Central afferent pathways conveying nociceptive input to the hypothalamic paraventricular nucleus as revealed by a combination of retrograde labeling and c-fos activation

Proximal colon distension induces Fos expression in oxytocin-, vasopressin-, CRF- and catecholamines-containing neurons in rat brain

“…In the VLM and NTS double-labeled Fos and TH neurons represent approximately 74% and 42% of the TH-IR neurons, respectively. While somatic nociceptive stimulation, such as thermal pain, was shown to activate catecholaminergic neurons in the VLM of rats (Pan et al, 1999), the activation of TH-IR neurons in relation to visceral pain stimuli has not been reported. Here we show that a significant subpopulation of brainstem catecholaminergic neurons is responsive to visceral pain-related signals arising from the colon.…”

“…Here we show that a significant subpopulation of brainstem catecholaminergic neurons is responsive to visceral pain-related signals arising from the colon. These catecholaminergic cell groups are interconnected with the PVN and preganglionic sympathetic and parasympathetic neurons in the brainstem and spinal cord (Pan et al, 1999; Tucker et al, 1987). In fact, a major afferent innervation of the PVN originates in noradrenergic ascending fibers arising from the VLM and NTS (Sawchenko and Swanson, 1982).…”

“…Main brain nuclei activated by distension of the proximal colon were located in the hypothalamus [paraventricular nucleus (PVN) and supraoptic nucleus (SON)] and the brainstem [nucleus tractus solitarius (NTS), ventrolateral medulla (VLM) and locus coeruleus (LC)-Barrington nucleus complex] (Martinez et al, 2006). These areas represent, respectively, centers of integration of neuroendocrine responses and the origin of efferent autonomic pathways involved mainly in the control of visceral and cardiovascular functions (Madden and Sved, 2003; Ness et al, 1999; Pan et al, 1999; Sawchenko et al, 1996; Sawchenko and Swanson, 1982; Weston et al, 2003). The PVN contains multiple neurotransmitters and neuronal hormones, including corticotropin-releasing factor (CRF), oxytocin (OT) and arginine-vasopressin (AVP), directly involved in responses to stress and visceral functions (Leng et al, 1999; Sawchenko et al, 1996; Swanson and Sawchenko, 1983).…”

“…The PVN contains multiple neurotransmitters and neuronal hormones, including corticotropin-releasing factor (CRF), oxytocin (OT) and arginine-vasopressin (AVP), directly involved in responses to stress and visceral functions (Leng et al, 1999; Sawchenko et al, 1996; Swanson and Sawchenko, 1983). Moreover, the PVN receives prominent inputs from catecholaminergic neurons in the brainstem, such as the VLM and LC, which are involved in sympathetic regulation of cardiovascular and visceral functions (Cunningham and Sawchenko, 1988), and were also activated during colonic distension (Card et al, 2006; Martinez et al, 2006; Pan et al, 1999). …”

The Possible Neuronal Mechanism of Acupuncture: Morphological Evidence of the Neuronal Connection between Groin A-Shi Point and Uterus

“…Electrically stimulating the raphe nucleus could induce analgesia, proving that the raphe nucleus plays a crucial role in pain inhibition response [40, 41]. The thermal stimulation from hind feet inducing Fos expression in the PVN showed that the PVN can receive the noxious input [42]. The activation of PVN initiates the hypothalamus-pituitary-adrenal hormone cascade by releasing corticotropin-releasing factor (CRF) and arginine vasopressin from its parvocellular cells [43].…”