Habenula and thalamus cell transplants mediate different specific patterns of innervation in the interpeduncular nucleus

Abstract

Innervation of specific peptidergic and cholinergic compartments of the interpeduncular nucleus (IPN) was investigated using embryonic cell suspension transplants immunoreactive for substance P (SP) and ChAT. In both neonatal and adult host rats, the IPN was first denervated of its normal SP and cholinergic input from the medial habenula by bilateral lesions of the fasciculi retroflexi (FR). In adult hosts, transplants of embryonic habenular cells placed near the denervated IPN mediated a return of the normal pattern of SP staining restricted to habenula- target subnuclei, plus an increase in staining intensity of SP cells intrinsic to the IPN. There was no recovery of ChAT staining. A similar pattern of SP staining resulted following habenular transplants into neonatal hosts, but in addition there was a partial recovery of normal ChAT staining in cholinergic subnuclei and anomalous ChAT staining in normally peptidergic subnuclei. Control transplants of embryonic thalamus cells placed into adult hosts produced a surprising pattern of ChAT staining in the IPN identical to that seen with habenula transplants placed into neonatal hosts; the adult IPN was thus able to support reinnervation mediated by an aberrant cholinergic source while being refractory to its normal habenular cholinergic afferents. This pattern of results implies regulation by the IPN of habenular SP and cholinergic innervation, and some interaction between the maturing normal cholinergic afferents and their targets that is missing when these afferent sources are abnormal.

Transplanted human neurons derived from a teratocarcinoma cell line (NTera‐2) mature, integrate, and survive for over 1 year in the nude mouse brain

“…All of the sections were counterstained with hematoxylin. Eckenrode et al, 1992;Freed et al, 1992;Pencer et al, 1992;Poltorak et al, 1992;Snyder et al, 1992;Wictorin et al, 1992;Widner et al, 1992;Suhr and Gage, 1993;Onifer et al, 1994). Specifically, we demonstrated that CNS grafts of human NT2N cells free of any contaminating non-neuronal cells acquired a mature neuronal phenotype in vivo, and that these neuron-like cells became integrated into the CNS of nude mice where > 89% of the grafts survived.…”

The habenula: from stress evasion to value-based decision-making

“…Removing the habenula output by lesioning the fasciculus retroflexus in rats reduces both the amount of time that rats spend in REM sleep and the atonia associated with REM sleep 15,16 . When fetal brain tissue that includes the habenula is transplanted into these rats the normal sleep pattern and atonia are restored 15,17 . Second, the firing of habenula neurons shows circadian rhythmicity 18 , even in slice preparations 19 .…”

MAP1B expression and microtubule stability in growing and regenerating axons

“…For example, the medial habenular neurons express high levels of MAP1B and their axons projecting to the interpendicular nucleus are highly immunostained by mAb 1B-P (Nothias et al, 1996). This pathway shows sprouting in response to partial deafferentation (Murray et al, 1979) and habenular transplants can re-innervate the interpenducluar nucleus (Eckenrode et al, 1992). Interestingly, the presence of MAP1B-P in adult CNS correlates with that of embryonic NCAM rich in polysialic acid (Le Gal la Salle et al, 1992), suggesting that in both cases the expression of these immature forms plays a role in structural remodelling in the adult.…”