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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 71 (1988), S. 291-297 
    ISSN: 1432-1106
    Keywords: ACTH ; Emotional response ; Motor activity ; Vasopressin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In an attempt to find whether vasopressin (VP) secretion is suppressed by learned emotional stress, we have given rats under a hypertonic condition simultaneously applied light and tone that had been paired previously with footshocks and have quantified immunoreactive VP (ir-VP) in the plasma. In a training session light (60 watt) and tone (2 kz) of 3-s duration which were paired with electric footshocks (50 Hz, 1-s duration) were given to rats 11 times at an interval of 30 s. Various lengths of time after the training, the rats were tested with light and tone, which were unpaired with footshocks and repeatedly applied every 15 s for 3 min in the box used for training. Hypertonic NaCl (0.5 M, 2 ml/ 100 g b. w.) was injected s. c. 30 min before testing to increase the basal level of plasma VP. After testing, plasma ir-VP was significantly less in the experimental group than in the 0-mA control group of rats that were trained without FS. The values for the experimental group were also significantly less than those of untested control rats that had been trained with FS but were not tested. Plasma osmolality and blood haemoglobin concentration were not significantly different between control and experimental groups. Plasma immunoreactive adrenocorticotrophic hormone (ir-ACTH) level was higher and motor activity as expressed by cumulative time period of body movement during testing was lower in the experimental group than in either of the control groups. The difference in plasma ir-VP between experimental and control groups was statistically significant two days but not seven days after training, whereas ACTH and motor activity in experimental groups were still significantly different from those in control groups seven days after training. The suppressive VP and augmentative ACTH responses to testing disappeared in the rats that had received light and tone repeatedly during the intervening period between training and testing. These data support the hypothesis that emotional stimuli suppress VP secretion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 48 (1982), S. 420-428 
    ISSN: 1432-1106
    Keywords: ADH-neurone ; Amygdala ; Rat ; Supraoptic nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of amygdala stimulation on the discharge activity of antidromically identified supraoptic neurosecretory neurones were studied in male rats anaesthetized with urethane. Stimulation of the medial and the basal amygdala produced excitation or inhibition of discharge activity both in phasically firing (“phasic”) and in continuously firing (”continuous”) neurones. More “phasic” neurones were excited than were inhibited after medial amygdala stimulation. On the other hand, fewer “continuous” neurones were excited by stimulation of the either amygdala area than were inhibited. This difference of responsiveness between “phasic” and “continuous” neurones is statistically significant. Synaptic inputs to supraoptic neurosecretory neurones after amygdala stimulation were also observed in rats with a lesion of the stria terminalis. Supraoptic nucleus stimulation activated antidromically 14 of the 336 amygdala neurones tested. Since “phasic” neurones have been identified as ADH-secreting neurones, it is concluded that ADH-secreting neurones in the rat supraoptic nucleus receive predominantly excitatory synaptic inputs from the medial amygdala and these amygdalar synaptic inputs are mediated by pathways which are at least in part monosynaptic and are not included in the stria terminalis.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 81 (1990), S. 53-58 
    ISSN: 1432-1106
    Keywords: Vasopressin ; Oxytocin ; Adrenocorticotrophic hormone ; Emotional stress ; Opioid ; Prolactin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of an opioid receptor antagonist, naloxone (NAL), were studied on the changes in pituitary hormone secretion induced by emotional stress. Male Wistar rats were trained with tone stimuli paired with electric footshocks and tested with the tone and environmental cue signals for emotional stress of fear acquired by learning as described previously (Onaka et al. 1988). Rats received s.c. injected NAL 30 min before testing at doses of 0, 0.2, 1.0, 5.0 and 25.0 mg/kg b.w. Half the rats were injected with 0.5 M NaCl (20 ml/kg b.w.) together with NAL. In these hypertonic rats plasma vasopressin level was slightly increased after NAL. The increment was statistically significant in control groups but not in experimental groups. However the suppression of vasopressin secretion by emotional stimuli was not changed by NAL. Plasma oxytocin levels were extremely high and not significantly different among experimental, unshocked control and untested control groups. NAL further increased the oxytocin level dose-dependently. NAL did not significantly change plasma adrenocorticotrophic hormone (ACTH) levels and hence did not modify the augmentative response in ACTH secretion to emotional stimuli. Plasma prolactin level was significantly elevated after emotional stimuli and NAL depressed the prolactin level in each of experimental and control groups. After NAL, the magnitude of the facilitatory response in prolactin secretion to emotional stimuli was decreased. Motor activity and its suppressive response to emotional stimuli were not influenced by NAL. In another half of rats under a normal osmotic condition the vasopressin response to emotional stimuli was not affected by NAL. NAL further augmented potentiation of oxytocin secretion after emotional stimuli dose-dependently. Effects of NAL on ACTH level, prolactin level and motor activity were similar to those in rats under hypertonic conditions. These results demonstrate that endogenous opioids are selectively and differentially involved in hypothalamo-hypophysial responses to fear-related emotional stress.
    Type of Medium: Electronic Resource
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