Hypothalamic-pituitary-adrenal axis responsivity to an acute novel stress in female rats subjected to the chronic mild stress paradigm.

The chronic mild stress (CMS) paradigm is the most frequently investigated animal model for major depression. The hypothalamic-pituitary-adrenal (HPA) axis participates in the generation of depressive symptomatology. We examined whether the depression-like state induced by CMS is associated with immediate changes in HPA axis activation in response to a novel acute stress and whether this response could be modified by hormonal status. Adult female Wistar rats were ovariectomized and received estrogen or vehicle pellets. After 2 weeks, rats were subjected to CMS (or control) conditions for 2.5 or 4.5 weeks. Rats were subsequently subjected to restraint stress for 1 h, and plasma corticosterone (CT) levels were determined before (2:00 p.m.) and after acute stress induction (3:00 and 4:00 p.m.). CT levels and FOS expression were measured in the medial parvocellular subdivision of the PVN (PaMP), central (CeA) and medial amygdala (MeA) and ventral subiculum of the hippocampus (vSub). Plasma CT levels in animals treated with 6.5 weeks of estrogen were elevated before and 1 h after restraint stress induction. Results indicate that the estrogen chronicity and CMS exposure impacted CT secretion. Neuronal PaMP, CeA, MeA and vSub activity decreased after 4.5 weeks of CMS in all groups. No differences were detected between CMS and non-CMS groups. These data suggest that the HPA central hyporesponsiveness observed in the experimental groups subjected to a longer protocol period was independent to CMS paradigm and estrogen treatment restored partially its activity. These data suggest that additional stressors could be responsible for the observed alterations of the HPA axis.

Role of central hydrogen sulfide on ventilatory and cardiovascular responses to hypoxia in spontaneous hypertensive rats.

Central hydrogen sulfide (H2S) has been reported to act as a gaseous neuromodulator involved in the ventilatory and cardiovascular control of normotensive rats, whereas no information is available in spontaneously hypertensive rats (SHR). We recorded minute ventilation (VE), mean arterial pressure (MAP) and heart rate (HR) before and after blocking of enzyme Cystathionine ß-synthase (CBS) producing H2S in neural tissue by microinjection of aminooxyacetate (inhibitor of CBS) into the fourth ventricle of Wistar normotensive rats (WNR) and SHR followed by 30min of normoxia (21% inspired O2) or hypoxia (10% inspired O2) exposure. Microinjection of AOA or saline (1µL) did not change VE, MAP and HR during normoxia in both WNR and SHR. In WNR, hypoxia caused an increase in VE, HR and a decrease in MAP and these responses were unaltered by AOA. In SHR, hypoxia produced a higher increase of VE, and decrease in MAP and HR when compared to WNR, and these responses were all blunted by AOA. In conclusion, endogenous H2S plays important modulatory roles on hypoxia-induced ventilatory and cardiovascular responses, inhibiting the cardiovascular and stimulating the respiratory systems in SHR.

Acute urinary retention in a pre-school girl with constipation / Retenção urinária aguda em pré-escolar feminina com constipação intestinal

Objective: To report a case of a preschool girl who developed acute urinary retention associated with constipation. Case description: A girl aged six years old presented a 24 h history of inability to urinate. She was went twice to the emergency room during this period. In the first admission, 12 h after the onset of the symptoms, she presented abdominal pain and acute urinary retention. After the drainage by urinary catheterization of 300 mL of clear urine, she presented relief of the symptoms and, as urinalysis had no change, the patient was discharged home. Twelve hours after the first visit, she returned to the emergency room complaining about the same symptoms. At physical examination, there was only a palpable and distended bladder up to the umbilicus with no other abnormalities. Again, a urinary catheterization was performed, which drained 450 mL of clear urine, with immediate relief of the symptoms. Urinalysis and urine culture had no abnormalities. During the anamnesis, the diagnosis of constipation was considered and a plain abdominal radiography was performed, which identified large amount of feces throughout the colon (fecal retention). An enema with a 12% glycerin solution was prescribed for three days. During follow-up, the child used laxatives and dietary modifications, this contributed to the resolution of the constipation. There were no other episodes of urinary retention after 6 months of follow-up. Comments: Acute urinary retention in children is a rare phenomenon and constipation should be considered as a cause.

Objetivo: Relatar um caso de criança que desenvolveu retenção urinária aguda associada à constipação intestinal. Descrição do caso: Menina, seis anos, havia 24 horas apresentara incapacidade de liberação de esfíncter vesical. Foi atendida por duas vezes em um serviço de emergência nesse período. Na primeira consulta, 12 horas após o início do quadro, apresentava dor abdominal e retenção urinária aguda e foi feita sondagem de alívio com saída de 300mL de urina clara. Houve alívio imediato dos sintomas e, como o exame de urina tipo 1 não apresentou alterações, a paciente recebeu alta. No segundo atendimento, 12 horas após a primeira consulta, apresentava as mesmas queixas. Ao exame físico, observou-se apenas bexiga palpável e distendida até a cicatriz umbilical, sem outras alterações. Nova sondagem vesical foi feita com saída de 450mL de urina clara, com alívio imediato dos sintomas. Nenhuma anormalidade foi observada no exame de urina tipo 1 e na urocultura. Durante a anamnese, foi levantada a hipótese diagnóstica de constipação intestinal. Foi feita radiografia simples de abdome, que identificou grande quantidade de fezes em todo o cólon (retenção fecal). Enema com solução glicerinada a 12% foi prescrito por três dias. Durante o seguimento a criança fez uso de laxativos e modificações na dieta que contribuíram para a resolução da constipação intestinal. Não houve repetição do quadro de retenção urinária aguda após seis meses de acompanhamento. Comentários: A retenção urinária aguda em crianças é um fenômeno raro e a constipação intestinal deve ser considerada como uma das causas.

[Acute urinary retention in a pre-school girl with constipation]. / Retenção urinária aguda em pré-escolar feminina com constipação intestinal.

OBJECTIVE: To report a case of a preschool girl who developed acute urinary retention associated with constipation. CASE DESCRIPTION: A girl aged six years old presented a 24 hour history of inability to urinate. She was went twice to the emergency room during this period. In the first admission, 12 hours after the onset of the symptoms, she presented abdominal pain and acute urinary retention. After the drainage by urinary catheterization of 300 mL of clear urine, she presented relief of the symptoms and, as urinalysis had no change, the patient was discharged home. Twelve hours after the first visit, she returned to the emergency room complaining about the same symptoms. At physical examination, there was only a palpable and distended bladder up to the umbilicus with no other abnormalities. Again, a urinary catheterization was performed, which drained 450 mL of clear urine, with immediate relief of the symptoms. Urinalysis and urine culture had no abnormalities. During the anamnesis, the diagnosis of constipation was considered and a plain abdominal radiography was performed, which identified large amount of feces throughout the colon (fecal retention). An enema with a 12% glycerin solution was prescribed for three days. During follow-up, the child used laxatives and dietary modifications, this contributed to the resolution of the constipation. There were no other episodes of urinary retention after 6 months of follow-up. COMMENTS: Acute urinary retention in children is a rare phenomenon and constipation should be considered as a cause.

Divergent roles of the CRH receptors in the control of gonadotropin secretion induced by acute restraint stress at proestrus.

CRH has been implicated as a mediator of stress-induced effects on the hypothalamus-pituitary-gonad axis, acting via CRH receptors in various brain regions. We investigated whether the effects of restraint stress on the secretion of gonadotropins on the morning of proestrus are mediated by the CRH-R1 or CRH-R2 receptors in the oval subdivision of the anterolateral BST, the central amygdala, the locus coeruleus (LC), or the A1 and A2 neuron groups in the medulla. At proestrus morning, rats were injected with antalarmin (a CRH-R1 antagonist), asstressin2-B (a CRH-R2 antagonist) or vehicles. Thirty minutes after the injection, the animals were placed into restraints for 30 min, and blood was sampled for 2 h. At the end of the experiment, the brains were removed for immunofluorescence analyses. Restraint stress increased the levels of FSH and LH. Antalarmin blocked the stress-induced increases in FSH and LH secretion, but astressin2-B only blocked the increase in FSH secretion. LC showed intense stress-induced neuronal activity. FOS/tyrosine-hydroxylase coexpression in LC was reduced by antalarmin, but not astressin2-B. The CRH-R1 receptor, more than CRH-R2 receptor, appears to be essential for the stimulation of the hypothalamus-pituitary-gonad axis by acute stress; this response is likely mediated in part by noradrenergic neurons in the LC. We postulate that the stress-induced facilitation of reproductive function is mediated, at least in part, by CRH action through CRH-R1 on noradrenaline neurons residing in the LC that trigger GnRH discharge and gonadotropin secretion.

The CRH-R1 receptor mediates luteinizing hormone, prolactin, corticosterone and progesterone secretion induced by restraint stress in estrogen-primed rats.

Acute stress has been shown to modify hypothalamus-pituitary-gonadal (HPG) axis activity. Corticotropin-releasing hormone (CRH), the principal regulator of the hypothalamus-pituitary-adrenal (HPA) axis, has been implicated as a mediator of stress-induced effects on the reproductive axis. The role of the specific CRH receptor subtypes in this response is not completely understood. In the current study, we investigated the role of the CRH-R(1) receptor on luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), progesterone (P) and corticosterone (CT) secretion in stress-induced responses under the influence of estrogen (E(2)). Estrogen-primed ovariectomized rats (estradiol cypionate, 10 µg sc) received an i.v. administration of antalarmin (0.1 or 1mg/kg), a selective CRH-R(1) antagonist, or vehicle before restraint stress for 40 min. Seven blood samples were collected from two experimental groups (one from 10:00 h to 14:00 h and the other from 10:00 h to 18:00 h). An increase of plasma LH induced by restraint acute-stress was followed by alteration of the secretion pattern in the estrogen-induced afternoon surge. In a similar manner, we observed a suppression of the afternoon surge in plasma FSH, a delay of E(2)-induced PRL secretion, and an increase in plasma P and CT. Antalarmin attenuated stress-induce LH increase, decreased CT and P secretion and blocked the stress effects on PRL secretion. These findings suggest that CRH-R(1) mediates, at least in part, the restraint stress effects on the HPA, PRL, and reproductive axes.