Cognitive, Behavioral and Systems NeuroscienceResearch PaperVasopressinergic network abnormalities potentiate conditioned anxious state of rats subjected to maternal hyperthyroidism
Section snippets
Animals
Wistar rats were used in this study. All animal procedures were approved by the local bioethical and biosecurity committees in accordance with the principles exposed in the Handbook for the Use of Animals in Neuroscience Research (Society for Neuroscience. Washington, D.C.1991). Animals were housed on a 12-h light schedule in a room with temperature between 20 and 24 °C with adequate ventilation and given access to standard rat chow and water ad libitum, unless otherwise specified.
The breeding
Significantly potentiated anxious state in MH occurred only after water deprivation
Unconditioned and conditioned anxious states were assessed using two well-validated behavioural tests, the EPM and the VCT. EPM evaluates the exploration versus avoidance state placing the rat in an unconditioned environment with the closed arm representing safety and the open-elevated arm denoting novelty, though risky. Diminished time spent in the open arm and reduced number of entries implies higher unconditioned anxious state. The MH showed no significant differences in these two measured
Discussion
Maternal hyperthyroidism due to Grave's disease and gestational transient thyrotoxicosis is a common endocrine condition during human pregnancy. Besides, inadequate doses for hormone replacement and insufficient monitoring could also put the fetal development under an iatrogenic hyperthyroid environment. In consonance with our previous study reporting that maternal hyperthyroid offspring possess a more reactive neuroendocrinological stress-coping system (Zhang et al., 2008), the results from
Conclusion
In conclusion, the initial EM observation of the reciprocal synaptic connections between AVP and CRF containing neurons in the hypothalamic paraventricular region from this study suggests the existence of synaptic pathways between these two main stress-coping related neuropeptidergic systems in stress over-reactive MH. Hence, our findings open a potential research area for the investigation of the anatomo-functional substrates underlying stress related emotional disturbances in MH offspring.
Acknowledgments
This study was supported by grants: UNAM IN210406, IN224407; CONACYT: 49704, 79641. LZ was on sabbatical leave at MRC Anatomical Neuropharmacology Unit, Oxford University—hospitality from Peter Somogyi and fellowships from DGAPA-UNAM and CONACYT Mexico are greatly acknowledged. MPM, VSH and FSE were supported by DGAPA-UNAM undergraduate scholarships. We would like to thank Paul Bolam (Oxford), Francesco Ferraguti (Innsbruck) and Teresa Morales (INB, UNAM), for critical reading of the
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