Cell culture of mechanoreceptor neurons innervating proleg sensory hairs in Manduca sexta larvae, and co-culture with target motoneurons.
Cell Tissue Res 2003;
311:117-30. [PMID:
12483291 DOI:
10.1007/s00441-002-0643-7]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2002] [Accepted: 09/13/2002] [Indexed: 11/26/2022]
Abstract
The tip of each proleg in Manduca sexta larvae bears a dense array of mechanosensory hairs termed planta hairs (PHs), each innervated by a single sensory neuron (termed a PH-SN) located in the underlying epidermis. In the CNS, axon terminals of PH-SNs make direct, excitatory, nicotinic cholinergic synapses with proleg retractor motoneurons including the accessory planta retractor (APR). These synapses mediate a proleg withdrawal reflex, exhibit multiple forms of activity-dependent plasticity and weaken during the prepupal peak of ecdysteroids. In the present study we developed methods to dissociate PH-SNs from the epidermis and culture them alone or with APRs. The PH-SNs were fluorescently labeled in situ by introducing dye through the cut hair shaft or by retrograde axonal staining. Alternatively, unlabeled PH-SNs were utilized. The epidermis beneath the planta hair array was separated from the cuticle, enzymatically treated and mechanically dissociated into single cells. PH-SNs were cultured on glass coverslips coated with concanavalin A and laminin, in modified Leibovitz's IL-15 medium. Supplementation with medium conditioned by an insect cell line produced the best results. Dissociated PH-SNs had somatic diameters of ~10 micro m and typically bore a stout dendrite consisting of the inner and, occasionally, the outer dendritic segment. An axonal stump was sometimes retained. Viable PH-SNs typically extended new processes and often survived for 2-4 weeks. When co-cultured, PH-SNs and APRs exhibited robust growth and made close anatomical appositions. This culture system provides convenient experimental access to PH-SNs and may potentially permit sensorimotor synapses to be investigated in vitro.
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