Effects of maternal deprivation on adrenal and behavioural responses in rats with anterodorsal thalami nuclei lesions.
There is evidence that repeated maternal isolation of neonatal rats may influence both emotional behavior and Hypothalamic-Pituitary Adrenal (HPA) activity. On the other hand the Anterodorsal Thalami Nuclei (ADTN) exerts an inhibitory influence on the hypophyso-adrenal system under basal and stressful conditions. In the present work we investigated whether neonatal maternal deprivation produces long term effects on the ADTN regulation of behavioral patterns (open field test) and on HPA axis activity. Specifically, we sought to determine whether adult female rats with ADTN lesions, previously isolated for 4.5 hours daily during the first 3 weeks of life, react in endocrinologically and behaviourally distinct manner as compared to controls. The examined groups were: non maternally deprived (NMD)/sham lesioned, NMD/lesioned, maternally deprived (MD)/sham lesioned, MD/lesioned with and without the open field test. At 3 months MD/sham lesioned animals showed a marked decrease in ambulation (P < 0.01), and with ADTN lesion, the rearing values were lower (P < 0.01) and grooming higher (P < 0.05) than NMD. This last data would indicate a high emotional index. Regarding the activity of the HPA axis, maternal deprivation induced a significant decrease in plasma ACTH concentration both in sham and lesioned animals (P < 0.001), and plasma Corticosterone (C) increased in sham animals (P < 0.001). This data would indicate a higher sensitivity of the adrenal glands. After the open field test ACTH and C were different between deprived and non-deprived animals depending on the ADTN lesion. Taking into consideration the increase of ACTH levels in sham lesioned MD animals exposed to the test, we could conclude that this new situation was a stressful situation. Finally in the present work, it was very difficult to relate the behavioral parameters with the endocrine data. It is known that depending on the context, corticosteroids may produce opposite effects on emotional behavior via different receptors in the brain.In summary, neonatal maternal deprivation induced alterations of behavioral patterns and affected the ADTN inhibitory influence on ACTH and C secretion.
Suárez
M
M
Cátedra de Fisiología Humana, Instituto de Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba. Santa Rosa 1085 (5000), Córdoba, Argentina. msuarez@mater.fcm.unc.edu.ar
Molina
S
S
Rivarola
M A
MA
Perassi
N I
NI
D000311:Adrenal Glands / Q000502:physiology*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D020643:Anterior Thalamic Nuclei / Q000033:anatomy & histology / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology; D003672:Defecation / Q000502:physiology; D005260:Female; D006120:Grooming; D006854:Hydrocortisone / Q000097:blood; D008426:Maternal Deprivation; D051381:Rats; D017208:Rats, Wistar
D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone