Hypothalamic disorders and it symptoms. The hypothalamus modulates the activities of the anterior and posterior lobes of the pituitary in two distinct ways. The neurohormones synthesized in the hypothalamus reach the anterior pituitary directly through a specialized portal vascular system and regulates the synthesis and secretion of six major peptide hormones of the pituitary. The pituitary hormones in turn regulate the peripheral endocrine glands ( the thyroid, adrenal and the gonads) as well as growth and lactation. No direct neural connections exists between the hypothalamus and the anterior pituitary.
In contrast,the posterior pituitary comprises axons, originating in neural cell bodies located in the hypothalamus. These axons serve as storage site for two peptide hormones synthesized in the hypothalamus, which act in the periphery to regulate the water balance, mil ejection, and uterine contraction. An intermediate lobe locate between the anterior and posterior lobes is present in some, but the specific cells are scattered throughout the anterior and posterior lobes in the adult humans. Virtually all hormones secreted by the hypothalamus and the pituitary are pulsatile that is in a burst lie fashion, interspersing brief periods of inactivity and activity. In addition some of the hormones lie(ACTH, growth hormone, and prolactin) have definite circadian or diurnal rhythms with increased secretion during specific hours of the day. Other hormones for example the leutinizing hormone and the follicle stimulating hormone which are involved in the menstrual cycle for women have, month long rhythms with evidence of superimposed circadian cycles.
Symptoms of hypothalamic disorder the manifestation of hypothalamic disorder or disease are neurologic defects, endocrine changes, and metabolic abnormalities such as hyperthermia and hyerphagia. The relative frequencies of hypothalamic disease can generally be quantified in relation to other endocrinological disorders or depending on the modification of ones circadian cycle. The possibility of hypothalamic pathology should be kept in mind in evaluating all patients with pituitary dysfunction, especially those with isolated deficiencies of single pituitary hormones. A condition of considerable interest is Kallmanns syndrome, the combination of hypogonadism due to low levels of circulating gonadotropins with partial or complete loss of the sense of smell(hyposmia or anosmia).
Embryologically, Gnrh neurons develop in the nose and migrate up the olfactory nerves and then through the brain to the hypothalamus. If this migration is prevented by congenital abnormalities in the olfactory pathways, the Gnrh neurons do not reach the hypothalamus and pubertal maturation of the gonads fails to occur. The syndrome is most common in men and in many cases mutation of a gene on the X chromosome that codes for what is apparently an adhesion molecule necessary for normal development of the olfactory nerve on which the Gnrh neurons migrate into the brain. However the condition is not completely unknown in women and can occur due to other genetically abnormalities. The hypothalamus is also subject to mass lesions and injuries from infections and hemorrhage. Lesions to the anterior and preoptic hypothalamus cause paradoxical vasoconstriction, tachycardia, and hyperthermia. Central disorders of thermoregulation occur from posterior hypothalamic damage.