Η ΑΔΕΝΟΫΠΟΦΥΣΗ: OI ΓΟΝΑΔΟΤΡΟΠΙΝΕΣ (FSH,( LH) ) ΚΑΙ Η ΠΡΟΛΑΚΤΙΝΗ (PRL( PRL) Κωνσταντίνος Καλλαράς Ιατρός Παθολόγος Καθηγητής Φυσιολογίας Εργαστήριο Πειραματικής Φυσιολογίας Ιατρικής Σχολής Α.Π.Θ.
FSH:ΜΒ 33000, περιεκτικότητα σε σιαλικό οξύ αρκετή LH (ICSH): ΜΒ 28000, περιεκτικότητα σε σιαλικό οξύ περιορισμένη α-υπομονάδα και των δύο: Μ.Β.14900 β-υπομονάδα FSH:110 αμινοξέα β-υπομονάδα LH: 121 αμινοξέα Ησύνθεσητωνβ-υπομονάδων καθοριστικό όριο (rate limiting) για την ποσότητα των γοναδοτροπινών «Ειδικότητα στο είδος» Μετρήσεις: βιομετρήσεις, RIA, RRA Σύνδεση με υποδοχείς με την α- υπομονάδα μόνο επί παρουσία της β G s αδενυλκυκλάση
Περιεκτικότητα υποφύσεως σε γοναδοτροπίνες ποικίλλει σημαντικά: μετά εμμηνόπαυση σε γυναίκες και μετά τα 50 στους άνδρες Στο αίμα: μετά εμμηνόπαυση σε γυναίκες και στο μέσον του κύκλου (φασική έκκριση) LΗ: στους άνδρες 8-10 εκκριτικές αιχμές στο 24ώρο με υψηλότερες τιμές την 6.00 πρωινή (τονική έκκριση) T 1/2 FSH = 3 h, T 1/2 LH = 60 min Ρυθμός νεφρικής κάθαρσης: FSH/LH 7:1.Έτσι στα ούρα πολύ μεγαλύτερες ποσότητες FSH παρά LH
Η ρύθμιση της εκκρίσεως των γοναδοτροπινών
Figure 23-34. Episodic secretion of LH (s) and FSH (d) during the follicular stage (top) and the luteal stage (bottom) of the menstrual cycle. The numbers above each graph indicate the numbers of LH pulses per 12 hours and the plasma estradiol (E2) and progesterone (P) concentrations at these two times of the cycle. (Reproduced, with permission, from Marshall JC, Kelch RO: Gonadotropin-releasing hormone: role of pulsatile secretion in the regulation of reproduction. N Engl J Med 1986;315:1459.)
Η προλακτίνη (PRL) M.B. = 26364, 198 αμινοξέα
Τιμές : : 6,2 ± 0,6 μg/l, : 9,0 ± 0,6 μg/l Αύξηση : 2 ο ήμισυ κυήσεως, αρχικές φάσεις γαλουχίας. Μεγαλύτερες τιμές στον τοκετό, προοδευτική πτώση από την 8 η ημέρα
Η ρύθμιση της έκκρισης της PRL
Figure 8-22 Effect of hyperprolactinemia on suppressing follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretory patterns leading to hypogonadotrophism in a female patient. PRL, prolactin. (Adapted from Tolis G. Prolactin: physiology and pathology. Hosp Pract 1980;15:85-95.) Kronenberg: Williams Textbook of Endocrinology, 11th ed.
Figure 23-39. Hormonal control of breast development and lactation in rats. Estrogens (E) plus some progesterone (P) and some prolactin in the presence of glucocorticoids (C), insulin (I), and growth hormone (GH) cause duct proliferation and growth at puberty (right). During pregnancy, all of these hormones bring about full alveolar development and some milk secretion (below). After delivery, increased secretion of prolactin and a decline in estrogen and progesterone levels bring about copious milk secretion and, in the presence of oxytocin, ejection of milk (left). Chorionic mammotropin is the lactogenic hormone presumably secreted by the placenta in rats and is analogous to hcs. It supplements the action of prolactin.
Η νευροϋπόφυση: οι ορμόνες Βαζοπρεσσίνη και Οξυτοκίνη
Figure 14-11. Structure of bovine prepropressophysin (left) and prepro-oxyphysin (right). Gly in the 10 position of both peptides is necessary for amidation of the Gly residue in position 9. aa, amino acid residues. (Reproduced, with permission, from Richter D: Molecular events in expression of vasopressin and oxytocin and their cognate receptors. Am J Physiol 1988;255:F207.)
Περιεκτικότητα πλάσματος σε ΑDH Α :1 pmol/l Χρόνος υποδιπλασιασμού ADH : 8-20min Χρόνος υποδιπλασιασμού OT: 5 min Mεταβολισμός ADH σε ήπαρ και νεφρούς ADH + ΟΤ ευρίσκεται επίσης σε υπερχιασματικό πυρήνα, γενννητικούς αδένες, φλοιό επινεφριδίων ΑDH V 1A (αγγειοδιασταλτική δράση), V 1B (δράση στα κορτικοτρόπα) PLC & Ca 2+ ΑDH V 2 (αντιδιουρητική δράση) αδενυλκυκλάση
Figure 14-8. Diagrammatic representation of the way in which changes in plasma osmolality and changes in ECF volume affect thirst by separate pathways.
Figure 14-7. Relation of plasma osmolality to thirst in healthy adult humans during infusion of hypertonic saline. The intensity of thirst is measured on a special analog scale. (Reproduced, with permission, from Thompson CJ et al: The osmotic thresholds for thirst and vasopressin release are similar in healthy humans. Clin Sci Lond 1986;71:651.)
Figure 14-12. Responses of magnocellular neurons to stimulation. The tracings show individual extracellularly recorded action potentials, discharge rates, and intramammary duct pressure. A: Response of an oxytocin-secreting neuron. HFD, high-frequency discharge; ME, milk ejection. Stimulation of nipples started before the onset of recording. B: Responses of a vasopressin-secreting neuron, showing no change in the slow firing rate in response to stimulation of nipples and a prompt increase in the firing rate when 5 ml of blood was drawn, followed by typical phasic discharge. (Tracings from Wakerly JB: Hypothalamic neurosecretory function: Insights from electrophysiological studies of the magnocellular nuclei. IBRO News 1985;4:15.)
Figure 14-13. Relation between plasma osmolality and plasma vasopressin in healthy adult humans during infusion of hypertonic saline. LD, limit of detection. (Reproduced, with permission, from Thompson CJ et al: The osmotic thresholds for thirst and vasopressin are similar in healthy humans. Clin Sci [Colch] 1986;71:651.)
Figure 14-14. Relation of mean arterial blood pressure to plasma vasopressin in healthy adult humans in whom a progressive decline in blood pressure was induced by infusion of graded doses of the ganglionic blocking drug trimethaphan. The relation is exponential rather than linear. (Drawn from data in Baylis PH: Osmoregulation and control of vasopressin secretion in healthy humans. Am J Physiol 1987;253:R671.)
Figure 14-15. Effect of hypovolemia and hyper-volemia on the relation between plasma vasopressin (pavp) and plasma osmolality (posm). Seven blood samples were drawn at various times from ten normal men when hypovolemia was induced by water deprivation (colored circles, dashed line) and again when hypervolemia was induced by infusion of hypertonic saline (black circles, solid line). Linear regression analysis defined the relationship pavp = 0.52 (posm - 283.5) for water deprivation and pavp = 0.38 (posm - 285.6) for hypertonic saline. LD, limit of detection. Note the steeper curve as well as the shift of the intercept to the left during hypovolemia. (Courtesy of CJ Thompson.)
Figure 32-7. Circumventricular organs. The neurohypophysis (NH), organum vasculosum of the lamina terminalis (OVLT, supraoptic crest), subfornical organ (SFO), and area postrema (AP) are shown projected on a sagittal section of the human brain. SCO, subcommissural organ; PI, pineal.