تأثير الهستامين ومستقبلاته في مستوى بعض افرازات الفص الامامي للغدة النخامية في ذكور الجرذان Rattus morvegicus
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Date
2009-10-15
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Abstract
This study was designed to determine the role of histamine in the level of
some secretions of anterior pituitary gland in male rate and to inrestigated the types
of receptors by which the histamine exerts its effects on the secretion of hormones,
besides, knowledge the effect of some blockers of histamine´s receptors in
secretion of those hormones.
In this study histamine was used in adose of 5 mg/kg, chlorpheneramine
(H1 blockor ) in adose of 10 mg/kg and cimetidine (H2 blocker) in adose of 80
mg/kg. All these drugs were injected intraperitoneally, the study included 3
experiments as :
1- Acute effect of histamine in the level of some anterior pituitary gland
secretions:
In this experiment the animals were divided into four groups (n=6) , In the first
group , blood samples were collected after 10 minntes from D.W. injection
(control group) , while the second , third and fourth groups were injected with
histamine and blood sample were collected after 10,20,30 minntes of histamine
injection respectivily .
2- Determination of the receptor by which histamine exerted its effects:
The animals of this experiment were divided into three groups (n=6). The first
group (control group) was injected with D.W. , 30 minutes later was injected
with histamine , blood samples were collected,30 minntes after histamine
injection . In the second and third groups histamine was injected after 30
minutes of injection of H1 and H2 blocker respectivily ,30 minutes later , blood
samples were colleled for hormones estimation.
A
3- Effects of histamine receptors blockers on the secretion of anterior pituitary:
The animals of this experiment were divided into three groups(n=6) . They
were injected with D.W. , H1 and H2 blocker respectivily and blood sample
were collected 30 minutes later .
The study was shown that :
1- Histamine exerted stimulatory effect on the secretion of LH, and ACTH via H1
and H2 receptor and on prolactin secretion via H2 receptors. However, the effect of
histamine on TSH secretion is inhibitory via H2 receptor, while it exerted no
effects on FSH secretion .
2- Injection of H1 blocker alone caused insignificant decline in LH level. However,
it caused significant (p<0.05) decline in the levels of ACTH , and caused
significant (p<0.05) increase in the levels of FSH . It exerted no effects on the
secretion of prolactin and TSH. On the other hand , H2 blocker caused significant
inhibition (p<0.05) in the secretion of LH and prolactin, and caused significant
(p<0.05) increase in the levels of TSH. However, the decline in the level of ACTH
was insignificant, and H2 blocker had no effects on FSH secretion .
As a conclusion , histamine had a regulatory role in the secretion of some
hormones of anterior pituitary gland in the male rats. It exerted this role either
indirectly via stimulation or inhibition of the hypothalamic stimulatory or
inhibitory factors because of the concentration of histaminergic cell in
hypothalamic areas, or the effect may exerted via its direct stimulation or inhibition
of hormones and neuroactive substances which mediated histamine action and
probability occurring interpenetrate actions of other brain neurotransmitters with
histamine action .