Cranial irradiation alters neuroinflammation and neural proliferation in the pituitary gland and induces late-onset hormone deficiency.

Cranial radiotherapy induces endocrine disorders and reproductive abnormalities, particularly in long-term female cancer survivors, and this might in part be caused by injury to the pituitary gland, but the underlying mechanisms are unknown. The aim of this study was to investigate the influence of cranial irradiation on the pituitary gland and related endocrine function. Female Wistar rat pups on postnatal day 11 were subjected to a single dose of 6 Gy whole-head irradiation, and hormone levels and organ structure in the reproductive system were examined at 20 weeks after irradiation. We found that brain irradiation reduced cell proliferation and induced persistent inflammation in the pituitary gland. The whole transcriptome analysis of the pituitary gland revealed that apoptosis and inflammation-related pathways were up-regulated after irradiation. In addition, irradiation led to significantly decreased levels of the pituitary hormones, growth hormone, adrenocorticotropic hormone, thyroid-stimulating hormone and the reproductive hormones testosterone and progesterone. To conclude, brain radiation induces reduction of pituitary and reproduction-related hormone secretion, this may due to reduced cell proliferation and increased pituitary inflammation after irradiation. Our results thus provide additional insight into the molecular mechanisms underlying complications after head irradiation and contribute to the discovery of preventive and therapeutic strategies related to brain injury following irradiation.

Signal Transduction Mechanisms for Glucagon-Induced Somatolactin Secretion and Gene Expression in Nile Tilapia (Oreochromis niloticus) Pituitary Cells.

Glucagon (GCG) plays a stimulatory role in pituitary hormone regulation, although previous studies have not defined the molecular mechanism whereby GCG affects pituitary hormone secretion. To this end, we identified two distinct proglucagons, Gcga and Gcgb, as well as GCG receptors, Gcgra and Gcgrb, in Nile tilapia (Oreochromis niloticus). Using the cAMP response element (CRE)-luciferase reporter system, tilapia GCGa and GCGb could reciprocally activate the two GCG receptors expressed in human embryonic kidney 293 (HEK293) cells. Quantitative real-time PCR analysis revealed that differential expression of the Gcga and Gcgb and their cognate receptors Gcgra and Gcgrb was found in the various tissues of tilapia. In particular, the Gcgrb is abundantly expressed in the neurointermediate lobe (NIL) of the pituitary gland. In primary cultures of tilapia NIL cells, GCGb effectively stimulated SL release, with parallel rises in the mRNA levels, and co-incubation with the GCG antagonist prevented GCGb-stimulated SL release. In parallel experiments, GCGb treatment dose-dependently enhanced intracellular cyclic adenosine monophosphate (cAMP) accumulation with increasing inositol 1,4,5-trisphosphate (IP3) concentration and the resulting in transient increases of Ca2+ signals in the primary NIL cell culture. Using selective pharmacological approaches, the adenylyl cyclase (AC)/cAMP/protein kinase A (PKA) and phospholipase C (PLC)/IP3/Ca2+/calmodulin (CaM)/CaMK-II pathways were shown to be involved in GCGb-induced SL release and mRNA expression. Together, these results provide evidence for the first time that GCGb can act at the pituitary level to stimulate SL release and gene expression via GCGRb through the activation of the AC/cAMP/PKA and PLC/IP3/Ca2+/CaM/CaMK-II cascades.

Melanin-concentrating hormone-expressing neurons adjust slow-wave sleep dynamics to catalyze paradoxical (REM) sleep.

Study Objectives: Experimental studies over the last 15 years established a role in sleep of the tuberal hypothalamic neurons that express melanin-concentrating hormone (MCH). Controversies still remain regarding their actual contribution to both slow-wave sleep (SWS) and paradoxical sleep (PS also known as REM sleep) or PS alone. Methods: To address this point, we compared effects of chemogenetic activation and inhibition of MCH neurons on SWS and PS amounts and EEG rhythmic activities in transgenic Pmch-cre mice. Results: In agreement with recently reported optogenetic data, the activation of MCH neurons invariably facilitates PS onset and maintenance. Our chemogenetic experiments further disclose that the ultradian rhythm of SWS is also notably related to the activity of MCH neurons. We observed that the mean duration of SWS episodes is significantly extended when MCH neurons are inhibited. Conversely, when they were excited, SWS bouts were drastically shortened and depicted substantial changes in δ rhythmic activities in electroencephalographic recording likely reflecting a deeper SWS. Conclusions: According to these original findings, we propose that when MCH neurons are physiologically recruited, SWS depth is increased and the extinction of SWS episodes is accelerated, two joint physiological processes strengthening the probability for natural SWS to PS transition and likely facilitating PS onset.

Adipokines (Leptin, Adiponectin, Resistin) Differentially Regulate All Hormonal Cell Types in Primary Anterior Pituitary Cell Cultures from Two Primate Species.

Adipose-tissue (AT) is an endocrine organ that dynamically secretes multiple hormones, the adipokines, which regulate key physiological processes. However, adipokines and their receptors are also expressed and regulated in other tissues, including the pituitary, suggesting that locally- and AT-produced adipokines might comprise a regulatory circuit that relevantly modulate pituitary cell-function. Here, we used primary pituitary cell-cultures from two normal nonhuman-primate species [Papio-anubis/Macaca-fascicularis] to determine the impact of different adipokines on the functioning of all anterior-pituitary cell-types. Leptin and resistin stimulated GH-release, a response that was blocked by somatostatin. Conversely, adiponectin decreased GH-release, and inhibited GHRH-, but not ghrelin-stimulated GH-secretion. Furthermore: 1) Leptin stimulated PRL/ACTH/FSH- but not LH/TSH-release; 2) adiponectin stimulated PRL-, inhibited ACTH- and did not alter LH/FSH/TSH-release; and 3) resistin increased ACTH-release and did not alter PRL/LH/FSH/TSH-secretion. These effects were mediated through the activation of common (AC/PKA) and distinct (PLC/PKC, intra-/extra-cellular calcium, PI3K/MAPK/mTOR) signaling-pathways, and by the gene-expression regulation of key receptors/transcriptional-factors involved in the functioning of these pituitary cell-types (e.g. GHRH/ghrelin/somatostatin/insulin/IGF-I-receptors/Pit-1). Finally, we found that primate pituitaries expressed leptin/adiponectin/resistin. Altogether, these and previous data suggest that local-production of adipokines/receptors, in conjunction with circulating adipokine-levels, might comprise a relevant regulatory circuit that contribute to the fine-regulation of pituitary functions.

Novel Neuroprotective Effects of Melanin-Concentrating Hormone in Parkinson's Disease.

Acupuncture has shown the therapeutic effect on various neurodegenerative disorders including Parkinson's disease (PD). While investigating the neuroprotective mechanism of acupuncture, we firstly found the novel function of melanin-concentrating hormone (MCH) as a potent neuroprotective candidate. Here, we explored whether hypothalamic MCH mediates the neuroprotective action of acupuncture. In addition, we aimed at evaluating the neuroprotective effects of MCH and elucidating underlying mechanism in vitro and in vivo PD models. First, we tested whether hypothalamic MCH mediates the neuroprotective effects of acupuncture by challenging MCH-R1 antagonist (i.p.) in mice PD model. We also investigated whether MCH has a beneficial role in dopaminergic neuronal protection in vitro primary midbrain and human neuronal cultures and in vivo MPTP-induced, Pitx3-/-, and A53T mutant mice PD models. Transcriptomics followed by quantitative PCR and western blot analyses were performed to reveal the neuroprotective mechanism of MCH. We first found that hypothalamic MCH biosynthesis was directly activated by acupuncture treatment and that administration of an MCH-R1 antagonist reverses the neuroprotective effects of acupuncture. A novel finding is that MCH showed a beneficial role in dopaminergic neuron protection via downstream pathways related to neuronal survival. This is the first study to suggest the novel neuroprotective action of MCH as well as the involvement of hypothalamic MCH in the acupuncture effects in PD, which holds great promise for the application of MCH in the therapy of neurodegenerative diseases.

Melanin-Concentrating Hormone and Its MCH-1 Receptor: Relationship Between Effects on Alcohol and Caloric Intake.

BACKGROUND: Reward and energy homeostasis are both regulated by a network of hypothalamic neuropeptide systems. The melanin-concentrating hormone (MCH) and its MCH-1 receptor (MCH1-R) modulate alcohol intake, but it remains unknown to what extent this reflects actions on energy balance or reward. Here, we evaluated the MCH1-R in regulation of caloric intake and motivation to consume alcohol in states of escalated consumption. METHODS: Rats had intermittent access (IA) to alcohol and were divided into high- and low-drinking groups. Food and alcohol consumption was assessed after administration of an MCH1-R antagonist, GW803430. Next, GW803430 was evaluated on alcohol self-administration in protracted abstinence induced by IA in high-drinking rats. Finally, the effect of GW803430 was assessed on alcohol self-administration in acute withdrawal in rats exposed to alcohol vapor. Gene expression of MCH and MCH1-R was measured in the hypothalamus and nucleus accumbens (NAc) in both acute and protracted abstinence. RESULTS: High-drinking IA rats consumed more calories from alcohol than chow and GW803430 decreased both chow and alcohol intake. In low-drinking rats, only food intake was affected. In protracted abstinence from IA, alcohol self-administration was significantly reduced by pretreatment with GW803430 and gene expression of both MCH and the MCH1-R were dysregulated in hypothalamus and NAc. In contrast, during acute withdrawal from vapor exposure, treatment with GW803430 did not affect alcohol self-administration, and no changes in MCH or MCH1-R gene expression were observed. CONCLUSIONS: Our data suggest a dual role of MCH and the MCH1-R in regulation of alcohol intake, possibly through mechanisms involving caloric intake and reward motivation. A selective suppression of alcohol self-administration during protracted abstinence by GW803430 was observed and accompanied by adaptations in gene expression of MCH and MCH1-R. Selective suppression of escalated consumption renders the MCH1-R an attractive target for treatment of alcohol use disorders.

Making pituitary hormone-producing cells in a dish [Review].

The hypothalamic-pituitary system is essential for maintaining life and controlling systemic homeostasis. The functional disorder makes patients suffer from various symptoms all their lives. Pluripotent stem cells, such as embryonic stem (ES) cells and induced pluripotent stem (iPS) cells, differentiate into neuroectodermal progenitors when cultured as floating aggregates under serum-free conditions. Recent results have shown that strict removal of exogenous patterning factors during the early differentiation period induces rostral hypothalamic-like progenitors from mouse ES cells. The use of growth factor-free, chemically defined medium was critical for this induction. The ES cell-derived hypothalamic-like progenitors generated rostral-dorsal hypothalamic neurons, in particular magnocellular vasopressinergic neurons. We subsequently reported self-formation of adenohypophysis in three-dimensional floating cultures of mouse ES cells. The ES cell aggregates were stimulated to differentiate into both non-neural head ectoderm and hypothalamic neuroectoderm in adjacent layers. Self-organization of Rathke's pouch-like structures occurred at the interface of the two epithelia in vitro. Various pituitary endocrine cells including corticotrophs and somatotrophs were subsequently produced from the Rathke's pouch-like structures. The induced corticotrophs efficiently secreted ACTH in response to CRH. Furthermore, when engrafted in vivo, these cells rescued systemic glucocorticoid levels in hypopituitary mice. Our latest study aimed to prepare hypothalamic and pituitary tissues from human pluripotent stem cells. We succeeded in establishing the differentiation method using human ES/iPS cells. The culture method is characterized by replication of stepwise embryonic differentiation. Therefore, these methods could potentially be used as developmental and disease models, as well as for future regenerative medicine.

Suckling-induced Fos activation and melanin-concentrating hormone immunoreactivity during late lactation.

AIMS: Melanin-concentrating hormone (MCH) is implicated in the control of food intake, body weight regulation and energy homeostasis. Lactation is an important physiological model to study the hypothalamic integration of peripheral sensory signals, such as suckling stimuli and those related to energy balance. MCH can be detected in the medial preoptic area (MPOA), especially around the 19th day of lactation, when this hormone is described as displaying a peak synthesis followed by a decrease after weaning. The physiological significance of this phenomenon is unclear. Therefore, we aimed to investigate hypothalamic changes associated to sensory stimulation by the litter, in special its influence over MCH synthesis. MAIN METHODS: Female Wistar rats (n=56) were euthanized everyday from lactation days 15-21, with or without suckling stimulus (WS and NS groups, respectively). MCH and Fos immunoreactivity were evaluated in the MPOA and lateral and incerto-hypothalamic areas (LHA and IHy). KEY FINDINGS: Suckling stimulus induced Fos synthesis in all regions studied. An increase on the number of suckling-induced Fos-ir neurons could be detected in the LHA after the 18th day. Conversely, the amount of MCH decreased in the MPOA from days 15-21, independent of suckling stimulation. No colocalization between MCH and Fos could be detected in any region analyzed. SIGNIFICANCE: Suckling stimulus is capable of stimulating hypothalamic regions not linked to maternal behavior, possibly to mediate energy balance aspects of lactation. Although dams are hyperphagic before weaning, this behavioral change does not appear to be mediated by MCH.

Endocrine dysfunction and follow-up outcomes in patients with pituitary abscess.

OBJECTIVE: Endocrine dysfunction caused by pituitary abscess (PA) and its outcomes have not been fully studied. This study aims to investigate endocrine dysfunction and outcomes in patients with PA. METHODS: Eight patients (3 males and 5 females) with PA were identified for collecting clinical, hormone, and therapeutic data before and after long-term follow-up lasting 12 to 116 months (median, 25 months) since the first hospitalization, which was regarded as the baseline time. All patients' pituitary and respective target gland functions were evaluated. Six patients had acute onset (less than 1 month), and the other 2 patients had chronic onset (more than 6 months). Five patients underwent surgical therapy, and the other 3 patients underwent conservative therapy. The factors associated with endocrine outcome were analyzed as well. RESULTS: At baseline, the release of 91.7% (22 of 24 total) of pituitary tropic hormones was impaired, but 59.1% (13 of 22) had normalized by the last follow-up. Male gender, acute onset mode, and normal baseline prolactin level seemed to be the factors that favored tropic hormone normalization, whereas surgical operation was not. Two patients received provocative test suggesting decreased reserves of both somatotrophin and prolactin or only somatotrophin. Only 1 patient suffered from permanent diabetes insipidus. CONCLUSION: The production of almost all pituitary tropic hormones was impaired with PA in the present study, but production of nearly 60% percent of the hormones normalized during follow-up of >1 year. A chronic abscess state may be the most important factor associated with permanent hormone deficiency.

Prostaglandins and n-3 polyunsaturated fatty acids in the regulation of the hypothalamic-pituitary axis.

The hypothalamic-pituitary (H-P) axis integrates complex physiological and environmental signals and responds to these cues by modulating the synthesis and secretion of multiple pituitary hormones to regulate peripheral tissues. Prostaglandins are a component of this regulatory system, affecting multiple hormone synthesis and secretion pathways in the H-P axis. The implications of these actions are that physiological processes or disease states that alter prostaglandin levels in the hypothalamus or pituitary can impinge on H-P axis function. Considering the role of prostaglandins in mediating inflammation, the potential for neuroinflammation to affect H-P axis function in this manner may be significant. In addition, the mitigating effects of n-3 polyunsaturated fatty acids (n-3 PUFA) on the inflammation-associated synthesis of prostaglandins and their role as substrates for pro-resolving lipid mediators may also include effects in the H-P axis. One context in which neuroinflammation may play a role is in the etiology of diet-induced obesity, which also correlates with altered pituitary hormone levels. This review will survey evidence for the actions of prostaglandins and other lipid mediators in the H-P axis, and will address the potential for obesity-associated inflammation and n-3 PUFA to impinge on these mechanisms.

Dynamic pituitary hormones change after traumatic brain injury.

OBJECTIVE: To study the dynamic changes of pituitary hormones in traumatic brain injury (TBI) and to correlate the severity and neurological outcome. PATIENTS AND METHODS: Dynamic changes in the pituitary hormones were evaluated in 164 patients with TBI on day-1, day-7, day-14, day-21, and day-28 post injury. Admission TBI severity and long-term outcome were assessed with Glasgow Coma Scale (GCS) score and Glasgow Outcome Scale (GOS) score. The pituitary hormonal changes were correlated with TBI severity and outcome. RESULTS: Of the 164 patients included in the study, pituitary dysfunction was found in 84 patients and in the remaining 80 patients pituitary function was normal. Most of the pituitary hormone deficiencies observed resolved over time; however, a significant proportion of patients had pituitary dysfunction at one month post injury. The hormones associated with poor outcome included growth hormone, thyrotropic hormone, and gonadotropic hormone. CONCLUSION: Dynamic changes of pituitary hormones in patients with TBI may reflect the severity of injury and also determine the outcome. Deficiency of growth hormone, gonadotropic hormone, and thyrotropic hormone can adversely affect neurological outcome.

Anterior pituitary morphology and hormone production during sustained critical illness in a rabbit model.

Prolonged critical illness is hallmarked by striking alterations in the somatrope, thyrotrope, and lactotrope axes, the severity of which is associated with the risk of morbidity and mortality. The exact role of the pituitary gland in these alterations is unknown. We studied the impact of sustained critical illness on pituitary morphology and hormone production in a standardized rabbit model of prolonged (7 days) burn injury-induced critical illness. In healthy and prolonged critically ill rabbits, we determined pituitary weight, size, morphology and orientation of the somatrope, lactotrope and thyrotrope cells and the pituitary expression of GH, PRL, and TSH at gene and protein level. The weight of the pituitary gland was unaltered by 7 days of critical illness. Also, spatial orientation and morphology of the GH, PRL, and TSH producing cells remained normal. In prolonged critically ill rabbits GH mRNA levels were higher and PRL mRNA levels were lower than in healthy controls, whereas TSH mRNA was not affected. The sizes of GH, PRL, or TSH producing cells and the pituitary content of GH, PRL, and TSH proteins were unaltered. In conclusion, in this rabbit model of prolonged critical illness, the morphology of the pituitary gland and the pituitary GH, PRL, and TSH content was normal. The alterations in pituitary hormone mRNA levels with sustained critical illness are compatible with altered hypothalamic and peripheral regulation of pituitary hormone release as previously suggested indirectly by responses to exogenous releasing factors.

The vertebrate diencephalic MCH system: a versatile neuronal population in an evolving brain.

Neurons synthesizing melanin-concentrating hormone (MCH) are described in the posterior hypothalamus of all vertebrates investigated so far. However, their anatomy is very different according to species: they are small and periventricular in lampreys, cartilaginous fishes or anurans, large and neuroendocrine in bony fishes, or distributed over large regions of the lateral hypothalamus in many mammals. An analysis of their comparative anatomy alongside recent data about the development of the forebrain, suggests that although very different, MCH neurons of the caudal hypothalamus are homologous. We further hypothesize that their divergent anatomy is linked to divergence in the forebrain - in particular telencephalic evolution.

Signal transduction mechanisms for autocrine/paracrine regulation of somatolactin-α secretion and synthesis in carp pituitary cells by somatolactin-α and -ß.

Pituitary hormones can act locally via autocrine/paracrine mechanisms to modulate pituitary functions, which represents an interesting aspect of pituitary regulation other than the traditional hypothalamic input and feedback signals from the periphery. Somatolactin, a member of the growth hormone (GH)/prolactin (PL) family, is a pleiotropic hormone with diverse functions, but its pituitary actions are still unknown. Recently, two SL isoforms, SLα and SLß, have been cloned in grass carp. Based on the sequences obtained, recombinant proteins of carp SLα and SLß with similar bioactivity in inducing pigment aggregation in carp melanophores were produced. In carp pituitary cells, SLα secretion and cell content were elevated by static incubation with recombinant carp SLα and SLß, respectively. These stimulatory actions occurred with a parallel rise in SLα mRNA level with no changes in SLß secretion, cell content, and gene expression. In contrast, SLα mRNA expression could be reduced by removing endogenous SLα and SLß with immunoneutralization. At the pituitary cell level, SLα release, cell content, and mRNA expression induced by carp SLα and SLß could be blocked by inhibiting JAK2/STAT5, PI3K/Akt, MEK1/2, and p38 MAPK, respectively. Furthermore, SLα and SLß induction also triggered rapid phosphorylation of STAT5, Akt, MEK1/2, ERK1/2, MKK3/6, and p38 MAPK. These results suggest that 1) SLα and SLß produced locally in the carp pituitary can serve as novel autocrine/paracrine stimulators for SLα secretion and synthesis and 2) SLα production induced by local release of SLα and SLß probably are mediated by the JAK2/STAT5, PI3K/Akt, and MAPK signaling pathways.

Effect of stress during handling, seawater acclimation, confinement, and induced spawning on plasma ion levels and somatolactin-expressing cells in mature female Liza ramada.

The present experiments were designed to determine the effect of different stress factors; handling, seawater acclimation, confinement, and induced spawning on plasma cortisol, hydro mineral balance as well as changes in size, number and integrated intensity of somatolactin (SL)-expressing cells in Liza ramada mature females confined to fresh water ponds. The plasma levels of cortisol, PO(4)(3-), Na(+), and K(+) were higher, while Ca(2+) and Mg(2+) were lower than controls during transportation without anesthesia. By using clove oil (5 mg L(-1)) as an anesthetic during transportation, the plasma cortisol, PO(4) (3-), Na(+), and K(+) were similar to controls, while Ca(2+) and Mg(2+) were higher. During seawater acclimation, the plasma cortisol and minerals were significantly higher except Na(+) which was lower than controls. In addition, during induction of spawning, the plasma levels of cortisol, PO(4)(3-), Na(+), K(+), and Mg(2+) were significantly higher than controls. The SL-producing cells are located in the pars intermedia (PI) bordering the neurohypophysis. The stress affected the number, size, and immunostaining of SL-expressing cells. During seawater acclimation, the size and the integrated intensity of SL immunoreactivity were lower, but the number of these cells was higher than controls. Furthermore, the number, size, and the integrated intensity of SL immunoreactivity were significantly lower than controls during handling and after spawning, which was opposite to confinement. The response of SL-expressing cells in PI in parallel with changes in cortisol and hydro mineral balance induced by stress support the possible role of SL in the adaptive response of fish to stress.

Insulin-like growth factor as a novel stimulator for somatolactin secretion and synthesis in carp pituitary cells via activation of MAPK cascades.

Somatolactin (SL), a member of the growth hormone/prolactin family, is a pituitary hormone unique to fish models. Although SL is known to have diverse functions in fish, the mechanisms regulating its secretion and synthesis have not been fully characterized. Using grass carp pituitary cells as a model, here we examined the role of insulin-like growth factor (IGF) in SL regulation at the pituitary level. As a first step, the antisera for the two SL isoforms expressed in the carp pituitary, SLα and SLß, were produced, and their specificity was confirmed by antiserum preabsorption and immunohistochemical staining in the carp pituitary. Western blot using these antisera revealed that grass carp SLα and SLß could be N-linked glycosylated and their basal secretion and cell content in carp pituitary cells could be elevated by IGF-I and -II treatment. These stimulatory effects occurred with parallel rises in SLα and SLß mRNA levels, and these SL gene expression responses were not mimicked by insulin but blocked by IGF-I receptor inactivation. In carp pituitary cells, IGF-I and -II could induce rapid phosphorylation of IGF-I receptor, MEK1/2, ERK1/2, MKK3/6, and p38 MAPK; and SLα and SLß secretion, protein production, and mRNA expression caused by IGF-I and -II stimulation were negated by inactivating MEK1/2 and p38 MAPK. Parallel inhibition of PI3K and Akt, however, were not effective in these regards. These results, taken together, provide evidence that IGF can upregulate SL secretion and synthesis at the pituitary level via stimulation of MAPK- but not PI3K/Akt-dependent pathways.

Vascular endothelial cells and pituitary hormone producing cells derived from embryonic stem cells therapy for hypopituitarism.

The common causes of hypopituitarism today are pituitary tumors, brain damage including traumatic brain injury, subarachnoid hemorrhage, neurosurgery, irradiation, and stroke. The main mechanism of hypopituitarism is vascular and neuronal damage of the hypothalamic-pituitary axis. At present, medical treatment of hypopituitarism caused by brain damage is hormone substitute with disadvantages of side effects, high expense and a requirement for daily injections over several years. A new protocol indicates that embryonic stem cells can be efficiently induced to differentiate into vascular endothelial cells, which integrated with host cells to form chimeric vasculature. Also, the growing body of recent evidence shows that specific hormone producing cells can be differentiated from embryonic stem cells under certain conditions. Additionally, a recent study demonstrates that endocrine cells generated from embryonic stem cells could integrate into the host in vivo and have endocrine function. Therefore, we hypothesize that vascular endothelial cells and pituitary hormone producing cells derived from embryonic stem cells labeled by iron oxide nanoparticles are injected into pituitary fossa by endoscopic transsphenoidal approach, the transplanted cells might restore vascular and neuronal damage of hypothalamic-pituitary axis, cellular therapy for hypopituitarism caused by brain damage.

Birthdating studies reshape models for pituitary gland cell specification.

The intermediate and anterior lobes of the pituitary gland are derived from an invagination of oral ectoderm that forms Rathke's pouch. During gestation proliferating cells are enriched around the pouch lumen, and they appear to delaminate as they exit the cell cycle and differentiate. During late mouse gestation and the postnatal period, anterior lobe progenitors re-enter the cell cycle and expand the populations of specialized, hormone-producing cells. At birth, all cell types are present, and their localization appears stratified based on cell type. We conducted a birth dating study of Rathke's pouch derivatives to determine whether the location of specialized cells at birth is correlated with the timing of cell cycle exit. We find that all of the anterior lobe cell types initiate differentiation concurrently with a peak between e11.5 and e13.5. Differentiation of intermediate lobe melanotropes is delayed relative to anterior lobe cell types. We discovered that specialized cell types are not grouped together based on birth date and are dispersed throughout the anterior lobe. Thus, the apparent stratification of specialized cells at birth is not correlated with cell cycle exit. Thus, the currently popular model of cell specification, dependent upon timing of extrinsic, directional gradients of signaling molecules, needs revision. We propose that signals intrinsic to Rathke's pouch are necessary for cell specification between e11.5 and e13.5 and that cell-cell communication likely plays an important role in regulating this process.

Sleep alterations in an environmental neurotoxin-induced model of parkinsonism.

Parkinson's disease (PD) is classically defined as a motor disorder resulting from decreased dopamine production in the basal ganglia circuit. In an attempt to better diagnose and treat PD before the onset of severe motor dysfunction, recent attention has focused on the early, non-motor symptoms, which include but are not limited to sleep disorders such as excessive daytime sleepiness (EDS) and REM behavioral disorder (RBD). However, few animal models have been able to replicate both the motor and non-motor symptoms of PD. Here, we present a progressive rat model of parkinsonism that displays disturbances in sleep/wake patterns. Epidemiological studies elucidated a link between the Guamanian variant of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) and the consumption of flour made from the washed seeds of the plant Cycas micronesica (cycad). Our study examined the effects of prolonged cycad consumption on sleep/wake activity in male, Sprague-Dawley rats. Cycad-fed rats exhibited an increase in length and/or number of bouts of rapid eye movement (REM) sleep and Non-REM (NREM) sleep at the expense of wakefulness during the active period when compared to control rats. This hypersomnolent behavior suggests an inability to maintain arousal. In addition, cycad-fed rats had significantly fewer orexin cells in the hypothalamus. Our results reveal a novel rodent model of parkinsonism that includes an EDS-like syndrome that may be associated with a dysregulation of orexin neurons. Further characterization of this early, non-motor symptom, may provide potential therapeutic interventions in the treatment of PD.

Comparison of melanin-concentrating hormone and hypocretin/orexin peptide expression patterns in a current parceling scheme of the lateral hypothalamic zone.

The distribution of hypothalamic neurons expressing the peptides melanin-concentrating hormone (MCH; 'MCH neurons') or hypocretin/orexin (H/O; 'H/O neurons') was assessed with immunocytochemistry in male rats at high spatial resolution. Data were plotted on a rat brain atlas that includes a recently revised parcellation scheme for the lateral hypothalamic zone. Quantitative analysis revealed approximately three times more MCH neurons than H/O neurons in the hypothalamus, and approximately twice as many within the parcellations of the lateral hypothalamic area (LHA). The LHA contained 60% of MCH neurons and 81% of H/O neurons, and the same five LHA regions contained the vast majority of MCH (87%) or H/O (93%) neurons present within the LHA: namely the LHA dorsal region (LHAd: 31% of H/O; 38% of MCH), suprafornical region (LHAs: 28% of H/O; 11% of MCH), ventral region medial zone (LHAvm: 15% of H/O; 16% of MCH), juxtadorsomedial region (LHAjd: 14% of H/O and MCH) and magnocellular nucleus (LHAm: 5% of H/O; 7% of MCH). The zona incerta (ZI) contained 18% of MCH neurons. A high co-abundance of MCH and H/O neurons outside of the LHA was present in the posterior hypothalamic nucleus (PH: 11% of H/O; 9% of MCH). Morphological analysis revealed MCH and H/O neurons as typically tri-polar with irregularly shaped somata. These data provide a quantitative analysis of neurons expressing either MCH or H/O peptides within the rat hypothalamus, and they clarify differences in the distribution pattern for different subsets of these neuron types, especially within the LHA.