Norma I. Perassi

Adrenal function response to chronic stress in rats with anterodorsal thalami nuclei lesions

The effects of chronic stress (forced immobilization, 15 min/day during 12 days), on the plasma corticosterone and the adrenal catecholamines response in rats with anterodorsal thalami nuclei (ADTN) lesions were studied. In sham lesioned rats, chronic stress produced a significant increase in plasma corticosterone (C), as compared to unstressed animals (p < 0.05). The adrenal C was, however, similar in both groups. There were no differences in plasma C values between unstressed and stressed lesioned rats. The adrenal C content, was significantly lower (P < 0.005) in stressed lesioned rats when compared with unstressed lesioned animals. Adrenal norepinephrine (NE) values, in sham lesioned rats after forced immobilization, were significantly below those found in unstressed sham lesioned ones (P < 0.05). There were no changes in adrenal epinephrine (E) response after forced immobilization. In lesioned rats, NE response to chronic stress showed the opposite pattern to that in sham lesioned ones; the adrenal glands of these animals showed a significant increase in NE content as compared to unstressed lesioned rats (P < 0.01). Similar alterations in the adrenal E concentration were found, post stress values were significantly higher (P < 0.01).

Periodic maternal deprivation and lesion of anterodorsal thalami nuclei induce alteration on hypophyso adrenal system activity in adult rats.

The hypothalamic-pituitary-adrenal (HPA) axis is normally regulated by extrahypothalamic limbic structures, among these, the anterodorsal thalami nuclei (ADTN), which exert an inhibitory influence on HPA, in basal and acute stress conditions in rats. In the present work we have investigated whether neonatal maternal deprivation (MD) produces long-term changes in the ADTN regulation of HPA activity. Maternal deprivation, in female rats, for 4.5 hs daily, during the first 3 weeks of life, produced at 3 months old, a significant decrease in plasma ACTH concentration (p<0.001) and an increase in plasma corticosterone (C) (p<0.001), compared to control non-deprived rats (NMD). Also MD showed higher plasma epinephrine (E) and norepinephrine (NE) levels than NMD rats. The increase of NE (66.6% p<0.001) was higher than that observed in E (19%). After 30 days of ADTN lesion, plasma ACTH values were higher than in sham lesioned rats, in both NMD and MD animals. ACTH response was greater in MD rats. Plasma C, in NMD, was higher, whereas in MD lesioned animals, it was significantly lower than in sham lesioned. In MD rats, lesion produced a significant increase in plasma E and NE (p<0.001), and again, NE increase was higher than E increase. The more accentuated increase of NE than E, suggests sympathetic nervous system hyperactivity. In summary, neonatal maternal deprivation induces long-term alterations on HPA axis sensitivity and medullo adrenal secretion; enhanced sympathetic nervous system activity and, therefore affected the ADTN inhibitory influence on ACTH and adrenal glands secretion.

Central and peripheral actions of α-MSH in the thermoregulation of rats

Abstract The effect of α-MSH on thermoregulation in rats at room temperature was examined. α-MSH (1 μg ICV or 30 μg IP) alone did not alter temperature. However, this peptide was a potent antipyretic when administered centrally or peripherally in rats treated with pyrogen derived from Salmonella typhi .

Effects of handling normal and bulbectomized rats at adrenal and plasma corticosterone levels

Normal and bulbectomized adult rats, male and female, handled daily for 4 weeks, show plasma and adrenal corticosterone values significantly lower than the non-handled ones.

Insulin Sensitivity and Glucose Tolerance in Rats Without Olfactory Bulbs

Blood sugar and hepatic glycogen were analyzed and glucose and insulin-tolerance tests were performed in male and female rats, 15 and 30 days after resection of the olfactory bulbs. No change was obse

Plasma Corticosterone in Adult and Immature Rats without Olfactory Bulbs

Plasma corticosterone levels and the weight of adrenal glands were studied in rats deprived of olfactory bulbs. The bulbectomy was performed in two groups: (A) adult rats; and (B) 30-day-old immature rats. It was found that plasma corticosterone decreased significantly in adult rats, 30 and 45 days after bulbectomy: from 29.6 ± 1.77 to 22.2 ± 1.12 µg/100 ml (p µg/100 ml in those bulbectomized (p

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.

Involvement of the Anterodorsal Thalami Nuclei on the Hypophysoadrenal Response to Chronic Stress in Rats

Anterodorsal thalami nuclei (ADTN) exert an inhibitory influence on the hypophysoadrenal system (HAS) under basal and acute stress conditions; however, after chronic stress, the effect is different. The response to chronic immobilization stress (IMO) (forced immobilization for 15 min/day for 12 days) and variable chronic stress (V) (24-day exposure to different stressors per day) of plasma ACTH and corticosterone (C) in rats with anterodorsal thalami nuclei lesions was studied. In sham-lesioned rats, chronic immobilization stress and variable chronic stress induced a significant increase in plasma ACTH and C and a reduction of adrenal C content. After exposure of lesioned rats to chronic immobilization stress, there was a decrease of plasma ACTH compared to that in unstressed lesioned rats. In contrast, there was significant increase in ACTH levels after variable chronic stress, this increase being smaller than the variable increase elicited in sham-lesioned rats. In all stressed lesioned animals, plasma C remained unchanged. However, adrenal C content decreased significantly compared to that in unstressed lesioned rats. These findings demonstrate that anterodorsal thalami nuclei lesions attenuated the hypophysoadrenal system response to chronic stress. These data are in contrast to those obtained in previous studies under basal and acute stress conditions. The reason for this discrepancy is at present unknown, and its elucidation will require further studies.

Removal of Olfactory Bulbs in Rats of Different Ages: Repercussion on Some Metabolic Constants

The object of this investigation is to study effects of bulbectomy on female rats operated on at 15 and 30 days of age (prepubescent), 50 days (pubescent) and 120 days (adult), with respect to various parameters: these comprise corporal weight, liver weight, blood sugar, liver glycogen, glucose tolerance test and serum free fatty acid. Results were as follows. Body weight: in all groups this was significantly less than in controls except for rats operated on at adult age. Liver weight: (% of body weight) decreases in all groups, but significantly only in animals operated on when 15 days old. Blood sugar: significantly lessened in rats operated on when 30 and 120 days old. Liver glycogen: lessens in rats operated on at 30 and 120 days of age, but significantly only in the former. Glucose tolerance test: the coefficient k is found to increase in rats operated on at 15, 30 and 120 days of age; there is a significant increase in the first two groups. Serum free fatty acids: no marked alterations in any of the groups.

Influence of Anterodorsal Thalami Nuclei on ACTH Release Under Basal and Stressful Conditions

Experiments were carried out to evaluate the effect of anterodorsal thalami nuclei (ADTN) lesions on plasma ACTH and corticosterone (C), in unstressed and stressed rats. Thirty days after lesion, basal values of plasma ACTH, plasma and adrenal C were significantly higher than those in sham lesioned rats (p < 0.05: p < 0.05; p < 0.01, respectively). Chronic stress (forced immobilization, 15 min/day, during 12 days) in sham-operated animals produced a significat increase in ACTH (p < 0.05) and plasma C (p < 0.05), and a slight decrease in adrenal C, as compared to unstressed rats. In lesioned stressed rats, plasma ACTH was below that found in unstressed lesioned and in sham-lesioned stressed rats (p < 0.05). Variations of plasma C concentrations of stressed lesioned rats were not significant. The adrenal glands of stressed lesioned rats showed a significantly lower content of C than that in unstressed lesioned rats (p < 0.005). It is concluded that ADTN in rats may play a significant role in regulating the hipophyso-adrenal system.