Exploring Vitamin B12 Deficiency in Sleeve Gastrectomy from a Histological Study of a Cadaveric Stomach and Ileum.

INTRODUCTION: Vitamin B12 deficiency is more commonly found among patients who have undergone Roux-en-Y gastric bypass (RYGB) as compared to those with post-sleeve gastrectomies (SG). The major difference between SG and RYGB is that the latter greatly bypasses the stomach whereas the former simply reduces the gastric volume. PURPOSE: The aim of this article was to study the stomach and the distal ileum histologically in a cadaver with SG to explain the higher rate of incidences of vitamin B12 deficiency seen in patients post-RYGB relative to patients post-SG. Since the stomach is the major variable in these two procedures, we hypothesize that it has the ability to regenerate and increase its surface area to compensate for the loss of its volume in SG patients. MATERIAL AND METHODS: Tissue biopsies and hematoxylin and eosin stains were performed from various anatomical locations of the GI tract, specifically the gastric fundus, body, and antrum, and from the distal ileum of the small intestine of a cadaver with SG and another without SG (control). RESULTS: Compared with the control, the SG cadaver's gastric tissue biopsies were significant for chronic gastritis and hypertrophy of the muscularis externa layer. More importantly, parietal cell hyperplasia and deeper mucosal glands were also noted in the SG cadaver supporting the hypothesis. CONCLUSIONS: The compensatory role of an intact stomach, given its ability to regenerate parietal cells and increase its numbers in the gastric fundus and body, can be better appreciated in a gastric-sparing procedure such as SG versus RYGB in terms of limiting vitamin B12 deficiencies.

Thalamic neuropeptide mediating the effects of nursing on lactation and maternal motivation.

Nursing has important physiological and psychological consequences on mothers during the postpartum period. Tuberoinfundibular peptide of 39 residues (TIP39) may contribute to its effects on prolactin release and maternal motivation. Since TIP39-containing fibers and the receptor for TIP39, the parathyroid hormone 2 receptor (PTH2 receptor) are abundant in the arcuate nucleus and the medial preoptic area, we antagonized TIP39 action locally to reveal its actions. Mediobasal hypothalamic injection of a virus encoding an antagonist of the PTH2 receptor markedly decreased basal serum prolactin levels and the suckling-induced prolactin release. In contrast, injecting this virus into the preoptic area had no effect on prolactin levels, but did dampen maternal motivation, judged by reduced time in a pup-associated cage during a place preference test. In support of an effect of TIP39 on maternal motivation, we observed that TIP39 containing fibers and terminals had the same distribution within the preoptic area as neurons expressing Fos in response to suckling. Furthermore, TIP39 terminals closely apposed the plasma membrane of 82% of Fos-ir neurons. Retrograde tracer injected into the arcuate nucleus and the medial preoptic area labeled TIP39 neurons in the posterior intralaminar complex of the thalamus (PIL), indicating that these cells but not other groups of TIP39 neurons project to these hypothalamic regions. We also found that TIP39 mRNA levels in the PIL markedly increased around parturition and remained elevated throughout the lactation period, demonstrating the availability of the peptide in postpartum mothers. Furthermore, suckling, but not pup exposure without physical contact, increased Fos expression by PIL TIP39 neurons. These results indicate that suckling activates TIP39 neurons in the PIL that affect prolactin release and maternal motivation via projections to the arcuate nucleus and the preoptic area, respectively.

Effect of concomitant progesterone administration or the effect of removal of estrogen capsule on changes caused by long-term estrogen treatment in pituitary VIP immunoreactivities.

In the anterior pituitary besides the classical tropic hormones, peptides of a small molecular weight are also synthesized. One of them is the vasoactive intestinal polypeptide (VIP). VIP immunoreactivity is readily detected in human and monkey pituitaries; however, in the rat VIP immunoreactive cells were observed in about 50% of intact rats. In estrogen treated rats VIP immunoreactive cells were observed in the anterior pituitary of all animals. In this work, we have examined the effect of long-term sexual steroid treatments on the VIP immunoreactivity of the anterior pituitary using diethylstilbestrol (DES) or progesterone (P) filled capsules. The effectiveness of steroid treatments was tested by the measurement of plasma prolactin (PRL) level and by the appearance of prolactinoma. DES enhanced the plasma PRL level and 5 months later it induced prolactinomas, the concomitant P treatment prevented both the elevation of plasma PRL level and the formation of prolactinomas. These results indicated that there was enough steroid in the capsules. There was a positive correlation between the duration of DES influence and the number of VIP immunoreactive cells. Two months after the implantation of DES there was a considerable number of VIP cells in the anterior pituitary, and 5 months after implantation the number of VIP cells was greatly increased so as to form a VIP-oma. Concomitant implantation of P prevented the formation of VIP-oma. Two months after the implantation, the DES capsule was removed. Already 2 months after removal the number of VIP cells approximated to the control level. It has been concluded that P can prevent the undesired effect of DES not only on the PRL, but on the VIP immunoreactivity as well.

Nesfatin-1/NUCB2 may participate in the activation of the hypothalamic-pituitary-adrenal axis in rats.

Nesfatin-1 is an anorexigenic peptide originating from nucleobinding-2 (NUCB2) protein. Nesfatin-1/NUCB2-immunoreactive neurons are present in the hypothalamic paraventricular nucleus, the center of the stress-axis, and in the medullary A1 and A2 catecholamine cell groups. The A1 and A2 cell groups mediate viscerosensory stress information toward the hypothalamic paraventricular nucleus. They contain noradrenaline, but subsets of these neurons also express prolactin-releasing peptide acting synergistically with noradrenaline in the activation of the hypothalamic paraventricular nucleus during stress. We investigated the possible role of nesfatin-1/NUCB2 in the stress response. Intracerebro-ventricular administration of nesfatin-1 elevated both plasma adrenocorticotropin and corticosterone levels, while in vitro stimulation of the hypophysis was ineffective. Single, long-duration restraint stress activated (Fos positivity) many of the nesfatin-1/NUCB2-immunoreactive neurons in the parvocellular part of the hypothalamic paraventricular nucleus, evoked nesfatin-1/NUCB2 mRNA expression in the parvocellular part of the paraventricular nucleus and in the A1, but not in the A2 cell group. Nesfatin-1/NUCB2 was shown to co-localize in a high percentage of prolactin-releasing peptide producing neurons, in both medullary catecholamine cell groups further supporting its involvement in the stress response. Finally, bilateral adrenalectomy evoked an increasing nesfatin-1/NUCB2 mRNA expression, indicating that it is under the negative feedback of adrenal steroids. These data provide the first evidence for possible participation of nesfatin-1/NUCB2 in the stress-axis regulation, both at the level of the brainstem and in the hypothalamus.

Dopamine-regulated adrenocorticotropic hormone secretion in lactating rats: functional plasticity of melanotropes.

Pro-opiomelanocortin (POMC) is processed to adrenocorticotropic hormone (ACTH) and beta-lipotropin in corticotropes of the anterior lobe, and to alpha-melanocyte-stimulating hormone (alpha-MSH) and beta-endorphin in melanotropes of the intermediate lobe (IL) of the pituitary gland. While ACTH secretion is predominantly under the stimulatory influence of the hypothalamic factors, hormone secretion of the IL is tonically inhibited by neuroendocrine dopamine (NEDA) neurons. Lobe-specific POMC processing is not absolute. For example, D(2) type DA receptor (D2R)-deficient mice have elevated plasma ACTH levels, although it is known that corticotropes do not express D2R(s). Moreover, observations that suckling does not influence alpha-MSH release, while it induces an increase in plasma ACTH is unexplained. The aim of the present study was to investigate the involvement of the NEDA system in the regulation of ACTH secretion and the participation of the IL in ACTH production in lactating rats. Untreated and estradiol (E(2))-substituted ovariectomized (OVX) females were also studied. The concentration of ACTH in the IL was higher in lactating rats than in OVX rats, while the opposite change in alpha-MSH level of the IL was observed. DA levels in the IL and the neural lobe were lower in lactating rats than in OVX rats. Suckling-induced ACTH response was eliminated by pretreatment with the DA receptor agonist, bromocriptine (BRC). Inhibition of DA biosynthesis by alpha-methyl-p-tyrosine (alphaMpT) and blockade of D2R by domperidone (DOM) elevated plasma ACTH levels, but did not influence plasma alpha-MSH levels in lactating rats. The same drugs had opposite effects in OVX and OVX + E(2) animals. In lactating mothers, BRC was able to block ACTH responses induced by both alphaMpT and DOM. Surgical denervation of the IL elevated basal plasma levels of ACTH. Taken together, these data indicate that melanotropes synthesize ACTH during lactation and its release from these cells is regulated by NEDA neurons.

Demonstration of autoantibody binding to muscarinic acetylcholine receptors in the salivary gland in primary Sjögren's syndrome.

A significant pathogenetic role of antimuscarinic acetylcholine receptor-3 (anti-m3AChR) autoantibodies in primary Sjögren's syndrome (pSS) has been suggested. However, the binding of these antibodies to the receptors in the target tissues has not yet been demonstrated. In this study, the binding characteristics of pSS sera and anti-m3AChR-monospecific sera affinity-purified from pSS patients to labial salivary gland samples from healthy subjects were studied with light- and electron microscopy. Furthermore, the ultrastructural localisation of in vivo deposited antibodies in pSS salivary glands was also investigated. Light microscopic immunohistochemistry revealed the binding of the anti-m3AChR-specific sera to the membrane of acinar cells. Similar reaction end-products were observed in the pSS salivary gland epithelial cell membranes. With electron microscopy, the autoantibody binding was observed to be localised to the junctions of epithelial cell membranes with nerve endings, both in normal and pSS glands. The results indicate that anti-m3AChR antibodies bind to the receptors in the salivary glands.

Somatostatin analogues stimulate p27 expression and inhibit the MAP kinase pathway in pituitary tumours.

OBJECTIVES: Somatostatin (SST) analogues play an important role in the medical management of somatotroph pituitary adenomas and new agonists have the potential to be effective in a wider group of pituitary and other tumours. The anti-proliferative effect of SST occurs through multiple mechanisms, one of which is cell-cycle arrest, where p27, a cyclin-dependent kinase inhibitor, is an important regulator. We hypothesised that SST may upregulate p27 protein levels and downregulate the MAP kinase pathway in these tumours. METHODS: Human pituitary adenoma cells and rat pituitary cell line (GH3) were cultured and treated in vitro with octreotide and the broad-spectrum SST agonist SOM230 (pasireotide). Immunoblotting for p27 and phospho-ERK (pERK) was performed and proliferation assessed by [3H]-thymidine incorporation. Histological samples from acromegalic patients treated with octreotide before surgery were immunostained for p27 and compared to samples from untreated patients matched for sex, age, tumour size, extension and invasiveness. RESULTS: We detected upregulation of p27 protein levels with SST analogue treatment in vitro in human pituitary adenoma samples. pERK1/2 was inhibited by SST analogues in both the human samples and GH3 cells. SST and its analogues inhibited the proliferation of GH3 cells. p27 immunostaining was stronger in samples from patients with longer preoperative octreotide treatment (more than 6 months) than in samples from patients with shorter treatment periods. CONCLUSIONS: This study demonstrates that SST-mediated growth inhibition is associated with the downregulation of pERK and upregulation of p27. More potent and broader-spectrum SST analogues are likely to play an increasing role in the treatment of tumours, where the MAP kinase pathway is overactivated.

Treatment of pituitary tumors: dopamine agonists.

The neurotransmitter/neuromodulator dopamine plays an important role in both the central nervous system and the periphery. In the hypothalamopituitary system its function is a dominant and tonic inhibitory regulation of pituitary hormone secretion including prolactin- and proopiomelanocortin-derived hormones. It is well known that dopamine agonists, such as bromocriptine, pergolide, quinagolide, cabergoline, and lisuride, can inhibit PRL secretion by binding to the D(2) dopamine receptors located on normal as well as tumorous pituitary cells. Moreover, they can effectively decrease excessive PRL secretion as well as the size of the tumor in patients having prolactinoma. Furthermore, dopamine agonists can also be used in other pituitary tumors. The major requirement for its use is that the tumor cells should express D(2) receptors. Therefore, in addition to prolactinomas, targets of dopamine agonist therapy are somatotroph tumors, nonfunctioning pituitary tumors, corticotroph pituitary tumors, Nelson's syndrome, gonadotropinomas, and thyrotropin-secreting pituitary tumors. It is also an option for the treatment of pituitary disease during pregnancy. Differences between the effectiveness and the resistance of different dopaminergic agents as well as the future perspectives of them in the therapy of pituitary tumors are discussed.

Salsolinol induces a decrease in cyclic AMP at the median eminence and an increase at the adenohypophysis in lactating rats.

Investigating the cellular events in the pituitary gland, the intracellular cyclic AMP (cAMP) of the median eminence (ME), neuro-intermediate lobe (NIL) and the anterior lobe (AL) have been measured following 15-min of intravenous injection of salsolinol (SAL). Parallel to the elevation of plasma prolactin (PRL), SAL induced a significant decrease of cAMP concentration in the ME. In contrast, SAL injection resulted in a significant increase of cAMP at the level of the AL. Changes in cAMP of the NIL as well as in the plasma level of vasopressin (VP) could not be detected. The observed changes in the level of cAMP following the acute treatment of SAL in the ME and the AL seems to be related to interacting neuroendocrine signals delivered from the ME to the AL through the long portal vessels to release PRL.

Non-NMDA glutamate receptor antagonist injected into the hypothalamic paraventricular nucleus blocks the suckling stimulus-induced release of prolactin.

The aim of the present investigations was to test the involvement of the glutamatergic innervation of the hypothalamic paraventricular nucleus in the prolactin response to the suckling stimulus. A non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-dione disodium (CNQX), or an NMDA receptor antagonist, dizocipine hydrogen malate (MK-801), was injected bilaterally into the hypothalamic paraventricular nucleus of lactating freely moving rats before the end of a 4-h separation of the dams from their pups. The litters were then returned. Blood samples for prolactin were taken at different time points. The effect of the non-NMDA receptor antagonist was also tested in animals receiving the drug bilaterally into the dorsomedial nucleus area or the arcuate nucleus. Bilateral injection of CNQX into the paraventricular nucleus blocked the elevation in plasma prolactin concentration induced by the suckling stimulus. In contrast, bilateral administration of the NMDA receptor antagonist MK-801 into the paraventricular nucleus or bilateral injection of CNQX into the dorsomedial nucleus area or the arcuate nucleus did not interfere with the prolactin response to the suckling stimulus. The findings indicate that the glutamatergic innervation of the paraventricular nucleus is involved in the mediation of the neural signal of the suckling stimulus inducing prolactin release.

Immobilization stress-induced increase in plasma catecholamine levels is inhibited by a prolactoliberin (salsolinol) administration.

Catecholamines (CAs) are significantly involved in the regulation of homeostasis of the organism at rest and especially during stressful situations. Stress induces increases in plasma CA (epinephrine and norepinephrine) levels and prolactin (PRL) release from the adenopituitary. We have recently observed that salsolinol, which is produced by the neuro-intermediate lobe of the pituitary gland and by the hypothalamus, can selectively release PRL. Salsolinol is therefore considered to be a putative endogenous PRL-releasing factor. Based on the similarity of CA and PRL responses to stressors, we investigated whether salsolinol plays a role in the regulation of plasma CA levels at rest and of CA release induced by immobilization stress (IMO). Salsolinol did not affect CA baseline levels; however, it did inhibit IMO-induced CA release. Thus, the present study shows for the first time that salsolinol is not only a PRL-releasing factor but is also a potent inhibitor of stress-induced release of epinephrine and norepinephrine.

Cocaine- and amphetamine-regulated transcript co-contained in thyrotropin-releasing hormone (TRH) neurons of the hypothalamic paraventricular nucleus modulates TRH-induced prolactin secretion.

TRH synthesized in hypophysiotropic neurons of the hypothalamic paraventricular nucleus (PVN) stimulates the release of TSH and prolactin from the anterior pituitary gland. Recent data from our laboratories have demonstrated that TRH and cocaine- and amphetamine-regulated transcript (CART) are co-contained only in hypophysiotropic neurons in the PVN. To determine whether CART and TRH interact in the regulation of anterior pituitary function, we have studied the effects of CART on TRH-induced release of TSH and prolactin in anterior pituitary cell cultures, and the effects of hypo- and hyperthyroidism on CART mRNA in the PVN. Dispersed anterior lobe cells from male rats were treated with CART (10(-6), 10(-8), 10(-10), and 10(-12) m) or TRH (10(-7) m) alone and TRH (10(-7) m) combined with various concentrations of CART for 4 h at 37 C. The medium was assayed for prolactin and TSH by RIA. TRH resulted in a marked increase of both prolactin and TSH release, whereas CART had no effect on prolactin or TSH secretion. When the two peptides were used in combination, CART dose-dependently inhibited TRH-induced prolactin release but had no significant effect on TRH-induced TSH release. By semiquantitative analysis of in situ hybridization autoradiographs, CART mRNA was significantly elevated in hypothyroid animals, whereas a reduction in CART mRNA was observed in hyperthyroid animals compared with euthyroid controls. These data raise the possibility that CART expressed in hypophysiotropic TRH neurons has an important role in the modulation of TRH-induced prolactin secretion. Increased secretion of CART may be responsible for the reduced TRH-induced prolactin response during hypothyroidism.

Effect of glutamate receptor antagonists on suckling-induced prolactin release in rats.

The aim of the present study was to investigate the role of endogenous excitatory amino acid receptors in suckling- induced prolactin (PRL) elevation. Glutamate is known to be the dominant excitatory neurotransmitter and may act simultaneously on different glutamatergic receptor subtypes. MK-801 (dizocilpine) is a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA), while GyKI 52466 is an antagonist of the R,S-alpha-amino- 3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/ kainate receptor subtypes. Using the combination of the two receptorsubtype antagonists, we tested the hypothesis that parallel blockade of more than one subtype is more effective. Low-dose MK-801 (0.033 mg/kg) had no effect on suckling-induced PRL elevation after 4 h of separation. When injected alone, 10 mg/kg of GyKI 52466 was also ineffective, but in combination with low-dose MK-801 it efficiently diminished the sucklinginduced PRL elevation while lactation proceeded. The same dose of GyKI 52466 combined with 0.2 mg/kg of MK-801 (a combination that in other studies was able to block the foot-shock-induced PRL elevation) was more effective. Simultaneous blockade of the two ionotropic glutamate receptors with 0.2 mg/kg of MK-801 and 10 mg/kg of GyKI 52466 caused a decline in plasma PRL concentration of continuously suckling mothers. We conclude that the endogenous glutamatergic system has an important role in suckling-induced PRL elevation and in the maintenance of constantly high PRL levels in lactating mothers. Furthermore, the NMDA and AMPA/kainate receptor subtypes can interact with each other in this process.

Physiological and pathological angiogenesis in the endocrine system.

Formation of new blood vessels occurs in many physiological states (during development of the embryo, cycling changes of the female reproductive tract), as well as in pathological processes (such as diabetic retinopathy and wound healing). Angiogenesis has been shown to be related to tumor formation, prognosis, and response to treatment in many tumor types. Intratumoral microvessels can be related to tumor behavior or hormone secretion in different endocrine tumors. For example, invasive prolactinomas are more vascular than noninvasive adenomas; a surgical approach is more successful in macroprolactinomas with lower microvessel density. A higher number of microvessels have been found in papillary thyroid carcinomas during recurrences. A correlation between microvessel count and prognosis in papillary and medullary thyroid carcinomas has been suggested. Several stimulating and inhibiting factors involved in the regulation of angiogenesis have been identified. Among them, vascular endothelial growth factor (VEGF) has been shown to be critically involved in angiogenesis and also in the neovascularization of solid tumors. Dopamine agonists (already in clinical use for prolactinomas) have potent inhibitory actions on VEGF signaling, and thus may be a new tool in antiangiogenic therapy. Secretion of VEGF in the great majority of human pituitary adenomas is inhibited by dexamethasone. This suggests that glucocorticoids can be considered in the treatment of certain pituitary tumors. The cyclic nature of angiogenesis in the female reproductive tract indicates that stimulation or inhibition of paracrine angiogenic factors may lead to new approaches for being able to influence reproductive endocrine disorders. Experimental and clinical aspects of interactions between angiogenic factors and tumor growth of the endocrine system are also discussed.

Physiological role of salsolinol: its hypophysiotrophic function in the regulation of pituitary prolactin secretion.

We have recently observed that 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol) produced by hypothalamic neurons can selectively release prolactin from the anterior lobe (AL) of the pituitary gland. Moreover, high affinity binding sites for SAL have been detected in areas, like median eminence (ME) and the neuro-intermediate lobe (NIL) that are known terminal fields of the tuberoinfundibular DAergic (TIDA) and tuberohypophysial (THDA)/periventricular (PHDA) DAergic systems of the hypothalamus, respectively. However, the in situ biosynthesis and the mechanism of action of SAL are still enigmatic, these observations clearly suggest that sites other than the AL might be targets of SAL action. Based on our recent observations it may be relevant to postulate that an "autosynaptocrine" regulatory mechanism functioning at the level of the DAergic terminals localized in both the ME and NIL, may play a role in the hypophyseotrophic regulation of PRL secretion. Furthermore, SAL may be a key player in these processes. The complete and precise mapping of these intra-terminal mechanisms should help us to understand the tonic DAerg regulation of PRL secretion. Moreover, it may also give insight into the role of pre-synaptic processes that most likely have distinct and significant functional as well as pathological roles in other brain areas using DAergic neurotransmission, like striatonigral and mesolimbic systems.