Extracellular microelectrode recordings were made from single neurones in the medial preoptic area and basal septum of normal female rats anaesthetised with urethane and the effects of stimulation of the ipsilateral amygdala (AMY) was tested.
Quiescent cells were excited with latencies between 4 and > 40 msec with the majority being between 10 and 27 msec. Variable latency, changing latency and recruitment were observed and suggest that many pathways are oligo- or polysynaptic.
A minority of spontaneously active units (20.6%) were excited with latencies between 5 and 36 msec. The predominant initial response was inhibition (67.1%). The remaining 12.3% of neurones did not respond.
A predominantly positive complex field potential was associated with excitation, particularly of quiescent neurones.
Inhibitory responses were classified according to duration (short: 20–60 msec; long: 100–400 msec). All responses contained an inhibitory component. Responses were further described on the basis of presence and rhythmicity of post-inhibitory excitation.
The majority of action potentials evoked from quiescent neurones were of small amplitude (80–150 μV) and occurred in small groups. These characteristics and their occurrence at the onset of inhibition are consistent with the view that all or a proportion of them may be generated by inhibitory interneurones.
Only minor differences were observed between response characteristics evoked by stimulation of the corticomedial or basolateral AMY indicating that differential effects of these regions on adenohypophysial hormone secretion are determined at the septopreoptic level.
This is a preview of subscription content, log in to check access.
We’re sorry, something doesn't seem to be working properly.
Please try refreshing the page. If that doesn't work, please contact support so we can address the problem.
Barraclough, C.A., Cross, B.A.: Unit activity in the hypothalamus of the cyclic female rat: Effect of genital stimuli and progesterone. J. Endocr. 26, 339–359 (1963)
Blackwell, R.E., Guillemin, R.: Hypothalamic control of adenohypophyseal secretions. Ann. Rev. Physiol. 35, 357–390 (1973)
Clemens, J.A., Shaar, C.J., Kleber, J.W., Tandy, W.A.: Areas of the brain stimulatory to LH and FSH secretion. Endrocrinology 88, 180–184 (1971)
Cross, B.A., Silver, I.A.: Electrophysiological studies on the hypothalamus. Brit. med. Bull. 22, 254–260 (1966)
De Groot, J.: The rat forebrain in stereotaxic coordinates. Verh. Kon. Med. Akad. Wet., B. Natururkunde 2, 1–40 (1959)
De Olmos, J.S., Ingram, W.R.: The projection field of the stria terminalis in the rat brain. An experimental study. J. comp. Neurol. 146, 303–334 (1972)
Dyer, R.G.: An electrophysiological dissection of the hypothalamic regions which regulate the pre-ovulatory secretion of luteinising hormone in the rat. J. Physiol. (Lond.) 234, 421–442 (1973)
Dyer, R.G., MacLeod, N.K., Ellendorff, F.: Electrophysiological evidence for sexual dimorphism and synaptic convergence in the preoptic and anterior hypothalamic areas of the rat. Proc. roy. Soc. B 193, 421–440 (1976)
Ellendorff, F., Colombo, J.A., Blake, C.A., Whitmoyer, D.J., Sawyer, C.H.: Effects of electrical stimulation of the amygdala on gonadotrophin release and ovulation in the rat. Proc. Soc. exp. Biol. (N.Y.) 142, 417–420 (1973)
Ellendorff, F., Parvizi, N.: Limbic midbrain control of LH secretion in the awake intact and castrated male miniature pig. Effects of electrical stimulation. Acta endocr. Suppl. 193, 77 (1975)
Fenske, M., Ellendorff, F., Wuttke, W.: Response of medial preoptic neurons to electrical stimulation of the mediobasal hypothalamus, amygdala and mesencephalon in normal, serotonin or catecholamine deprived female rats. Exp. Brain Res. 22, 495–507 (1975)
Fink, G., Jamieson, M.G.: Effect of preoptic stimulation on luteinising hormone releasing factor in pituitary stalk blood during the oestrous cycle of the rat. J. Physiol. (Lond.) 241, 128–130P (1974)
Gardner, C.R.: The release and mechanisms of action of some putative neurotransmitters in experimental epilepsy. Thesis University College, London 1973
Gardner, C.R., Phillips, S.W.: Neuronal circuitry in the basal septum and preoptic area of the rat. Brain Res. in press (1977)
Gloor, P.: Electrophysiological studies on the connections of the amygdaloid nucleus in the cat. I. The neuronal organisation of the amygdaloid projection system. Electroenceph. clin. Neurophysiol. 7, 223–242 (1955a)
Gloor, P.: Electrophysiological studies on the connections of the amygdaloid nucleus in the cat. II. The electrophysiological properties of the amygdaloid projection system. Electroenceph. clin. Neurophysiol. 7, 243–264 (1955b)
Hayward, J.H., Hilliard, J., Sawyer, C.H.: Time of release of pituitary gonadotrophin induced by electrical stimulation of the rabbit brain. Endocrinology 74, 108–113 (1964)
Hellon, R.F.: The marking of electrode tip positions in nervous tissue. J. Physiol. (Lond.) 214, 12P (1971)
Ito, N., Ishida, H., Mikakawa, F., Naito, H.: Microelectrode study of projections from the amygdaloid complex to the nucleus accumbens in the cat. Brain Res. 67, 338–341 (1974)
Jell, R.M., Gloor, P.: Distribution of thermosensitive and non-thermosensitive preoptic and anterior hypothalamus neurones in unanaesthetised cats and the effects of some anaesthetics. Can. J. Physiol. Pharmacol. 50, 890–901 (1972)
Koikegami, H., Yamada, T., Ursin, K.: Stimulation of the amygdaloid nuclei and periamygdaloid cortex with special reference to its effects on uterine movements and ovulation. Folia psychiat. neurol. jap. 8, 9–27 (1954)
Lichtensteiger, W., Keller, P.J.: Tuberoinfundibular dopamine neurones and the secretion of luteinizing hormone and prolactin: Extrahypothalamic influences, interaction with cholinergic systems and the effect of urethane anaesthesia. Brain Res. 74, 279–303 (1974)
Lincoln, D.W.: Unit activity in the hypothalamus, septum and preoptic area of the rat: Characteristics of spontaneous activity and the effect of oestrogen. J. Endocr. 37, 177–189 (1967)
Lincoln, D.W., Cross, B.A.: Effect of oestrogen on the responsiveness of neurones in the hypothalamus, septum and preoptic area of rats with light-induced persistent oestrous. J. Endocr. 37, 191–203 (1967)
Martin, J.B., Kontor, J., Mead, P.: Plasma GH responses to hypothalamic, hippocampal and amygdaloid electrical stimulation: Effects of variation in stimulus parameters and treatment with α-methyl-p-tyrosine (α-MT). Endocrinology 92, 1354–1361 (1973)
McLennan, H., Miller, J.J.: The hippocampal control of neuronal discharges in the septum of the rat. J. Physiol. (Lond.) 237, 607–624 (1974)
Murphy, J.T., Renaud, L.: Mechanisms of inhibition in the ventromedial nucleus of the hypothalamus. J. Neurophysiol. 32, 85–102 (1969)
Pfaff, D.W., Pfaffmann, C.: Olfactory and hormonal influences on the basal forebrain of the male rat. Brain Res. 15, 137–156 (1969)
Raisman, G., Field, P.M.: Sexual dimorphism in the neuropil of the preoptic area of the rat and its dependence on neonatal androgen. Brain Res. 54, 1–29 (1973)
Renaud, L.P.: An electrophysiological study of amygdalohypothalamic projections to the ventromedial nucleus of the rat. Brain Res. 105, 45–58 (1976)
Renaud, L.P., Martin, J.B.: Electrophysiological studies of connections of hypothalamic ventromedial nucleus neurones in the rat: evidence for a role in neuroendocrine regulation. Brain Res. 93, 145–151 (1975)
Sawyer, C.H.: Functions of the amygdala related to the feedback actions of gonadal steroid hormones. In: The Neurobiology of the Amygdala (ed. B.E. Eleftheriou), pp. 745–762. New York: Plenum Press 1972
Ursin, M., Kaada, B.R.: Functional localisation within the amygdaloid complex in the cat. Electroenceph. clin. Neurophysiol. 12, 1–20 (1960)
Velasco, M.E., Taleisnik, S.: Release of gonadotrophins induced by amygdaloid stimulation in the rat. Endocrinology 84, 132–139 (1969)
About this article
Cite this article
Gardner, C.R., Phillips, S.W. The influence of the amygdala on the basal septum and preoptic area of the rat. Exp Brain Res 29, 249–263 (1977). https://doi.org/10.1007/BF00237045
- Preoptic area
- Basal septum