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6961938 
Journal Article 
Modulation of luteinizing hormone secretion by neuropeptide Y and epinephrine in the male rat 
Misra, M; Kant, PA; Saxena, RN; , 
1999 
HORMONE RESEARCH CENTER 
KWANGJU 
264-270 
WOS:000081156600040 
The present study was undertaken to evaluate the role of Neuropeptide Y (NPY) and Epinephrine (EP) in the regulation of luteinizing hormone (LH) release in male rats. Intraventricular (III v) injection of NPY, EP or NPY+EP were given to immature (23-30 days) and adult (80-100 days) male rats and plasma was collected at different intervals up to 120 mins and assayed for LH. NPY alone failed to alter plasma LPI in immature rats whereas, in adults it caused a rise in LH levels. This indicates that the LHRH neuronal system remains insensitive to NPY before the onset of puberty. However, a stimulatory role of EP on plasma LH was observed in all age groups. NPY negated the positive effect of EP when two were administered together in immature rats which was possibly mediated via activation of other inhibitory neurons like dopaminergic and serotoninergic. However, in adults, our results propose a synergistic action between NPY and EP to stimulate LH release. In the in vitro studies, collagenase dispersed anterior pituitary (AP) cells from both age groups were incubated with luteinizing hormone releasing hormone (LHRH), NPY and EP alone and LHRH in combination with NPY and EP. The results show that NPY or EP alone failed to stimulate LH release from AP cells obtained from both age groups whereas, when given along with LHRH, only NPY resulted in dose related potentiation of LH response from adult AP cells. NPY probably acts at the level of gonadotropes and enhances the binding of LHRH to its specific receptors in adult rats. Thus, our results indicate that NPY might have dual site of action- hypothalamus and pituitary whereas, EP possibly acts only at the level of hypothalamus to modulate LH release. 
Kwon, HB; Joss, JM; Ishii, S; 
89-85670-37-9 
3rd International Symposium of Asia-and-Oceania-Society-for-Comparative-Endocrinology on Recent Progress in Molecular and Comparative Endocrinology 
KWANGJU, SOUTH KOREA