Polybrominated diphenyl ethers (PBDEs) are flame‐retardants associated with impaired cognitive and behavioral deficits in children. PBDEs are endocrine‐disrupting chemicals that also have neurotoxicological actions. In humans, PBDEs have been associated with disrupted attention, hyperactivity and lower IQ scores. This study evaluates behaviors relevant to autism spectrum disorder (ASD) and examines correlative changes in forebrain expression of genes after perinatal exposure to the industrial PBDE mixture, DE‐71. Genes for vasopressin (Avp) and oxytocin signaling (Oxtr) serve as markers for social circuits. Pituitary adenylate cyclase activating polypeptide, PACAP (Adcyap1r1), and its receptor, PAC1R (Adcyap1r1) are critical for neurodevelopment. Female C57BL/6 dams were dosed for 10 weeks (pre‐conception: 4 weeks; gestation: 3 weeks; lactation: 3 weeks). Dosing consisted of low dose (0.1 mg/kg/d), high dose (0.4 mg/kg/d), or corn oil vehicle (control) via ingestion of infused corn flakes. Exposed progeny were subjected to behavioral testing: Sociability (PND 21), Open Field (PND 30–40), Marble Burying (PND 40–50), Social Recognition (PND 55–60), and Elevated Plus Maze (PND 60–65). High dose DE‐71 treatment produced a sex‐independent decrease in repetitive behavior (F2,54=5.96, p<0.005). In males, high dose DE‐71 treatment produced hyperactivity (p<0.05). The social recognition test revealed significant preference for a novel conspecific in control males (F1,23=7.38, p<0.05) and females (F1,22=18.05, p<0.0005) but not in any DE‐71 groups. The latter could not be attributed to reduced sociability. Plasma showed reduced (p<0.05) and increased (p<0.05) plasma arginine‐vasopressin in low and high dose males, respectively. qPCR analysis revealed an apparent decrease in Avp gene expression in lateral septum and medial amygdala of low dose DE‐71 males compared to controls. In contrast, the supraoptic nucleus displayed significantly increased Avp expression in low dose DE‐71 mice (p=0.243). These mice also showed an apparent decrease in Oxtr, Adcyap1 and Adcyap1r1 expression in amygdala and in Adcyap1r1 in cingulate cortex compared to controls. Preliminary histological analysis has revealed a significant transient increase in cell density of the cingulate cortex at PND 7 (p=0.012) in high dose males compared to controls. By PND 71, the cell density of the cingulate cortex becomes significantly decreased (p<0.001) in high dose males compared to controls (n=2–3/group). We conclude that developmental PBDEs produce ASD‐relevant neurodevelopmental and behavioral abnormalities that maybe due, in part, to changes in vasopressinergic and PACAPergic circuits.Support or Funding InformationSupport: APS (G.G.), MARC (G.G., J.V, R.G.), UCMEXUS (M.C‐C., M.L‐O.), NSF (M.V.) and Sigma Xi (G.G., M.V.).

Research suggests that chronic stress and subsequent activation of the sympathetic nervous system contribute to the development of hypertension. Recent work suggests that pituitary adenylate cyclase‐activating polypeptide (PACAP)‐dependent mechanisms sustain sympathoadrenal responses to prolonged but not acute stress. Group‐housed rats were placed in a sound chamber 25 cm from speakers randomly emitting four pure tones (5, 11, 15, and 19 kHz) for 30 min. After daily sound stress for 4 weeks rats were lightly anesthetized (isoflurane: 4% induction; 1.75% maintenance) and blood pressure was measured by tail‐cuff plethysmography. Stressed rats did not exhibit changes in diastolic blood pressure but showed a significant increase in systolic blood pressure compared to age‐matched controls: 118.3 ± 1.6 and 96.9 ± 1.7 mmHg, respectively (n=8; p<0.05) suggesting increased sympathetic drive originating in central autonomic and/or pre‐autonomic nuclei. Following blood pressure measurement, brains were removed and tissue from the hypothalamic paraventricular nucleus (PVN) was subjected to qPCR. In pilot experiments we observed elevated gene expression for PACAP (normalized to ribosomal protein L30) in stressed animals (9.10 ± 4.73) versus controls (1.12 ± 0.26; n=8; p=0.1). A similar elevation was observed for the PACAP receptor PAC1R: 5.27 ± 2.47 and 1.12 ± 0.21, respectively (n=8, p=0.1).

Our lab has previously shown that vasopressinergic magnocellular neuroendocrine cells (MNCs) express various NMDA receptor subunits including the obligatory NR1. Other reports show that NMDA receptors (NMDAr) mediate osmotically‐induced vasopressin (VP) release from the hypothalamo‐neurohypophysial system (HNS). Recently, Panatier et al 2006 revealed that D‐serine is the endogenous coagonist for NMDAr in MNCs of the supraoptic nucleus (SON). Therefore, we investigated the role of D‐serine in NMDAr‐mediated VP release from acutely dissected HNS explants taken from adult male C57BL/6 mice and incubated in a perifusion chamber from which samples were analyzed for vasopressin (VP) using EIA (Gregg & Sladek 1984). After a 4 hr incubation, explants were treated with 5‐100 uM NMDA for 1 hr in the presence and absence of SR inhibitor, L‐Aspartic acid β‐hydroxamate (LA‐βH; 3 mM). We found that NMDAr‐mediated VP release was reduced by LA‐βH suggesting that SR activity and D‐serine signaling are required. In immunohistochemical experiments using adult SON sections, we found marked colocalization of green SR immunoreactivity (ir) with either of two astrocyte specific markers, glial fibrillary acidic protein (GFAP) and glial excitatory amino acid transporter GLT‐1 labeled red. In other experiments animals were injected with Evans Blue (EB), which retrogradely labels VP and oxytocin‐producing MNCs projecting to the posterior pituitary with red fluorescence (excitation/emission maxima ~540/680 nm). SR ir was examined under two osmotic states: hyperosmotic (3.5M NaCl) or normosmotic (0.9% NaCl; 0.6cc/100g bw, i.p.). EB‐positive MNCs showed little or no SR ir, which was redistributed in hyperosmotic animals. We hypothesize that a significant proportion of SR is expressed in astrocytes and that D‐serine gliotransmission contributes to VP responses in SON MNCs. Grant Funding Source: Supported by APS STRIDE summer fellowship (JV), APS Porter fellowship (MV), and MARC (GG, RF, RG).

Magnocellular neuroendocrine cells (MNCs) in the supraoptic nucleus (SON) of the hypothalamus release the antidiuretic hormone, vasopressin (VP), in response to hyperosmotic and hypovolemic stimulation. Transient Receptor Potential Vanilloid 1 (TRPV1) receptor channels mediate osmosensitive electrical responses in MNCs and systemic VP release (Naeini et. al., 2006) but the specific mechanism linking TRPV1 channels and secretion of VP has yet to be determined. To examine the role of TRPV1 channels in somatodendritic VP release during hyperosmotic stimulation we treated acutely dissected SON punches in vitro with 350 mOsm/l Locke's solution in the presence and absence of the TRPV1 antagonist, 5‐iodoresiniferatoxin (SB366791). VP values were quantified using enzyme‐linked immunoassay. Hyperosmotic stimulation enhanced VP release and 1.5μM SB366791 attenuated this (p<0.05; n= 39). Mean (±s.e.m.) values for extracellular VP levels in isosmotic, hyperosmotic and hyperosmotic/SB366791 were 7.15±1.7, 11.1±2.8, 3.68±0.7 pg/ml μg protein, respectively. Doses of 0.15 and 10μM also reduced VP levels to 5.5±1.0 and 5.1±1.0, respectively. Immunohistochemistry showed TRPV1 immunoreactivity in SON MNCs. We conclude that TRPV1 channels in SON MNCs are activated during hyperosmotic stimulation and are required for somatodendritic VP secretion during osmotic challenge. (Supported by UC MEXUS)

Soybean oil is a major component of the American diet and its increased consumption correlates positively with the prevalence of obesity and diabetes in the U.S. Our previous findings showed that a high fat diet (HFD) enriched in soybean oil, similar to the American diet, induces more obesity, diabetes, insulin resistance and fatty liver in male mice than an isocaloric diet consisting of coconut oil (CO), as well as a substantial dysregulation of liver gene expression (PMID:28970503, 26200659). Here, RNA-seq analysis reveals that HFDs based on conventional soybean oil (SO), which is high in linoleic acid (LA), and a genetically modified, low-LA soybean oil called Plenish, have similar, albeit non identical, effects on hypothalamic gene expression; in contrast, a CO HFD has a negligible effect compared to the low fat vivarium chow (Viv) diet. Genes related to inflammation and oxidative stress, metabolism, obesity and diabetes, as well as those linked to neurological disorders, are dysregulated by SO and Plenish. Oxt , which encodes the neuropeptide oxytocin (OXT), is the only gene with metabolic and neurological significance upregulated by both soybean oil diets, but not CO, suggesting that Oxt gene expression is altered by neither LA nor the saturated fatty acids present in CO. In contrast, immunohistochemistry (IHC) shows that the two soybean oil diets reduce oxytocin protein (OXT) levels in the supraoptic and paraventricular nuclei of the hypothalamus, while OXT peptide levels are increased in the circulating blood, suggesting that a decrease in hypothalamic OXT may be responsible for SO-induced obesity and diabetes. The phytosterol stigmasterol found in both the SO and Plenish diets did not induce either obesity or diabetes nor affect the oxytocin pathway, suggesting that a component in soybean oil other than LA or stigmasterol is responsible for its metabolic effects. Given the impact that Oxt can have on metabolic processes as well as developmental disorders of social behavior including autism, depression and schizophrenia, the American diet based largely on soybean oil may have a broader impact on human health than previously appreciated.(Funding: NIH NIDDK, NIEHS T32, CCFA, Seed Grant-UCR).