PILOT STUDY--PROLACTIN RELEASING PEPTIDE AND NICOTINE

催乳素(PRL)的分泌不仅是为了支持生殖功能和哺乳，也是为了在应激状态下维持体内平衡功能。因此，PRL的释放不仅受内源性释放因子的调节，还受具有抗应激活性的外源性化学物质的调节。其中最突出的是尼古丁，它通过作用于中枢神经系统的部位，特别是孤束核(NTS)，导致催乳素的释放。尼古丁调节催乳素释放的机制还知之甚少。最近，从原代培养的垂体细胞中分离到一种能有效诱导催乳素释放的3I-氨基酸多肽，命名为催乳素释放肽(PrRP)。我们的初步数据表明，PrRP mRNA存在于NTS，其受体存在于下丘脑。这些数据表明，PrRP可能是尼古丁诱导的PRL释放的另一个重要介质。在尼古丁刺激下，PrRP可能从NTS释放出来，作用于下丘脑并诱导其他催乳素释放多肽的释放，或者通过在静脉血中分泌并直接作用于垂体。因此，我们建议通过证明PrRP存在于尼古丁敏感(阳性)的NTS神经元，并且尼古丁诱导脑脊液中PrRP的释放，来检验PrRP和尼古丁之间存在直接联系的假说。

Prolactin (PRL) is secreted not only to support reproductive functions and lactation but also to maintain homeostatic functions under stress. Consequently, PRL release is known to be regulated not only by endogenous releasing factors but also by exogenous chemical substances with anti-stress activities. Prominent among these is nicotine which causes the release of PRL by acting CNS sites, in particular the nucleus tractus solitarius (NTS). The mechanism by which nicotine modulates PRL release is poorly understood. Recently, a 3 I-amino acid peptide, named the Prolactin Releasing Peptide (PrRP), was isolated which potently induced prolactin release from primary pituitary cells. Our preliminary data indicate that the PrRP mRNA is present in the NTS while its receptor is found in the hypothalamus. These data suggest that PrRP may be another important mediator of nicotine-induced PRL release. Upon nicotine stimulation, PrRP may be released from the NTS to act either on the hypothalamus and induce the release of other prolactin-releasing peptides or by being secreted in the potal blood and acting directly on the pituitary. We therefore propose to test the hypothesis of a direct link between PrRP and nicotine, by showing that PrRP is present in the nicotine sensitive (~ positive) NTS neurons and that nicotine induces PrRP release in the cerebrospinal fluid.