Chang Y M, Kelliher K R, Baum M J
Department of Biology, Boston University, Boston, MA 02215, USA.
J Neuroendocrinol. 2001 Jun;13(6):551-60. doi: 10.1046/j.1365-2826.2001.00670.x.
Previous research demonstrated that exposing gonadectomized adult ferrets to odours in oestrous female bedding induced nuclear Fos-immunoreactivity (Fos-IR; a marker of neuronal activity) in the main as opposed to the accessory olfactory system in a sexually dimorphic fashion, which was further augmented in both sexes by treatment with testosterone propionate. Ferrets are born in an altricial state and presumably use maternal odour cues to locate the nipples until the eyes open after postnatal (P) day 23. We investigated whether maternal odours augment neuronal Fos preferentially in the main versus accessory olfactory system of neonatal male and female ferret kits. Circulating testosterone levels peak in male ferrets on postnatal day P15, and mothers provide maximal anogenital stimulation (AGS) to males at this same age. Therefore, we assessed the ability of maternal odours to augment Fos-IR in the accessory olfactory bulb (AOB), the main olfactory bulb (MOB) and other forebrain regions of male and female ferret kits on P15 and investigated whether artificial AGS (provided with a paintbrush) would further enhance any effects of maternal odours. After separation from their mothers for 4 h, groups of male and female kits that were placed for 1.5 h with their anaesthetized mother had significantly more Fos-IR cells in the MOB granule cell layer and in the anterior-cortical amygdala, but not in the AOB cell layer, compared to control kits that were left on the heating pad. Artificial AGS failed to amplify these effects of maternal odours. Maternal odours (with or without concurrent AGS) failed to augment neuronal Fos-IR in medial amygdaloid and hypothalamic regions that are activated in adult ferrets by social odours. In neonatal ferrets of both sexes, as in adults, socially relevant odours are detected by the main olfactory epithelium and initially processed by the MOB and the anterior-cortical amygdala. In neonates, unlike adults, medial amygdaloid and hypothalamic neurones either do not respond to these inputs or respond in a manner that fails to induce Fos expression.
先前的研究表明，将成年去势雪貂暴露于处于发情期的雌性雪貂的垫料气味中，会以性别二态性的方式在主要嗅觉系统而非附属嗅觉系统中诱导核Fos免疫反应性（Fos-IR；神经元活动的标志物），用丙酸睾酮处理会使两性的这种反应进一步增强。雪貂出生时处于未成熟状态，大概会利用母体气味线索来找到乳头，直到出生后（P）第23天眼睛睁开。我们研究了母体气味是否会在新生雄性和雌性雪貂幼崽的主要嗅觉系统与附属嗅觉系统中优先增强神经元Fos。雄性雪貂出生后第15天循环睾酮水平达到峰值，此时母亲会对相同年龄的雄性提供最大程度的肛门生殖器刺激（AGS）。因此，我们评估了母体气味增强P15期雄性和雌性雪貂幼崽附属嗅球（AOB）、主要嗅球（MOB）和其他前脑区域中Fos-IR的能力，并研究了人工AGS（用画笔提供）是否会进一步增强母体气味的任何作用。与留在加热垫上的对照幼崽相比，与麻醉的母亲放置1.5小时的雄性和雌性幼崽组在与母亲分离4小时后，MOB颗粒细胞层和前皮质杏仁核中有明显更多的Fos-IR细胞，但AOB细胞层中没有。人工AGS未能放大母体气味的这些作用。母体气味（无论是否同时进行AGS）未能增强成年雪貂中被社交气味激活的内侧杏仁核和下丘脑区域的神经元Fos-IR。在两性新生雪貂中，与成年雪貂一样，社交相关气味由主要嗅觉上皮检测到，并最初由MOB和前皮质杏仁核进行处理。在新生儿中，与成年人不同，内侧杏仁核和下丘脑神经元要么对这些输入没有反应，要么以未能诱导Fos表达的方式做出反应。
