Maternal Acetate Supplementation Reverses Blood Pressure Increase in Male Offspring Induced by Exposure to Minocycline during Pregnancy and Lactation.

Emerging evidence supports that hypertension can be programmed or reprogrammed by maternal nutrition. Maternal exposures during pregnancy, such as maternal nutrition or antibiotic use, could alter the offspring's gut microbiota. Short-chain fatty acids (SCFAs) are the major gut microbiota-derived metabolites. Acetate, the most dominant SCFA, has shown its antihypertensive effect. Limited information exists regarding whether maternal acetate supplementation can prevent maternal minocycline-induced hypertension in adult offspring. We exposed pregnant Sprague Dawley rats to normal diet (ND), minocycline (MI, 50 mg/kg/day), magnesium acetate (AC, 200 mmol/L in drinking water), and MI + AC from gestation to lactation period. At 12 weeks of age, four groups (n = 8/group) of male progeny were sacrificed. Maternal acetate supplementation protected adult offspring against minocycline-induced hypertension. Minocycline administration reduced plasma acetic acid level, which maternal acetate supplementation prevented. Additionally, acetate supplementation increased the protein level of SCFA receptor G protein-coupled receptor 41 in the offspring kidneys. Further, minocycline administration and acetate supplementation significantly altered gut microbiota composition. Maternal acetate supplementation protected minocycline-induced hypertension accompanying by the increases in genera Roseburia, Bifidobacterium, and Coprococcus. In sum, our results cast new light on targeting gut microbial metabolites as early interventions to prevent the development of hypertension, which could help alleviate the global burden of hypertension.

Baroreflex functionality in the eye of diffusion tensor imaging.

By applying diffusion tensor imaging (DTI) as a physiological tool to evaluate changes in functional connectivity between key brainstem nuclei in the baroreflex neural circuits of mice and rats, recent work has revealed several hitherto unidentified phenomena regarding baroreflex functionality. (1) The presence of robust functional connectivity between nucleus tractus solitarii (NTS) and nucleus ambiguus (NA) or rostral ventrolateral medulla (RVLM) offers a holistic view on the moment-to-moment modus operandi of the cardiac vagal baroreflex or baroreflex-mediated sympathetic vasomotor tone. (2) Under pathophysiological conditions (e.g. neurogenic hypertension), the disruption of functional connectivity between key nuclei in the baroreflex circuits is reversible. However, fatality ensues on progression from pathophysiological to pathological conditions (e.g. hepatic encephalopathy) when the functional connectivity between NTS and NA or RVLM is irreversibly severed. (3) The absence of functional connectivity between the NTS and caudal ventrolateral medulla (CVLM) necessitates partial rewiring of the classical neural circuit that includes CVLM as an inhibitory intermediate between the NTS and RVLM. (4) Sustained functional connectivity between the NTS and NA is responsible for the vital period between brain death and the inevitable cardiac death. (5) Reduced functional connectivity between the NTS and RVLM or NA points to inherent anomalous baroreflex functionality in floxed and Cre-Lox mice. (6) Disrupted NTS-NA functional connectivity in Flk-1 (VEGFR2) deficient mice offers an explanation for the hypertensive side-effect of anti-vascular endothelial growth factor therapy (anti-VEGF) therapy. These newly identified baroreflex functionalities revealed by DTI bear clinical and therapeutic implications.

Maternal Melatonin Therapy Attenuates Methyl-Donor Diet-Induced Programmed Hypertension in Male Adult Rat Offspring.

Although pregnant women are advised to consume methyl-donor food, some reports suggest an adverse outcome. We investigated whether maternal melatonin therapy can prevent hypertension induced by a high methyl-donor diet. Female Sprague-Dawley rats received either a normal diet, a methyl-deficient diet (L-MD), or a high methyl-donor diet (H-MD) during gestation and lactation. Male offspring were assigned to four groups (n = 7⁻8/group): control, L-MD, H-MD, and H-MD rats were given melatonin (100 mg/L) with their drinking water throughout the period of pregnancy and lactation (H-MD+M). At 12 weeks of age, male offspring exposed to a L-MD or a H-MD diet developed programmed hypertension. Maternal melatonin therapy attenuated high methyl-donor diet-induced programmed hypertension. A maternal L-MD diet and H-MD diet caused respectively 938 and 806 renal transcripts to be modified in adult offspring. The protective effects of melatonin against programmed hypertension relate to reduced oxidative stress, increased urinary NO2- level, and reduced renal expression of sodium transporters. A H-MD or L-MD diet may upset the balance of methylation status, leading to alterations of renal transcriptome and programmed hypertension. A better understanding of reprogramming effects of melatonin might aid in developing a therapeutic strategy for the prevention of hypertension in adult offspring exposed to an excessive maternal methyl-supplemented diet.

Targeting arachidonic acid pathway to prevent programmed hypertension in maternal fructose-fed male adult rat offspring.

Hypertension can be programmed in response to nutritional insults in early life. Maternal high-fructose (HF) intake induced programmed hypertension in adult male offspring, which is associated with renal programming and arachidonic acid metabolism pathway. We examined whether early treatment with a soluble epoxide hydrolase (SEH) inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA) or 15-Deoxy-Δ12,14-prostagandin J2 (15dPGJ2) can prevent HF-induced programmed hypertension. Pregnant Sprague Dawley rats received regular chow or chow supplemented with fructose (60% diet by weight) during the whole period of pregnancy and lactation. Four groups of male offspring were studied: control, HF, HF+AUDA and HF+15dPGJ2. In HF+AUDA group, mother rats received AUDA 25 mg/L in drinking water during lactation. In the HF+15dPGJ2 group, male offspring received 15dPGJ2 1.5 mg/kg body weight by subcutaneous injection once daily for 1 week after birth. Rats were sacrificed at 12 weeks of age. Maternal HF-induced programmed hypertension is associated with increased renal protein level of SEH and oxidative stress, which early AUDA therapy prevents. Comparison of AUDA and 15dPGJ2 treatments demonstrated that AUDA was more effective in preventing HF-induced programmed hypertension. AUDA therapy increases angiotensin converting enzyme-2 (ACE2) protein levels and PGE2 levels in adult offspring kidney exposed to maternal HF. 15dPGJ2 therapy increases plasma asymmetric dimethylarginine (ADMA) levels and decreases L-arginine-to-ADMA ratio. Better understanding of the impact of arachidonic acid pathway, especially inhibition of SEH, on renal programming may aid in developing reprogramming strategy to prevent programmed hypertension in children exposed to antenatal HF intake.

Hyperbaric Oxygen Therapy Alleviates Carbon Monoxide Poisoning-Induced Delayed Memory Impairment by Preserving Brain-Derived Neurotrophic Factor-Dependent Hippocampal Neurogenesis.

OBJECTIVE: To test the hypothesis that hyperbaric oxygen therapy ameliorates delayed cognitive impairment after acute carbon monoxide poisoning by promoting neurogenesis through upregulating the brain-derived neurotrophic factor in the hippocampus. DESIGN: Laboratory animal experiments. SETTING: University/Medical center research laboratory. SUBJECTS: Adult, male Sprague-Dawley rats. INTERVENTIONS: Rats were divided into five groups: (1) non-carbon monoxide-treated control, (2) acute carbon monoxide poisoning, (3) acute carbon monoxide poisoning followed by 7-day hyperbaric oxygen treatment, (4) carbon monoxide + hyperbaric oxygen with additional intracerebroventricular infusion of Fc fragment of tyrosine kinase receptor B protein (TrkB-Fc) chimera, and (5) acute carbon monoxide poisoning followed by intracerebroventricular infusion of brain-derived neurotrophic factor. Acute carbon monoxide poisoning was achieved by exposing the rats to carbon monoxide at 2,500 ppm for 40 minutes, followed by 3,000 ppm for 20 minutes. Hyperbaric oxygen therapy (at 2.5 atmospheres absolute with 100% oxygen for 60 min) was conducted during the first 7 days after carbon monoxide poisoning. Recombinant human TrkB-Fc chimera or brain-derived neurotrophic factor was infused into the lateral ventricle via the implanted osmotic minipump. For labeling of mitotic cells in the hippocampus, bromodeoxyuridine was injected into the peritoneal cavity. Distribution of bromodeoxyuridine and two additional adult neurogenesis markers, Ki-67 and doublecortin, in the hippocampus was evaluated by immunohistochemistry or immunofluorescence staining. Tissue level of brain-derived neurotrophic factor was assessed by enzyme-linked immunosorbent assay. Cognitive behavior was evaluated by the use of eight-arm radial maze. MEASUREMENTS AND MAIN RESULTS: Acute carbon monoxide poisoning significantly suppressed adult hippocampal neurogenesis evident by the reduction in number of bromodeoxyuridine-positive, Ki-67⁺, and doublecortin⁺ cells in the subgranular zone of the dentate gyrus. This suppression of adult neurogenesis by the carbon monoxide poisoning was appreciably alleviated by early treatment of hyperbaric oxygen. The hyperbaric oxygen treatment also promoted a sustained increase in hippocampal brain-derived neurotrophic factor level. Blockade of hippocampal brain-derived neurotrophic factor signaling with intracerebroventricular infusion of recombinant human TrkB-Fc chimera significantly blunted the protection by the hyperbaric oxygen on hippocampal neurogenesis; whereas intracerebroventricular infusion of brain-derived neurotrophic factor mimicked the action of hyperbaric oxygen and preserved hippocampal neurogenesis after acute carbon monoxide poisoning. Furthermore, acute carbon monoxide poisoning resulted in a delayed impairment of cognitive function. The hyperbaric oxygen treatment notably restored the cognitive impairment in a brain-derived neurotrophic factor-dependent manner. CONCLUSIONS: The early hyperbaric oxygen treatment may alleviate delayed memory impairment after acute carbon monoxide poisoning by preserving adult neurogenesis via an increase in hippocampal brain-derived neurotrophic factor content.

Differential effects of bevacizumab, ranibizumab and aflibercept on cell viability, phagocytosis and mitochondrial bioenergetics of retinal pigment epithelial cell.

PURPOSE: To evaluate the short- and long-term effects of most clinically used anti-vascular endothelial growth factor agents, including bevacizumab, ranibizumab or aflibercept, on cell viability, phagocytosis, mitochondrial bioenergetics and the oxidant acrolein-induced oxidative stress of human adult retinal pigment epithelial (ARPE)-19 cells. METHODS: In cultured ARPE-19 cells, cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, phagocytotic activity and intracellular reactive oxygen species (ROS) level were determined by flow cytometry, mitochondrial bioenergetics was assessed using a Seahorse XF24 Extracellular Flux Analyzer, and protein expression was measured by Western blotting. RESULTS: Long-term exposure to all three agents had no effect on cell viability; but rescued the ARPE-19 cells from acrolein-induced decrease in cell viability. Bevacizumab, but not ranibizumab or aflibercept, suppressed the phagocytotic activity of ARPE-19 cells and exerted significantly less protection against acrolein-induced inhibition of phagocytosis. Both ranibizumab and aflibercept increased basal respiratory rate and maximal mitochondrial respiratory capacity after 1-hr exposure; but returned to baseline following 24- or 72-hr exposure. In contrast, both responses were reduced on short-term exposure, but augmented after long-term exposure to bevacizumab. Long-term pretreatment with all three agents reversed acrolein-induced impairment of mitochondrial bioenergetics, overproduction of ROS and phosphorylation of the mitogen-activated protein kinases in ARPE-19 cells. CONCLUSION: Bevacizumab might affect mitochondrial bioenergetics differently from that by ranibizumab and aflibercept. Ranibizumab and aflibercept at their therapeutic dose protect against acrolein-induced oxidative cytotoxicity in human ARPE-19 cells via an increase in mitochondrial bioenergetics. An early protective action on mitochondrial bioenergetic capacity might be used to predict possible long-term antioxidative effects of the agents in the eye.

Maternal fructose-intake-induced renal programming in adult male offspring.

Nutrition in pregnancy can elicit long-term effects on the health of offspring. Although fructose consumption has increased globally and is linked to metabolic syndrome, little is known about the long-term effects of maternal high-fructose (HF) exposure during gestation and lactation, especially on renal programming. We examined potential key genes and pathways that are associated with HF-induced renal programming using whole-genome RNA next-generation sequencing (NGS) to quantify the abundance of RNA transcripts in kidneys from 1-day-, 3-week-, and 3-month-old male offspring. Pregnant Sprague-Dawley rats received regular chow or chow supplemented with HF (60% diet by weight) during the entire period of pregnancy and lactation. Male offspring exhibited programmed hypertension at 3 months of age. Maternal HF intake modified over 200 renal transcripts from nephrogenesis stage to adulthood. We observed that 20 differentially expressed genes identified in 1-day-old kidney are related to regulation of blood pressure. Among them, Hmox1, Bdkrb2, Adra2b, Ptgs2, Col1a2 and Tbxa2r are associated with endothelium-derived hyperpolarizing factor (EDHF). NGS also identified genes in arachidonic acid metabolism (Cyp2c23, Hpgds, Ptgds and Ptges) that may be potential key genes/pathways contributing to renal programming and hypertension. Collectively, our NGS data suggest that maternal HF intake elicits a defective adaptation of interrelated EDHFs during nephrogenesis which may lead to renal programming and hypertension in later life. Moreover, our results highlight genes and pathways involved in renal programming as potential targets for therapeutic approaches to prevent metabolic-syndrome-related comorbidities in children with HF exposure in early life.

Maternal citrulline supplementation prevents prenatal N(G)-nitro-L-arginine-methyl ester (L-NAME)-induced programmed hypertension in rats.

Nitric oxide (NO) deficiency induced by the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine-methyl ester (L-NAME) resulted in hypertension. L-citrulline (CIT) can be converted to L-arginine to generate NO. We examined whether maternal CIT supplementation can prevent L-NAME-induced programmed hypertension. Pregnant Sprague-Dawley rats were assigned to four groups: control, L-NAME, control + citrulline (CIT), and L-NAME + citrulline (L-NAME+CIT). Pregnant rats received L-NAME administration at 60 mg/kg/day subcutaneously during pregnancy alone or with additional 0.25% l-citrulline solution in drinking water during the whole period of pregnancy and lactation. Male offspring were sacrificed at 12 wk of age. L-NAME exposure during pregnancy induces hypertension in the 12-wk-old offspring. Maternal CIT therapy prevented L-NAME-induced programmed hypertension, which was associated with a decreased asymmetric dimethylarginine (ADMA) concentration and an increased L-arginine-to-ADMA ratio in the kidney, increased urinary cGMP levels, and decreased renal protein levels of type 3 sodium hydrogen exchanger (NHE3). Together, our data suggest that the beneficial effects of CIT supplementation are attributed to its ability to increase NO level in the kidney and inhibition of NHE3 expression. Our results suggest that supplementing CIT in pregnant women with NO deficiency can improve fetal development and prevent programmed hypertension.

Melatonin prevents maternal fructose intake-induced programmed hypertension in the offspring: roles of nitric oxide and arachidonic acid metabolites.

Fructose intake has increased globally and is linked to hypertension. Melatonin was reported to prevent hypertension development. In this study, we examined whether maternal high fructose (HF) intake causes programmed hypertension and whether melatonin therapy confers protection against the process, with a focus on the link to epigenetic changes in the kidney using next-generation RNA sequencing (NGS) technology. Pregnant Sprague-Dawley rats received regular chow or chow supplemented with HF (60% diet by weight) alone or with additional 0.01% melatonin in drinking water during the whole period of pregnancy and lactation. Male offspring were assigned to four groups: control, HF, control + melatonin (M), and HF + M. Maternal HF caused increases in blood pressure (BP) in the 12-wk-old offspring. Melatonin therapy blunted the HF-induced programmed hypertension and increased nitric oxide (NO) level in the kidney. The identified differential expressed gene (DEGs) that are related to regulation of BP included Ephx2, Col1a2, Gucy1a3, Npr3, Aqp2, Hba-a2, and Ptgs1. Of which, melatonin therapy inhibited expression and activity of soluble epoxide hydrolase (SEH, Ephx2 gene encoding protein). In addition, we found genes in arachidonic acid metabolism were potentially involved in the HF-induced programmed hypertension and were affected by melatonin therapy. Together, our data suggest that the beneficial effects of melatonin are attributed to its ability to increase NO level in the kidney, epigenetic regulation of genes related to BP control, and inhibition of SEH expression. The roles of DEGs by the NGS in long-term epigenetic changes in the adult offspring kidney require further clarification.

Resveratrol stimulates mitochondrial bioenergetics to protect retinal pigment epithelial cells from oxidative damage.

PURPOSE: Resveratrol (RSV) alleviates oxidative damage in human adult retinal pigment epithelial (ARPE) cells. Mitochondrial bioenergetics is associated with oxidative stress. The purpose of this study was to examine the role of mitochondrial bioenergetics in the cytoprotective effect of RSV. Its role in protection against the adverse effects of cigarette smoke (CS) in experimental choroidal neovascularization (CNV) was also examined. METHODS: Cultured ARPE-19 cells were treated with acrolein alone or acrolein with added RSV. Temporal changes in cell viability, expression of the antioxidant protein, and mitochondrial bioenergetics were evaluated. In an animal study, CNV lesions were created in Brown Norway rats by laser-induced photocoagulation. Effects of CS alone or with additional RSV treatment on CNV lesions were quantified by fundus fluorescein angiography. RESULTS: In ARPE-19 cells, RSV rescued acrolein-induced cell death, alongside reversal of acrolein-induced superoxide dismutase expression. Resveratrol increased the mitochondrial bioenergetics, including basal respiratory rate, adenosine triphosphate synthesis via oxidative phosphorylation, and maximal mitochondrial capacity. In animal experiments, CS induced a significant increase in CNV following laser injury, and this increase in CNV was appreciably prevented following peripheral infusion of RSV. CONCLUSIONS: Our results indicate that RSV, a major polyphenol found in red wine, exerts protection against acrolein-induced cytotoxicity in human ARPE-19 cells via increases in the mitochondrial bioenergetics. In addition, the antioxidant effect of RSV may contribute to protection against laser-induced CNV in animals exposed to CS. Therefore, RSV might be beneficial for treatment of acrolein-induced or CS-evoked RPE degeneration.

Redox-sensitive oxidation and phosphorylation of PTEN contribute to enhanced activation of PI3K/Akt signaling in rostral ventrolateral medulla and neurogenic hypertension in spontaneously hypertensive rats.

AIMS: The activity of phosphoinositide 3-kinase (PI3K)/serine/threonine protein kinase (Akt) is enhanced under hypertension. The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a negative regulator of PI3K signaling, and its activity is redox-sensitive. In the rostral ventrolateral medulla (RVLM), which is responsible for the maintenance of blood pressure, oxidative stress plays a pivotal role in neurogenic hypertension. The present study evaluated the hypothesis that redox-sensitive inactivation of PTEN results in enhanced PI3K/Akt signaling in RVLM, leading to neurogenic hypertension. RESULTS: Compared to age-matched normotensive Wistar-Kyoto (WKY) rats, PTEN inactivation in the form of oxidation and phosphorylation were greater in RVLM of spontaneously hypertensive rats (SHR). PTEN inactivation was accompanied by augmented PI3K activity and PI3K/Akt signaling, as reflected by the increase in phosphorylation of Akt and mammalian target of rapamycin. Intracisternal infusion of tempol or microinjection into the bilateral RVLM of adenovirus encoding superoxide dismutase significantly antagonized the PTEN inactivation and blunted the enhanced PI3K/Akt signaling in SHR. Gene transfer of PTEN to RVLM in SHR also abrogated the enhanced Akt activation and promoted antihypertension. Silencing PTEN expression in RVLM with small-interfering RNA, on the other hand, augmented PI3K/Akt signaling and promoted long-term pressor response in normotensive WKY rats. INNOVATION: The present study demonstrated for the first time that the redox-sensitive check-and-balance process between PTEN and PI3K/Akt signaling is engaged in the pathogenesis of hypertension. CONCLUSION: We conclude that an aberrant interplay between the redox-sensitive PTEN and PI3k/Akt signaling in RVLM underpins neural mechanism of hypertension.

Upregulation of AT1 receptor gene on activation of protein kinase Cbeta/nicotinamide adenine dinucleotide diphosphate oxidase/ERK1/2/c-fos signaling cascade mediates long-term pressor effect of angiotensin II in rostral ventrolateral medulla.

OBJECTIVE: Angiotensin II induces the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) 1/2 via the activation of nicotinamide adenine dinucleotide diphosphate (NADPH) oxidase on stimulation of the angiotensin subtype 1 receptor (AT1R) in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons for the maintenance of vasomotor tone and blood pressure are located. Angiotensin II-activated p38 MAPK in RVLM promotes a short-term pressor effect via augmented glutamatergic neurotransmission. We tested the hypothesis that the NADPH oxidase-dependent phosphorylation of ERK1/2 after the activation of conventional protein kinase C (PKC) mediates the AT1R-dependent long-term pressor effects of angiotensin II via transcriptional induction of the proto-oncogene c-fos gene in RVLM. METHODS AND RESULTS: In Sprague-Dawley rats, a microinjection of angiotensin II bilaterally into the RVLM induced membrane-bound translocation of the conventional PKCalpha, PKCbeta or PKCgamma isoform, phosphorylation of the p47 subunit of NADPH oxidase and ERK1/2, followed by phosphorylation of the transcription factor cyclic adenosine monophosphate response element binding protein (CREB), and c-fos induction. The PKC inhibitor antagonized angiotensin II-induced p47 phosphorylation, and an antisense oligonucleotide (ASON) complementary to PKCbeta messenger RNA suppressed angiotensin II-induced ERK1/2 activation, phosphorylation or DNA binding activity of CREB, and upregulation of c-fos mRNA expression in the ventrolateral medulla. Furthermore, a microinjection of ERK1/2, CREB or c-fos ASON into the RVLM significantly reduced the long-term pressor effect and augmented AT1R expression in the ventrolateral medulla induced by intracerebroventricular infusion of angiotensin II. CONCLUSION: We concluded that the PKCbeta/NADPH oxidase/ERK1/2/CREB/c-fos cascade represents a novel signaling cascade that mediates the long-term pressor effect induced by angiotensin II in the RVLM.

Coenzyme q10 confers cardiovascular protection against acute mevinphos intoxication by ameliorating bioenergetic failure and hypoxia in the rostral ventrolateral medulla of the rat.

Coenzyme Q10 (CoQ10, ubiquinone) is a highly mobile electron carrier in the mitochondrial respiratory chain that also acts as an antioxidant. We evaluated the cardiovascular protective efficacy of CoQ10 at the rostral ventrolateral medulla (RVLM), a medullary site where sympathetic vasomotor tone originates and where the organophosphate poison mevinphos (Mev) acts to elicit cardiovascular intoxication. Experiments were carried out in adult male Sprague-Dawley rats that were maintained under propofol anesthesia. Microinjection bilaterally of Mev (10 nmol) into the RVLM induced progressive hypotension and minor bradycardia, alongside significant depression of the activity of NADH cytochrome c reductase (enzyme marker for Complexes I and III) or cytochrome c oxidase (enzyme marker for Complex IV) in the mitochondrial respiratory chain, reduction in ATP concentration, or tissue hypoxia in the RVLM. On the other hand, the activity of succinate cytochrome c reductase (enzyme marker for Complexes II and III) remained unaltered. The Mev-induced hypotension, bioenergetic failure, or hypoxia was significantly reversed when CoQ10 (4 microg) was coadministered bilaterally into the RVLM with the organophosphate poison. We conclude that CoQ10 confers cardiovascular protection against acute Mev intoxication by acting on the RVLM, whose neuronal activity is intimately related to the "life-and-death" process. We also showed that amelioration of the selective dysfunction of respiratory enzyme Complexes I and IV in the mitochondrial respiratory chain, the reduced ATP level, and the induced tissue hypoxia in the RVLM are among some of the underlying mechanisms for the elicited protection.

Up-regulation of glutamate receptors in nucleus tractus solitarii underlies potentiation of baroreceptor reflex by heat shock protein 70.

Whereas induction of the 70-kDa heat shock protein (HSP70) in the nucleus tractus solitarii (NTS), the terminal site in the brain stem for primary baroreceptor afferents, augments baroreceptor reflex (BRR) response, the underlying cellular and molecular mechanism is essentially unexplored. In Sprague-Dawley rats, we evaluated the hypothesis that HSP70 may potentiate BRR response by up-regulating the molecular synthesis and functional expression of glutamate receptors in the NTS. Animals subjected to brief hyperthermic heat shock (HS; 42 degrees C for 15 min) exhibited augmented expression of NR1 or NR2A subunit of N-methyl-D-aspartate (NMDA) receptors, GluR1 or GluR4 subunits of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors and KA1 subunit of kainate receptors in the NTS. Intriguingly, this up-regulation of glutamate receptors was preceded by an increase in HSP70 expression at the NTS. The HS-induced augmentation in responsiveness of barosensitive NTS neurons to transient hypertension or potentiation of BRR response was discernibly blunted by MK-801 or 6-cyano-7-nitroquinoxaline-2,3-dione. Bilateral microinjection into the NTS of an antisense hsp70 oligonucleotide (50 pmol) before HS significantly suppressed the induced expression of HSP70 or the increase in glutamate receptor subunits in the dorsal medulla and discernibly attenuated the potentiation of BRR response. Control microinjection into the NTS of sense or scrambled hsp70 oligonucleotide (50 pmol) was ineffective. These findings suggest that HSP70 induced by HS may enhance BRR response by up-regulating the molecular synthesis and functional expression of NR1 or NR2A subunit of NMDA receptors and GluR1, GluR4, or KA1 subunit of non-NMDA receptors in the NTS.