Dose-dependent neuromodulation has been well established; however, the molecular mechanisms underlying astrocytic involvement in this process remain largely unexplored. Using the autoregulation of supraoptic oxytocin (OT) neurons (OTNs) as a model, we investigated the role of distinct astrocytic G proteins and their targets in the dose-dependent effects of OT on OTN activity. The results showed that OT in a low concentration (10 pmol/L, L-OT) excited OTN activity, whereas a high concentration (1 nmol/L, H-OT) inhibited it in brain slices. These effects were abolished upon disruption of astrocytic plasticity using L-aminoadipic acid, a gliotoxin. In primary astrocyte cultures, L-OT slightly reduced the current through astrocyte-specific inwardly rectifying K⁺ channel 4.1 (Kir4.1) while H-OT strongly enhanced it. Selectively blocking Kir4.1 with BaCl₂ (100 µmol/L) did not affect the basal activity but blocked the excitatory effect of L-OT in brain slices. In cultured astrocytes, L-OT mobilized Gαq subunit expression, increased glial fibrillary acidic protein (GFAP) filaments, and quickly expanded astrocytic volume, predominantly visible at the somata. Conversely, H-OT released Gαi subunits and induced progressive volume expansion. Pretreatment of brain slices with U73122 (a Gq inhibitor) or SQ22536 (a Gs inhibitor) suppressed L-OT-induced excitation. Conversely, activation of adenylyl cyclase with forskolin reversed the inhibitory effect of H-OT, and inhibition of Gi with pertussis toxin blocked H-OT-induced inhibition. These findings imply that the dose-dependent effects of OT on OTN activity are mediated, at least partially, by different receptor-coupled G proteins and their subsequent modulation of astrocytic Kir4.1 currents, GFAP expression, and volume dynamics. This mechanism underlying the autoregulation of OTN activity provides an important reference for understanding the concentration-dependent neuromodulation.

Embedding clinically relevant learning experience in basic science subjects is desired for the preclinical phase of undergraduate medical education. The present study aimed to modify case-based learning (CBL) with a role-playing situational teaching method and assess the student feedback and learning effect. One hundred seventy-six sophomore students majoring in clinical medicine from Harbin Medical University were randomly divided into two groups: the control group (n = 90), who received traditional hybrid teaching, and the experimental group (n = 86), who received the role-playing situational teaching. Students in the experimental group were given a 1-wk preclass preparation to dramatize a hyperthyroidism scenario through online autonomous learning of thyroid physiology and performed the patient's consultation process in class, followed by a student presentation about key points of lecture content and a question-driven discussion. A posttest and questionnaire survey were conducted after class. The test scores of the two groups had no statistical differences, whereas the rate of excellence (high scores) of the experimental group was significantly higher than that of the control group. Furthermore, the record of online self-directed learning engagements was significantly improved in the experimental group. In the questionnaire, >70% of the students showed positive attitudes toward the role-playing situational teaching method and were willing to participate in other chapters of the physiology course. Such results show that CBL supported by a role-playing situational teaching method encourages active learning and improves the application of basic knowledge of physiology, which can be incorporated in the preclinical curricula to bridge the gap between theory and practice.NEW & NOTEWORTHY Formal application through structured role-play is often overlooked in physiology education. In traditional case-based learning (CBL), clinical cases are the subject and unfocused discussion often occurs. The present study aimed to modify CBL with a role-playing situational teaching method and assess the student feedback and learning effect. The results show that the new teaching model encourages active learning and improves the application of basic knowledge of physiology.

BACKGROUND:In the post-pandemic era of higher education, hybrid teaching has emerged as a prevalent approach and is anticipated to persist as a defining trend in the future teaching reforms worldwide. However, despite its widespread adoption, certain limitations have become apparent. The objective of this study is to identify the genuine factors that impact students' performance, explore strategies that teachers can employ to enhance their teaching effectiveness and enhance students' academic self-efficacy. METHODS:The study was performed among undergraduate medical students enrolled in Physiology course at Harbin Medical University in 2020 and 2022. Since 2020, influenced by the COVID-19 pandemic, a hybrid teaching method based on an established offline teaching model called BOPPPS was implemented. A questionnaire was performed in both 2020 and 2022 to evaluate students' satisfaction and efficiency of our hybrid teaching. A comparison was also carried out on the final examination scores of students majoring in Pharmacy and Clinical Pharmacy across the years 2020 to 2022. RESULTS:The final examination scores of students in 2022 were significantly lower than those in 2020 and 2021 both in Pharmacy and Clinical Pharmacy majors. There was also a decrease of the score in students of Clinical Pharmacy in 2021 compared to 2020. The questionnaire indicated that over half (52.0%) of the students in 2022 preferred offline teaching method, in contrast to 39.1% in 2020. There were obvious changes in students from 2020 to 2022 about the disadvantages of hybrid teaching, the improvement of students' learning ability and the duration of students' autonomous learning. Through cross statistical analysis, online learning styles, learning ability improvement and students' learning burden have been identified as the primary factors influencing their preference for future teaching method. CONCLUSIONS:Hybrid teaching is still a necessary trend in the future teaching reform base on its multiple advantages. However, in order to improve the teaching outcomes and foster students' participation and learning initiatives, it is imperative to undertake additional reforms in the future teaching process.

Oxytocin can regulate immunological activity directly or indirectly; however, immunological functions and mechanisms of oxytocin actions under chronic stress like cesarean delivery (CD) are poorly understood. Our study found that abnormal oxytocin production and secretion in CD rats caused atrophy of thymic tissues. Neurotoxin kainic acid microinjected into the dorsolateral supraoptic nucleus in male rats selectively reduced hypothalamic oxytocin levels, increased corticotrophin-releasing hormone and plasma interleukin-1β while reducing plasma oxytocin, thyroxine and testosterone levels and causing atrophy of immune tissues. Thus, plasma oxytocin is essential for immunological homeostasis, which involves oxytocin facilitation of thyroid hormone and sex steroid secretion.

Oxytocin (OT), a hypothalamic nonaneuropeptide, can extensively modulate mental and physical activities; however, the regulation of its secretion from hypothalamic OT neurons remains poorly understood. OT neuronal activity is generally modulated by neurochemical environment, synaptic inputs, astrocytic plasticity, and interneuronal interactions. By changing intracellular signals and ion channel activity, these extracellular factors dynamically regulate OT neuronal activity and OT release in a microdomain-specific manner. In this process, OT receptor (OTR) and OTR-coupled G proteins are pivotal, typically observed during lactation. Suckling-elicited somatodendritic release of OT causes sequential activation of Gq and Gs proteins to increase the firing rate gradually and trigger burst firing transiently, and then of Gi/o protein to cause post-burst inhibition as a result of potential bolus somatodendritic release of OT during the burst-like discharges. Under chronic social stress like mother-baby separation and cesarean section, excessive somatodendritic secretion of OT and over-excitation of OT neurons cause post-excitation inhibition of OT neuronal activity and reduction of OT secretion. In this process, dominance of G protein that couples to OTR is switched from Gq to Gi/o type because of inhibition of OTR-Gq signaling following negative feedback of downstream Gq signaling or crosstalk of Gq with Gs and Gi signals. This review summarizes our current understandings of OT/OTR signaling in the autoregulation of OT neuronal activity under physiological and pathological conditions.

INTRODUCTION:Cerebral swelling and brain injury in ischemic stroke are closely related to increased vasopressin (VP) secretion. How to alleviate ischemic brain injury by suppressing VP hypersecretion through simply available approaches remains to be established. METHODS:Using a rat model of middle cerebral artery occlusion (MCAO), testing effects of the intranasal application of low concentration saline-0.09% NaCl (IAL) on brain damage, VP neuronal activity, synaptic inputs, astrocytic plasticity, and olfactory bulb (OB) activity in immunohistochemistry, patch-clamp recording, Western blotting, and co-immunoprecipitation. RESULTS:IAL reduced MCAO-evoked neurological disorders, brain swelling, injury and loss of neurons, increase in c-Fos expression, and excitation of supraoptic VP neurons. The effects of IAL on VP neurons were associated with its suppression of MCAO-evoked increase in the frequency of excitatory synaptic inputs and decrease in the expression of glial fibrillary acidic protein (GFAP) filaments around VP neurons. MCAO and IAL also caused similar but weaker reactions in putative oxytocin neurons. In the OB, MCAO increased the firing rate of mitral cells on the MCAO side, which was reduced by IAL. A direct hypotonic challenge of OB slices increased the expression of glutamine synthetase and GFAP filaments in the glomerular bodies while reducing the firing rate of mitral cells. Blocking aquaporin 4 activity in the supraoptic and paraventricular nuclei on the MCAO side reduced MCAO-evoked VP increase and brain damage. CONCLUSION:IAL reduces ischemic stroke-evoked brain injury in association with suppression of VP neuronal activity through reducing excitatory synaptic inputs and astrocytic process retraction, which likely result from reducing mitral cell activation in ischemic side.

Teaching biomedical technology is critical for the success of research of both domestic and international postgraduate students (DPSs and IPSs). However, difference in the learning characteristics between the two cohorts as well as appropriate teaching modality remains largely unexplored. In the present work, we studied these issues by recruiting 33 IPSs and 32 DPSs who selected the course of ‘Patch-Clamp Technique and Its Application in Life Science Research’ at Harbin Medical University in China in 2019. Questionnaires were performed to investigate their learning obstacles and style preferences. Correspondingly, we designed a new teaching modality, i.e. lecture enriched with practicum, research proposal and post-course advice (LEPPA in brief) and tested its effect. This modality was positively evaluated by all the IPSs and 90% of the DPSs. The LEPPA can efficiently resolve the concerns of both IPSs and DPSs while promoting their transition from undergraduates to research students.

Introduction: In the regulation of oxytocin (OT) neuronal activity, hydrogen sulfide (H2S), a gaseous neurotransmitter, likely exerts an excitatory role. This role is associated with increased expression of astrocytic cystathionine-β-synthase (CBS), the key enzyme for H2S synthesis. However, it remains unclear whether H2S is mainly produced in astrocytes and contributes to the autoregulation of OT neurons. Methods: In hypothalamic slices of male rats, OT and H2S-associated drug effects were observed on the firing activity and spontaneous excitatory postsynaptic currents (sEPSCs) of putative OT neurons in the supraoptic nucleus (SON) in whole-cell patch-clamp recording. Expression of glial fibrillary acidic protein (GFAP) in the SON was analyzed in Western blots. In addition, changes in the length of rat pups’ hypothalamic astrocytic processes were observed in primary cultures. Results: In brain slices, OT significantly increased the firing rate of OT neurons, which was simulated by CBS allosteric agonist S-adenosyl-L-methionine (SAM) and H2S slow-releasing donor GYY4137 but blocked by CBS inhibitor aminooxyacetic acid (AOAA). L-α-aminoadipic acid (a gliotoxin) blocked SAM-evoked excitation. OT and SAM also increased the frequency and amplitude of sEPSCs; the effect of OT was blocked by AOAA. Both OT and GYY4137 reduced GFAP expression in the SON. Morphologically, OT or GYY4137 time-dependently reduced the length of astrocytic processes in primary cultures. Conclusions: These findings indicate that the auto-excitatory effect of OT on OT neurons is mediated by H2S from astrocytes at least partially and astrocytic H2S can elicit retraction of astrocytic processes that subsequently increase OT neuronal excitability.

We assessed interactions between the astrocytic volume-regulated anion channel (VRAC) and aquaporin 4 (AQP4) in the supraoptic nucleus (SON). Acute SON slices and cultures of hypothalamic astrocytes prepared from rats received hyposmotic challenge (HOC) with/without VRAC or AQP4 blockers. In acute slices, HOC caused an early decrease with a late rebound in the neuronal firing rate of vasopressin neurons, which required activity of astrocytic AQP4 and VRAC. HOC also caused a persistent decrease in the excitatory postsynaptic current frequency, supported by VRAC and AQP4 activity in early HOC; late HOC required only VRAC activity. These events were associated with the dynamics of glial fibrillary acidic protein (GFAP) filaments, the late retraction of which was mediated by VRAC activity; this activity also mediated an HOC-evoked early increase in AQP4 expression and late subside in GFAP-AQP4 colocalization. AQP4 activity supported an early HOC-evoked increase in VRAC levels and its colocalization with GFAP. In cultured astrocytes, late HOC augmented VRAC currents, the activation of which depended on AQP4 pre-HOC/HOC activity. HOC caused an early increase in VRAC expression followed by a late rebound, requiring AQP4 and VRAC, or only AQP4 activity, respectively. Astrocytic swelling in early HOC depended on AQP4 activity, and so did the early extension of GFAP filaments. VRAC and AQP4 activity supported late regulatory volume decrease, the retraction of GFAP filaments, and subside in GFAP-VRAC colocalization. Taken together, astrocytic morphological plasticity relies on the coordinated activities of VRAC and AQP4, which are mutually regulated in the astrocytic mediation of HOC-evoked modulation of vasopressin neuronal activity.

Abstract Background Online teaching has become increasingly common in higher education of the post-pandemic era. While a traditional face-to-face lecture or offline teaching remains very important and necessary for students to learn the medical knowledge systematically, guided by the BOPPPS teaching model, combination of online and offline learning approaches has become an unavoidable trend for maximizing teaching efficiency. However, in physiological education, the effectiveness of combined online teaching and offline teaching models remains poorly assessed. The present study aims at providing an assessment to the hybrid teaching model. Methods The study was performed among undergraduate medical students of Class 2017 ~ 2019 in the Physiology course in Harbin Medical University during 2018-2020. Based on established offline teaching model with BOPPPS components in 2018, we incorporated online teaching contents into it to form a hybrid BOPPPS teaching model (HBOPPPS, in brief), preliminarily in 2019 and completely in 2020. HBOPPPS effectiveness was assessed through comparing the final examination scores of both objective (multi-choice and single answer questions) and subjective (short and long essays) questions between classes taught with different modalities. Results The final examination score of students in Class 2019 (83.9 ± 0.5) who were taught with the HBOPPPS was significantly higher than that in Class 2017 (81.1 ± 0.6) taught with offline BOPPPS and in Class 2018 (82.0 ± 0.5) taught with immature HBOPPPS. The difference mainly attributed to the increase in average subjective scores (41.6 ± 0.3 in Class 2019, 41.4 ± 0.3 in Class 2018, and 38.2 ± 0.4 in Class 2017). In the questionnaire about the HBOPPPS among students in Class 2019, 86.2% responded positively and 79.4% perceived improvement in their learning ability. In addition, 73.5% of the students appreciated the reproducibility of learning content and 54.2% valued the flexibility of HBOPPPS. Lastly, 61.7% of the students preferred the HBOPPPS relative to BOPPPS in future learning. Conclusions HBOPPPS is likely a more effective teaching model and useful for enhancing effectiveness of Physiology teaching. This is attributable to the reproducibility and flexibility as well as the increased learning initiatives.

Oxytocin (OT), a nonapeptide, has a variety of functions. Despite extensive studies on OT over past decades, our understanding of its neural functions and their regulation remains incomplete. OT is mainly produced in OT neurons in the supraoptic nucleus (SON), paraventricular nucleus (PVN) and accessory nuclei between the SON and PVN. OT exerts neuromodulatory effects in the brain and spinal cord. While magnocellular OT neurons in the SON and PVN mainly innervate the pituitary and forebrain regions, and parvocellular OT neurons in the PVN innervate brainstem and spinal cord, the two sets of OT neurons have close interactions histologically and functionally. OT expression occurs at early life to promote mental and physical development, while its subsequent decrease in expression in later life stage accompanies aging and diseases. Adaptive changes in this OT system, however, take place under different conditions and upon the maturation of OT release machinery. OT can modulate social recognition and behaviors, learning and memory, emotion, reward, and other higher brain functions. OT also regulates eating and drinking, sleep and wakefulness, nociception and analgesia, sexual behavior, parturition, lactation and other instinctive behaviors. OT regulates the autonomic nervous system, and somatic and specialized senses. Notably, OT can have different modulatory effects on the same function under different conditions. Such divergence may derive from different neural connections, OT receptor gene dimorphism and methylation, and complex interactions with other hormones. In this review, brain functions of OT and their underlying neural mechanisms as well as the perspectives of their clinical usage are presented.

Astrocytic morphological plasticity and its modulation of adjacent neuronal activity are largely determined by astrocytic volume regulation, in which glial fibrillary acidic protein (GFAP), aquaporin 4 (AQP4), and potassium channels including inwardly rectifying K+ channel 4.1 (Kir4.1) are essential. However, associations of astrocyte-dominant Kir4.1 with other molecules in astrocytic volume regulation and the subsequent influence on neuronal activity remain unclear. Here, we report our study on these issues using primary cultures of rat pups' hypothalamic astrocytes and male adult rat brain slices. In astrocyte culture, hyposmotic challenge (HOC) significantly decreased GFAP monomer expression and astrocytic volume at 1.5 min and increased Kir4.1 expression and inwardly rectifying currents (IRCs) at 10 min. BaCl2 (100 μmol/l) suppressed the HOC-increased IRCs, which was simulated by VU0134992 (2 μmol/l), a Kir4.1 blocker. Preincubation of the astrocyte culture with TGN-020 (10 μmol/l, a specific AQP4 blocker) made the HOC-increased Kir4.1 currents insignificant. In hypothalamic brain slices, HOC initially decreased and then increased the firing rate of vasopressin (VP) neurons in the supraoptic nucleus. In the presence of BaCl2 or VU0134992, HOC-elicited rebound increase in VP neuronal activity was blocked. GFAP was molecularly associated with Kir4.1, which was increased by HOC at 20 min; this increase was blocked by BaCl2 . These results suggest that HOC-evoked astrocytic retraction or decrease in the volume and length of its processes is associated with increased Kir4.1 activity. Kir4.1 involvement in HOC-elicited astrocytic retraction is associated with AQP4 activity and GFAP plasticity, which together determines the rebound excitation of VP neurons.

Oxytocin (OT), a neuropeptide produced in the supraoptic (SON) and paraventricular (PVN) nuclei, is not only essential for lactation and maternal behavior but also for normal immunological activity. However, mechanisms underlying OT regulation of maternal behavior and its association with immunity around parturition, particularly under mental and physical stress, remain unclear. Here, we observed effects of OT on maternal behavior in association with immunological activity in rats after cesarean delivery (CD), a model of reproductive stress. CD significantly reduced maternal interests to the pups throughout postpartum day 1-8. On postpartum day 5, CD decreased plasma OT levels and thymic index but increased vasopressin, interleukin (IL)-1β, IL-6 and IL-10 levels. CD had no significant effect on plasma adrenocorticotropic hormone and corticosterone levels. In the hypothalamus, CD decreased corticotropin-releasing hormone contents in the PVN but increased OT contents in the PVN and SON and OT release from hypothalamic implants. CD also increased c-Fos expression, particularly in the cytoplasm of OT neurons. Lastly, CD depolarized resting membrane potential and increased spike width while increasing the variability of the firing rate of OT neurons in brain slices. Thus, CD can increase hypothalamic OT contents and release but reduce pituitary release of OT into the blood, which is associated with depressive-like maternal behavior, increased inflammatory cytokine release and decreased relative weight of the thymus.

AIM:Glial fibrillary acidic protein (GFAP) molecularly associates with aquaporin 4 (AQP4) in astrocytic plasticity. Here, we further examined how AQP4 modulates osmotic effects on vasopressin (VP) neurons in rat supraoptic nucleus (SON) through interactions with GFAP in astrocytes.METHODS:Brain slices from adult male rats were kept under osmotic stimulation. Western blot, co-immunoprecipitation, immunohistochemistry and patch-clamp recordings were used for analysis of expressions and interactions between GFAP and AQP4, astrocyte-specific proteins in the SON, as well as their influence on VP neuronal activity. Data were analysed using SPSS software.RESULTS:Hyposmotic challenge (HOC) of acute SON slices caused an early (within 5 minutes) and transient increase in the colocalization of AQP4 with GFAP filaments. This effect was prominent at astrocytic processes surrounding VP neuron somata and was accompanied by inhibition of VP neuronal activity. Similar HOC effect was seen in the SON isolated from rats subjected to in vivo HOC, wherein a transiently increased molecular association between GFAP and AQP4 was detected using co-immunoprecipitation. The late stage rebound excitation (10 minutes) of VP neurons in brain slices subjected to HOC and the associated astrocytic GFAP's 'return to normal' were both hampered by 2-(nicotinamide)-1,3,4-thiadiazole, a specific AQP4 channel blocker that itself did not influence VP neuronal activity. Moreover, this agent prevented hyperosmotic stress-evoked excitation of VP neurons and associated reduction in GFAP filaments.CONCLUSION:These findings indicate that osmotically driven increase in VP neuronal activity requires the activation of AQP4, which determines a retraction of GFAP filaments.

Oxytocin (OT) is a key factor for maternal behavior. However, neurochemical regulation of OT neurons, the major source of OT, remains incompletely understood. Here we report the effect of intranasally-applied OT (IAO) on OT neuronal activity in the supraoptic nucleus (SON) and on maternal behavior in a rat model of cesarean delivery (CD) at day 4–5 (stage I) and day 8–9 (stage II) following delivery. We found that at stage I, CD dams exhibited significantly longer latency of pup retrieval, lower number of anogenital licks and smaller acinar area of the mammary glands. In the SON, the number of OT neurons expressing phosphorylated extracellular signal-regulated protein kinase 1/2 (pERK 1/2) decreased significantly. IAO reversed the depressive-like maternal behavior and involution-like change in the mammary glands, and restored the number of pERK1/2-positive OT neurons in CD dams. At stage II, CD did not significantly influence the latency of retrieval and pERK1/2 expression in the SON. However, CD still reduced the number of anogenital licks during suckling, which was reversed by IAO. Notably, IAO but not hypodermic OT application in CD dams significantly increased litter’s body weight gains. In brain slices, CD but not CD plus IAO significantly depolarized membrane potential and increased spike duration in OT neurons. In vasopressin neurons, CD, but not CD plus IAO, significantly depolarized membrane potential and increased the firing rate. Thus, decreased OT neuronal activity and increased vasopressin neuronal activity impair maternal behavior in CD dams, which can be prevented by IAO .

Oxytocin (OT) neuronal activity is the key factor for breastfeeding and it can be disrupted by mother-baby separation. To explore cellular mechanisms underlying OT neuronal activity, we studied the role of protein kinase A (PKA) in OT neuronal activity in the supraoptic nucleus (SON) using a rodent model of pup deprivation (PD) Intermittent (IPD) or continuous (CPD) PD significantly reduced suckling duration and number of milk ejections in lactating rats, particularly those with CPD. In Western blots of the SON, PD increased expressions of OT receptor (OTR) and its immediate downstream effectors, Gαq and Gβ subunits, particularly IPD, but reduced the expression of catalytic subunit of PKA (cPKA). In brain slices, inhibition of PKA blocked prostaglandin E2-evoked increase in firing activity including burst firing in OT neurons. In IPD dams, filamentous actin formed ring-like structures in the cytoplasmic region of OT neurons, which was reduced in CPD. Moreover, molecular association between actin and cPKA also reduced in PD dams. Incubation of brain slices with OT reduced the expression of cPKA, which was blocked by pretreatment with atosiban, an antagonist of OTR. These results indicate that PD disrupts OT neuronal activity through dissociating the Gq proteins and PKA in OTR-associated signaling cascade, which couples with reduced interactions between filamentous actin and PKA in OT neurons in the SON. This study highlights that PKA can be a novel target treating abnormal OT neuronal activity and its associated diseases.

In higher education, it is a great challenge for instructors to teach international medical students (IMSs) efficiently. These students usually have different learning obstacles and learning style preferences from domestic students. Thus it is necessary to use teaching modalities targeting the specific characteristics of IMSs. Accordingly, we have developed a teaching modality composed of classical teacher-centered approach (TCA), enriched with components of student-centered approach (SCA) and online interactions targeting the learning characteristics of IMSs, which we defined as TESOT (an acronym made of the underlined words' initials). Aside from the online interactions that provide both answers to questions raised by students and guidance throughout a course, this modality contains additional in-classroom components (i.e., pre-lecture quiz, student-led summary, and post-lecture quiz). The effectiveness of this modality was tested in the nervous system module of the Physiology course for IMSs. The final exam scores in the nervous system module in the year taught with TESOT were higher than those earned by students taught with a classical TCA modality in preceding 2 yr. The improvement of teaching effectiveness is attributable to increasing communication, bridging course contexts, and meeting diverse learning style preferences. These results indicate that TESOT as an effective teaching modality is useful for enhancing efficiency of teaching IMSs.

Maternal social stress among breastfeeding women can be adapted in chronic process. However, neuroendocrine mechanisms underlying such adaptation remain to be identified. Here, we report the effects of 2 hr/day unfamiliar male rat invasion (UMI) stress on maternal behaviors in lactating rats during postpartum day 8 (UMI8) to postpartum day 12 (UMI12). Rat dams at UMI8 presented signs of maternal anxiety, depression, and attacks toward male intruder. These changes partially reversed at UMI12 except the sign of anxiety. In the supraoptic nucleus (SON), UMI12 but not UMI8 significantly increased the expression of c-Fos and phosphorylated extracellular signal-regulated protein kinase 1/2. At UMI8 but not UMI12, length of glial fibrillary acidic protein (GFAP, astrocytic cytoskeletal element) filaments around oxytocin (OT) neurons was significantly longer than that of their controls; the amount of GFAP fragments at UMI12 was significantly less than that at UMI8. Expression of cystathionine β-synthase (CBS, enzyme for H2S synthesis) at UMI12 was significantly higher than that at UMI8. CBS expression did not change significantly in the somatic zone of the SON but decreased significantly at the ventral glia lamina at UMI8. In brain slices of the SON, aminooxyacetate (a CBS blocker) significantly increased the expression of GFAP proteins that were molecularly associated with CBS. Aminooxyacetate also reduced the firing rate of OT neurons whereas Na2S, a donor of H2S, increased it. The adaptation during chronic social stress is possibly attributable to the increased production of H2S by astrocytes and the subsequent retraction of astrocytic processes around OT neurons.

Vasopressin (VP) is a key factor in the development of brain injury in ischemic stroke. However, the regulation of VP secretion in basilar artery occlusion (BAO) remains unclear. To clarify the regulation of VP secretion in BAO and the underlying mechanisms, we performed this study in a rat model of BAO with (BC) or without common carotid artery occlusion (CCAO). The results showed that BAO and BC time-dependently increased neurological scores and that BC also increased water contents in the medulla at 2 h and in the pontine at 8 h. Moreover, plasma VP level increased significantly at BAO-8 h, CCAO and BC-2 h but not at BC-8 h; however, VP expressions increased in the supraoptic nucleus (SON) at BC-8 h. The neurological scores were highly correlated with pontine water contents and plasma VP levels. The number of phosphorylated extracellular signal-regulated protein kinase1/2-positive VP neurons increased significantly in the SON at BC-8 h. Similarly, the number of c-Fos-positive VP neurons increased significantly in the SON at BAO-8 h and BC-8 h. In addition, the length of glial fibrillary acidic protein (GFAP) filaments increased significantly in BC compared to BAO only. Aquaporin 4 (AQP4) puncta around VP neurons increased significantly at BC-8 h relative to BC-2 h, which had negative correlation with plasma VP levels. These findings indicate that BAO facilitates VP secretion and increases VP neuronal activity in the SON. The peripheral VP release is possibly under a negative feedback regulation of central VP neuronal activity through increasing GFAP and AQP4 expression in astrocytic processes.