Abstract
The effect of elevated external [K+] compared to luteinizing hormone-releasing hormone (LHRH) on gonadotropin secretion was studied in vitro in superfused pituitary fragments from cyclic female rats. Challenging proestrous but not estrous pituitaries with a 2-h pulse of 0.8 nM LHRH produces two distinct peaks in the curve for the first derivative of gonadotropin secretion versus time; the second peak exceeds the initial one and represents expression of LHRH self-priming. Challenging proestrous pituitaries with a 2-h pulse of raised [K+] results in an initial increase in secretion followed by a positive slope of the secretion rate curve for LH but a constant rate for follicle-stimulating hormone (FSH); the positive slope is blocked by cycloheximide and not found with estrous pituitaries pulsed with raised [K+]. Proestrous pituitaries exhibit a graded response to 10-min pulses of raised external [K+] from 10-91 mM for LH and 10-47 mM for FSH secretion. LHRH followed by elevated [K+] primed the LH and FSH response to the secretagogue, but the reverse sequence did not. The results show 1) a concentration dependence of elevated [K+]-induced LH and FSH secretion, 2) a LHRH specific initiation of priming that does not require the immediate presence of LHRH for its subsequent expression, and 3) a gonadotropin secretory response to elevated [K+] that varies during the estrous cycle and can be modified by protein synthesis inhibition or progesterone administration.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Endocrinology and Metabolism |
| Volume | 7 |
| Issue number | 2 |
| State | Published - 1983 |
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ASJC Scopus subject areas
- Biochemistry
- Endocrinology
- Physiology
Cite this
Comparison between K+-induced and LHRH-induced gonadotropin secretion in vitro. / Turgeon, Judith L; Waring, D. W.
In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 7, No. 2, 1983.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Comparison between K+-induced and LHRH-induced gonadotropin secretion in vitro
AU - Turgeon, Judith L
AU - Waring, D. W.
PY - 1983
Y1 - 1983
N2 - The effect of elevated external [K+] compared to luteinizing hormone-releasing hormone (LHRH) on gonadotropin secretion was studied in vitro in superfused pituitary fragments from cyclic female rats. Challenging proestrous but not estrous pituitaries with a 2-h pulse of 0.8 nM LHRH produces two distinct peaks in the curve for the first derivative of gonadotropin secretion versus time; the second peak exceeds the initial one and represents expression of LHRH self-priming. Challenging proestrous pituitaries with a 2-h pulse of raised [K+] results in an initial increase in secretion followed by a positive slope of the secretion rate curve for LH but a constant rate for follicle-stimulating hormone (FSH); the positive slope is blocked by cycloheximide and not found with estrous pituitaries pulsed with raised [K+]. Proestrous pituitaries exhibit a graded response to 10-min pulses of raised external [K+] from 10-91 mM for LH and 10-47 mM for FSH secretion. LHRH followed by elevated [K+] primed the LH and FSH response to the secretagogue, but the reverse sequence did not. The results show 1) a concentration dependence of elevated [K+]-induced LH and FSH secretion, 2) a LHRH specific initiation of priming that does not require the immediate presence of LHRH for its subsequent expression, and 3) a gonadotropin secretory response to elevated [K+] that varies during the estrous cycle and can be modified by protein synthesis inhibition or progesterone administration.
AB - The effect of elevated external [K+] compared to luteinizing hormone-releasing hormone (LHRH) on gonadotropin secretion was studied in vitro in superfused pituitary fragments from cyclic female rats. Challenging proestrous but not estrous pituitaries with a 2-h pulse of 0.8 nM LHRH produces two distinct peaks in the curve for the first derivative of gonadotropin secretion versus time; the second peak exceeds the initial one and represents expression of LHRH self-priming. Challenging proestrous pituitaries with a 2-h pulse of raised [K+] results in an initial increase in secretion followed by a positive slope of the secretion rate curve for LH but a constant rate for follicle-stimulating hormone (FSH); the positive slope is blocked by cycloheximide and not found with estrous pituitaries pulsed with raised [K+]. Proestrous pituitaries exhibit a graded response to 10-min pulses of raised external [K+] from 10-91 mM for LH and 10-47 mM for FSH secretion. LHRH followed by elevated [K+] primed the LH and FSH response to the secretagogue, but the reverse sequence did not. The results show 1) a concentration dependence of elevated [K+]-induced LH and FSH secretion, 2) a LHRH specific initiation of priming that does not require the immediate presence of LHRH for its subsequent expression, and 3) a gonadotropin secretory response to elevated [K+] that varies during the estrous cycle and can be modified by protein synthesis inhibition or progesterone administration.
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UR - http://www.scopus.com/inward/citedby.url?scp=0020657050&partnerID=8YFLogxK
M3 - Article
C2 - 6401932
AN - SCOPUS:0020657050
VL - 7
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 2
ER -