Table 3.
Densities of varicosities labeled for arousal neurotransmitters or anterograde tracer in the VLPO core (average of two to three cases each)
| Source of fibers | Varicosities per mm2 |
|---|---|
| Histamine | 36,000 |
| Dopamine-β-hydroxylase (noradrenaline) | 32,300 |
| Serotonin transporter | 30,200 |
| Phenyl-ethanolamine-N-methyl transferase (adrenaline) | 5,700 |
| Orexin | 7,700 |
| Choline acetyltransferase | 550 |
| Infralimbic cortex | 13,400 |
| Lateral septal nucleus | 21,800 |
| Median preoptic nucleus | 15,225 |
| Medial preoptic area | 1,850 |
| Suprachiasmatic nucleus | 1,050 |
| Subparaventricular zone | 1,300 |
| Dorsomedial hypothalamic nucleus | 25,300 |
| Ventromedial hypothalamic nucleus | 1,100 |
| Lateral hypothalamic area3-a | 6,350 |
| Medial amygdala | 1,200 |
| Supramammillary nucleus | 933 |
| Lateral parabrachial nucleus | 12,850 |
Moderate to heavy inputs (>10,000 varicosities per square millimeter) are highlighted in bold text. Monoaminergic terminals provide the apparently densest inputs to the VLPO, despite the relatively low numbers of retrogradely labeled monoaminergic neurons.
F3-a
The lateral hypothalamic area (LHA) is a particularly large brain region in the rat, and our anterograde tracer injections filled only a small fraction of this area; hence, varicosities arising from LHA injections may underestimate the intensity of this afferent to the VLPO.