its maximum at 24:00h as compared to controls. These data show that GABA and TAU content exhibit specific daily patterns in each hypothalamic region studied. PRL differentially affects the daily pattern of these amino acids in each hypothalamic region analyzed.     

Cadmium effects on hypothalamic-pituitary-testicular axis in male rats

This study analyzes cadmium effects at the hypothalamic-pituitary-testicular axis. Male rats were given cadmium during puberty or adulthood. Cadmium exposure through puberty increased norepinephrine content in all hypothalamic areas studied, but not in the median eminence. Metal exposure increased serotonin turnover in median eminence and the anterior hypothalamus, while decreased it in mediobasal hypothalamus. Also, decreased plasma levels of testosterone were found. Cadmium exposure during adulthood increased norepinephrine content in posterior hypothalamus and decreased the neuro-transmitter content in anterior and mediobasal hypothalamus. Decreased circulating levels of luteinizing hormone (LH) and testosterone and increased plasma follicle stimulating hormone (FSH) levels were also observed. Cadmium accumulated in all analyzed tissues. Various parameters showed age-dependent changes. These data suggest that cadmium globally effects hypothalamic-pituitary-testicular axis function by acting at the three levels analyzed and that an interaction between cadmium exposure and age emerge.     

Estrus induction in the bitch using a combination diethylstilbestrol and FSH-P

The purpose of the study was to induce estrus and ovulation in normal bitches using a combination of diethylstilbestrol (DES) and follicle stimulating hormone of porcine pituitary origin (FSH-P). Thirteen mature mongrel female dogs were divided into two groups, the first group was treated for estrus induction during late anestrus and the second group during mid-anestrus. The dogs were monitored by teasing, vaginal cytology, and hormonal assay during the induced (n = 13) and the previous spontaneous estrous cycle (n = 9). Six of eight and three of five bitches came into standing estrus in the first and second group, respectively. Of the bitches that came into estrus, three conceived in the first group and one in the second. The average induced litter size was 7.0 versus 7.5 for the colony. Based on vaginal cytology the induced proestrus and estrus lasted 1.7 (0 to 3) and 12.9 (4 to 24) d, respectively, while the spontaneous proestrus and estrus lasted 5.8 (0-17) and 12.8 (9-15) d, respectively. Progesterone profiles were similar between the induced and spontaneous estrous cycles, although the progesterone peak was higher during the spontaneous cycle. The preovulatory luteinizing hormone (LH) surge was observed in only one induced estrous cycle. Modest results were obtained with this therapy. However, the litter sizes were normal and the induced cycles were very similar to the physiologic ones. No side effects were seen with the oral form of DES.