Effect of epidermal growth factor on adrenaline induced effects in isolated rabbit heart

Acute psychological stressors induce damage in organs as heart. Catecholamines are responsible for acute stress effects. Adrenaline, through 1-adrenergic receptors; stimulates EOF release to the blood. Because plasma catecholamine concentration is high during the stress and afterwards, organs are exposed to combined effects of both catecholamines and EGF. Intermale fighting [IF stress model] does not raise plasma creatine kinase [CK] activity ,while increases plasma transaminase and lactate dehydrogenase [LDH] activities, So the heart is protected. EGF may protect the heart against the harmful effects of epinephrine. The present research studied EGF administration on adrenaline induced effects in the rabbit heart [invitro] of 8 groups of male white New Zealand rabbits. Heart tissues were excised and incubated. revealed a significant decrease in heart rate, contractility and coronary flow rate in Epidermal growth factor gp. A non significant change in heart rate and coronary flow rate and heart contractility after infusion of alpha blocker and adrenaline.While a significant decrease in heart rate, heart contractility and coronary flow rate in either adrenaline with beta Blocker group and or EGF with adrenaline and a blocker group. EGF with adrenaline and beta Blocker group produced a significant increase in heart rate, heart contractility and coronary flow rate. In spite of EGF positive effects on heart properties, it interfered with the adrenaline positive effects through Beta receptors

Altered gonodal hormone level and constant light-induced stress interfere with the response of the adrenal medulla to oxytocin

The effect of oxytocin (0.25 IU/100 g per day) on the adrenal medulla was examined in intact, intact estrogen-treated, castrated and castrated testosterone-treated adult male Wistar rats. Stereological analysis of the gland (N = 5 rats per group) revealed that in intact animals the number of chromaffin cells (x10(3)) was significantly increased after 3-day (saline: 467.6 +/- 27.4; oxytocin: 567.6 +/- 28.9) or 7-day (saline: 486.2 +/- 39.1; oxytocin: 618.7 +/- 36.8) oxytocin administration. During 7 days of recovery after the 7-day treatment, the chromaffin cell number returned to the control level (saline: 491.4 +/- 12.6; oxytocin: 554.4 +/- 28.7). The effect of oxytocin on chromaffin cell number was also observed in rats simultaneously injected with estradiol (0.3 microg/100 g per day) for 10 days (estradiol: 454.3 +/- 32.8; estradiol + oxytocin: 576.1 +/- 25.0), as well as in 10-day castrated rats (saline: 594.7 +/- 22.7; oxytocin: 765.3 +/- 33.1). Testosterone replacement (0.6 mg/100 g per day) abolished the medullary response to oxytocin (testosterone + saline: 528.5 +/- 24.7; testosterone + oxytocin: 620.8 +/- 56.0). There was a 20 percent rise in adrenal dopamine content (from 0.236 +/- 0.015 to 0.283 +/- 0.015 microg per pair of glands; N = 9-12) in intact rats injected with oxytocin for 3 days. Oxytocin had no effect on any of the catecholamine levels in adrenal glands of rats exposed to stress induced by constant lighting. The present data indicate that the proliferative response of chromaffin tissue to oxytocin depends on the gonadal hormone level and the basal activity of the adrenal medulla.

Histological and ultrastructural study on the suprarenal gland in adult rabbit

This work was carried out on the adrenal gland of twenty adult rabbits [by use of light and electron microscope] to study its structure and to correlate some structural changes to functional activities. The gland was formed of outer cortex, inner medulla and surrounded with multilayered fibrous capsule containing capillaries and nerves. The cortex was composed of three layers which were different in cell arrangement and in their staining affinity. They were zona glomerulosa [outer thin], zona fasciculata [middle thick] and zona reticularis [inner thin]. Zona fasciculata contained the highest amount of mitochondria. SER and lipid droplets. Corticomedullary junction was irregular and formed of interdigitations between cells. Basophilic medulla contained adrenalin and noradrenalin secreting cells with intervening blood vessels, nerve fibers and terminals and Schwann cells. Both types of catecholamine granules occasionally appeared in a single chromaffin cell. For this reason differentiation between chromaffin cells needs caution

Evidence for adrenal medulla involvement in cold adaptation of preoptic-lesioned rats

The cold-adaptation process was examined in preoptic-lesioned (PO, 18 rats) and adrenaldemedullated-preoptic-lesioned rats (ADPO, 16 rats). PO rats and ADPO female Wistar rats wee cold acclimatized to 5-C for 2 h a day for 2 weeks, or maintained at 25C, starting one week after the operation. Control animals (20 rats) were sham-operated and then treated exactly like the lesioned rats. Lesions int he PO region caused a decrease in the ability to maintain normal body temperature in a cold environment (5-C for 2h). Theri colonic temperature fell even by the end of the 2nd h of cold exposure (-1.1-C for PO rats and -1.25-C for ADPO rats, P<0.01). However, after 2 weeks of cold acclimattion the PO rats, but not the ADPO rats were able to thermoregulate in the cold and showed a normal increase in interscapular brown adipose tissue weight (79%, P < 0.01). These data suggest that the PO is not an essential link for cold adaptation when a mild col-adaptation methods is used. Furthermore, the data show that increased adrenal medullary activity is required for the cold adaptation process in PO rats