Lamprey Neuropeptides

Cross references:     Neuropeptide Receptor  Lamprey Hormones   

The reticular formation of lampreys (Petromyzonidae)--a target area for exohypothalamic vasotocinergic fibres.
    "The octapeptide vasotocin, which is formed in the classical neurosecretory nuclei of lampreys (Petromyzonidae), is transported, bound to the carrier protein neurophysin, not only to the neurohypophysis but also to various other regions of the brain via exohypothalamic fibres. A target area of this exohypothalamic vasotocinergic system is, in the brook lamprey (Lampetra planeri Bloch), a relatively well circumscribed area in the isthmus region of the rhombencephalic tegmentum motoricum, which is called area lateralis tegmenti. In this area, which belongs to the reticular formation, the vasotocinergic fibres form synaptic contacts with nerve cell perikarya and processes. The vesicles contained in the fibres were identified, ultrahistochemically, as neurophysin vesicles. They correspond to the neurophysin vesicles observed in the neurohypophysis of the same species. The functional significance of the vasotocinergic supply to portions of the reticular formation in lampreys is open to discussion." 
    118 Related citations:  

Arginine vasotocin from the pituitary gland of the lamprey (Petromyzon marinus): isolation and amino acid sequence. 

Abstract only available online.  I may try to get PDF from the library.  
Arginine vasotocin (AVT) was isolated from extracts of sea lamprey pituitary glands (Petromyzon marinus). The amino acid sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Arg-Gly-NH2 is identical to the molecule isolated from teleosts and tetrapods. The total yield was estimated to be 9.6 pmol per gland. No evidence could be found for the existence of a second neurohypophyseal nonapeptide in the lamprey pituitary."  

found when searching PubMed for "Grillner S"

1996   160<349
Tachykinin-mediated modulation of sensory neurons, interneurons, and synaptic transmission in the lamprey spinal cord .
    "1. Tachykinin-like immunoreactivity is found in the dorsal roots, dorsal horn, and dorsal column of the lamprey. The effect of tachykinins on sensory processing was examined by recording intracellularly from primary sensory dorsal cells and second-order spinobulbar giant interneurons. Modulation of synaptic transmission was examined by making paired recordings from dorsal cells and giant interneurons, or by eliciting compound depolarizations in the giant interneurons by stimulating the dorsal root or dorsal column.
    2. Bath application of tachykinins depolarized the dorsal cells. This effect was mimicked by stimulation of the dorsal root, suggesting that dorsal root afferents may be a source of endogenous tachykinin input to the spinal cord. The depolarization was reduced by removal of sodium or calcium from the Ringer, or when potassium conductances were blocked, and was not associated with a measurable change in input resistance. Dorsal root stimulation also caused a depolarization in the dorsal cells, and this effect and that of bath-applied substance P, was blocked by the tachykinin antagonist spantide.  
    3. The tachykinin substance P could reduce inward and outward rectification in the dorsal cells, the effect on outward rectification only being seen when potassium conductances were blocked by tetraethylammonium (TEA).  
    4. Substance P increased the excitability of the dorsal cells and giant interneurons, shown by the increased spiking in response to depolarizing current pulses. The increased excitability was blocked by the tachykinin antagonist spantide.  
    5. Substance P modulated the dorsal cell action potential, by increasing the spike duration and reducing the amplitude of the afterhyperpolarization. The spike amplitude was not consistently affected.  
    6. Stimulation of the dorsal column resulted in either depolarizing or hyperpolarizing potentials in the giant interneurons. The amplitude of the depolarization was increased by substance P, whereas the amplitude of the hyperpolarization was reduced. These effects occurred independently of a measurable change in postsynaptic input resistance, suggesting that the modulation occurred presynaptically. Paired recordings from dorsal cells and giant interneurons failed to reveal an effect of substance P on dorsal cell-evoked excitatory postsynaptic potentials (EPSPs), suggesting that the potentiation of the dorsal column-evoked depolarization was due to an effect on other axons in the dorsal column. Dorsal root-evoked potentials could also be increased in the presence of substance P, although this effect was less consistent than the effect on dorsal column stimulation.
    7. These results suggest that tachykinins modulate sensory input to the lamprey spinal cord by increasing the excitability of primary afferents and second-order giant interneurons, and also by modulating synaptic transmission. Tachykinins may result in potentiation of local spinal reflexes and also modulation of descending reticulospinal inputs to the spinal locomotor network as a result of potentiation of spinobulbar inputs."

147<349     Free Article   
Substance P modulates NMDA responses and causes long-term protein synthesis-dependent modulation of the lamprey locomotor network.
Substance P 

1998 142<349
Cellular and synaptic modulation underlying substance P-mediated plasticity of the lamprey locomotor network     
Free Article 
    "The tachykinin substance P modulates the lamprey locomotor network by increasing the frequency of NMDA-evoked ventral root bursts and by making the burst activity more regular. ... 
   Substance P potentiated the amplitude of monosynaptic glutamatergic inputs from excitatory interneurons and reticulospinal axons. The amplitude and frequency of miniature EPSPs was increased, suggesting that the synaptic modulation was mediated presynaptically and postsynaptically. The postsynaptic modulation was caused by a specific effect of substance P on the NMDA component of the synaptic input, whereas the presynaptic component was calcium-independent.  
    Substance P did not affect monosynaptic glycinergic inputs from lateral interneurons, crossed inhibitory interneurons, or ipsilateral segmental interneurons or postsynaptic GABAA or GABAB responses, suggesting that it has little effect on inhibitory synaptic transmission.  
    At the cellular level, substance P increased synaptic inputs, resulting in membrane potential oscillations in motor neurons, crossed caudal interneurons, lateral interneurons, and excitatory interneurons. The spiking in response to depolarizing current pulses was increased in motor neurons, lateral interneurons, and excitatory interneurons, but usually was reduced in crossed inhibitory interneurons. Substance P reduced the calcium-dependent afterhyperpolarization after an action potential in motor neurons and lateral interneurons, but did not affect this conductance in excitatory or crossed inhibitory interneurons. The relevance of these cellular and synaptic changes to the modulation of the locomotor network is discussed."  
    Neurotransmitters,  Neuromodulators and Neuropeptides
Characterization of the neurohypophysial hormone gene loci in elephant shark and the Japanese lamprey: origin of the vertebrate neurohypophysial hormone genes.  
  - Free PMC Article -     
Full length HTML and PDF available online for free. 
    Full length: 
    "Neurohypophysial hormones are an ancient family of hormones with representatives found in diverse taxa among invertebrates and vertebrates. ... All jawed vertebrates contain at least one member each of vasopressin- and oxytocin-family peptides. ... In jawless vertebrates ... only a vasotocin gene has been cloned so far ... we sequenced the neurohypophysial gene loci in ... a jawless vertebrate, the Japanese lamprey."  
The vasopressin- and oxytocin-family of neurohypophysial hormones evolved in a common ancestor of jawed vertebrates through tandem duplication of the ancestral vasotocin gene. The duplicated genes were linked tail-to-head like their homologs in elephant shark, coelacanth and non-eutherian tetrapods. In contrast to the conserved linkage of the neurohypophysial genes in these vertebrates, the neurohypophysial hormone gene locus has experienced extensive rearrangements in the teleost lineage." 

Free Article   
Endocannabinoids mediate tachykinin-induced effects in the lamprey locomotor network. 

2015     8<349     
Free PMC Article   
Substance P Depolarizes Lamprey Spinal Cord Neurons by Inhibiting Background Potassium Channels.