33
Volume 04 Issue 02-2022
The American Journal of Medical Sciences and Pharmaceutical Research
(ISSN
–
2689-1026)
VOLUME
04
I
SSUE
02
Pages:
33-37
SJIF
I
MPACT
FACTOR
(2020:
5.
286
)
(2021:
5.
64
)
OCLC
–
1121105510
METADATA
IF
–
7.569
Publisher:
The USA Journals
ABSTRACT
This article discusses hormonal function of adenohypophysis, which produces a number of hormones that regulate
the growth of the child. The production of adenohypophysis hormones, in turn, depends on liberins and statins,
hormones of the hypothalamus that enter the pituitary portal system.
KEYWORDS
Adenohypophysis, adenohypophysis hormones, hormonal function, growth of the child, liberins, statins.
INTRODUCTION
The secretion of liberins and statins is controlled by
adrenergic, cholinergic and dopaminergic neurons of
higher nerve centers [1]. In addition, the secretion of
certain hormones of the adenohypophysis and liberins
is inhibited by the hormones of the peripheral
endocrine glands according to the principle of negative
feedback. Thus, hormones of the hypothalamus,
adenohypophysis, and peripheral endocrine glands,
the targets of adenohypophyseal hormones, are
involved in growth regulation [2]. 7 hormones were
isolated from the extract of the anterior pituitary
gland: growth hormone, or somatotropic hormone,
Research Article
HORMONAL FUNCTION OF ADENOHYPOPHISIS
Submission Date:
February 10, 2022,
Accepted Date:
February 20, 2022,
Published Date:
February 28, 2022 |
Crossref doi:
https://doi.org/10.37547/TAJMSPR/Volume04Issue02-08
Sadik Tursunovich Khudaiberdiev
Candidate of Medical Sciences of the Department of Pathological Anatomy and Forensic Medicine, Andijan
State Medical Institute, Uzbekistan
Journal
Website:
https://theamericanjou
rnals.com/index.php/ta
jmspr
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
34
Volume 04 Issue 02-2022
The American Journal of Medical Sciences and Pharmaceutical Research
(ISSN
–
2689-1026)
VOLUME
04
I
SSUE
02
Pages:
33-37
SJIF
I
MPACT
FACTOR
(2020:
5.
286
)
(2021:
5.
64
)
OCLC
–
1121105510
METADATA
IF
–
7.569
Publisher:
The USA Journals
thyroid-stimulating
hormone,
follicle-stimulating
hormone, luteinizing hormone, luteotropic hormone,
prolactin
(lactogenic)
and
adrenocorticotropic
hormone (ACTH). All hormones of the anterior lobe are
of a protein nature and are obtained in a purified form,
some of them, such as growth hormone and
lactogenic, are isolated in crystalline form, others are
synthesized (for example, ACTH). Thyroid-stimulating
and gonadotropic hormones are produced by
basophilic cells, which, in accordance with this, are
divided into two types: the so-called. thyrotrophs and
gonadotrophs. Oxyphilic cells produce growth
hormone and prolactin. The question of cells
producing ACTH has not been resolved; it is probably
formed by basophils [3].
MATERIALS AND METHODS
A growth hormone. STG family. It includes growth
hormone and prolactin, as well as a hormone formed in
the placenta - placental lactogen. All these hormones
consist of one non-glycosylated polypeptide chain and
are characterized by a significant similarity of the
primary structure.
STH is synthesized in somatotropic cells, has a
molecular weight of 22,000 and contains 191 amino
acids. The physiological effects of STG are usually
divided into direct and indirect. Direct effects of
growth hormone: stimulation of the synthesis and
secretion of IGF in the liver and other organs and
tissues, stimulation of lipolysis in adipose tissue and
stimulation of glucose production in the liver. The
indirect effects of GH are its growth-promoting and
anabolic effects. These effects are mediated by IGF-I.
The main source of IGF-I is the liver. IGF-I stimulates the
growth of bone, cartilage and soft tissues. The indirect
effects of growth hormone are suppressed by
glucocorticoids.
This peptide hormone is produced in somatotropic
cells of the adenohypophysis. Synthesis and secretion
of growth hormone are controlled by two
hypothalamic
hormones:
somatoliberin
and
somatostatin.
Somatoliberin
stimulates,
and
somatostatin suppresses the secretion of growth
hormone and blocks the stimulating effect of
somatoliberin. It has been established that
somatostatin is produced not only in the
hypothalamus, but also in other parts of the nervous
system, as well as in the gastrointestinal tract.
Somatostatin suppresses the secretion of many
hormones, including insulin, glucagon, and gastrin [72].
The level of GH secretion depends on the ratio of
somatoliberin and somatostatin concentrations. Once
in the blood, GH interacts with a GH-binding protein
homologous to the extracellular domain of the GH
receptor.
The growth-stimulating effect of GH is mediated by IGF
- hormones that are formed under the influence of GH
in the liver and other tissues. Two types of IGF have
been identified: IGF-I and IGF-II. These are single-chain
proteins similar in structure to proinsulin. IGF-I and IGF-
II are present in serum mainly in the form of complexes
with binding proteins. The most common IGF-binding
protein type 3. IGF-I and IGF-II affect target cells in
different ways. This is due to differences in the
interaction of IGF with receptors. Both IGF-I and IGF-II
bind to IGF-I receptors, but the similarity of IGF-I to IGF-
I receptors is much greater than that of IGF-II. Both
IGFs are involved in fetal development; in the
postembryonic period, IGF-I plays a major role in
growth regulation. It stimulates the proliferation of
cells of all tissues, primarily cartilage and bone. The
physiological role of IGF-II in the development of a child
and in an adult organism has not yet been elucidated.
As well as growth hormone, both IGFs act on the
hypothalamus and adenohypophysis on the feedback
35
Volume 04 Issue 02-2022
The American Journal of Medical Sciences and Pharmaceutical Research
(ISSN
–
2689-1026)
VOLUME
04
I
SSUE
02
Pages:
33-37
SJIF
I
MPACT
FACTOR
(2020:
5.
286
)
(2021:
5.
64
)
OCLC
–
1121105510
METADATA
IF
–
7.569
Publisher:
The USA Journals
principle, controlling the synthesis of somatoliberin
and somatostatin and the secretion of growth
hormone. Surgical removal of the pituitary gland in a
young animal results in growth arrest. Injection of a
pituitary extract containing growth hormone into such
animals restores their normal growth. The introduction
of growth hormone into young growing animals
sharply stimulates growth and leads to gigantism
(giant ambistoma, rats, dogs, and other animals were
obtained in the experiment): in humans, excessive
secretion of growth hormone causes a disease with
symptoms of gigantism or acromegaly. Decreased
secretion of growth hormone causes dwarf growth.
Prolactin is synthesized in lactotropic cells, has a
molecular weight of 22,500 and contains 198 amino
acids. The main target of prolactin is the mammary
glands. Prolactin stimulates the growth of the
mammary glands during pregnancy and lactation after
childbirth. During pregnancy, the lactogenic effect of
prolactin is blocked by estrogens and progesterone.
Prolactin receptors are found in the hypothalamus,
liver, testicles, and ovaries, but the effect of prolactin
on these organs has not been studied enough.
Hyperprolactinemia depresses the hypothalamic-
pituitary-gonadal system and is a common cause of
infertility in women. It has recently been shown that
prolactin receptors are present on T-lymphocytes and
that prolactin influences immune responses.
The family of glycoprotein hormones includes the
adenohypophyseal hormones LH, FSH, and TSH, as well
as the placental hormone hCG. These hormones
consist of two highly glycosylated polypeptide chains
(subunits) - alpha and beta. All hormones have identical
alpha subunits: they include 92 amino acids arranged in
the same sequence. In contrast, the amino acid
sequences in the beta subunits differ. It is these
differences that determine the specificity of the action
of glycoprotein hormones on target tissues. The
molecular weight of LH, FSH, TSH, and CG is not the
same and depends primarily on the number of
carbohydrate residues [4].
LH and FSH are synthesized in gonadotropic cells. In
both hormones, the beta subunit includes 115 amino
acids, and the molecular weight is 29400 and 32600,
respectively. LH and FSH regulate the synthesis and
secretion of sex hormones and gametogenesis [5]. In
the ovaries, LH stimulates ovulation and secretion of
progesterone. LH and CG receptors are present on the
cells of the outer shell and granular layer of the follicles
and on the interstitial cells. FSH stimulates estrogen
secretion, growth and maturation of follicles. FSH
receptors are present only on the cells of the granular
layer. In the testicles, LH stimulates the secretion of
testosterone. LH and CG receptors are present only on
Leydig cells. FSH does not affect androgen synthesis,
but is required for spermatogenesis. FSH receptors are
found only on Sertoli cells.
Follicle-stimulating,
luteinizing
and
luteotropic
hormones. Atrophy of the reproductive system that
occurs after the removal of the pituitary gland can be
prevented by the introduction of gonadotropic
hormones. In infantile animals, the administration of
these hormones causes precocious puberty. Injection
of a pituitary extract containing gonadotropic
hormones
to
frogs
causes
spawning
and
spermatogenesis in them in autumn and winter;
normal tadpoles develop from eggs after fertilization.
LH and FSH. These are glycoprotein hormones
secreted
by
gonadotropic
cells
of
the
adenohypophysis. The production of LH and FSH is
regulated by GnRH. From the beginning of puberty, LH
and FSH regulate the synthesis and secretion of sex
hormones and gametogenesis. LH stimulates the
secretion of progesterone in the ovaries and
36
Volume 04 Issue 02-2022
The American Journal of Medical Sciences and Pharmaceutical Research
(ISSN
–
2689-1026)
VOLUME
04
I
SSUE
02
Pages:
33-37
SJIF
I
MPACT
FACTOR
(2020:
5.
286
)
(2021:
5.
64
)
OCLC
–
1121105510
METADATA
IF
–
7.569
Publisher:
The USA Journals
testosterone in the testicles. FSH stimulates the
secretion of estrogen in the ovaries. Estrogens and
testosterone
determine
the
development
of
secondary sexual characteristics, pubertal growth
acceleration and closure of the epiphyseal growth
zones of long bones. Like other hormones of the
peripheral
endocrine
glands,
estrogens
and
testosterone, by the principle of negative feedback,
inhibit the secretion of GnRH, LH and FSH.
Follicle-stimulating hormone regulates the growth of
follicles in the ovaries and spermatogenesis. In
females, luteinizing hormone causes premature
follicular growth, ovulation, and the formation of a
corpus luteum, and in males, secretion of the male sex
hormone by interstitial testicular cells, i.e., Leydig cells.
Luteotropic hormone supports the function of the
corpus luteum; in some animals (rat, sheep) this
hormone causes lactation. Prolactin (lactogenic
hormone). Participates in the regulation of the process
of milk secretion. Removal of the anterior pituitary in
lactating females stops milk secretion; the introduction
of prolactin restores lactation.
Thyroid-stimulating hormone. TSH is synthesized in
thyroid-stimulating cells, has a molecular weight of
30,500; the beta subunit contains 112 amino acids. The
main role of TSH is to stimulate the synthesis of thyroid
hormones. TSH controls almost all stages of synthesis,
including the addition of inorganic iodine to
thyroglobulin and the formation of T3 and T4 from
mono- and diiodotyrosine.
This glycoprotein hormone is produced in the thyroid-
stimulating cells of the adenohypophysis. Synthesis
and secretion of TSH are controlled by thyroliberin.
TSH stimulates the synthesis and secretion of thyroid
hormones (T3 and T4) - the most important growth
regulators of all div tissues. By inhibiting the
synthesis of thyroliberin and the secretion of TSH, T3
and T4 close a negative feedback loop in the
hypothalamic-pituitary-thyroid system. Removal of the
anterior pituitary gland causes atrophy of the thyroid
gland and, as a result, a decrease in basal metabolism.
Injections of a pituitary extract containing thyroid-
stimulating hormone cause an increase in the thyroid
gland and an increase in its function.
RESULTS AND DISCUSSIONS
A family of proopiomelanocortin derivatives.
Corticotropic cells of the adenohypophysis secrete
several hormones: ACTH, alpha and beta MSH, beta
and gamma lipotropins, and endorphins. All these
hormones contain the heptapeptide Met-Glu-Gis-Phen-
Arg-Trp-Gly and are formed from a large precursor
molecule, proopiomelanocortin (molecular weight
31,000).
ACTH has a molecular weight of 4500 and contains 39
amino acids. ACTH stimulates the synthesis of
hormones in the adrenal cortex, primarily the synthesis
of glucocorticoids in the fascicular and reticular zones.
The release of ACTH from corticotropic cells or the
administration of a large dose of ACTH can cause a
short-term rise in aldosterone levels. Another effect of
ACTH is the stimulation of melanin synthesis in
melanocytes. Apparently, this is the cause of
hyperpigmentation in Nelson's syndrome and primary
adrenal insufficiency.
The
functions
of
other
derivatives
of
proopiomelanocortin are less well understood. It has
been established that alpha-MSH stimulates the
synthesis of melanin in melanocytes, and gamma-MSH
stimulates the synthesis of aldosterone in the adrenal
cortex. In experiments on cell cultures of the adrenal
cortex, it was shown that beta-lipotropin stimulates
the synthesis of corticosteroids, and the effect of beta-
lipotropin is mediated by ACTH receptors.
37
Volume 04 Issue 02-2022
The American Journal of Medical Sciences and Pharmaceutical Research
(ISSN
–
2689-1026)
VOLUME
04
I
SSUE
02
Pages:
33-37
SJIF
I
MPACT
FACTOR
(2020:
5.
286
)
(2021:
5.
64
)
OCLC
–
1121105510
METADATA
IF
–
7.569
Publisher:
The USA Journals
The synthesis of ACTH in the corticotropic cells of the
adenohypophysis and the secretion of ACTH are
controlled by corticoliberin. Acting on the cells of the
adrenal cortex, ACTH stimulates the synthesis and
secretion of cortisol, a hormone with a wide spectrum
of action. In vitro and in vivo studies have shown that
low concentrations of cortisol are necessary for cell
growth, but even a small excess of this hormone
inhibits cell proliferation. ACTH stimulates the activity
of the adrenal cortex and the release of corticosteroid
hormones by it, and also restores the gland atrophied
as a result of the removal of the pituitary gland. The
influence of the anterior pituitary gland on metabolism
is carried out through growth hormone, ACTH and
other hormones.
The middle lobe of the pituitary gland produces the
intermediate hormone, or melanocyte-stimulating
hormone, which affects the color of the skin of fish and
amphibians. The physiological significance of this
hormone in birds and mammals is unclear.
The posterior pituitary gland is involved in the
regulation of blood pressure, urination (hormone
vasopressin) and the activity of the muscles of the
uterus (hormone oxytocin). Vasopressin and oxytocin
are produced in the paraventricular and supraoptic
nuclei of the hypothalamus, from where they enter the
posterior pituitary gland. Both hormones are
synthesized.
CONCLUSION
The functions of the pituitary gland depend on
environmental conditions. From experiments carried
out on birds and mammals, it was established that light
regulates
the
gonadotropic,
thyrotropic
and
adrenocorticotropic functions of the pituitary gland;
The action of light on the pituitary gland is carried out
through the central nervous system. It has also been
proven that the endocrine functions of the pituitary
gland are under the control of the hypothalamus, in
which special neurohumoral substances of a peptide
nature are produced - the so-called. releasing, or
releasing factors, humorally stimulating the secretion
of pituitary hormones. [6]
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Aleshen B.V., Brindak O.I. Regulation of the
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