Simultaneous measurement of luteinizing hormone (LH)-releasing hormone, LH, and follicle-stimulating hormone release in intact and short-term castrate XXXX .

@entity35 @entity230 @entity7438 @entity1640
The temporal relationship between @entity7438 release and gonadotropin secretion as well as the effects of castration on @entity7438 release were investigated in conscious, freely moving male @entity35 . @entity7438 release was measured in @entity1640 /median eminence perfusates, while levels of pituitary gonadotropins (LH, FSH) were determined in sequential blood samples obtained via atrial catheters. Twenty-four to 26 h before experiments, @entity35 underwent sham surgery or castration. @entity7438 release in push-pull perfusates from both groups was pulsatile, and nearly all identified LH pulses (83.3%) were temporally associated with @entity7438 pulses. Of the fewer irregular FSH pulses that were observed, only 43.7% were temporally associated with @entity7438 pulses. Mean @entity7438 pulse amplitude and mean @entity7438 levels were not different in intact and castrate animals. The frequency of @entity7438 pulses was moderately increased in castrate @entity35 (1.30 pulses/h) compared to that in intact animals (0.83 pulses/h), and this acceleration was accompanied by a significant increase in LH pulse frequency, pulse amplitude, and mean level. It was also noted that the number of silent @entity7438 pulses (those not associated with LH pulses) was dramatically reduced in castrate animals. Characteristics of gonadotropin release (pulse frequency, pulse amplitude, and mean level) were not significantly different in animals undergoing push-pull perfusion/bleeding procedures from those in @entity35 not receiving push-pull cannula implants. We conclude from these studies that 1) LH pulses show a high concordance with @entity7438 pulses, providing evidence that the @entity7438 pulse generator operates as the neural determinant of LH pulses in male @entity35 , 2) FSH secretion is not associated with @entity7438 release in an obvious and consistent manner, suggesting that @entity7438 /FSH relationships are not easily discerned in these animals or that a FSH-releasing factor distinct from the @entity7438 decapeptide may regulate FSH secretion, 3) a modest increase in @entity7438 pulse frequency occurs 24-30 h after castration, and 4) silent @entity7438 pulses occur with much greater regularity in intact than in castrate @entity35 . The latter two observations suggest that both @entity1640 and intrapituitary sequelae of castration may be critically important in the development of postcastration increases in LH secretion and the negative feedback of gonadal @entity230 .
