Hypothalamic Biogenic Amines and the Regulation of Luteinizing Hormone Release in the Rat

Effects of Various Types of Hypothalamic Deafferentation on Luteinizing Hormone Pulses in Ovariectomized Rats

“…Therefore, several workers assume that the LHRH pulse generator is located in the preoptic/anterior hypothalamic area: The local application of a specific a,-receptor antagonist into that area, but not into the MBH, caused a reduction of LH pulsatility (6); the inverse pattern of LH release and y-aminobutyric acid release from the preoptic/anterior hypothalamic area was seen (7). Furthermore, subchiasmatic LHRH neuronal fibres (8), which may be left intact by the hypothalamic deafferentation, could maintain the LH pulses after CD. Thus, there has been controversy over the location and nature of the mechanism generating LHRH pulses (9).…”

Effect of Hypothalamic Deafferentation on the Pulsatile Secretion of Luteinizing Hormone in Ovariectomized Lactating Rats*

“…However, the possibility that subchiasmatic LHRH fibres (9), which might be spared by the deafferentation in vivo, maintained the pulsatile secretory pattern could not be ignored.…”

“…The putative pulse generator regulating pulsatile LHRH release has been thought to be located in the mediobasal hypothalamus (MBH), since pulsatile LH secretion has been observed in either cyclic or ovariectomized rats with complete deafferentation of the MBH (6, 7), and since LHRH has been reported to be released in a pulsatile manner from the MBH in vitro (8). However, the possibility that subchiasmatic LHRH fibres (9), which might be spared by the deafferentation in vivo, maintained the pulsatile secretory pattern could not be ignored. Tindal(l0) has identified the central pathways which convey the suckling stimulus for oxytocin and prolactin (PRL) release in the rabbit.…”

Influences of Norepinephrine, and Adrenergic Agonists and Antagonists on Gonadotropin Secretion from Dispersed Pituitary Cells of Goldfish, <i>Carassius auratu</i><i>s</i>

“…In mammals, and especially in rats, it is generally accepted that catecholaminergic neurotransmitter systems modulate lu teinizing hormone (LH) release by actions on hypothalamic neuroendocrine regulators [for a review, see 1], In general, nor epinephrine (NE) stimulates LH release by increasing gonado tropin (GTH)-releasing hormone (GnRH) secretion; however, inhibitory influences of NE on pulsatile LH release have also been reported [for reviews, see [2][3][4]. The stimulatory and inhibi tory activities of NE are usually associated with the activation of a-, and a-or P-adrenergic receptors, respectively [for re views, see [2][3][4].…”

“…The stimulatory and inhibi tory activities of NE are usually associated with the activation of a-, and a-or P-adrenergic receptors, respectively [for re views, see [2][3][4].…”