Action of thyrotropin-releasing hormone on mammotrophs and thyrotrophs

1981 ◽  
Vol 241 (4) ◽  
pp. E298-E304
Author(s):  
G. Snyder ◽  
Z. Naor ◽  
C. P. Fawcett ◽  
S. M. McCann
Keyword(s):  
Anterior Pituitary ◽  
Thyrotropin Releasing Hormone ◽  
Female Rats ◽  
Pituitary Cells ◽  
Cell Distribution ◽  
Camp Content ◽  
Releasing Hormone ◽  
Gravity Sedimentation ◽  
Unit Gravity Sedimentation ◽  
Region Ii

Anterior pituitary cells from 15-day female rats were separated by unit gravity sedimentation into four populations (designated regions I-IV) based on the profile of cell distribution and the resulting content of radioimmunoassayable (RIA) hormones. The cells in regions II and IV released thyrotropin (TSH) in response to thyrotropin-releasing hormone (TRH, 5 ng/ml); however, those in region IV released only approximately 5% of their RIA content, whereas those in region II released approximately 26% in response to the same stimulus. Concomitant elevation of cAMP and of cGMP occurred in region II cells but only cGMP was elevated in region IV cells. Mammotrophs were localized in region III. They responded to TRH by releasing prolactin (PRL) and exhibiting increased cAMP content. These data provide support for the existence of two functionally distinct populations of thyrotrophs in 15-day-old female rats. The data also imply that cAMP is involved in TRH induced PRL release, whereas cGMP is involved in TRH-induced TSH release.

Thyrotropin-Releasing Hormone Gene Expression in Cultured Anterior Pituitary Cells: Role of Gender

1995 ◽  
Vol 61 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Thomas O. Bruhn ◽  
Jan M.M. Rondeel ◽  
Thomas G. Bolduc ◽  
Ivor M.D. Jackson
Keyword(s):  
Gene Expression ◽  
Anterior Pituitary ◽  
Thyrotropin Releasing Hormone ◽  
Pituitary Cells ◽  
Releasing Hormone ◽  
Anterior Pituitary Cells

Effects of the daily administration of gonadotrophin-releasing hormone on the anterior pituitary gland of rats with restricted feeding

1992 ◽  
Vol 134 (2) ◽  
pp. 177-NP ◽  
Author(s):  
F. Kotsuji ◽  
K. Hosokawa ◽  
T. Tominaga
Keyword(s):  
Weight Loss ◽  
Weight Reduction ◽  
Anterior Pituitary ◽  
Serum Levels ◽  
Female Rats ◽  
Daily Administration ◽  
Pituitary Cells ◽  
Restricted Feeding ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

ABSTRACT To investigate the influence of weight reduction on pituitary function and its modulation by gonadotrophin-releasing hormone (GnRH), female rats were restricted to 10 g food/day for 60 days. GnRH (5 μg) or saline (0·2 ml) were administered daily between days 31 and 60 of the period of underfeeding. Underfeeding brought about a decrease in the pituitary gonadotrophin content, serum levels of gonadotrophins and oestradiol, and the number and size of both LH- and FSH-positive pituitary cells. The administration of GnRH to underfed rats produced an increase in the pituitary and serum gonadotrophin levels and the number and size of both LH- and FSH-positive pituitary cells. These observations suggest that underfeeding and/or weight loss diminish the number and activity of the pituitary gonadotrophs, and that daily administration of GnRH both increases the number of gonadotrophs and augments their activity. Journal of Endocrinology (1992) 134, 177–182

Electrophysiological response to thyrotropin-releasing hormone of rat lactotrophs in primary culture

1990 ◽  
Vol 258 (2) ◽  
pp. E311-E319 ◽  
Author(s):  
P. Sartor ◽  
L. Dufy-Barbe ◽  
J. B. Corcuff ◽  
A. Taupignon ◽  
B. Dufy
Keyword(s):  
Primary Culture ◽  
Input Resistance ◽  
Thyrotropin Releasing Hormone ◽  
Female Rats ◽  
Resting Potential ◽  
Pituitary Cells ◽  
Releasing Hormone ◽  
Electrophysiological Properties ◽  
L Cells ◽  
D Cells

The response of rat pituitary cells to thyrotropin-releasing hormone (TRH) in primary culture was studied in the whole-cell configuration with the patch-clamp technique. Prolactin (PRL)-containing cells were identified in the culture with a peroxidase-antiperoxidase immunocytochemical method. The cells were cultured from the pituitaries of diestrous (D) and lactating (L) female rats. Membrane electrophysiological properties (resting potential and input resistance) of pituitary cells in primary culture varied widely. Under the recording conditions reported here, the mean resting potential of lactotrophs was about -30 mV. There were spontaneous fluctuations in membrane resting potential (10-15 mV) as well as of membrane input resistance, making these parameters difficult to evaluate accurately. Most of the cells exhibited spontaneous firing activity that was shown to be mainly calcium-dependent. There was no difference between L and D cells in resting membrane electrophysiological properties. TRH (10(-7) M) induced a transient hyperpolarization of the membrane similar to that previously described in the GH3 clonal pituitary cell line. Voltage-clamp studies showed that this hyperpolarization resulted from activation of an outward current, the reversal potential of which ranged from -48 to -86.5 mV. Experimental manipulations of the ionic composition of internal and external recording media suggested that both K+ and Cl- were involved. This hyperpolarizing response was observed both in D and L cells, although L cells had larger and faster responses than D cells. This observation may be of physiological significance because lactotrophs have been reported to exist in various subtypes.

Sign in / Sign up

Export Citation Format

Share Document