EFFECT OF AGING AND HISTAMINE BLOCKADE ON SOME CHANGES INDUCED BY CERTAIN TYPES OF STRESS

Abstract

A wide array of physical and psychological stressors alter the secretion of anterior pituitary hormones. However, both qualitative and quantitative features of stressors as well as its dura­ tion markedly influence the final response. The aim of the present work was to study the effect of aging on some stress-induced changes. And to investigate the role of HI-and H2- histaminergic antagonists in mediating these responses in young rats. The 3 forms of stresses were used in this study include immobilization. cold and ether stresses. The durations of each form of stress were 5 min. 20 min & 120 min, according to the group of study. This research was done on 240 male albino rats of the local strain. They were divided into four categories : I -Young Category: They were of about I year old. They were divided into: Control Group. Immobilization Stressed Group, Cold Stressed Group and Ether Stressed Group 11 - Old Category : They were of about 2 years old. They were divide'd into four groups as in the young cat­ egory. III - HI blockade Category : The young rats pretreated with SC 0.1 mg ofTavegyl (HI blocker) for each rat, 2 hours be­ fore the experiment were used in this study. The rats were divided also as in the young cat­ egory. IV - H2 blockade Category : The young rats pretreated with SC 7.2 mg of Tagamet (H2 blocker) for each rat. 2 hours before the experiment were used in this study. The rats Were divided also as in the young cat­ egory. At the end of the experimental period. blood samples were collected retro-orbitally. and the level of PRL. Glucose. & Total Lipids were measured in serum in all categories. The results of this study revealed that the PRL levels significantly increased in response to different stresses. The increase is higher in the young thail in the old rats. except in ether stress. where they are more or less similar. The PRL levels in non stressed Hl or H2 blockade• rats were significantly higher than in the control young rats. Except with ether stress, stresses seemed to decreaSe the PRL levels in Hl blockade cat­ egory. On the other hand. it appears that, stresses didrl't change PRL levels too much in H2 blockade categories. j The stress-hyperglycemia which was more pronouliced in young than in the old rats as shown by the extent of change of glucose level in stressed rats relative to non stressed. It appeared in the results of present study that, both H1 & H2 blockers tend to attenuate stress-hypt:rglycemia. This effect appeared clearly with'all stresses of H2 blockade category while it occurred markedly in ether stressed H l blockade rats & in some durations of im­ mobilization & cold stresses. The present study showed that. stress-hyperlipidemia was more upparent with immobiliza­ tion stress i.n the young cutegory. However. stress-hyperlipidemia was inorc pronounced with cold stress in old rats. While both H l & H2 blockers markedly attenuate stress-hyperlipidemia with all kinds of stress used. • • Thus antihistaminics may play a protective role agail1st atherosclerosis and thrombosis. Key \Vords : Stress. Aging. Stress Hyperglycemia. Stress Hyperlipidemi<l. Histamine Re­ ceptor Antagonists. PRL.