scholarly journals Toxoplasma gondii Infection Causes an Atypical Abundance of Oxytocin and Its Receptor in the Female Rat Brain

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1495
Author(s):  
Samira Abdulai-Saiku ◽  
Ajai Vyas
Keyword(s):  
Toxoplasma Gondii ◽  
Sexual Behaviors ◽  
Behavioral Change ◽  
Messenger Rna ◽  
Gonadal Steroids ◽  
Female Rats ◽  
Male Rats ◽  
Sexually Dimorphic ◽  
Female Rat ◽  
Male And Female Rats

Infection with the protozoan Toxoplasma gondii causes loss of innate fear of cat odors in both male and female rats. This behavioral change is presumed to reflect a parasitic manipulation that increases transmission of the parasite from its intermediate to definitive host. The host behavioral change in male rats is dependent on gonadal steroids. In contrast, the loss of fear in female rats is not accompanied by greater gonadal steroids and cannot be rescued by gonadectomy. This disparity suggests that proximate mechanisms of the post infection host behavioral change in rats are sexually dimorphic. Here, we report that female rats infected with Toxoplasma gondii exhibit greater abundance of messenger RNA for oxytocin and oxytocin receptors in the paraventricular nucleus of the hypothalamus and posterodorsal medial amygdala, respectively. Brain oxytocin is critical for sex-typical social and sexual behaviors in female rodents. The change in oxytocin and its receptor could potentially alter activity in the social salience circuits, leading to a reduction in defensive behaviors and an increase in approach to ambivalent environmental cues. Our results argue that sexually dimorphic neural substrates underpin sexually monomorphic host behavioral change in this host–parasite association.

scholarly journals Glutathione Conjugates of Ochratoxin a as Biomarkers of Exposure / Glutationski Konjugati Okratoksina A Kao Biomarkeri Izloženosti

2012 ◽  
Vol 63 (4) ◽  
pp. 417-427 ◽  
Author(s):  
Mariana Tozlovanu ◽  
Delphine Canadas ◽  
Annie Pfohl-Leszkowicz ◽  
Christine Frenette ◽  
Robert J. Paugh ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Rat Kidney ◽  
Female Rats ◽  
Amide Bond ◽  
Male Rats ◽  
Dark Agouti ◽  
Female Rat ◽  
Male And Female ◽  
Male And Female Rats ◽  
Liver And Kidney

AbstractIn the present study the photoreactivity of the fungal carcinogen ochratoxin A (OTA) has been utilised to generate authentic samples of reduced glutathione (GSH) and N-acetylcysteine (NAC) conjugates of the parent toxin. These conjugates, along with the nontoxic OTα, which is generated through hydrolysis of the amide bond of OTA by carboxypeptidase A, were utilised as biomarkers to study the metabolism of OTA in the liver and kidney of male and female Dark Agouti rats. Male rats are more susceptible than female rats to OTA carcinogenesis with the kidney being the target organ. Our studies show that the distribution of OTA in male and female rat kidney is not significantly different. However, the extent of OTA metabolism was greater in male than female rats. Much higher levels of OTα were detected in the liver compared to the kidney, and formation of OTα is a detoxification pathway for OTA. These findings suggest that differences in metabolism between male and female rats could provide an explanation for the higher sensitivity of male rats to OTA toxicity

γ-Aminobutyric acid regulation of neurohypophysial hormone secretion in male and female rats

1989 ◽  
Vol 121 (2) ◽  
pp. 343-349 ◽  
Author(s):  
E. Saridaki ◽  
D. A. Carter ◽  
S. L. Lightman
Keyword(s):  
Hormone Secretion ◽  
Model Systems ◽  
Female Rats ◽  
Aminobutyric Acid ◽  
Male Rats ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Endogenous Gaba ◽  
Male And Female Rats

ABSTRACT The role of γ-aminobutyric acid (GABA) in the control of oxytocin and arginine vasopressin (AVP) release from the posterior pituitary was investigated using the GABA agonist muscimol and the GABA antagonists bicuculline and picrotoxin. Two perifusion model systems were studied using (a) intact isolated posterior pituitaries (IPP) and (b) neurosecretosomes from both male and female rats. In experiments on tissue from male rats, the stimulated release of oxytocin and AVP in both models was inhibited by muscimol, an effect which was reversed in the presence of bicuculline. Bicuculline alone increased the release of oxytocin only. Although similar responses to muscimol or bicuculline were seen in neurosecretosomes from female animals, neither agent affected oxytocin and AVP release from the intact IPP. Picrotoxin had a similar effect to bicuculline on oxytocin in isolated posterior pituitaries from male as well as female rats, although at the neurosecretosome level a paradoxical inhibition was observed. These results provide evidence for an endogenous GABA receptor mechanism at the level of the neurosecretory terminals in both male and female rats. The sexually dimorphic IPP response suggests a second more complex mechanism involving either pituicytenerve terminal interactions and/or a secondary role of other neurotransmitters in the GABA regulation of neurohypophysial hormones. Journal of Endocrinology (1989) 121, 343–349

Change from beta- to alpha-adrenergic glycogenolysis induced by corticosteroids in female rat liver

1997 ◽  
Vol 273 (1) ◽  
pp. R153-R160
Author(s):  
M. Moriyama ◽  
Y. Nakanishi ◽  
S. Tsuyama ◽  
Y. Kannan ◽  
M. Ohta ◽  
...  
Keyword(s):  
Glucose Production ◽  
Plasma Corticosterone ◽  
Mature Female ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Circadian Variations ◽  
Male And Female ◽  
Male And Female Rats ◽  
The Difference

The conversion of beta- to alpha-adrenergic glycogenolysis by corticosteroids was studied in perfused livers of mature female rats. Isoproterenol stimulated glucose production more effectively in female rats than in male rats, but the difference in its stimulatory effect disappeared in adrenalectomized (ADX) rats, whereas it remained in adrenodemedulated rats. When ADX female rats were treated with dexamethasone sulfate, alpha-responses increased and beta-responses decreased, depending on the concentration of dexamethasone sulfate. The treatment of female rats with 1.5 mg/kg dexamethasone sulfate changed the levels of the alpha- and beta-responses to those observed in male rats, and the changes were associated with changes in the number of receptors. Although periodicity of changes in plasma corticosterone levels was observed in both male and female rats, the extent of circadian variations was significantly lower in female rats during the estrous cycle than in male rats. The variations in plasma corticosterone levels and in both alpha- and beta-responses after ovariectomy approached those in male rats. The results suggest that the level of plasma corticosterone might play an important role in the regulation of the relative levels of alpha- and beta-adrenergic responses in female rats.

Gonadal Steroids Regulate Neural Plasticity in the Sexually Dimorphic Nucleus of the Preoptic Area of Adult Male and Female Rats

2008 ◽  
Vol 88 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Brittany N. Dugger ◽  
John A. Morris ◽  
Cynthia L. Jordan ◽  
S. Marc Breedlove
Keyword(s):  
Adult Male ◽  
Neural Plasticity ◽  
Preoptic Area ◽  
Gonadal Steroids ◽  
Female Rats ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Male And Female Rats ◽  
Sexually Dimorphic Nucleus

A SEXUALLY DIMORPHIC RHYTHM IN OESTRADIOL-ACTIVATED LORDOSIS BEHAVIOUR IN THE RAT

1979 ◽  
Vol 83 (2) ◽  
pp. 267-274 ◽  
Author(s):  
S. HANSEN ◽  
P. SÖDERSTEN ◽  
P. ENEROTH ◽  
B. SREBRO ◽  
K. HOLE
Keyword(s):  
Daily Rhythm ◽  
Female Rats ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Sexually Dimorphic ◽  
Female Rat ◽  
Suprachiasmatic Nuclei ◽  
Light Darkness ◽  
Lordosis Behaviour ◽  
Neonatal Castration

Ovariectomized rats exposed to constant plasma levels of oestradiol showed a daily rhythm in lordosis behaviour, with high levels of lordosis occurring during the dark portion of the daily light: darkness cycle and low levels during the light period. Similarly treated male rats failed to show a rhythm in lordosis behaviour. However, neonatal castration permitted the expression of the lordosis rhythm in male rats; conversely, an injection of 1·25 mg testosterone propionate on day 4 of life abolished the rhythm in female rats. Pinealectomy, adrenalectomy or depletion of brain 5-hydroxytryptamine levels did not affect the periodicity in lordosis behaviour but lesions in the suprachiasmatic nuclei of the hypothalamus disrupted the rhythm. It is suggested that the daily rhythm in lordosis behaviour participates in the control of the termination of heat in the female rat and that the perinatal hormone milieu may exert permanent effects on periodic functions.

scholarly journals Mode of GH administration and gene expression in the female rat brain

2017 ◽  
Vol 233 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Marion Walser ◽  
Linus Schiöler ◽  
Jan Oscarsson ◽  
Maria A I Åberg ◽  
Ruth Wickelgren ◽  
...  
Keyword(s):  
Mixed Model ◽  
Brain Regions ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Sexually Dimorphic ◽  
Female Rat ◽  
Expression Levels ◽  
Mixed Model Analysis ◽  
Significant Difference

The endogenous secretion of growth hormone (GH) is sexually dimorphic in rats with females having a more even and males a more pulsatile secretion and low trough levels. The mode of GH administration, mimicking the sexually dimorphic secretion, has different systemic effects. In the brains of male rats, we have previously found that the mode of GH administration differently affects neuron–haemoglobin beta (Hbb) expression whereas effects on other transcripts were moderate. The different modes of GH administration could have different effects on brain transcripts in female rats. Hypophysectomised female rats were given GH either as injections twice daily or as continuous infusion and GH-responsive transcripts were assessed by quantitative reverse transcription polymerase chain reaction in the hippocampus and parietal cortex (cortex). The different modes of GH-administration markedly increased Hbb and 5′-aminolevulinate synthase 2 (Alas2) in both brain regions. As other effects were relatively moderate, a mixed model analysis (MMA) was used to investigate general effects of the treatments. In the hippocampus, MMA showed that GH-infusion suppressed glia- and neuron-related transcript expression levels, whereas GH-injections increased expression levels. In the cortex, GH-infusion instead increased neuron-related transcripts, whereas GH-injections had no significant effect. Interestingly, this contrasts to previous results obtained from male rat cortex where GH-infusion generally decreased expression levels. In conclusion, the results indicate that there is a small but significant difference in response to mode of GH administration in the hippocampus as compared to the cortex. For both modes of GH administration, there was a robust effect on Hbb and Alas2.

Properties and Sex-Specific Differences of GABAA Receptors in Neurons Expressing γ1 Subunit mRNA in the Preoptic Area of the Rat

1999 ◽  
Vol 81 (1) ◽  
pp. 192-203 ◽  
Author(s):  
Sholeen T. Nett ◽  
Juan Carlos Jorge-Rivera ◽  
Margaret Myers ◽  
Ann S. Clark ◽  
Leslie P. Henderson
Keyword(s):  
Sexual Behaviors ◽  
Preoptic Area ◽  
Critical Role ◽  
Female Rats ◽  
Male Rats ◽  
Response Analysis ◽  
Gamma Aminobutyric Acid ◽  
Subunit Mrna ◽  
Receptor Modulation ◽  
Male And Female Rats

Nett, Sholeen T., Juan C. Jorge-Rivera, Margaret Myers, Ann S. Clark, and Leslie P. Henderson. Properties and sex-specific differences of GABAA receptors in neurons expressing γ1 subunit mRNA in the preoptic area of the rat. J. Neurophysiol. 81: 192–203, 1999. Gamma-aminobutyric acid type A (GABAA) receptors expressed within the medial preoptic area (mPOA) are known to play a critical role in regulating sexual and neuroendocrine functions. In the rat brain, high levels of expression of the γ1 subunit mRNA of the GABAA receptor are restricted to a limited number of regions that mediate sexual behaviors, including the mPOA. The biophysical and pharmacological profiles of native γ1-containing receptors in neurons are unknown. Here, we have characterized the properties of GABAA receptor-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) and currents elicited by fast perfusion of GABA to isolated mPOA neurons of juvenile male and female rats. No significant sex-specific differences were evident in the mean peak amplitude, distribution of event amplitudes, kinetics of current decay, or the frequency of sIPSCs. The profile of modulation of sIPSCs by diazepam, β-CCM and zolpidem, allosteric modulators that act at the benzodiazepine (BZ) site of the GABAA receptor, support the assertion that mPOA neurons of both sexes express functional γ1-containing receptors. The ability of zolpidem to modulate both sIPSC amplitude and currents elicited by rapid perfusion of GABA to mPOA neurons differed significantly between the sexes. Zolpidem reversibly induced negative modulation of currents in mPOA neurons isolated from male rats, but had no effect in mPOA neurons from female rats. Concentration-response analysis of responses in neurons acutely isolated from male rats indicated an IC50 of 58 nM with maximal decreases of ∼50% of control peak current amplitude. In situ hybridization analysis demonstrated that levels of the γ1 subunit mRNA are significantly higher in mPOA neurons from male than female rats. No significant sex-specific differences were detected in the levels of α1, α2, or α5 mRNAs. These results suggest that native γ1-containing receptors are expressed in primary neurons of the mPOA and that sex-specific differences in the expression of this subunit may contribute to sexual dimorphism in GABAA receptor modulation by compounds acting at the BZ site.

EFFECTS OF OESTRADIOL AND PROGESTERONE ON THE CONCENTRATION OF α2-MACROGLOBULIN IN THE SERA OF INJURED MALE AND FEMALE RATS

1980 ◽  
Vol 86 (1) ◽  
pp. 189-191 ◽  
Author(s):  
S. C. BELL
Keyword(s):  
Tissue Injury ◽  
Ovarian Hormones ◽  
Female Rats ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Female Rat ◽  
Intact Female ◽  
Male And Female Rats ◽  
Α2 Macroglobulin ◽  
The Mean

The effects of ovarian hormones on the synthesis of α2-macroglobulin in response to injury were investigated. After injection of turpentine to provoke synthesis of α2-macroglobulin, the mean concentrations of this protein in serum were lower in intact female than in male rats. Sera from injured ovariectomized rats contained levels of α2-macroglobulin similar to those of injured male animals. Administration to ovariectomized animals of oestradiol or oestradiol plus progesterone substantially reduced the levels of α2-macroglobulin produced in response to injury. Administration of progesterone only resulted in a small increase in the response of ovariectomized animals to injury. Oestradiol and progesterone had no effect on the response of male rats to injury. These findings suggest that only in the female rat can these steroid hormones, especially oestradiol, regulate the synthesis of α2-macroglobulin in response to tissue injury.

Effect of gonadectomy on AgRP-induced weight gain in rats

2008 ◽  
Vol 295 (6) ◽  
pp. R1747-R1753 ◽  
Author(s):  
Sean Z. Goodin ◽  
Alicia R. Keichler ◽  
Marissa Smith ◽  
Donna Wendt ◽  
April D. Strader
Keyword(s):  
Weight Gain ◽  
Food Intake ◽  
Activity Level ◽  
Female Rats ◽  
Male Rats ◽  
Sexually Dimorphic ◽  
Cell Surface Molecule ◽  
Male And Female ◽  
Male And Female Rats ◽  
The Central Nervous System

Agouti-related peptide (AgRP), the endogenous antagonist to the melanocortin 3 and 4 receptors, elicits robust hyperphagia and weight gain in rodents when administered directly into the central nervous system. The relative influence of AgRP to cause weight gain in rodents partially depends on the activity level of the melanocortin agonist-producing proopiomelanocortin neurons. Both proopiomelanocortin and AgRP neurons within the arcuate nucleus receive energy storage information from circulating peripheral signals such as leptin and insulin. Another modulator of AgRP activity includes the cell surface molecule syndecan-3. Because leptin and insulin affect food intake in a sexually dimorphic way in rodents and syndecan-3-deficient mice regulate adiposity levels through distinct physiological mechanisms, we hypothesized that AgRP-induced weight gain would also be sexually dimorphic in rats. In the present study, the behavioral and physiological effects of centrally-administered AgRP in male and female were investigated. In male rats, AgRP (1 nmol) induced 5 days ( P < 0.0001) of significantly elevated feeding compared with vehicle-treated controls, while females displayed 3 days of hyperphagia ( P < 0.05). However, 1 wk after the injection, both male and female rats gained the same percent body weight (6%). Interestingly, female rats exhibited a greater reduction in energy expenditure (vo2) following AgRP compared with male rats ( P < 0.05). Removal of the gonads did not alter cumulative food intake in male or female rats but did attenuate the dramatic reduction in Vo2 exhibited by females. Both intact and gonadectomized rats demonstrated significantly increased respiratory quotient supporting the anabolic action of AgRP ( P < 0.01). These findings are novel in that they reveal sex-specific underlying physiology used to achieve weight gain following central AgRP in rats.

SERUM CONCENTRATIONS OF TESTOSTERONE, OESTROGENS, LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE IN MALE AND FEMALE RATS DURING THE CRITICAL PERIOD OF NEURAL SEXUAL DIFFERENTIATION

1979 ◽  
Vol 80 (1) ◽  
pp. 103-110 ◽  
Author(s):  
S. F. PANG ◽  
A. R. CAGGIULA ◽  
V. L. GAY ◽  
R. L. GOODMAN ◽  
C. S. F. PANG
Keyword(s):  
Post Partum ◽  
Serum Levels ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Serum Concentrations ◽  
Male And Female ◽  
Rat Pups ◽  
Male And Female Rats ◽  
Sampling Times

Untreated male and female rat pups were killed 1–5 days post partum and the serum concentrations of testosterone, oestrogens, LH and FSH were determined by radioimmunoassay. At all five sampling times, the serum concentrations of testosterone in male rats were about three times higher than those in female rats, but serum levels of oestrogens did not differ between the sexes. Serum concentrations of LH and FSH were lower in male than in female pups. In another study, rats were decapitated 1–10 days after birth and serum concentrations of testosterone were determined with a different radioimmunoassay. Again, at all four sampling times, the concentration of testosterone was significantly higher in the male than in the female pups.

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