Noradrenergic Nuclei that Receive Sensory Input During Mating and Project to the Ventromedial Hypothalamus Play a Role in Mating‐Induced Pseudopregnancy in the Female Rat

Abstract

In female rats, vaginal-cervical stimulation (VCS) received during mating induces bicircadian prolactin surges that are required for the maintenance of pregnancy or pseudopregnancy (PSP). The neural circuits that transmit VCS inputs to the brain have not been fully described, although mating stimulation is known to activate medullary noradrenergic cell groups that project to the forebrain. In response to VCS, these neurones release noradrenaline within the ventrolateral division of the ventromedial hypothalamus (VMHvl) and the posterodorsal medial amygdala (MePD), two forebrain sites that are implicated in the initiation of PSP. Noradrenaline receptor activation within the VMHvl is both necessary and sufficient for PSP induction, suggesting that noradrenaline acting within the VMHvl is particularly important in mediating the effects of VCS towards the establishment of PSP. We therefore investigated whether or not endogenous, VCS-induced noradrenaline release within the VMHvl is involved in PSP induction in the rat. Before the receipt of sufficient mating stimulation to induce PSP, a retrograde neurotoxin, dopamine-β-hydroxylase-saporin (DBH-SAP), was infused bilaterally into the either the VMHvl or the MePD to selectively destroy afferent noradrenergic nuclei in the brainstem. DBH-SAP infusions into the VMHvl lesioned mating-responsive noradrenergic neurones in A1 and A2 medullary nuclei and reduced the incidence of PSP by 50%. Infusions of DBH-SAP into the MePD had no effect on the subsequent induction of PSP. These results suggest that VCS is conveyed to mating-responsive forebrain areas by brainstem noradrenergic neurones, and that the activity of noradrenergic cells projecting to the VMHvl is involved in the induction of PSP.

Cervical stimulation activates A1 and locus coeruleus neurons that project to the paraventricular nucleus of the hypothalamus

“…However, the importance of TH neurons that do not project to the PVN cannot be excluded, these neurons may comprise projections that have permissive roles for the onset of pregnancy/pseudopregnancy in intact animals. This possibility is supported by findings showing that destruction of these projections decreases the incidence of pseudopregnancy by 50% in mated rats [43]. …”

Does the Act of Copulation per se, without Considering Seminal Deposition, Change the Expression of Genes in the Porcine Female Genital Tract?

“…The highest amount of DEGs was found in the endocervix and the distal and proximal parts of the uterine horn (D-Endom and P-Endom). These findings are not surprising since the uterus is widely known to act as a sensory transducer, converting the mechanical exteroceptive stimulus of copulation into neural electrical signals through the pelvic nerve [21]. To date, the literature points to vagino-cervical stimulation-which also occurs during AI-as the main agent responsible for generating electrical signals ascending from the cervix and reaching much of the limbic system and the hypothalamus, where several areas containing neurons receptive to vagino-cervical input have been identified [22].…”

A New Analysis of Resting State Connectivity and Graph Theory Reveals Distinctive Short-Term Modulations due to Whisker Stimulation in Rats

“…Lesions in the lateral hypothalamus profoundly impair the ability to orient to stimuli on the contralateral side (Marshall et al, 1971 ). This deficit is not from motor impairments, but rather a lack of responsiveness to the stimulus, which indicates a direct connection between sensory input and the lateral hypothalamus (Marshall et al, 1971 ; Northrop et al, 2010 ). In contrast to the decreased connectivity between hypothalamus and cortex, the RS connection between hypothalamus and amygdala (mainly basolateral amygdala) was strongly enhanced by whisker stimulation.…”